docs: caption all screenshots and screencasts with program context

- Every gallery image and video in all 16 org files now carries a
  caption paragraph below it, written from the corresponding program
  source (algorithms, parameters, controls, exit conditions)
- Fix broken media links left by the capture renaming (old
  "screenshot, N.png" / "<name>.png" targets now point at the
  "<Program> - Screenshot N.png" / "- Screencast N.mp4" files):
  Interferogram, 3D graph, Galaxy explorer, Maze explorer,
  Game of life, Truth table, Multiplication trainer,
  Sine computation, Lottery, Windowing system, Mouse driver
- List previously unlisted captures: 3D graph screenshots 0/1 +
  screencast, Galaxy/Maze explorer screencasts, Multiplication
  trainer screencast, mousedrv native-res screenshot, school-clock
  electronics photos (v1 README + v3 tutorial)
- Add new gallery sections: Pressed key test (Misc), and a Tutorial
  category with the qsort3 quicksort visualization

diff --git a/2D GFX/Animations/index.org b/2D GFX/Animations/index.org
index f2a9d17..3389ef6 100644 (file)
--- a/2D GFX/Animations/index.org
+++ b/2D GFX/Animations/index.org
@@ -49,6 +49,15 @@ to surfaces without increasing geometric complexity.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The square on the left is the raw height map: random raised dots plus
+two diagonal ridges, drawn once in white. To its right the same
+surface is re-rendered every frame as a bump-mapped animation — the
+small red circle is the light source, whose position follows
+overlapping sine waves, and each pixel's brightness (grayscale
+palette entries 16-31) is derived from the distance to the light and
+the local slope of the height map. The bumps appear to swell and
+shade as the light wanders, until any key is pressed.
+

 How It Works:
 
 1. *Surface Generation* : The program starts by generating a height
 How It Works:
 
 1. *Surface Generation* : The program starts by generating a height


@@ -80,6 +89,16 @@ beautiful structures, reminiscent of natural tree growth patterns.
 #+attr_html: :class responsive-img
 [[file:Tree - Screenshot 0.png]]
 
 #+attr_html: :class responsive-img
 [[file:Tree - Screenshot 0.png]]
 

+A finished grayscale fractal tree on a black background. A fat,
+bright trunk of overlapping filled circles near the lower right
+splits into ever thinner curling branches that taper into tiny hooks.
+The program starts from a single branch and doubles the population
+six times, giving each offspring a random drift; every branch is then
+drawn as a trail of filled circles whose radius decays slightly per
+step while the heading slowly turns. The custom 16-step grayscale
+palette makes thickness read as brightness, and the tint of each
+circle follows the branch angle.
+

 [[file:Tree.bas][Source code]]
 
 #+INCLUDE: "Tree.bas" src basic-qb45
 [[file:Tree.bas][Source code]]
 
 #+INCLUDE: "Tree.bas" src basic-qb45


@@ -104,6 +123,14 @@ representation of how sine and cosine functions can be used to achieve
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A tilted square lattice of small white dots on a black background —
+a 21×21 grid of points caught mid-rotation. Each frame adds 0.01
+radians to the angle, applies the sine/cosine rotation matrix to
+every grid point around the origin, scales the result by seven and
+centers it on screen, then redraws each point in white after erasing
+its previous position. The lattice keeps spinning smoothly until any
+key is pressed.
+

 [[file:2D rotation.bas][Source code]]
 
 #+INCLUDE: "2D rotation.bas" src basic-qb45
 [[file:2D rotation.bas][Source code]]
 
 #+INCLUDE: "2D rotation.bas" src basic-qb45


@@ -127,6 +154,15 @@ colors to create dynamic visual effects in a console environment.
 </div>
   #+end_export
 
 </div>
   #+end_export
 

+Four effects are layered on a single 80×50 text screen. The source
+code of mkcircle.bas scrolls upward in dark red, a blue lattice of
+asterisks wraps around the screen along sine-driven paths, a wobbling
+circle filled with random multicolored characters pulses on the
+right, and horizontal and vertical lines of green '#' characters
+bounce between the edges, flashing brighter where they cross an
+asterisk. The whole composition keeps running until any key is
+pressed.
+

 [[file:text mode animation.bas][Source code]]
 
 * Snowfall
 [[file:text mode animation.bas][Source code]]
 
 * Snowfall


@@ -151,6 +187,15 @@ physics simulations and graphical programming.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+White snowflake pixels drift down a black sky and pile up on a giant
+wobbly cyan "SNOW" sign at the bottom of the screen. The program
+animates 500 particles, each falling one pixel per step with a small
+random sideways jitter; a POINT-based collision check detects when a
+flake lands on the sign, on a settled flake, or on the ground, at
+which moment it turns bright white and a fresh flake respawns at the
+top. The sign itself is built by printing "SNOW" in text mode and
+re-rendering each letter pixel as a wavy cyan block.
+

 
 What's in it for the Reader?
 
 
 What's in it for the Reader?
 


@@ -192,6 +237,15 @@ engaging visual effects.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Hundreds of thin rainbow-colored straight lines weave an elliptical,
+eye-shaped string-art envelope on a black background. Each frame
+draws about 200 lines between two points that travel along sine and
+cosine curves at different speeds, so the envelope slowly morphs and
+rotates; the line color cycles through the palette, producing the
+rainbow gradient. Drawing happens on a hidden video page that is
+copied to the screen with PCOPY, keeping the motion flicker-free
+until any key is pressed.
+

 [[file:Screensaver.bas][Source code]]
 
 #+INCLUDE: "Screensaver.bas" src basic-qb45
 [[file:Screensaver.bas][Source code]]
 
 #+INCLUDE: "Screensaver.bas" src basic-qb45


@@ -216,6 +270,15 @@ personal computing.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Ten fan-shaped bundles of straight lines drift and twirl on a black
+background, each fan radiating eleven spokes from a single moving
+anchor point. Every anchor glides along its own sine/cosine path
+while the spread and tilt of its spokes are modulated by further sine
+waves, making the fans open, close and sweep like folding hand fans.
+The VGA palette registers themselves are reprogrammed every frame, so
+the colors continuously glide through greens, blues, yellows and
+reds. Drawing is double-buffered with PCOPY; any key exits.
+

 [[file:Screensaver, flying hand fans.bas][Source code]]
 
 #+INCLUDE: "Screensaver, flying hand fans.bas" src basic-qb45
 [[file:Screensaver, flying hand fans.bas][Source code]]
 
 #+INCLUDE: "Screensaver, flying hand fans.bas" src basic-qb45


@@ -239,6 +302,15 @@ rendering geometric shapes and handling randomness.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The screen is gradually papered over with overlapping flat-shaded
+triangles in vivid random colors — cyan, red, yellow, magenta and
+olive among them. Every iteration picks three random vertices and
+fills the triangle with a random palette color using a home-grown
+scanline filler: each edge is walked vertically while its
+x-coordinate is buffered per scanline, and horizontal spans are drawn
+between the stored and the current edge position. Triangles keep
+piling up at a steady pace until any key is pressed.
+

 [[file:Polygon.bas][Source code]]
 
 #+INCLUDE: "Polygon.bas" src basic-qb45
 [[file:Polygon.bas][Source code]]
 
 #+INCLUDE: "Polygon.bas" src basic-qb45


@@ -262,6 +334,19 @@ textures are applied to polygons.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A spirograph-like ring of triangles swept around the screen center:
+the rotating demo draws one textured triangle per step, and because
+the screen is never cleared between frames the traces accumulate into
+a toothed wheel. Each triangle is filled not with a flat color but
+with a sample texture of random colored circles prepared at startup,
+stretched and sheared differently in every triangle. The mapper works
+scanline by scanline — polygon edges are walked while texture
+coordinates are interpolated alongside, then horizontal spans copy
+pixels straight out of the texture image. Earlier frames of the
+screencast show a single textured triangle jumping to random
+positions; later ones keep the triangle fixed and rotate the texture
+coordinates instead.
+

 [[file:Polygon textured.bas][Source code]]
 
 * Yin and yang animation
 [[file:Polygon textured.bas][Source code]]
 
 * Yin and yang animation


@@ -285,6 +370,15 @@ important for cohesion of the whole.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The classic yin-yang symbol on a deep blue background, slowly
+rotating. The symbol is composed from just two circles orbiting the
+center in opposite phase, each drawn as a stack of concentric rings:
+the outer half of the stack takes one color and the inner half the
+opposite, so as the two circles sweep over the screen the
+interlocking teardrop shapes emerge. One circle is black-on-white,
+the other white-on-black, and the angle advances by 0.05 radians per
+frame until any key is pressed.
+

 [[file:Yin and yang.bas][Source code]]
 
 #+INCLUDE: "Yin and yang.bas" src basic-qb45
 [[file:Yin and yang.bas][Source code]]
 
 #+INCLUDE: "Yin and yang.bas" src basic-qb45


@@ -308,6 +402,16 @@ mesmerizing effect.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A starburst of colored filled circles on a black background, each
+tethered to the screen center by a thin line of the same color.
+Fifty particles with random colors, radii and phases orbit the
+middle: the horizontal position follows the sine of the particle's
+angle while the circle's radius is scaled by the cosine of that same
+angle, so a particle swells as it swings toward the viewer and
+shrinks as it recedes — a cheap pseudo-3D orbit effect. Every angle
+advances by 0.1 per frame and the animation runs until any key is
+pressed.
+

 [[file:Orbiting particles.bas][Source code]]
 
 #+INCLUDE: "Orbiting particles.bas" src basic-qb45
 [[file:Orbiting particles.bas][Source code]]
 
 #+INCLUDE: "Orbiting particles.bas" src basic-qb45


@@ -329,6 +433,16 @@ resembles animation as seen in the movies :)
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A cartoon DNA double helix on a black background: two intertwining
+strands of cyan and red spheres twist down the screen, cross-linked
+by white horizontal rungs. Each frame places twenty points per strand
+along phase-shifted sine waves and rotates the pair by 0.1 radians;
+a pseudo-depth value picks both the sphere's radius and the order in
+which it is drawn, so closer spheres appear larger and overlap the
+distant ones, faking 3D. The frame is assembled on a hidden video
+page and flipped on screen with PCOPY; the helix keeps spinning until
+any key is pressed.
+

 [[file:DNA.bas][Source code]]
 
 #+INCLUDE: "DNA.bas" src basic-qb45
 [[file:DNA.bas][Source code]]
 
 #+INCLUDE: "DNA.bas" src basic-qb45


@@ -349,6 +463,15 @@ Effect inspired by "The Matrix" movie.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Green angular glyphs rain down a black screen in vertical streams,
+each stream head glowing bright while the trail behind fades through
+darker greens. The glyphs are nine home-drawn rune shapes that the
+program renders with LINE, anti-aliases with a recursive
+pixel-smoothing pass and captures into sprite arrays with GET; eight
+streams then walk down a 19×14 grid, and every cell ages through
+three pre-rendered brightness variants before being erased. The
+frame rate is throttled with a TIMER busy-wait; any key exits.
+

 [[file:matrix.bas][Source code]]
 
 * Matrix - the opening scene
 [[file:matrix.bas][Source code]]
 
 * Matrix - the opening scene


@@ -371,6 +494,17 @@ sure the line is clear?" appear as the decoding progresses.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A green-on-black terminal re-enacting the phone-trace scene: at the
+top a number is decoded digit by digit — "11 4867" has been revealed
+so far — next to the taunting message "Are you sure the line is
+clear?", while the rest of the screen fills with endlessly cascading
+random digits. Every hundred frames one more digit of the code is
+locked into a random position and the remaining length shortens; the
+message changes as the trace progresses, and once it has fully played
+out the program exits. The cascade itself is just one fresh line of
+random digits printed each frame at the bottom of a scrolling
+viewport, accompanied by a pulsing high-pitch tone.
+

 [[file:matrix2.bas][Source code]]
 
 * Hacker
 [[file:matrix2.bas][Source code]]
 
 * Hacker


@@ -391,6 +525,18 @@ a waterfall of knowledge across thy monitor.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A 40×25 wall of green alphanumeric gibberish scrolls downward in
+several intensities of green, with single characters mutating as they
+go — the essence of every movie hacking scene. Each frame shifts the
+whole character buffer down one row and wraps the top row around to
+the bottom, then cycles through eight actions: replacing random
+characters, painting horizontal and vertical streaks in brighter
+greens, letting colors decay one step, resetting every other row or
+column, and peppering random cells with color. A custom five-shade
+green palette is programmed straight into the VGA palette registers,
+and a rotating sound array produces the clicking beeps. The
+animation runs until any key is pressed.
+

 [[file:hacker.bas][Source code]]
 
 * Circular patterns
 [[file:hacker.bas][Source code]]
 
 * Circular patterns


@@ -414,6 +560,15 @@ the circular pattern.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A black-and-white field of concentric rings radiating from several
+bright "atom" centers, their ripples interfering into moiré fringes.
+The whole picture comes from a single formula evaluated per pixel —
+sin((x² + y²) / 10) * 6 + 23, clamped to palette entries 16-31 —
+with x and y measured in a coordinate window that shrinks every frame
+as the zoom factor is divided by 1.1. The result is a continuous
+dive into the circular interference pattern, and the program stops on
+its own once the zoom factor drops below 5.
+

 [[file:circular patterns.bas][Source code]]
 
 * Sun, earth and moon
 [[file:circular patterns.bas][Source code]]
 
 * Sun, earth and moon


@@ -436,6 +591,17 @@ Z-sorting.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A big red sun sits left of center on a black background while a
+small blue earth circles it, an even smaller yellow moon in tow. The
+earth follows a flattened elliptical orbit driven by sine and cosine
+of a slowly advancing angle, and both its size and the moon's scale
+with the y-coordinate to fake perspective — bodies nearer the bottom
+of the screen are drawn larger. Instead of real Z-sorting the
+program simply checks whether the earth is below or above the sun's
+center line (and likewise moon versus earth) to pick the drawing
+order, so the bodies correctly pass in front of and behind each
+other.
+

 [[file:sun&eart.bas][Source code]]
 
 * Maze
 [[file:sun&eart.bas][Source code]]
 
 * Maze


@@ -459,6 +625,16 @@ are drawn.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Colored wireframe segments streak across a black void — an early
+frame of a 3D maze that grows one segment per frame. Each step
+extends the path along a randomly chosen axis by a random amount and
+gives the new segment a random color, while the camera position and
+both rotation angles drift on sine waves. Every point is rotated
+around two axes, projected with perspective division, and any segment
+with an endpoint behind the viewer is skipped entirely. Frames are
+drawn on a hidden video page and flipped with PCOPY; the program
+stops by itself after 1200 frames.
+

 [[file:maze.BAS][Source code]]
 
 * Fancy text mode animations
 [[file:maze.BAS][Source code]]
 
 * Fancy text mode animations


@@ -482,4 +658,14 @@ horizontal lines bouncing between the screen edges.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+An 80×50 text screen layered with several effects at once: the
+program's own source code scrolls upward in dark red, a woven blue
+lattice of asterisks crawls across the screen along sine-driven
+paths, and horizontal plus vertical lines of green '#' characters
+bounce between the screen edges, glowing brighter where they cross an
+asterisk. A wobbling circle filled with random multicolored
+characters periodically swells into view on top of it all. Each frame
+is composed in an off-screen buffer and printed in a single pass; any
+key exits.
+

 [[file:mkcircle.bas][Source code]]
 [[file:mkcircle.bas][Source code]]

diff --git a/2D GFX/Fractals/index.org b/2D GFX/Fractals/index.org
index 27d94c8..6a85c32 100644 (file)
--- a/2D GFX/Fractals/index.org
+++ b/2D GFX/Fractals/index.org
@@ -42,6 +42,15 @@ geometry, recursive programming, and graphical design.
 #+attr_latex: :width 1000px
 [[file:fractal circles.bas][file:fractal%20circles%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:fractal circles.bas][file:fractal%20circles%20-%20Screenshot%200.png]]
 

+A single finished spiral fractal. The recursion starts with the large
+white circle in the center; every circle then sprouts up to three
+child circles (the direction pointing back at the parent is skipped),
+placed 2.5 radii away at a steadily increasing angle, which is what
+curls the chains into spirals. Children shrink by a
+direction-dependent divisor (5, 2 or 1.4), colors alternate between
+white on even recursion depths and light green on odd ones, and the
+recursion stops once the radius drops below 0.2 pixels.
+

 - Color and Depth :: The color of each circle alternates based on the
   recursion depth, adding visual complexity to the fractal.
 - Termination Condition :: The recursion terminates when the size of
 - Color and Depth :: The color of each circle alternates based on the
   recursion depth, adding visual complexity to the fractal.
 - Termination Condition :: The recursion terminates when the size of


@@ -67,6 +76,18 @@ system to control the animation's progression.
   </video>
 </div>
 #+end_export
   </video>
 </div>
 #+end_export

+
+The same circle-spiral recursion as the static version, but here every
+parameter is animated by a keyframe timer system: arrays of (time,
+value) pairs are linearly interpolated each frame (processTimers) and
+drive the spiral's position, size and twist angle, the sine-modulated
+branch scale factors, the two stacked ellipses in the upper left
+(yellow rim, green and dark cores), and the sliding "KHK" and
+"Infotehno-loogia" labels built from small colored squares. Each frame
+is drawn on an off-screen video page and flipped in with PCOPY onto a
+solid white background; the demo terminates by itself when its
+timeline runs past 26 seconds.
+

 [[file:fractal circles animated.bas][Source code]]
 
 * Fractal of squares
 [[file:fractal circles animated.bas][Source code]]
 
 * Fractal of squares


@@ -80,10 +101,21 @@ This QBasic program generates and displays a fractal pattern composed of squares
 #+attr_latex: :width 1000px
 [[file:fractal squares.bas][file:fractal%20squares%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:fractal squares.bas][file:fractal%20squares%20-%20Screenshot%200.png]]
 

+The first phase of the program: a single square fractal in one light
+green color. Every outlined square recursively places another square
+at each of its four corners with the size divided by 2.3, and the
+recursion continues until the squares shrink below one pixel.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:fractal squares.bas][file:fractal%20squares%20-%20Screenshot%201.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:fractal squares.bas][file:fractal%20squares%20-%20Screenshot%201.png]]
 

+The second phase: after clearing the screen, the program overlays 26
+of these square fractals on the same spot, growing the root size from
+1 to 128 in steps of 5 and picking a new random color (in the 7-14
+range) for each pass. The superimposed corner-recursions interfere
+with each other and produce the dense rainbow moiré cloud.
+

 * Fractal of squares animated
 :PROPERTIES:
 :CUSTOM_ID: fractal-of-squares-animated
 * Fractal of squares animated
 :PROPERTIES:
 :CUSTOM_ID: fractal-of-squares-animated


@@ -103,6 +135,14 @@ resulting in a dynamic and ever-changing geometric pattern.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Every frame redraws the corner-recursing square fractal with filled
+boxes whose color encodes the current recursion depth. The four corner
+divisors are independent sine waves with different periods (19, 12, 17
+and 22 frames), so each diagonal branch shrinks at its own slowly
+changing rate and the pattern keeps pulsing and leaning
+asymmetrically. Frames are double-buffered with PCOPY in SCREEN 7, and
+any key press exits the program.
+

 [[file:fractal squares animated.bas][Source code]]
 
 * Fractal of trees
 [[file:fractal squares animated.bas][Source code]]
 
 * Fractal of trees


@@ -123,5 +163,14 @@ resembles a tree, with branches that grow and change over time.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+An animated ternary tree drawn with plain white lines on black: every
+node sprouts three branches (up-left, up-right and straight up) and
+recurses into the three tips with reduced length. Three sine-driven
+modifiers with different periods (19, 12 and 17 frames) control how
+fast each branch shrinks, while six additional sine oscillators
+continuously bend the two side-branch vectors, so the whole tree
+sways, folds and regrows like in wind. Double-buffered with PCOPY; any
+key press exits.
+

 
 [[file:fractal trees.bas][Source code]]
 
 [[file:fractal trees.bas][Source code]]

diff --git a/2D GFX/Spirals/index.org b/2D GFX/Spirals/index.org
index cb8a4ff..361f8d7 100644 (file)
--- a/2D GFX/Spirals/index.org
+++ b/2D GFX/Spirals/index.org
@@ -95,6 +95,16 @@ then in the next step the points are connected using lines:
 #+attr_latex: :width 1000px
 [[file:spiral, 4 - Screenshot 0.png]]
 
 #+attr_latex: :width 1000px
 [[file:spiral, 4 - Screenshot 0.png]]
 

+The screenshot shows the first stage of the program: a point
+cloud plotted with PSET before any key is pressed. Four spiral
+arms are generated one after another, each with a halved scale
+factor (InitialSize divided by 1, 2, 4 and 8) and its own
+vertical offset, so the dots trace nested spherical shells
+stacked on top of each other, with small ellipses at the poles.
+After a key press the screen is cleared and every stored point
+is connected with LINE to its neighbor and to the point 42
+positions ahead, turning the cloud into a wireframe mesh.
+

 [[file:spiral, 4.bas]]
 
 #+INCLUDE: "spiral, 4.bas" src basic-qb45
 [[file:spiral, 4.bas]]
 
 #+INCLUDE: "spiral, 4.bas" src basic-qb45

diff --git a/2D GFX/Textures/index.org b/2D GFX/Textures/index.org
index 1bc383f..1ac18ab 100644 (file)
--- a/2D GFX/Textures/index.org
+++ b/2D GFX/Textures/index.org
@@ -52,6 +52,16 @@ algorithms can produce intricate and visually appealing results.
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Circular waves - Screenshot 0.png]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Circular waves - Screenshot 0.png]]

+
+The screen is filled with a repeating grid of concentric rings,
+like ripples tiled across the surface. Each pixel's color comes
+from SIN((x^2 + y^2) / 10) * 10, clamped to the 0-15 range and
+shifted by 16 to reach into the upper palette. Because the
+squared distance grows quickly, the sine oscillates faster and
+faster away from the origin, and the discrete pixel grid aliases
+these rapid oscillations into the regular moire-like clusters of
+rings seen here.
+

 [[file:Circular waves.bas][Source code]]
 
 #+INCLUDE: "Circular waves.bas" src basic-qb45
 [[file:Circular waves.bas][Source code]]
 
 #+INCLUDE: "Circular waves.bas" src basic-qb45


@@ -69,6 +79,17 @@ textures in computer graphics.
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Diamond square clouds - Screenshot 0.png]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Diamond square clouds - Screenshot 0.png]]

+
+Soft bluish cloud blotches emerge from the black background,
+their bright misty cores fading into darkness. The palette is
+custom-programmed so that blue dominates while red and green are
+scaled down, giving the fractal its cold, smoky tone. The
+algorithm starts with a coarse 256-pixel grid and halves the
+scale on every pass: each midpoint and edge center receives the
+average of its neighbors plus a random displacement proportional
+to the current scale, clamped to a maximum lightness of 127, so
+large features appear first and finer detail layers on top.
+

 [[file:Diamond square clouds.bas][Source code]]
 
 #+INCLUDE: "Diamond square clouds.bas" src basic-qb45
 [[file:Diamond square clouds.bas][Source code]]
 
 #+INCLUDE: "Diamond square clouds.bas" src basic-qb45


@@ -95,6 +116,17 @@ randomness, mimicking the fibrous texture of paper.
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Old paper - Screenshot 0.png]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Old paper - Screenshot 0.png]]

+
+The surface reads as aged paper: a smooth gray gradient that
+darkens towards the bottom, with fibrous vertical streaks along
+the left side. A grayscale palette of 64 shades is programmed
+first. Every pixel then averages the pixel directly above it
+with the previously computed color, adds a small random jitter,
+and periodically subtracts a fresh random noise offset roughly
+every ten steps. This feedback loop keeps the tones continuous
+from row to row while the accumulated noise produces the rough,
+fibrous grain of worn paper.
+

 [[file:Old paper.bas][Source code]]
 
 #+INCLUDE: "Old paper.bas" src basic-qb45
 [[file:Old paper.bas][Source code]]
 
 #+INCLUDE: "Old paper.bas" src basic-qb45


@@ -111,6 +143,17 @@ using simple graphical techniques.
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Wood - Screenshot 1.png]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Wood - Screenshot 1.png]]

+
+Overlapping wooden boards fill the screen, each showing wavy
+horizontal grain, vertical plank seams and bright beveled edges.
+A sixteen-color palette ramps from black to warm orange, with
+blue fixed at zero. Each board is framed by nested black, gray
+and white rectangles, then filled pixel by pixel: the new color
+is a weighted average of the pixels above and behind plus the
+previous result and a pinch of noise, while a sine-wave counter
+SIN((y + phaseOffset) / 100) bends the grain into waves. The
+main loop keeps drawing new boards at random positions forever.
+

 [[file:Wood.bas][Source code]]
 
 #+INCLUDE: "Wood.bas" src basic-qb45
 [[file:Wood.bas][Source code]]
 
 #+INCLUDE: "Wood.bas" src basic-qb45


@@ -136,6 +179,17 @@ natural, flickering effect.
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Yellow flame - Screenshot 0.png]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Yellow flame - Screenshot 0.png]]

+
+The texture glows like fire: bright yellow-white tongues at the
+bottom cool into orange and deep red swirls towards the top.
+The palette itself is built from three sine waves with different
+periods (21, 34 and 10 for red, green and blue), producing a
+smooth flame-like color gradient. Every pixel averages four
+already-drawn neighbors, the ones above, left, diagonally
+up-left and two to the left, and adds a random jitter between
+-2 and +2, so the heat appears to diffuse and flicker as it
+rises across the screen.
+

 [[file:Yellow flame.bas][Source code]]
 
 #+INCLUDE: "Yellow flame.bas" src basic-qb45
 [[file:Yellow flame.bas][Source code]]
 
 #+INCLUDE: "Yellow flame.bas" src basic-qb45

diff --git a/3D GFX/3D Synthezier/doc/index.org b/3D GFX/3D Synthezier/doc/index.org
index d48cbcc..7fb6cbb 100644 (file)
--- a/3D GFX/3D Synthezier/doc/index.org
+++ b/3D GFX/3D Synthezier/doc/index.org
@@ -67,13 +67,38 @@ They were produced by importing generated [[https://en.wikipedia.org/wiki/Wavefr
 #+attr_latex: :width 1000px
 [[file:rectangular city, 1.jpeg]]
 
 #+attr_latex: :width 1000px
 [[file:rectangular city, 1.jpeg]]
 

+An oblique aerial view over the generated rectangular city: boxy
+high-rise blocks with gridded window strips, octagonal rooftop
+structures and small vehicles scattered between the towers, all
+bathed in warm orange light. The scene was described entirely in
+the scene language - the city1.3d script stamps out copies of the
+maja (building) and cars sub-objects with obj commands, offsetting
+and rotating each instance - then parsed into a Wavefront OBJ file
+and rendered in Blender.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:rectangular city, 2.jpeg]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:rectangular city, 2.jpeg]]
 

+A night-time canyon view from street level between the rectangular
+towers, their facades glowing with rows of lit windows against a
+deep blue haze. Because buildings are composed from shared
+sub-objects, every tower inherits the same window geometry; the
+parser expands each obj reference, applies the requested
+translations and rotations, and emits the resulting polygons into
+the OBJ file with materials taken from the shared result.mtl
+library.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:rectangular city, 3.jpeg]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:rectangular city, 3.jpeg]]

+
+Looking down at the rooftops of the rectangular city in a cool
+teal light: octagonal roof caps, rooftop clutter and vehicles
+perched at different heights are clearly visible. The scene script
+places cars at several altitude layers - some parked on the
+ground, others floating high above the streets - simply by adding
+different y offsets to instances of the same cars sub-object.

 ** Hexagonal city
 :PROPERTIES:
 :CUSTOM_ID: hexagonal-city
 ** Hexagonal city
 :PROPERTIES:
 :CUSTOM_ID: hexagonal-city


@@ -83,13 +108,35 @@ They were produced by importing generated [[https://en.wikipedia.org/wiki/Wavefr
 #+attr_latex: :width 1000px
 [[file:hexagonal city, 1.jpeg]]
 
 #+attr_latex: :width 1000px
 [[file:hexagonal city, 1.jpeg]]
 

+A distant view of the hexagonal city at dusk: a cluster of
+hexagonal towers crowned with translucent domes rises from a
+low-poly plain under an orange sky. The city2.3d script builds
+this by stacking block sub-objects and placing stone ring and
+glass kuppel (dome) objects at hexagon vertex offsets - multiples
+of sin and cos of 30 degrees - scaled twentyfold with the x*20
+z*20 size modifiers.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:hexagonal city, 2.jpeg]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:hexagonal city, 2.jpeg]]
 

+A closer aerial look at the hexagonal tower cluster, showing the
+blue-tinted glass domes sitting on their stone rings with roads
+threading between the towers. Each dome and ring is a separate
+sub-object pulled from the include directory and positioned by the
+obj command, while materials are switched between kivi (stone) and
+glass_transp with mtl commands before each placement.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:hexagonal city, 3.jpeg]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:hexagonal city, 3.jpeg]]

+
+Street-level view inside the hexagonal city: low-poly cars in
+blue, yellow and red dot the roads between the towers. The
+vehicles are the same car sub-objects reused dozens of times with
+different x, z and y offsets and xz rotations, illustrating how
+the language composes complex scenes from a handful of cached
+primitive objects.

 * Scene description language
 :PROPERTIES:
 :CUSTOM_ID: scene-description-language
 * Scene description language
 :PROPERTIES:
 :CUSTOM_ID: scene-description-language


@@ -149,6 +196,12 @@ See also examples.
  500 lines files.
 
  [[file:rotation.png]]
  500 lines files.
 
  [[file:rotation.png]]

+
+The diagram illustrates the three rotation planes available to the
+obj command: X-Z, Y-Z and X-Y, each drawn as a curved arrow
+sweeping around the green axis. Suffixes like xz45 or xy20 on an
+obj line rotate the included sub-object by the given number of
+degrees in the named plane before it is merged into the scene.

 ** rnd
 :PROPERTIES:
 :CUSTOM_ID: rnd
 ** rnd
 :PROPERTIES:
 :CUSTOM_ID: rnd

diff --git a/3D GFX/Miscellaneous/index.org b/3D GFX/Miscellaneous/index.org
index 5dc6d57..1e5b86a 100644 (file)
--- a/3D GFX/Miscellaneous/index.org
+++ b/3D GFX/Miscellaneous/index.org
@@ -44,6 +44,14 @@ Wireframe 3D model of a rotating exclamation mark.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A white wireframe exclamation mark tumbles against the black
+screen, its beveled bar and dot alternately foreshortening and
+opening up as they turn. The model is defined by DATA statements:
+32 vertices describing front and back faces plus the lines joining
+them. Each frame rotates every vertex with precomputed sine and
+cosine lookup tables and connects the projected points with lines.
+Arrow keys and w/z steer the rotation, space slows it down.
+

 [[file:!.bas][Source code]]
 
 * 3D bouncing ball
 [[file:!.bas][Source code]]
 
 * 3D bouncing ball


@@ -64,6 +72,15 @@ of early computer graphics techniques.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A sphere woven from 500 glowing points bounces around the dark
+screen, tumbling as it travels and kicking off in a new direction
+with every impact. Each point is rotated by three successive 2D
+rotations, perspective-projected, and then offset by the ball's
+position. Gravity accelerates the ball downward each frame; when
+it crosses the floor or a side wall its velocity is inverted, a
+random horizontal kick is added, and new spin velocities are
+chosen for the point cloud.
+

 [[file:3D%20ball.bas][Source code]]
 
 * 3D text in a room
 [[file:3D%20ball.bas][Source code]]
 
 * 3D text in a room


@@ -83,6 +100,14 @@ fly around in all directions.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The camera glides through a wireframe room whose floor is paved
+with octagonal tiles, while green wireframe text hangs floating in
+the middle of the space. The scenery is assembled point by point:
+a large rectangle forms the walls, octagons and small squares tile
+the floor, and glyph outlines are read from a vector font file and
+laid out in the room as line segments. Cursor keys steer the view,
++ and - move up and down, and space slows the flight.
+

 [[file:3D%20text.bas][Source code]]
 
 * 3D bouncing cubes on grid floor
 [[file:3D%20text.bas][Source code]]
 
 * 3D bouncing cubes on grid floor


@@ -102,6 +127,14 @@ dynamic visual effect.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Wireframe cubes leap and bounce above a glowing green grid floor
+while the camera drifts among them. The floor is a lattice of
+points joined into a mesh; each cube is a separate point set with
+its own velocity vector that is integrated every frame and
+inverted by the collider logic whenever a cube hits the ground.
+Arrow keys fly the camera around the scene, the numeric keys
+2/4/6/8 turn the view, and +/- adjust its altitude.
+

 [[file:Bouncing%20cubes.bas][Source code]]
 
 * Matrix math for rotation in 3D space
 [[file:Bouncing%20cubes.bas][Source code]]
 
 * Matrix math for rotation in 3D space


@@ -121,6 +154,14 @@ rotated by using matrix multiplications.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A rippling white surface made of a point grid twists into new
+orientations between frames. The height of each grid point is
+computed as a sine wave of its Manhattan distance from the center,
+producing concentric dunes. Instead of chained 2D rotors, every
+point is transformed in a single step by a 3x3 rotation matrix
+built from the alpha, beta and gamma angles, then
+perspective-projected; keys 7/9, 4/6 and 1/3 nudge each angle.
+

 [[file:Matrix%20math.bas][Source code]]
 
 * Maze explorer
 [[file:Matrix%20math.bas][Source code]]
 
 * Maze explorer


@@ -136,7 +177,34 @@ changes as they navigate through it.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Maze%20explorer.bas][file:Maze%20explorer.png]]
+[[file:Maze%20explorer.bas][file:Maze%20explorer%20-%20Screenshot%200.png]]
+
+A tangle of brightly colored line segments stretches into the
+darkness: the maze is a single 3D random walk in which each new
+segment picks a random color and a random displacement along one
+axis. Only 500 points exist at a time, so as the walk continues
+the oldest geometry is recycled and the labyrinth appears to grow
+and rebuild itself endlessly around the viewer. Navigation uses
+WASD plus the TSR mouse driver: dragging looks around, and mouse
+button combinations slide the camera along the axes.
+
+#+begin_export html
+<div class="flex-center">
+  <video controls loop autoplay>
+    <source src="Maze explorer - Screencast 0.mp4" type="video/mp4">
+    Your browser does not support the video tag.
+  </video>
+</div>
+#+end_export
+
+The viewpoint plunges down a corridor of brightly colored line
+segments that stretches away in one-point perspective, fresh
+geometry appearing ahead as the flight continues. Each frame the
+random walk appends another point and a randomly colored line
+along one axis, up to a 500-point cap; every vertex is then
+rotated, perspective-projected and joined with LINE. Mouse
+drags steer the view while WASD slides the camera through the
+maze.

 
 [[file:Maze explorer.bas][Source code]]
 
 
 [[file:Maze explorer.bas][Source code]]
 


@@ -157,6 +225,14 @@ look and fly around in all directions.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A green wireframe tank shuttles back and forth across a long
+wireframe bridge, its track links visibly churning in sync with
+the movement. The tank, bridge and track segments are all built
+from DATA statement coordinates; the track animation recycles a
+pool of small segments around the wheels as the tank drives.
+Rotation uses precomputed sine/cosine lookup tables, and the arrow
+keys plus +/- provide a freely flying camera around the scene.
+

 [[file:Tank.bas][Source code]]
 
 * Tiled room
 [[file:Tank.bas][Source code]]
 
 * Tiled room


@@ -176,4 +252,13 @@ around.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The camera sweeps through a spacious wireframe room decorated with
+geometric tiles: square and hexagonal outlines pattern the floor
+and walls in green and white. The tiles are generated
+procedurally - helper subroutines stamp out squares, hexagons and
+cube edges as point-and-line data - then every vertex is rotated
+with precomputed trigonometric tables and perspective-projected.
+Cursor keys fly the camera, 2/4/6/8 tilt the view, and space slows
+the movement.
+

 [[file:Tiled%20room.bas][Source code]]
 [[file:Tiled%20room.bas][Source code]]

diff --git a/3D GFX/Space/index.org b/3D GFX/Space/index.org
index 91a1def..6181f4f 100644 (file)
--- a/3D GFX/Space/index.org
+++ b/3D GFX/Space/index.org
@@ -40,7 +40,33 @@ galaxy with stars distributed in a spiral pattern.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Galaxy%20explorer.bas][file:Galaxy%20explorer.png]]
+[[file:Galaxy%20explorer.bas][file:Galaxy%20explorer%20-%20Screenshot%200.png]]
+
+A spiral galaxy of thousands of colored points - red, green, cyan
+and violet stars - floats against the black void, its swirling
+disk clearly visible from this tilted viewpoint. The galaxy is
+generated as a point cloud of up to 12000 stars with per-star
+colors, then rotated by three angles and perspective-projected
+each frame. WASD keys and the TSR mouse driver fly the viewer
+freely through the swarm.
+
+#+begin_export html
+<div class="flex-center">
+  <video controls loop autoplay>
+    <source src="Galaxy explorer - Screencast 0.mp4" type="video/mp4">
+    Your browser does not support the video tag.
+  </video>
+</div>
+#+end_export
+
+The camera glides through the swarm as the whole spiral galaxy
+wheels past: thousands of individually colored stars thicken
+toward the glowing core and trail off into spiral arms. The
+point cloud is generated once by the mkGalaxy routine with
+random spiral offsets, then every frame each star is rotated by
+the camera angles, perspective-projected and plotted with PSET.
+WASD keys and mouse-button drags accelerate the viewer freely
+through the cloud.

 
 [[file:Galaxy%20explorer.bas][Source code]]
 
 
 [[file:Galaxy%20explorer.bas][Source code]]
 


@@ -63,6 +89,15 @@ observe the rocket's trajectory from various angles.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A green wireframe globe built from latitude and longitude rings
+fills the lower half of the screen while a small wireframe rocket
+climbs away from its surface, leaving a growing dotted trail
+behind it; diagnostic counters flicker at the top. The planet and
+rocket are procedural point-and-line models, and each frame
+integrates the rocket's velocity, appends fresh trail points, and
+re-projects the whole scene. Arrow keys fly the camera, 2/4/6/8
+turn the view, and +/- change altitude.
+

 [[file:Rocket simulator.bas][Source code]]
 
 * Stars
 [[file:Rocket simulator.bas][Source code]]
 
 * Stars


@@ -98,6 +133,15 @@ How the Program Works:
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Hundreds of white stars stream outward across the screen,
+brightening as they approach, giving the sensation of flying
+through space while the view gently sways. Each star's 3D position
+is perspective-projected, rotated by a slowly oscillating camera
+angle, and nudged by sinusoidal offsets. Stars are pulled toward
+the viewer every frame; any star that gets too close is respawned
+in the far distance, and its brightness is computed as 3000/z,
+capped at palette color 31.
+

 [[file:Stars.bas][Source code]]
 
 * Universe explorer
 [[file:Stars.bas][Source code]]
 
 * Universe explorer


@@ -137,12 +181,34 @@ What's in it for the Reader?
 #+attr_latex: :width 1000px
 [[file:Universe%20explorer/Universe%20explorer.bas][file:Universe%20explorer/1.png]]
 
 #+attr_latex: :width 1000px
 [[file:Universe%20explorer/Universe%20explorer.bas][file:Universe%20explorer/1.png]]
 

+A dense, multicolored ball of stars - a whole galaxy seen from the
+outside - dominates the view, surrounded by the sparse specks of
+neighboring systems. The program builds the universe as clusters
+of galaxies made of individual stars, but only nearby regions are
+materialized at full detail; distant ones stay as coarse clouds,
+keeping the rendered star count within limits while the user flies
+freely with mouse and keyboard.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Universe%20explorer/Universe%20explorer.bas][file:Universe%20explorer/2.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Universe%20explorer/Universe%20explorer.bas][file:Universe%20explorer/2.png]]
 

+Here the camera sits inside a galaxy: stars form a luminous ring
+around a bright core, with colorful specks drifting past at close
+range. This is the level-of-detail algorithm at work - the region
+surrounding the viewer has been refined into thousands of
+individually placed and colored stars, while farther regions
+remain compressed into simple point clouds until approached.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Universe%20explorer/Universe%20explorer.bas][file:Universe%20explorer/3.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Universe%20explorer/Universe%20explorer.bas][file:Universe%20explorer/3.png]]
 

+Deep intergalactic space: only a single compact star cluster and a
+handful of faint distant specks remain visible in the void. At
+this range the universe is rendered at its coarsest level - whole
+galaxies collapse into tiny point groups - demonstrating how the
+program sheds detail with distance so that even an astronomically
+large universe stays navigable in real time.
+

 [[file:Universe%20explorer/Universe%20explorer.bas][Source code]]
 [[file:Universe%20explorer/Universe%20explorer.bas][Source code]]

diff --git a/Math/Plotting/index.org b/Math/Plotting/index.org
index 7512bc5..14de44c 100644 (file)
--- a/Math/Plotting/index.org
+++ b/Math/Plotting/index.org
@@ -46,6 +46,14 @@ based on a user-defined mathematical function.
 #+attr_latex: :width 1000px
 [[file:2D%20graph%20plot.bas][file:2D%20graph%20plot%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20graph%20plot.bas][file:2D%20graph%20plot%20-%20Screenshot%200.png]]
 

+The function y = 1 - cos(2x) + sin(2x) plotted in yellow across the
+range x = -3.2 .. 3.2 at 100 pixels per unit. Dark blue grid lines
+mark every unit and the cyan axes cross at the origin. The curve
+oscillates around the line y = 1, dipping toward the x-axis
+wherever the sine and cosine terms momentarily cancel each other,
+and each segment is drawn only when both of its endpoints fall
+inside the screen.
+

 [[file:2D%20graph%20plot.bas][Source code]]
 
 * 3D graph
 [[file:2D%20graph%20plot.bas][Source code]]
 
 * 3D graph


@@ -78,7 +86,60 @@ grid.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:3D%20graph.bas][file:3D%20graph.png]]
+[[file:3D%20graph.bas][file:3D%20graph%20-%20Screenshot%200.png]]
+
+The heightmap as seen from the camera's starting position, floating
+outside the grid volume and looking in at an oblique angle. The
+yellow wireframe dome is the spherical cap SQR((15+v)*(15-v))-10,
+its surface rippled by the diagonal SIN(x+y) waves that are also
+enabled in the formula subroutine. Cyan measuring grids line the
+three axis planes behind and below the surface, and the light red
+3D cross marks the zero point at the center of the scene.
+
+#+attr_html: :class responsive-img
+#+attr_latex: :width 1000px
+[[file:3D%20graph.bas][file:3D%20graph%20-%20Screenshot%201.png]]
+
+The same dome after flying the camera closer and lower with the
+cursor keys, so the cap's rim and the crests of the diagonal waves
+fill the frame. The wave term SIN(x+y)*SIN(tm/10) is modulated by
+the frame counter tm, so the ripples slowly grow and shrink as the
+program runs. Every frame the graaf subroutine re-evaluates the
+formula on the 21 by 21 point grid and reconnects neighboring
+points into the yellow mesh.
+
+#+attr_html: :class responsive-img
+#+attr_latex: :width 1000px
+[[file:3D%20graph.bas][file:3D%20graph%20-%20Screenshot%202.png]]
+
+The yellow wireframe is the heightmap of the two formulas currently
+enabled in the "formula" subroutine: a spherical cap
+SQR((15+v)*(15-v))-10, where v is the distance from the center,
+plus diagonal waves SIN(x+y) that the frame counter slowly
+modulates over time. Cyan measuring grids along the three axis
+planes and the light red 3D cross mark the scale and the zero
+point. The camera is flown with the cursor keys, + and - climb and
+sink, 4/6/8/2 spin the view, and space halves all motion.
+
+#+begin_export html
+<div class="flex-center">
+  <video controls loop autoplay>
+    <source src="3D graph - Screencast 0.mp4" type="video/mp4">
+    Your browser does not support the video tag.
+  </video>
+</div>
+#+end_export
+
+A flight through the scene in real time. The recording opens on
+the wide establishing view of the dome inside its three cyan grid
+planes, then the camera is steered around and finally right up
+against the surface, ending with a close-up of the rippling
+wireframe mesh from beneath. The cursor keys move the camera
+forward and sideways, + and - make it climb and sink, 4/6/8/2
+spin the view, and space halves all motion for finer control.
+Meanwhile the diagonal waves pulse on their own as SIN(tm/10)
+modulates their amplitude, and each frame every line of the mesh
+is erased at its previous position and redrawn at the new one.

 
 [[file:3D%20graph.bas][Source code]]
 
 
 [[file:3D%20graph.bas][Source code]]
 


@@ -99,6 +160,14 @@ visualized.
 #+attr_latex: :width 1000px
 [[file:Deriviative%20calculator.bas][file:Deriviative%20calculator%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Deriviative%20calculator.bas][file:Deriviative%20calculator%20-%20Screenshot%200.png]]
 

+The light green curve plots f(x) = x^3 - 3x with its two turning
+points; the yellow curve beneath is the derivative, computed
+numerically as the per-step difference of the function and scaled
+back up by the scale factor, forming the parabola 3x^2 - 3 that
+crosses zero exactly under the function's extrema. Blue grid lines
+mark single units, red lines every fifth unit, and the cyan axes
+cross at the origin; the scale is 50 pixels per unit.
+

 [[file:Deriviative%20calculator.bas][Source code]]
 
 * Sine and cosine table
 [[file:Deriviative%20calculator.bas][Source code]]
 
 * Sine and cosine table


@@ -115,4 +184,12 @@ visual representation of these fundamental trigonometric functions.
 #+attr_latex: :width 1000px
 [[file:Sine%20and%20cosine%20table.bas][file:Sine%20and%20cosine%20table%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Sine%20and%20cosine%20table.bas][file:Sine%20and%20cosine%20table%20-%20Screenshot%200.png]]
 

+Sine (white) and cosine (light red) plotted together over 0 to 10
+radians in steps of 0.05, each labeled "sin" and "cos" where its
+curve ends. Dark gray grid lines divide the screen into ten columns
+numbered 1-10 along the bottom edge, yellow lines mark the central
+axes, and the -1, 0 and 1 labels at the right give the vertical
+scale, so the plot doubles as a graphical lookup table for the two
+functions.
+

 [[file:Sine%20and%20cosine%20table.bas][Source code]]
 [[file:Sine%20and%20cosine%20table.bas][Source code]]

diff --git a/Math/Simulation/index.org b/Math/Simulation/index.org
index 4e49fca..2bf5b58 100644 (file)
--- a/Math/Simulation/index.org
+++ b/Math/Simulation/index.org
@@ -59,6 +59,15 @@ conditions by setting velocities to zero at wall boundaries.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The 100x100 pressure grid drawn pixel-by-pixel in the top-left
+corner: the quiet gas shows as gray, and the high-pressure block
+seeded on the left detonates into a shock front that sweeps right
+in red, green and yellow bands. The dark red frame and the diagonal
+lines are solid walls that zero the local velocities, so the wave
+reflects off the boundary and funnels through the obstacle field
+before diffusing. The number printed at the bottom is the
+negative-pressure residual the correction loop is damping out.
+

 [[file:Explosion%20simulator.bas][Source code]]
 
 * Gravity in 2D
 [[file:Explosion%20simulator.bas][Source code]]
 
 * Gravity in 2D


@@ -82,6 +91,14 @@ educational tool for understanding basic orbital mechanics.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The large cyan circle is the central mass and the tiny yellow dot
+the orbiting object, which leaves a dotted trail as it loops
+around. A dark blue line connects the object to the center every
+frame. Because the pull falls off as 1/distance rather than
+1/distance^2, the orbit never closes: it precesses into a slowly
+rotating three-lobed rosette, and the accumulated radius lines
+weave the dense blue web filling the interior. Any key press exits.
+

 [[file:Gravity%20in%202D.bas][Source code]]
 
 * Gravity in 3D
 [[file:Gravity%20in%202D.bas][Source code]]
 
 * Gravity in 3D


@@ -111,6 +128,15 @@ will reach stable configuration.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Thirty white circles — perspective-projected spheres whose drawn
+radius shrinks with depth — start at random positions and fall
+toward each other. The pairwise force follows 1/(d-1), so it
+attracts at range but flips into a strong repulsion once two
+spheres close in past the critical distance, and dividing the
+velocities by 1.01 every step bleeds off energy. The swarm
+collapses, bounces, and settles into the compact overlapping
+cluster seen at the center of the screen.
+

 [[file:Gravity%20in%203D.bas][Source code]]
 
 * Interference
 [[file:Gravity%20in%203D.bas][Source code]]
 
 * Interference


@@ -136,6 +162,14 @@ displayed as a third waveform.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Two traveling sine waves scroll across the upper part of the
+screen: the blue one is a plain SIN(frame + x/4), while the green
+one carries an extra phase shift that grows with x, so the two
+slide in and out of phase along the axis. The white waveform below
+is their point-by-point sum, and its periodically swelling and
+collapsing amplitude envelope is the classic beating pattern of two
+slightly detuned frequencies.
+

 [[file:Interference.bas][Source code]]
 
 * Interferogram
 [[file:Interference.bas][Source code]]
 
 * Interferogram


@@ -150,7 +184,16 @@ used in physics and engineering to analyze wave interactions.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Interferogram.bas][file:Interferogram.png]]
+[[file:Interferogram.bas][file:Interferogram%20-%20Screenshot%200.png]]
+
+A single white line on black. For every horizontal pixel the
+program sums |SIN(t) + SIN(k*t)| over 5000 time steps, with the
+detune factor k sweeping linearly around 1 from left to right.
+Where the frequencies differ, the sum settles into a low, finely
+rippled baseline; at the exact center k = 1 and the two waves
+coincide perfectly, so the accumulated amplitude spikes into a tall
+narrow pulse with symmetric ringing side lobes — the signature
+shape of an interferogram.

 
 [[file:Interferogram.bas][Source code]]
 
 
 [[file:Interferogram.bas][Source code]]
 


@@ -183,6 +226,14 @@ water cell if surrounded by a high density of water cells.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+An 80x50 text-mode screen where "#" cells are water and "." cells
+are empty. The simulation starts from pure random noise, and the
+Moore-neighborhood rules — a water cell survives only with more
+than three neighbors, an empty cell fills in with more than four —
+act like surface tension: isolated specks evaporate, ragged edges
+get smoothed, and the liquid gathers into the rounded, slowly
+wandering blobs visible here.
+

 [[file:Surface%20tension.bas][Source code]]
 
 * Wave 1
 [[file:Surface%20tension.bas][Source code]]
 
 * Wave 1


@@ -208,6 +259,14 @@ loss.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A filled white water column on a black background, initially given
+a rectangular bump in the middle. The bump collapses under the
+neighbor-averaging update and sends ripples racing out toward both
+walls; with the velocity damped by 1.01 per step, the sloshing
+gradually calms and the surface settles back toward flat. The
+height array drives both the black clearing lines above the surface
+and the white fill below it.
+

 [[file:Wave%201.bas][Source code]]
 
 * Wave 2
 [[file:Wave%201.bas][Source code]]
 
 * Wave 2


@@ -231,4 +290,11 @@ understanding wave mechanics.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A thin white wave line across a black screen, drawn point by point
+from the surface height array. Random rain droplets keep kicking
+the surface: each impact injects a half-sine splash of random width
+and amplitude, and the neighbor-averaging propagation with light
+damping spreads the disturbance into clean traveling ripples that
+cross, superimpose, and fade.
+

 [[file:Wave%202.bas][Source code]]
 [[file:Wave%202.bas][Source code]]

diff --git a/Miscellaneous/Automated school clock/v1/README.org b/Miscellaneous/Automated school clock/v1/README.org
index 4fa68d3..7ed7316 100644 (file)
--- a/Miscellaneous/Automated school clock/v1/README.org
+++ b/Miscellaneous/Automated school clock/v1/README.org
@@ -26,6 +26,38 @@ nummerdatud nuppu paigutusega:
            <3>
 #+END_VERSE
 
            <3>
 #+END_VERSE
 

+#+attr_html: :class responsive-img
+[[file:Electronics/skeem.png]]
+
+Liidese elektriskeem. Printeri pesa (LPT1) andmeliinid D0–D7
+juhivad KT3102 transistoride kaudu kahe seitsmesegmendilise
+LED-indikaatori segmente: ülemine indikaator näitab tunde ja
+alumine minuteid. Liinidele 16, 17 ja 18 on dioodide kaudu
+ühendatud klaviatuuri kolm nuppu ning liin 4 juhib releed, mille
+kontaktid (88) lülitavad kella 220 V vooluahelat. Paremal on
+toodud printeri pesa jalgade numbrid ja komponentide nimistu
+(takistid 500 Ω ja 10 kΩ, transistor KT3102, diood, relee).
+
+#+attr_html: :class responsive-img
+[[file:Electronics/3%20key%20keyboard.png]]
+
+Kolmeklahviline klaviatuur käsitsi ehitatud trükkplaadil. Kolm
+mikrolüklit vastavad juhendis kirjeldatud paigutusele <1>, <2>
+ja <3>, millega saab kella käsitsi lasta, aega muuta ja uuendatud
+graafikuid tööle võtta. Üleval servas on näha kaks dioodi, mis
+eraldavad nuppude signaalid printeri pesa liinidel 16, 17 ja 18
+(vt skeemi); kollased ja tumedad juhtmed viivad signaalid liidese
+plaadile.
+
+#+attr_html: :class responsive-img
+[[file:Electronics/4.png]]
+
+Liidese trükkplaat relee poolelt: vasakul on printeri pessa
+(LPT1) minev DB-25 pistik, üleval kahekohaline seitsmesegmendiline
+LED-indikaator tundide ja minutite näitamiseks ning paremal 220 V
+kellaahelat lülitav relee. Pistikule joodetud takistid ja
+transistorid juhivad indikaatori segmente vastavalt skeemile.
+

 Programm on ettenähtud iseseisvalt töötama, kuid on ka võimalus
 erandkorras kгitsi kella lasta, aega muuta jne.. Programm eristab
 tavalisi nupuvajutusi ja topeltklõpse. Eesmärgiga suurendada
 Programm on ettenähtud iseseisvalt töötama, kuid on ka võimalus
 erandkorras kгitsi kella lasta, aega muuta jne.. Programm eristab
 tavalisi nupuvajutusi ja topeltklõpse. Eesmärgiga suurendada

diff --git a/Miscellaneous/Automated school clock/v3/tutorial.org b/Miscellaneous/Automated school clock/v3/tutorial.org
index 7cc898d..ecd0d8d 100644 (file)
--- a/Miscellaneous/Automated school clock/v3/tutorial.org
+++ b/Miscellaneous/Automated school clock/v3/tutorial.org
@@ -42,6 +42,17 @@ mõeldud kella ja toiteallikaga vooluahelasse jadamisi
 paralleelselt, siis saab kella lasta nii endisest nupust kui ka\r
 arvutiga.\r
 \r
 paralleelselt, siis saab kella lasta nii endisest nupust kui ka\r
 arvutiga.\r
 \r

+#+attr_html: :class responsive-img\r
+[[file:skeem.png]]\r
+\r
+Liidese skeem kella vooluahelaga ühendamiseks. Printeri pesa\r
+(LPT1) liin 4 juhib transistori KT3102 kaudu releed, mille\r
+kontaktid (88) on ühendatud jadamisi kella ja toiteallika 220 V\r
+ahelasse. Releega rööbiti olev diood kaitseb transistorit\r
+induktiivse pingepülve eest. Liides ise voolu ei anna — relee\r
+toimib vaid lülitina, mistõttu võib selle ühendada ka olemasoleva\r
+käsitsi kella laskmise nupuga paralleelselt.\r
+\r

 Programm on ettenähtud iseseisvalt töötama, kuid on ka võimalus\r
 erandkorras k2sitsi kella lasta, aega muuta jne.  Selleks tuleb\r
 vajutada erinevaid klahve klaviatuuril.  K2ivitudes kuvab programm\r
 Programm on ettenähtud iseseisvalt töötama, kuid on ka võimalus\r
 erandkorras k2sitsi kella lasta, aega muuta jne.  Selleks tuleb\r
 vajutada erinevaid klahve klaviatuuril.  K2ivitudes kuvab programm\r

diff --git a/Miscellaneous/Mouse driver/index.org b/Miscellaneous/Mouse driver/index.org
index 41a9bec..28e6502 100644 (file)
--- a/Miscellaneous/Mouse driver/index.org
+++ b/Miscellaneous/Mouse driver/index.org
@@ -135,6 +135,29 @@ are printed as they occur. Press any key to exit.
 #+attr_latex: :width 1000px\r
 [[file:mousedrv.bas][file:screenshot.png]]\r
 \r
 #+attr_latex: :width 1000px\r
 [[file:mousedrv.bas][file:screenshot.png]]\r
 \r

+The demonstration program running in 320x200 256-color graphics\r
+mode (SCREEN 13). The green circle is the mouse cursor: on every\r
+frame the program reads the accumulated X and Y movement deltas\r
+from the TSR's shared memory table with PEEK (and resets them back\r
+to zero with POKE), clamps each step to at most 50 pixels, erases\r
+the old circle and redraws it at the updated position. The top\r
+line shows the current cursor coordinates together with a running\r
+frame counter, while button presses read from the latched Button\r
+Status field would be printed below as they occur.\r
+\r
+#+attr_html: :class responsive-img\r
+#+attr_latex: :width 1000px\r
+[[file:mousedrv.bas][file:mousedrv%20-%20Screenshot%200.png]]\r
+\r
+The same demonstration program, captured at the native 320x200\r
+resolution of SCREEN 13. The top line shows the cursor position\r
+(X: 56, Y: 109) beside the running frame counter, and the green\r
+circle on the left follows the mouse. The lone 0 on line five is\r
+the Button Status word read from the TSR's shared table: the demo\r
+prints it every frame and immediately resets the field with POKE,\r
+so a nonzero value appears only in the frame where a button was\r
+pressed.\r
+\r

 [[file:mousedrv.bas][mousedrv.bas - source code]]\r
 \r
 Here are more practical examples where this mouse driver is being\r
 [[file:mousedrv.bas][mousedrv.bas - source code]]\r
 \r
 Here are more practical examples where this mouse driver is being\r

diff --git a/Networking/Digital data over analog audio/index.org b/Networking/Digital data over analog audio/index.org
index bc3472c..ca48243 100755 (executable)
--- a/Networking/Digital data over analog audio/index.org
+++ b/Networking/Digital data over analog audio/index.org
@@ -68,6 +68,17 @@ transmitted over telephone lines.
 \r
 [[file:screenshot.png]]\r
 \r
 \r
 [[file:screenshot.png]]\r
 \r

+The *xi2msg* decoder at work in 640x480 graphics mode (SCREEN 12).\r
+The status pane on the left traces the decoding stages: searching\r
+for the header tone, locking onto the beginning point, and running\r
+the statistical analysis that measures ten peak distances to derive\r
+the threshold separating '0' bits (long gaps) from '1' bits (short\r
+gaps). The top-right pane scrolls the incoming bit stream, showing\r
+each completed byte as bits, decimal, hexadecimal and character.\r
+The lower-left pane plots the audio waveform itself, with detected\r
+peaks marked and vertical cursors tracking the analysis window,\r
+while the bottom line prints the decoded message as it emerges:\r
+"This is a sample encoded message ! ..."\r

 \r
 Download source code: [[file:xi2msg.bas][Source code]]\r
 \r
 \r
 Download source code: [[file:xi2msg.bas][Source code]]\r
 \r

diff --git a/Networking/LPT communication driver/index.org b/Networking/LPT communication driver/index.org
index 4e58eff..beefe9b 100755 (executable)
--- a/Networking/LPT communication driver/index.org
+++ b/Networking/LPT communication driver/index.org
@@ -33,6 +33,16 @@ Out of [[https://en.wikipedia.org/wiki/Parallel_port][25 physical wires in LPT p
 \r
 [[file:diagram.png]]\r
 \r
 \r
 [[file:diagram.png]]\r
 \r

+Wiring diagram of the cable, drawn as the front view of a male\r
+DB-25 parallel port connector. Of the 25 pins only three matter:\r
+pin 14 (highlighted blue) carries the synchronization clock, pin\r
+17 (highlighted green) is the bidirectional serial data line, and\r
+pin 18 is the common ground. The connection is straight-through —\r
+pin 14 to 14, 17 to 17 and 18 to 18 between the two computers —\r
+so both ends run the same unmodified driver, taking turns\r
+bit-banging bytes over the single data wire in half-duplex\r
+fashion.\r
+\r

 By utilizing only three wires and software controlled bit-banging\r
 algorithm, custom, comparatively simple, cheap and long cable can be\r
 built to connect 2 computers in a DIY network setup.\r
 By utilizing only three wires and software controlled bit-banging\r
 algorithm, custom, comparatively simple, cheap and long cable can be\r
 built to connect 2 computers in a DIY network setup.\r

diff --git a/index.org b/index.org
index 25166fd..3f424a9 100644 (file)
--- a/index.org
+++ b/index.org
@@ -58,6 +58,13 @@ algorithms and getting fun looking results quite easily.
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Animations/index.html][file:2D%20GFX/Animations/logo.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Animations/index.html][file:2D%20GFX/Animations/logo.png]]
 

+A four-panel teaser of the collection: an interference moiré of
+overlapping circle rings, a DNA-style double helix assembled from
+marching circles, a starfield snowfall spelling "SNOW", and a
+rotating yin-yang symbol. Each demo in the collection is a small
+self-contained experiment in 2D animation -- trigonometric motion,
+particle systems and palette effects rendered in real time.
+

 [[file:2D%20GFX/Animations/index.html][See entire animations collection]]
 
 ** Fractals
 [[file:2D%20GFX/Animations/index.html][See entire animations collection]]
 
 ** Fractals


@@ -70,6 +77,13 @@ algorithms and getting fun looking results quite easily.
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Fractals/index.html][file:2D%20GFX/Fractals/fractal%20squares%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Fractals/index.html][file:2D%20GFX/Fractals/fractal%20squares%20-%20Screenshot%200.png]]
 

+A single completed square fractal from the fractal squares program.
+The recursion starts from one large outlined square; every square
+then spawns a child square at each of its four corners with the size
+divided by 2.3, and the process repeats until the squares shrink
+below one pixel. The result is a self-similar lattice of light green
+outlines on a white background.
+

 [[file:2D GFX/Fractals/index.html][See entire fractals collection]]
 
 ** Spiral series
 [[file:2D GFX/Fractals/index.html][See entire fractals collection]]
 
 ** Spiral series


@@ -86,6 +100,13 @@ screen. Every iteration built upon previous result.
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Spirals/index.html][file:2D%20GFX/Spirals/logo.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Spirals/index.html][file:2D%20GFX/Spirals/logo.png]]
 

+Four stages of the spiral series: a sweeping wireframe ribbon
+spiral, a spiral sheet twisted into a rising vortex, spirals plotted
+from scattered points, and a checkered sphere built entirely from
+spiral bands. What began as a single flat spiral on the screen grew,
+iteration by iteration, into shaded and textured spherical spirals
+rendered in 3D perspective.
+

 [[file:2D%20GFX/Spirals/index.html][See entire spiral collection]]
 
 ** Algorithmic textures
 [[file:2D%20GFX/Spirals/index.html][See entire spiral collection]]
 
 ** Algorithmic textures


@@ -98,6 +119,12 @@ screen. Every iteration built upon previous result.
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Textures/index.html][file:2D%20GFX/Textures/logo.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Textures/index.html][file:2D%20GFX/Textures/logo.png]]
 

+A four-panel sampler of the generated textures: soft diamond-square
+clouds, a brushed streak pattern, a wooden plank floor and
+marble-like veining. Every texture is produced purely
+algorithmically -- noise fields, circular wave interference and
+recursive subdivision turned into pixel patterns.
+

 [[file:2D%20GFX/Textures/index.html][See entire texture collection]]
 
 ** Miscellaneous
 [[file:2D%20GFX/Textures/index.html][See entire texture collection]]
 
 ** Miscellaneous


@@ -117,6 +144,12 @@ as pixel manipulation, geometric shapes, and simple animations.
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Hello%20friend.bas][file:2D%20GFX/Hello%20friend%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Hello%20friend.bas][file:2D%20GFX/Hello%20friend%20-%20Screenshot%200.png]]
 

+The greeting screen of the program: a large blue chevron triangle
+points down at the "Hello friend!" message, underlined by a solid
+blue bar. Behind this simple composition the code exercises the
+basics of QBasic graphics -- plotting pixels, drawing geometric
+shapes and animating them frame by frame.
+

 Download source code: [[file:2D%20GFX/Hello%20friend.bas][Hello friend.bas]]
 
 #+INCLUDE: "2D GFX/Hello friend.bas" src basic-qb45
 Download source code: [[file:2D%20GFX/Hello%20friend.bas][Hello friend.bas]]
 
 #+INCLUDE: "2D GFX/Hello friend.bas" src basic-qb45


@@ -138,6 +171,12 @@ animated transitions and effects.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The opening slide of the presentation: a glowing green "HEADER"
+title hovers over five color-coded stick figures while the ground
+under them ripples like a wave. The program plays a sequence of such
+slides, animating each scene and moving between them with transition
+effects.
+

 Download source code: [[file:2D%20GFX/People.bas][People.bas]]
 
 *** Stroboscope
 Download source code: [[file:2D%20GFX/People.bas][People.bas]]
 
 *** Stroboscope


@@ -155,10 +194,22 @@ diagrams.
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Stroboscope.bas][file:2D%20GFX/Stroboscope%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Stroboscope.bas][file:2D%20GFX/Stroboscope%20-%20Screenshot%200.png]]
 

+The title slide of the presentation: "Presentation about:" on a
+magenta banner, followed by the word "STROBOSCOPE" in large letters
+with a red-to-yellow gradient fill, signed by the author at the
+bottom. Animated transitions like this lead the viewer through the
+slides.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Stroboscope%20-%20Screenshot%201.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Stroboscope%20-%20Screenshot%201.png]]
 

+The "Principal schematic" slide: a cyan circuit diagram on a black
+background showing the stroboscope's parts -- resistors, a D336B
+diode, a high-voltage capacitor, a trimmer and the trigger
+transformer. The program draws the whole schematic with line and
+shape primitives and annotates each component value.
+

 Download source code: [[file:2D%20GFX/Stroboscope.bas][Stroboscope.bas]]
 
 *** Truncated cone
 Download source code: [[file:2D%20GFX/Stroboscope.bas][Stroboscope.bas]]
 
 *** Truncated cone


@@ -176,6 +227,12 @@ the viability of generating images of 3D shapes using code.
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Truncated%20cone.bas][file:2D%20GFX/Truncated%20cone%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:2D%20GFX/Truncated%20cone.bas][file:2D%20GFX/Truncated%20cone%20-%20Screenshot%200.png]]
 

+The finished drawing: a top cylinder with diagonal hatching on its
+end face, a tapering frustum in the middle and a smaller cylinder at
+the bottom, all outlined against the black screen. Vertical gradient
+bands across each surface fake the shading, testing how convincingly
+a 3D solid can be suggested with plain 2D line and fill primitives.
+

 Download source code: [[file:2D%20GFX/Truncated%20cone.bas][Truncated cone.bas]]
 
 #+INCLUDE: "2D GFX/Truncated cone.bas" src basic-qb45
 Download source code: [[file:2D%20GFX/Truncated%20cone.bas][Truncated cone.bas]]
 
 #+INCLUDE: "2D GFX/Truncated cone.bas" src basic-qb45


@@ -195,6 +252,13 @@ Download source code: [[file:2D%20GFX/Truncated%20cone.bas][Truncated cone.bas]]
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Miscellaneous/index.html][file:3D%20GFX/Miscellaneous/logo.png]]
 
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Miscellaneous/index.html][file:3D%20GFX/Miscellaneous/logo.png]]
 

+A four-panel wireframe sampler of the 3D demo collection: cubes
+resting on a grid floor, a tilted plane propped on supports, an
+intersecting girder-like structure and an open box with a tiled
+floor. All of it is rendered by the same homegrown 3D pipeline --
+vertices transformed, edges projected and drawn as lines in real
+time.
+

 [[file:3D GFX/Miscellaneous/index.html][See entire miscellaneous 3D demo applications collection]]
 
 ** Space related animations
 [[file:3D GFX/Miscellaneous/index.html][See entire miscellaneous 3D demo applications collection]]
 
 ** Space related animations


@@ -207,6 +271,13 @@ Download source code: [[file:2D%20GFX/Truncated%20cone.bas][Truncated cone.bas]]
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Space/index.html][file:3D%20GFX/Space/logo.png]]
 
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Space/index.html][file:3D%20GFX/Space/logo.png]]
 

+Four scenes from the space programs: a globular star cluster, a
+spiral galaxy trailing debris, a deep starfield with a small comet,
+and a wireframe parabolic antenna dish with raw numeric readouts
+ticking above it. Each program simulates a piece of space -- from
+orbiting stars to a flying rocket -- with simple physics and
+projected 3D graphics.
+

 [[file:3D GFX/Space/index.html][See entire space themed applications collection]]
 
 ** 3D Synthezier
 [[file:3D GFX/Space/index.html][See entire space themed applications collection]]
 
 ** 3D Synthezier


@@ -225,6 +296,13 @@ See directory:
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/3D%20Synthezier/doc/index.html][file:3D%20GFX/3D%20Synthezier/doc/hexagonal%20city,%202.jpeg]]
 
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/3D%20Synthezier/doc/index.html][file:3D%20GFX/3D%20Synthezier/doc/hexagonal%20city,%202.jpeg]]
 

+A ray-traced rendering of the generated "hexagonal city" scene: a
+cluster of glass hexagonal towers with dark domed roofs and lit
+windows, small colored cubes floating between them, all standing on
+a reflective floor. The scene was described in the program's own
+scene definition language, exported as a Wavefront obj file and then
+rendered with an external renderer.
+

 [[file:3D%20GFX/3D%20Synthezier/doc/index.html][Read more]]
 
 ** Helicopter demo
 [[file:3D%20GFX/3D%20Synthezier/doc/index.html][Read more]]
 
 ** Helicopter demo


@@ -251,6 +329,13 @@ moves across the terrain and picks up objects.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The demo opens with a glowing "HELICOPTER" title over the terrain,
+then the flight begins: a blue wireframe helicopter skims over a
+green wireframe landscape whose hills were grown by a fractal
+subdivision algorithm, dipping down to pick up the yellow objects
+scattered across the ridges. Terrain, craft and cargo are all
+transformed and projected in real time.
+

 [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=3D+GFX/Helicopter;hb=HEAD][Project files]]
 
 ** Swapping 3D engine
 [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=3D+GFX/Helicopter;hb=HEAD][Project files]]
 
 ** Swapping 3D engine


@@ -273,10 +358,24 @@ into RAM, allowing for the potential rendering of very large worlds.
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Swapping%203D%20engine/screenshot.png]]
 
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Swapping%203D%20engine/screenshot.png]]
 

+Inside the wireframe world: the blue perspective lattice is the
+partitioning grid -- the world is chopped into cube-shaped fragments
+that are paged between disk and RAM as the viewer moves. Colored
+wireframe objects (green letters, red and cyan shapes) inhabit the
+cells, and the counters in the top corners report the engine's
+position and loaded-fragment state.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Swapping%203D%20engine/screenshot,%202.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Swapping%203D%20engine/screenshot,%202.png]]
 

+A top-down view across the same world: the dense blue grid of
+partition cubes stretches to the horizon with wireframe objects
+embedded in it. Only the cubes near the viewer are kept in memory;
+the rest stay on disk until needed, which is what lets the engine
+present a potentially endless world on a machine with very little
+RAM.
+

 Download source code: [[file:3D%20GFX/Swapping%203D%20engine/engine.bas][engine.bas]]
 
 ** 3D land
 Download source code: [[file:3D%20GFX/Swapping%203D%20engine/engine.bas][engine.bas]]
 
 ** 3D land


@@ -304,6 +403,13 @@ filled with colors that alternate to create a checkerboard pattern.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A yellow-and-black checkerboard sheet bulges into a smooth hill at
+its center and settles back again. The program walks a grid of
+points, displaces each one with a cosine of its distance from the
+center, applies a perspective projection and fills the resulting
+quadrilaterals in alternating colors, animating the distortion over
+time.
+

 Download source code: [[file:3D%20GFX/3D%20land.bas][3D land.bas]]
 
 #+INCLUDE: "3D GFX/3D land.bas" src basic-qb45
 Download source code: [[file:3D%20GFX/3D%20land.bas][3D land.bas]]
 
 #+INCLUDE: "3D GFX/3D land.bas" src basic-qb45


@@ -334,6 +440,13 @@ in stereoscopy and 3D visualization.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Wireframe cubes tumble and bounce above a spherical grid arena,
+every edge drawn twice -- once in red, once in cyan -- with the
+offset between the two copies encoding depth. Viewed through
+red/cyan glasses the double image fuses into a stereoscopic scene;
+without them the colored fringes show exactly how the anaglyph
+parallax is constructed.
+

 [[file:3D%20GFX/Anaglyph.bas][Anaglyph.bas]]
 
 ** Ray casting engine
 [[file:3D%20GFX/Anaglyph.bas][Anaglyph.bas]]
 
 ** Ray casting engine


@@ -362,10 +475,22 @@ specified keys to turn, look up/down, and even jump.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A first-person walk through the ray-cast world: a blue checkerboard
+floor, rainbow-striped pyramids and towers, colored pillars and
+hills ringed with contour bands. The engine casts rays through a
+height map and adapts its rendering resolution on the fly to hold a
+steady 10 frames per second, which is why surfaces smear into coarse
+stripes when the camera gets close.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Ray%20casting%20engine%20-%20Screenshot%200.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:3D%20GFX/Ray%20casting%20engine%20-%20Screenshot%200.png]]
 

+The engine's frozen welcome screen: "Press any key to continue..."
+hangs above a still render of the same landscape -- a
+rainbow-striped wall on the left, a contour-ringed mound on the
+right and the checkered ground plane stretching between them.
+

 Download source code: [[file:3D%20GFX/Ray%20casting%20engine.bas][Ray casting engine.bas]]
 
 * Games
 Download source code: [[file:3D%20GFX/Ray%20casting%20engine.bas][Ray casting engine.bas]]
 
 * Games


@@ -391,6 +516,12 @@ between screens. Player has to avoid contact with evil hedgehogs.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+Gameplay of the first Pomppu Paavo: the little character hops across
+purple block platforms outlined in cyan, past trees and pink bushes,
+gathering coins while white hedgehogs patrol the ledges. The top
+line tracks collected coins and remaining lives; touching a hedgehog
+costs a life, and clearing a screen opens the way to the next one.
+

 [[file:Games/Pomppu%20Paavo/Pomppu%20Paavo.bas][Source code]]
 
 ** Pomppu Paavo 2
 [[file:Games/Pomppu%20Paavo/Pomppu%20Paavo.bas][Source code]]
 
 ** Pomppu Paavo 2


@@ -412,10 +543,22 @@ between screens. Player has to avoid contact with evil snails.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The sequel trades the dark maze for daylight: blue sky with dithered
+clouds, grey brick platforms and green bushes. The hero in the red
+cap jumps between ledges collecting golden coins laid out in arcs,
+while red snails crawl along the bricks. The bottom line shows the
+coin purse and the remaining lives.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Games/Pomppu%20Paavo%202/Pomppu%20Paavo%20-%20Screenshot%200.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Games/Pomppu%20Paavo%202/Pomppu%20Paavo%20-%20Screenshot%200.png]]
 

+A mid-game still: coins arc over a gap between brick platforms,
+trees and bushes decorate the skyline, and the small red character
+stands at the left edge planning the next jump. The icons at the
+bottom left count collected coins and the three spare lives. Level
+graphics are loaded from separate image asset files at startup.
+

 [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=Games/Pomppu+Paavo+2][Source code]]
 
 Source code organization:
 [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=Games/Pomppu+Paavo+2][Source code]]
 
 Source code organization:


@@ -448,6 +591,13 @@ it loses one life.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+A multiplayer match in progress on the blue grid arena inside a
+green brick wall: dotted worms in white, yellow, red and green weave
+around each other hunting the fruit. The side panel shows the
+current level, every player's score and remaining lives, including
+the AI-controlled worms; eating enough fruit advances everyone to
+the next level.
+

 [[file:Games/Worm/worm.bas][Source code]]
 
 Levels are stored in [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=Games/Worm;hb=HEAD]['lvl' files]] that are directly editable using text
 [[file:Games/Worm/worm.bas][Source code]]
 
 Levels are stored in [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=Games/Worm;hb=HEAD]['lvl' files]] that are directly editable using text


@@ -471,6 +621,13 @@ utilize when possible.
 #+attr_latex: :width 1000px
 [[file:Games/checkers.bas][file:Games/checkers%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Games/checkers.bas][file:Games/checkers%20-%20Screenshot%200.png]]
 

+The monochrome 10x10 board in high-resolution two-color graphics,
+partway through a game, with the "From where?" prompt waiting for
+input. Moves are made with an arrow-key cursor and the ENTER key --
+pick up a piece, place it on a reachable square -- while the program
+enforces the capture rules and the pattern-driven AI plans its
+reply.
+

 ** Checkers 2
 :PROPERTIES:
 :CUSTOM_ID: checkers-2
 ** Checkers 2
 :PROPERTIES:
 :CUSTOM_ID: checkers-2


@@ -493,6 +650,13 @@ larder board size.
 #+attr_latex: :width 1000px
 [[file:Games/checkers2.bas][file:Games/checkers2%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Games/checkers2.bas][file:Games/checkers2%20-%20Screenshot%200.png]]
 

+The 6x6 board of the second checkers program, with green column
+letters A-F and row numbers 1-6 along the edges. The transcript on
+the right is the AI thinking out loud: "positions processed: 428057"
+-- hundreds of thousands of board positions evaluated by the
+recursive lookahead before each computer move, followed by prompts
+like "You may eat." when a capture is available.
+

 * Math
 :PROPERTIES:
 :CUSTOM_ID: math
 * Math
 :PROPERTIES:
 :CUSTOM_ID: math


@@ -521,12 +685,19 @@ scene is rendered frame by frame.
 #+begin_export html
 <div class="flex-center">
   <video controls loop autoplay>
 #+begin_export html
 <div class="flex-center">
   <video controls loop autoplay>

-    <source src="Math/Game%20of%20life%20in%203D.webm" type="video/webm">
+    <source src="Math/Game of life in 3D - Screencast 0.mp4" type="video/mp4">

     Your browser does not support the video tag.
   </video>
 </div>
 #+end_export
 
     Your browser does not support the video tag.
   </video>
 </div>
 #+end_export
 

+Clusters of white and green wireframe cubes hang in dark space while
+the camera slowly orbits around them. Each cube is one live cell of
+Conway's Game of Life; on every step the grid is updated by the
+classic neighbor rules and the scene is redrawn, so whole
+constellations of cubes blink in and out of existence as the pattern
+evolves.
+

 Download source code: [[file:Math/Game%20of%20life%20in%203D.bas][Source code]]
 
 ** Game of life studio
 Download source code: [[file:Math/Game%20of%20life%20in%203D.bas][Source code]]
 
 ** Game of life studio


@@ -541,7 +712,23 @@ configurations of the Game of Life.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Math/Game%20of%20life/Game%20of%20life.bas][file:Math/Game%20of%20life/screenshot.png]]
+[[file:Math/Game%20of%20life/Game%20of%20life.bas][file:Math/Game%20of%20life/Game%20of%20life%20-%20Screenshot%200.png]]
+
+A running simulation on the blue editing grid: green cells form
+gliders, oscillators and still lifes scattered across the field,
+while the "frame: 4" counter in the corner tracks the current
+generation. Patterns evolve automatically once the simulation is
+started.
+
+#+attr_html: :class responsive-img
+#+attr_latex: :width 1000px
+[[file:Math/Game%20of%20life/Game%20of%20life%20-%20Screenshot%201.png]]
+
+Editing mode: a white selection rectangle is drawn around a stored
+pattern at the bottom of the grid while a larger structure sits at
+the top. Configurations can be painted cell by cell, moved, saved
+and reloaded, turning the program into a small studio for
+experimenting with Game of Life patterns.

 
 [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=Math/Game+of+life;hb=HEAD][Source code]]
 
 
 [[https://www2.svjatoslav.eu/gitweb/?p=qbasicapps.git;a=tree;f=Math/Game+of+life;hb=HEAD][Source code]]
 


@@ -557,6 +744,12 @@ functions.
 #+attr_latex: :width 1000px
 [[file:Math/Plotting/index.html][file:Math/Plotting/logo.png]]
 
 #+attr_latex: :width 1000px
 [[file:Math/Plotting/index.html][file:Math/Plotting/logo.png]]
 

+A collage of the plotting programs at work: a 2D function graph with
+its tangent line, a 3D wireframe surface rising into a central
+spike, layered polynomial curves, and a labeled sine/cosine table
+plot. Each program sweeps a mathematical function across the screen,
+scaling axes and drawing grid lines along the way.
+

 [[file:Math/Plotting/index.html][See entire collection of mathematical plots]]
 
 ** Simulations
 [[file:Math/Plotting/index.html][See entire collection of mathematical plots]]
 
 ** Simulations


@@ -571,6 +764,13 @@ mathematical and physical effects.
 #+attr_latex: :width 1000px
 [[file:Math/Simulation/index.html][file:Math/Simulation/logo.png]]
 
 #+attr_latex: :width 1000px
 [[file:Math/Simulation/index.html][file:Math/Simulation/logo.png]]
 

+Four of the physics and math simulations: a sharp impulse waveform,
+a spirograph-like rosette of nested dotted circles, a field of
+random dots from a cellular-style process, and paired oscillating
+waves. The collection covers gravity in 2D and 3D, wave
+interference, surface tension and explosions -- each one a small
+numerical model animated step by step.
+

 [[file:Math/Simulation/index.html][See entire collection of simulations]]
 
 ** Truth table calculator
 [[file:Math/Simulation/index.html][See entire collection of simulations]]
 
 ** Truth table calculator


@@ -584,7 +784,20 @@ table).
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Math/Truth%20table/index.html][file:Math/Truth%20table/img/screenshot,%202.png]]
+[[file:Math/Truth%20table/index.html][file:Math/Truth%20table/truth%20-%20Screenshot%202.png]]
+
+The equation entry screen: the prompt lists the numeric keys that
+insert logical operators (equivalence, implication, OR, AND, NOT)
+together with an example formula, and the user has typed in a
+three-variable equation ready to be evaluated.
+
+#+attr_html: :class responsive-img
+#+attr_latex: :width 1000px
+[[file:Math/Truth%20table/truth%20-%20Screenshot%203.png]]
+
+The computed truth table for the entered formula: one row per
+combination of the variables, with color-coded t/f values for every
+input column and the final result column on the right.

 
 [[file:Math/Truth%20table/index.html][Read more about truth table calculator]]
 
 
 [[file:Math/Truth%20table/index.html][Read more about truth table calculator]]
 


@@ -610,7 +823,29 @@ assigns a grade based on the percentage of correct answers.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Math/Multiplication%20trainer.bas][file:Math/Multiplication%20trainer.png]]
+[[file:Math/Multiplication%20trainer.bas][file:Math/Multiplication%20trainer%20-%20Screenshot%200.png]]
+
+A training session in progress: the program asks "How much is: 8 X
+8", rejects the answer 3 with "Wrong!" and shows the correct
+product, then accepts 12 for 3 X 4 with "Correct!". Questions are
+random pairs of single digits, and after the run the program scores
+the answers and assigns a grade.
+
+#+begin_export html
+<div class="flex-center">
+  <video controls loop autoplay>
+    <source src="Math/Multiplication trainer - Screencast 0.mp4" type="video/mp4">
+    Your browser does not support the video tag.
+  </video>
+</div>
+#+end_export
+
+A full session from greeting to quiz: the "Math teaching program"
+banner sits over a gradient backdrop while an animated red light bar
+sweeps the bottom of the screen and the program asks for the
+player's name and the number of questions (10). The drill then
+begins with "How much is: 1 X 5 ?" -- the answer 5 earns a
+"Correct !" before the next pair, 6 X 8, is presented.

 
 [[file:Math/Multiplication%20trainer.bas][Source code]]
 
 
 [[file:Math/Multiplication%20trainer.bas][Source code]]
 


@@ -625,9 +860,15 @@ function to compare results. 1 pixel vertical shift is intentional.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Math/Sine%20computation.bas][file:Math/Sine%20computation.png]]
+[[file:Math/Sine%20computation.bas][file:Math/Sine%20computation%20-%20Screenshot%200.png]]

 
 

-[[file:Math/Multiplication%20trainer.bas][Source code]]
+One full period of the sine wave plotted twice: one curve is the
+built-in SIN function and the fringe hugging it is the custom finite
+formula, deliberately shifted one pixel so the two can be compared.
+The near-perfect overlap shows how closely the invented
+approximation tracks the real thing.
+
+[[file:Math/Sine%20computation.bas][Source code]]

 
 ** Lottery analysis
 :PROPERTIES:
 
 ** Lottery analysis
 :PROPERTIES:


@@ -647,7 +888,12 @@ become easily detectable in visual graphs.
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Math/Lottery/Lottery%20analysis.bas][file:Math/Lottery/screenshot,%203.png]]
+[[file:Math/Lottery/Lottery%20analysis.bas][file:Math/Lottery/Lottery%20analysis%20-%20Screenshot%200.png]]
+
+The dot graph view: every draw becomes a vertical column of green
+dots, one dot per drawn number, with the dense band of all
+historical draws packed across the top. Deliberately repeated
+patterns in the example data show up as matching columns.

 
 Graphical Representations:
 
 
 Graphical Representations:
 


@@ -657,7 +903,12 @@ Graphical Representations:
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px

-[[file:Math/Lottery/Lottery%20analysis.bas][file:Math/Lottery/screenshot,%202.png]]
+[[file:Math/Lottery/Lottery%20analysis.bas][file:Math/Lottery/Lottery%20analysis%20-%20Screenshot%201.png]]
+
+The main menu and the statistics view: the program offers dot graph,
+line graph, combinatorics and statistics modes, and here it lists
+how often each number appeared in the recent draws and how many
+draws ago it was last seen.

 
 - Line Graph :: Shows a dynamic line graph connecting consecutive
   lottery numbers, providing a visual representation of number trends
 
 - Line Graph :: Shows a dynamic line graph connecting consecutive
   lottery numbers, providing a visual representation of number trends


@@ -669,9 +920,20 @@ Graphical Representations:
   visible at a single resolution. This feature introduces the concept
   of combinatorics and pattern recognition in data visualization.
 
   visible at a single resolution. This feature introduces the concept
   of combinatorics and pattern recognition in data visualization.
 

-#+attr_html: :class responsive-img
-#+attr_latex: :width 1000px
-[[file:Math/Lottery/Lottery%20analysis.bas][file:Math/Lottery/screenshot,%201.png]]
+#+begin_export html
+<div class="flex-center">
+  <video controls loop autoplay>
+    <source src="Math/Lottery/Lottery analysis - Screencast 1.mp4" type="video/mp4">
+    Your browser does not support the video tag.
+  </video>
+</div>
+#+end_export
+
+The combinatorics view being drawn: the same draw data is re-fitted
+at every possible resolution, sweeping from a tiny mesh squeezed
+into the corner up to full-screen columns of colored segments.
+Watching the graph rebuild at each scale makes hidden repetitions in
+the data pop out at whatever resolution they live on.

 
 [[file:Math/Lottery/Lottery%20analysis.bas][Source code]]
 
 
 [[file:Math/Lottery/Lottery%20analysis.bas][Source code]]
 


@@ -696,6 +958,12 @@ written in x86 assembly and a QBasic demonstration program.
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Mouse%20driver/index.html][file:Miscellaneous/Mouse%20driver/screenshot.png]]
 
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Mouse%20driver/index.html][file:Miscellaneous/Mouse%20driver/screenshot.png]]
 

+The demo program running under the TSR mouse driver: the green
+circle is the mouse cursor gliding across the graphics screen, and
+the readout in the corner ("X: 218 Y: 143", plus a frame counter)
+tracks its live position. The assembly TSR hooks the mouse interrupt
+and hands coordinates and button state to plain QBasic code.
+

 [[file:Miscellaneous/Mouse%20driver/index.html][Read more about mouse driver for QBasic]]
 
 ** Alien font
 [[file:Miscellaneous/Mouse%20driver/index.html][Read more about mouse driver for QBasic]]
 
 ** Alien font


@@ -714,6 +982,12 @@ abstract art.
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Alien%20font.bas][file:Miscellaneous/Alien%20font%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Alien%20font.bas][file:Miscellaneous/Alien%20font%20-%20Screenshot%200.png]]
 

+A page of the generated alien script: every glyph is a square
+subdivided into four triangles, some filled black and some left
+white, so each character reads as an abstract triangular mosaic.
+Strung together in dense rows, the procedural glyphs form a
+convincing but completely imaginary writing system.
+

 ** Custom palette
 :PROPERTIES:
 :CUSTOM_ID: custom-palette
 ** Custom palette
 :PROPERTIES:
 :CUSTOM_ID: custom-palette


@@ -737,10 +1011,22 @@ palette, providing a visual representation of all available colors:
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Custom%20palette.bas][file:Miscellaneous/Custom%20palette%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Custom%20palette.bas][file:Miscellaneous/Custom%20palette%20-%20Screenshot%200.png]]
 

+The generated 6x6x6 palette shown as vertical gradient strips: each
+column fixes two of the RGB components and sweeps the third from
+dark to bright, walking through greens, cyans, blues, magentas, reds
+and white. The 216 register values are written straight to the VGA
+palette ports.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Custom%20palette.bas][file:Miscellaneous/Custom%20palette%20-%20Screenshot%201.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Custom%20palette.bas][file:Miscellaneous/Custom%20palette%20-%20Screenshot%201.png]]
 

+The palette in action: six tiles filled with concentric circle
+fills, one tile per color family -- greyscale, pastels and saturated
+primaries. Because every ring picks its color from the same
+216-entry palette, the demo doubles as a visual index of what the
+palette can express.
+

 The dithering process helps to mitigate the limitations of the
 256-color palette, making the gradients appear smoother to the eye:
 
 The dithering process helps to mitigate the limitations of the
 256-color palette, making the gradients appear smoother to the eye:
 


@@ -748,6 +1034,12 @@ The dithering process helps to mitigate the limitations of the
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Custom%20palette.bas][file:Miscellaneous/Custom%20palette%20-%20Screenshot%202.png]]
 
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Custom%20palette.bas][file:Miscellaneous/Custom%20palette%20-%20Screenshot%202.png]]
 

+The same tiles re-rendered with dithering: radial gradients now
+blend smoothly from the center outward, mixing palette colors in
+checkerboard pixels to fake the shades in between. The eye averages
+the speckles into continuous color, stretching the 256-color limit
+much further than flat fills could.
+

 ** Alarm 1
 :PROPERTIES:
 :CUSTOM_ID: alarm-1
 ** Alarm 1
 :PROPERTIES:
 :CUSTOM_ID: alarm-1


@@ -907,6 +1199,12 @@ see multiple overlayed 3D shapes at the same time.
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/4D%20engine.bas][file:Miscellaneous/4D%20engine%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/4D%20engine.bas][file:Miscellaneous/4D%20engine%20-%20Screenshot%200.png]]
 

+The engine's help screen: the full control map for four dimensions.
+Keys rotate the pentatope in each of the six 4D planes (qw, as, zx
+for the familiar XZ/YZ/XY planes, er, df, cv for the novel QX/QY/QZ
+ones), other key pairs move the viewer along the x, y, z and q axes,
+and ESC quits.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/4D%20engine%20-%20Screenshot%201.png]]
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/4D%20engine%20-%20Screenshot%201.png]]


@@ -938,13 +1236,19 @@ of the active window, creating a dynamic visual effect.
 #+begin_export html
 <div class="flex-center">
   <video controls loop autoplay>
 #+begin_export html
 <div class="flex-center">
   <video controls loop autoplay>

-    <source src="Miscellaneous/Windowing%20system.webm" type="video/webm">
+    <source src="Miscellaneous/wsystem - Screencast 0.mp4" type="video/mp4">

     Your browser does not support the video tag.
   </video>
 </div>
 #+end_export
 
     Your browser does not support the video tag.
   </video>
 </div>
 #+end_export
 

-Download source code: [[file:Miscellaneous/Windowing%20system.bas][Windowing system.bas]]
+Overlapping text windows on a dark blue desktop: one window scrolls
+the demo's own description, others display BASIC source code, each
+framed with a cyan border and a title bar. The program loads text
+files into windows, supports horizontal and vertical scrolling and
+animates the active window's content.
+
+Download source code: [[file:Miscellaneous/wsystem.bas][Windowing system.bas]]

 
 ** Password lock
 :PROPERTIES:
 
 ** Password lock
 :PROPERTIES:


@@ -979,12 +1283,48 @@ message.
 </div>
 #+end_export
 
 </div>
 #+end_export
 

+The rocket ground control desktop comes up: an oscilloscope window
+traces a green waveform, a stack-dump window scrolls binary digits
+above the words "Running rocket ground control system", and the
+central dialog demands "ENTER PASSWORD:". Windows with yellow title
+bars sit on a grey grid backdrop while the program waits for input.
+

 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Password%20lock/passw.bas][file:Miscellaneous/Password%20lock/screenshot,%202.png]]
 
 #+attr_html: :class responsive-img
 #+attr_latex: :width 1000px
 [[file:Miscellaneous/Password%20lock/passw.bas][file:Miscellaneous/Password%20lock/screenshot,%202.png]]
 

+Three wrong guesses later: the central dialog reports "Wrong
+password / 0 chances left / SYSTEM HALTED SUCCESSFULLY!!" while the
+oscilloscope and stack-dump windows freeze in the background. The
+password itself lives in an external passw.dat file, and each failed
+attempt decrements the remaining-tries counter.
+

 Download source code: [[file:Miscellaneous/Password%20lock/passw.bas][passw.bas]]
 
 Download source code: [[file:Miscellaneous/Password%20lock/passw.bas][passw.bas]]
 

+** Pressed key test
+:PROPERTIES:
+:CUSTOM_ID: pressed-key-test
+:END:
+
+This tiny QBasic utility shows what the keyboard actually delivers to
+a program: it waits for a key press with INKEY$, echoes the typed
+character, and prints the ASCII value of the first and the last
+character of the returned string -- handy for discovering the
+two-byte codes that extended keys produce.
+
+#+attr_html: :class responsive-img
+#+attr_latex: :width 1000px
+[[file:Miscellaneous/Pressed%20key%20test.bas][file:Miscellaneous/Pressed%20key%20test%20-%20Screenshot%200.png]]
+
+The utility echoing keys as they are pressed: each "You typed:" line
+repeats the character (o, e, u, then H, e, l, l, o as "Hello" is
+entered), followed by the ASCII value of the first and last
+character of the returned string -- 72 for 'H'. For ordinary keys
+the two values match, while extended keys arrive as two-character
+strings whose codes the program reports separately.
+
+[[file:Miscellaneous/Pressed%20key%20test.bas][Source code]]
+

 * Networking
 :PROPERTIES:
 :CUSTOM_ID: networking
 * Networking
 :PROPERTIES:
 :CUSTOM_ID: networking


@@ -1012,6 +1352,12 @@ The program uses bit manipulation to control individual pins.
 #+attr_latex: :width 1000px
 [[file:Networking/LPT%20pin%20control.bas][file:Networking/LPT%20pin%20control.png]]
 
 #+attr_latex: :width 1000px
 [[file:Networking/LPT%20pin%20control.bas][file:Networking/LPT%20pin%20control.png]]
 

+The pin control panel: eight numbered positions for the parallel
+port's data pins, with blue squares lit above the pins that are
+currently driven high. Pressing keys 1-8 flips the matching bit in
+the port's data register, raising or dropping the voltage on the
+corresponding physical pin.
+

 Download source code: [[file:Networking/LPT%20pin%20control.bas][LPT pin control.bas]]
 
 ** COM port text terminal
 Download source code: [[file:Networking/LPT%20pin%20control.bas][LPT pin control.bas]]
 
 ** COM port text terminal


@@ -1103,6 +1449,13 @@ Utilities to encode digital data to sound file and back.
 #+attr_latex: :width 1000px
 [[file:Networking/Digital%20data%20over%20analog%20audio/index.html][file:Networking/Digital%20data%20over%20analog%20audio/screenshot.png]]
 
 #+attr_latex: :width 1000px
 [[file:Networking/Digital%20data%20over%20analog%20audio/index.html][file:Networking/Digital%20data%20over%20analog%20audio/screenshot.png]]
 

+The decoder at work: columns list each recovered byte as binary,
+decimal, hexadecimal and character while the program searches the
+digitized audio for the sync pattern ("searching for beginning...
+Beginning point found!") and completes its statistical analyze pass.
+On the right a crosshair walks the recovered bit grid, and the
+decoded sample message prints at the bottom.
+

 [[file:Networking/Digital%20data%20over%20analog%20audio/index.html][Read more]]
 
 ** Morse
 [[file:Networking/Digital%20data%20over%20analog%20audio/index.html][Read more]]
 
 ** Morse


@@ -1128,8 +1481,52 @@ represented by short beeps, and dashes by longer beeps.
 #+attr_latex: :width 1000px
 [[file:Networking/Morse.bas][file:Networking/Morse%20-%20Screenshot%200.png]]
 
 #+attr_latex: :width 1000px
 [[file:Networking/Morse.bas][file:Networking/Morse%20-%20Screenshot%200.png]]
 

+A Morse session in the text screen: after the "Type '.bye' to quit"
+hint, each typed line ("Hello", "What a nice day !") is echoed back
+while the PC speaker beeps out every character's dot and dash
+pattern looked up from Morse.txt -- short beeps for dots, long ones
+for dashes.
+

 Download source code: [[file:Networking/Morse.bas][Morse.bas]]
 
 Download source code: [[file:Networking/Morse.bas][Morse.bas]]
 

+* Tutorial
+:PROPERTIES:
+:CUSTOM_ID: tutorial
+:END:
+
+** Quicksort visualization
+:PROPERTIES:
+:CUSTOM_ID: quicksort-visualization
+:END:
+
+This QBasic program visualizes a recursive quicksort on 45 random
+values in an 80x50 text screen, highlighting the active partition
+range, the scanning pointers and the split point as the sort
+progresses, and re-checks the result after every run.
+
+#+begin_export html
+<div class="flex-center">
+  <video controls loop autoplay>
+    <source src="Tutorial/qsort3 - Screencast 0.mp4" type="video/mp4">
+    Your browser does not support the video tag.
+  </video>
+</div>
+#+end_export
+
+Each row shows one array element (value and index). Instead of a
+median pivot the program splits each range at the midpoint between
+its minimum and maximum, shown at the top right (49.5, then 80.5 as
+the upper partition is sorted). The blue bars mark the two scanning
+pointers that walk towards each other swapping out-of-place
+elements, the red bar marks the range endpoints of the active
+partition, and the split index flashes yellow before the recursion
+descends into the two halves. When a run finishes, the program
+verifies the array is ordered and, on any failure, restores the
+original data and re-sorts it step by step waiting for a keypress
+per redraw.
+
+Download source code: [[file:Tutorial/qsort3.bas][qsort3.bas]]
+

 * Download
 :PROPERTIES:
 :CUSTOM_ID: download
 * Download
 :PROPERTIES:
 :CUSTOM_ID: download