From 403109d4994bf604ffe489048fde0f1e325a3643 Mon Sep 17 00:00:00 2001
From: Svjatoslav Agejenko <svjatoslav@svjatoslav.eu>
Date: Wed, 25 Jun 2025 17:46:27 +0300
Subject: [PATCH] Better code readability

---
 3D GFX/Maze explorer/mazeexplorer.bas | 306 ++++++++++++--------------
 3D GFX/Ray casting engine/raycast.bas | 272 ++++++++++++-----------
 2 files changed, 278 insertions(+), 300 deletions(-)

diff --git a/3D GFX/Maze explorer/mazeexplorer.bas b/3D GFX/Maze explorer/mazeexplorer.bas
index 3b7353d..2810ade 100755
--- a/3D GFX/Maze explorer/mazeexplorer.bas	
+++ b/3D GFX/Maze explorer/mazeexplorer.bas	
@@ -1,4 +1,3 @@
-DECLARE SUB verifyTsrIsLoaded ()
 ' Evolving 3D Maze explorer.
 '
 ' By Svjatoslav Agejenko.
@@ -7,7 +6,7 @@ DECLARE SUB verifyTsrIsLoaded ()
 
 ' Changelog:
 ' 2003.12, Initial version
-' 2024, Improved program readability using AI
+' 2024 - 2025, Improved program readability
 '
 ' Navigation:
 '   WASD - move around
@@ -17,210 +16,216 @@ DECLARE SUB verifyTsrIsLoaded ()
 '
 ' Press 'q' to quit the program
 
+DECLARE SUB verifyTsrIsLoaded ()
 DECLARE SUB startText ()
-DECLARE SUB control ()
+DECLARE SUB handleInput ()
 DECLARE SUB putByte (addr!, dat!)
 DECLARE SUB putWord (addr!, dat!)
 DECLARE FUNCTION getWord! (addr!)
 DECLARE FUNCTION getByte! (addr!)
-DECLARE SUB start ()
-DECLARE SUB animate ()
+DECLARE SUB initializeProgram ()
+DECLARE SUB render3DScene ()
 
-DIM SHARED px(1 TO 500)
-DIM SHARED py(1 TO 500)
-DIM SHARED pz(1 TO 500)
-DIM SHARED rpx(1 TO 500)
-DIM SHARED rpy(1 TO 500)
-DIM SHARED rpe(1 TO 500)
+DIM SHARED pointX(1 TO 500)
+DIM SHARED pointY(1 TO 500)
+DIM SHARED pointZ(1 TO 500)
+DIM SHARED renderedPointX(1 TO 500)
+DIM SHARED renderedPointY(1 TO 500)
+DIM SHARED renderedPointEnabled(1 TO 500)
 
-DIM SHARED l1(1 TO 500)
-DIM SHARED l2(1 TO 500)
-DIM SHARED lc(1 TO 500)
+DIM SHARED lineStart(1 TO 500)
+DIM SHARED lineEnd(1 TO 500)
+DIM SHARED lineColor(1 TO 500)
 
-DIM SHARED nl, np
+DIM SHARED lineCount, pointCount
 
-DIM SHARED an1, an2, an3
+DIM SHARED angleY, angleX, angleZ
 
-DIM SHARED tim
+DIM SHARED frameTime
 
-DIM SHARED extSEG, extADDR
+DIM SHARED extensionSegment, extensionAddress
 
-DIM SHARED myx, myy, myz
-DIM SHARED myxs, myys, myzs
-DIM SHARED buttonL, buttonR
-DIM SHARED maxmove
+DIM SHARED cameraX, cameraY, cameraZ
+DIM SHARED cameraXSpeed, cameraYSpeed, cameraZSpeed
+DIM SHARED leftMouseButton, rightMouseButton
+DIM SHARED maxMove
 
-nl = 0
-np = 0
+lineCount = 0
+pointCount = 0
 
-start
+initializeProgram
 
 ' Initialize position variables
-cx = 0
-cy = 0
-cz = 0
+currentX = 0
+currentY = 0
+currentZ = 0
 
-np = 1
-px(1) = 0
-py(1) = 0
-pz(1) = 0
+pointCount = 1
+pointX(pointCount) = currentX
+pointY(pointCount) = currentY
+pointZ(pointCount) = currentZ
 
 1
 
-IF np < 500 THEN
+IF pointCount < 500 THEN
 
   ' Increase the number of points and add a new point at the current position
-  np = np + 1
-  px(np) = cx
-  py(np) = cy
-  pz(np) = cz
+  pointCount = pointCount + 1
+  pointX(pointCount) = currentX
+  pointY(pointCount) = currentY
+  pointZ(pointCount) = currentZ
 
   ' Increase the number of lines and define a line between the new point and the previous one
-  nl = nl + 1
-  l1(nl) = np
-  l2(nl) = np - 1
-  lc(nl) = INT(RND * 15) + 1
+  lineCount = lineCount + 1
+  lineStart(lineCount) = pointCount
+  lineEnd(lineCount) = pointCount - 1
+  lineColor(lineCount) = INT(RND * 15) + 1
 
- 
-  SELECT CASE INT(RND * 3)  ' Randomly choose orientation for the next move
+  ' Randomly choose orientation for the next move
+  SELECT CASE INT(RND * 3)
   CASE 0
-    cx = RND * 500 - 250
+    currentX = RND * 500 - 250
   CASE 1
-    cy = RND * 100 - 50
+    currentY = RND * 100 - 50
   CASE 2
-    cz = RND * 500 - 250
+    currentZ = RND * 500 - 250
   END SELECT
 END IF
 
-
-control
-animate
+handleInput
+render3DScene
 
 ' Copy the current screen to page 1 and clear the screen
 PCOPY 0, 1
 CLS
 GOTO 1
 
-SUB animate
+SUB render3DScene
 
-s1 = SIN(an1)
-s2 = SIN(an2)
-s3 = SIN(an3)
+' Calculate sine and cosine for Y-axis rotation
+sinY = SIN(angleY)
+cosY = COS(angleY)
 
-c1 = COS(an1)
-c2 = COS(an2)
-c3 = COS(an3)
+' Calculate sine and cosine for X-axis rotation
+sinX = SIN(angleX)
+cosX = COS(angleX)
+
+' Calculate sine and cosine for Z-axis rotation (not used in current code)
+sinZ = SIN(angleZ)
+cosZ = COS(angleZ)
 
 ' Project 3D points to 2D screen coordinates
-FOR a = 1 TO np
-  x = px(a) - myx
-  y = py(a) - myy
-  z = pz(a) - myz
-
-  ' Rotate around the Y axis
-  x1 = x * c1 + z * s1
-  z1 = z * c1 - x * s1
-
-  ' Rotate around the X axis
-  y1 = y * c2 + z1 * s2
-  z2 = z1 * c2 - y * s2
-
-  ' Check if the point is in front of the camera
-  IF z2 > 3 THEN
-    rpe(a) = 1
-    rpx(a) = x1 / z2 * 130 + 160
-    rpy(a) = y1 / z2 * 130 + 100
+FOR a = 1 TO pointCount
+  deltaX = pointX(a) - cameraX
+  deltaY = pointY(a) - cameraY
+  deltaZ = pointZ(a) - cameraZ
+
+  ' Rotate around Y axis
+  rotatedX = deltaX * cosY + deltaZ * sinY
+  rotatedZ = deltaZ * cosY - deltaX * sinY
+
+  ' Rotate around X axis
+  rotatedY = deltaY * cosX + rotatedZ * sinX
+  finalZ = rotatedZ * cosX - deltaY * sinX
+
+  ' Check if the point is in front of the camera (finalZ > 3)
+  IF finalZ > 3 THEN
+    renderedPointEnabled(a) = 1
+    renderedPointX(a) = rotatedX / finalZ * 130 + 160
+    renderedPointY(a) = rotatedY / finalZ * 130 + 100
   ELSE
-    rpe(a) = 0
+    renderedPointEnabled(a) = 0
   END IF
 NEXT a
 
 ' Draw lines between visible points
-FOR a = 1 TO nl
+FOR a = 1 TO lineCount
 
-  p1 = l1(a)
-  p2 = l2(a)
-  IF (rpe(p1) = 1) AND (rpe(p2) = 1) THEN LINE (rpx(p1), rpy(p1))-(rpx(p2), rpy(p2)), lc(a)
+  p1 = lineStart(a)
+  p2 = lineEnd(a)
+  IF (renderedPointEnabled(p1) = 1) AND (renderedPointEnabled(p2) = 1) THEN
+    LINE (renderedPointX(p1), renderedPointY(p1))-(renderedPointX(p2), renderedPointY(p2)), lineColor(a)
+  END IF
 
 NEXT a
 
 END SUB
 
-SUB control
+SUB handleInput
 
 ' Read mouse data
 IF getByte(8) <> 0 THEN
   putByte 8, 0
-  ' read mouse translation along x axis
-  xp = getWord(2)
+  ' Read mouse translation along x axis
+  mouseXDelta = getWord(2)
   putWord 2, 0
-  ' read mouse translation along y axis
-  yp = getWord(4)
+  ' Read mouse translation along y axis
+  mouseYDelta = getWord(4)
   putWord 4, 0
-  ' read pressed mouse buttons
+  ' Read pressed mouse buttons
   button = getWord(6)
   putWord 6, 0
 
-  ' detect if left, right or both mouse buttons were pressed
-  buttonL = 0
-  buttonR = 0
-  IF button = 1 THEN buttonL = 1
-  IF button = 2 THEN buttonR = 1
-  IF button = 3 THEN buttonL = 1: buttonR = 1
+  ' Detect if left, right or both mouse buttons were pressed
+  leftMouseButton = 0
+  rightMouseButton = 0
+  IF button = 1 THEN leftMouseButton = 1
+  IF button = 2 THEN rightMouseButton = 1
+  IF button = 3 THEN leftMouseButton = 1: rightMouseButton = 1
 
-  IF buttonR = 1 THEN
-    IF buttonL = 1 THEN
+  IF rightMouseButton = 1 THEN
+    IF leftMouseButton = 1 THEN
       ' If mouse left and right buttons are pressed at the same time,
       ' use mouse translation to move avatar around X and Z axis.
-      myxs = myxs + SIN(an1) * yp / 4
-      myzs = myzs - COS(an1) * yp / 4
+      cameraXSpeed = cameraXSpeed + SIN(angleY) * mouseYDelta / 4
+      cameraZSpeed = cameraZSpeed - COS(angleY) * mouseYDelta / 4
       GOTO 3
     END IF
     ' If only right button is pressed, move around Y axis
-    myys = myys + yp / 4
+    cameraYSpeed = cameraYSpeed + mouseYDelta / 4
 3
-    yp = 0
+    mouseYDelta = 0
   END IF
 
 END IF
 
-' Limit mouse movement to maxmove
-IF xp < -maxmove THEN xp = -maxmove
-IF xp > maxmove THEN xp = maxmove
-an1 = an1 - xp / 150
+' Limit mouse movement to maxMove
+IF mouseXDelta < -maxMove THEN mouseXDelta = -maxMove
+IF mouseXDelta > maxMove THEN mouseXDelta = maxMove
+angleY = angleY - mouseXDelta / 150
 
-IF yp < -maxmove THEN yp = -maxmove
-IF yp > maxmove THEN yp = maxmove
-an2 = an2 - yp / 150
+IF mouseYDelta < -maxMove THEN mouseYDelta = -maxMove
+IF mouseYDelta > maxMove THEN mouseYDelta = maxMove
+angleX = angleX - mouseYDelta / 150
 
 ' Read keyboard input and update player position
-a$ = INKEY$
+keyInput$ = INKEY$
 
-IF a$ = "a" THEN myxs = myxs - COS(an1): myzs = myzs - SIN(an1)
-IF a$ = "d" THEN myxs = myxs + COS(an1): myzs = myzs + SIN(an1)
-IF a$ = "w" THEN myxs = myxs - SIN(an1): myzs = myzs + COS(an1)
-IF a$ = "s" THEN myxs = myxs + SIN(an1): myzs = myzs - COS(an1)
-IF a$ = "q" THEN SYSTEM
+IF keyInput$ = "a" THEN cameraXSpeed = cameraXSpeed - COS(angleY): cameraZSpeed = cameraZSpeed - SIN(angleY)
+IF keyInput$ = "d" THEN cameraXSpeed = cameraXSpeed + COS(angleY): cameraZSpeed = cameraZSpeed + SIN(angleY)
+IF keyInput$ = "w" THEN cameraXSpeed = cameraXSpeed - SIN(angleY): cameraZSpeed = cameraZSpeed + COS(angleY)
+IF keyInput$ = "s" THEN cameraXSpeed = cameraXSpeed + SIN(angleY): cameraZSpeed = cameraZSpeed - COS(angleY)
+IF keyInput$ = "q" THEN SYSTEM
 
 ' Apply friction to player movement
-myxs = myxs / 1.1
-myys = myys / 1.1
-myzs = myzs / 1.1
+cameraXSpeed = cameraXSpeed / 1.1
+cameraYSpeed = cameraYSpeed / 1.1
+cameraZSpeed = cameraZSpeed / 1.1
 
 ' Update player position
-myx = myx + myxs
-myz = myz + myzs
-myy = myy + myys
+cameraX = cameraX + cameraXSpeed
+cameraZ = cameraZ + cameraZSpeed
+cameraY = cameraY + cameraYSpeed
 
 END SUB
 
 FUNCTION getByte (addr)
-getByte = PEEK(extADDR + addr)
+getByte = PEEK(extensionAddress + addr)
 END FUNCTION
 
 FUNCTION getWord (addr)
-a = PEEK(extADDR + addr)
-b = PEEK(extADDR + addr + 1)
+a = PEEK(extensionAddress + addr)
+b = PEEK(extensionAddress + addr + 1)
 
 ' Convert bytes to a hex string and then to an integer
 c$ = HEX$(a)
@@ -232,42 +237,8 @@ c = VAL("&H" + HEX$(b) + c$)
 getWord = c
 END FUNCTION
 
-SUB mousedemo
-
-cx = 150
-cy = 100
-maxmove = 50
-100
-frm = frm + 1
-
-LOCATE 1, 1
-PRINT cx, cy
-PRINT frm
-
-CIRCLE (cx, cy), 10, 0
-xp = getWord(2)
-putWord 2, 0
-yp = getWord(4)
-putWord 4, 0
-
-IF xp < -maxmove THEN xp = -maxmove
-IF xp > maxmove THEN xp = maxmove
-cx = cx + xp
-
-IF yp < -maxmove THEN yp = -maxmove
-IF yp > maxmove THEN yp = maxmove
-cy = cy + yp
-
-CIRCLE (cx, cy), 10, 10
-
-SOUND 0, .05
-GOTO 100
-
-END SUB
-
 SUB putByte (addr, dat)
-
-POKE (extADDR + addr), dat
+POKE (extensionAddress + addr), dat
 END SUB
 
 SUB putWord (addr, dat)
@@ -280,36 +251,38 @@ IF LEN(b$) < 4 THEN b$ = "0" + b$: GOTO 2
 n1 = VAL("&H" + LEFT$(b$, 2))
 n2 = VAL("&H" + RIGHT$(b$, 2))
 
-POKE (extADDR + addr), n2
-POKE (extADDR + addr + 1), n1
+POKE (extensionAddress + addr), n2
+POKE (extensionAddress + addr + 1), n1
 
 END SUB
 
-SUB start
+SUB initializeProgram
 verifyTsrIsLoaded
 
 SCREEN 7, , , 1
 
-maxmove = 50
+' Set camera speed limit
+maxMove = 50
 
 END SUB
 
 SUB verifyTsrIsLoaded
 
-DEF SEG = 0     ' read first from interrupt table
+DEF SEG = 0     ' Read first from interrupt table
 
-extSEG = PEEK(&H79 * 4 + 3) * 256
-extSEG = extSEG + PEEK(&H79 * 4 + 2)
+extensionSegment = PEEK(&H79 * 4 + 3) * 256
+extensionSegment = extensionSegment + PEEK(&H79 * 4 + 2)
 
-PRINT "Segment is: " + HEX$(extSEG)
+PRINT "Segment is: " + HEX$(extensionSegment)
 
-extADDR = PEEK(&H79 * 4 + 1) * 256
-extADDR = extADDR + PEEK(&H79 * 4 + 0)
+extensionAddress = PEEK(&H79 * 4 + 1) * 256
+extensionAddress = extensionAddress + PEEK(&H79 * 4 + 0)
 
-PRINT "relative address is:"; extADDR
+PRINT "relative address is:"; extensionAddress
 
-DEF SEG = extSEG
+DEF SEG = extensionSegment
 
+' Verify TSR signature
 IF getWord(0) <> 1983 THEN
   PRINT "FATAL ERROR:  you must load"
   PRINT "QBasic extension TSR first!"
@@ -317,4 +290,3 @@ IF getWord(0) <> 1983 THEN
 END IF
 
 END SUB
-
diff --git a/3D GFX/Ray casting engine/raycast.bas b/3D GFX/Ray casting engine/raycast.bas
index 7a36760..46be305 100755
--- a/3D GFX/Ray casting engine/raycast.bas	
+++ b/3D GFX/Ray casting engine/raycast.bas	
@@ -1,3 +1,12 @@
+DECLARE SUB InitializeProgram ()
+DECLARE SUB GenerateLandscape ()
+DECLARE SUB DisplayTopDownLandscape ()
+DECLARE SUB DisplayFrame ()
+DECLARE FUNCTION getcol! (r!, g!, b!)
+DECLARE SUB FillSquareArea (x1%, y1%, x2%, y2%, c%, h%)
+DECLARE SUB CreateTower (towerX%, towerY%)
+DECLARE SUB SetupPalette ()
+DECLARE SUB DrawLineFromPlayer (x%, y%, xl%)
 ' Realtime 3D rendering with ray casting engine.
 
 ' By Svjatoslav Agejenko.
@@ -6,7 +15,7 @@
 
 ' Changelog:
 ' 2003.03, Initial version
-' 2024.10, Improved program readability using AI
+' 2024 - 2025, Improved program readability
 
 ' 3D engine automatically adjusts quality to keep constant framerate at 10 fps.
 ' When framerate is lower than 10 fps, quality will be decreased to speed up rendering.
@@ -21,11 +30,7 @@
 ' Space      - jump up (fly)
 ' ESC        - exit program
 
-DECLARE FUNCTION getcol! (r!, g!, b!)
 DEFINT A-Y
-DECLARE SUB traceline (x%, y%, xl%)
-DECLARE SUB tower (x%, y%)
-DECLARE SUB square (x1%, y1%, x2%, y2%, c%, h%)
 
 DIM SHARED landh(0 TO 180, 0 TO 180)
 DIM SHARED landc(0 TO 180, 0 TO 180)
@@ -152,13 +157,29 @@ myx = zmyx
 DisplayFrame
 GOTO 1
 
+SUB CreateTower (towerX%, towerY%)
+
+' Draw a tower at the specified position
+FOR a = 10 TO 0 STEP -1
+    ' Fill each level of the tower with color
+    FillSquareArea towerX% - a, towerY% - a, towerX% + a, towerY% + a, getcol(100, 0, a * 20), 20 - a
+NEXT a
+
+' Draw the top of the tower
+FillSquareArea towerX% - 11, towerY% - 11, towerX% - 9, towerY% - 9, getcol(255, 0, 0), 20
+FillSquareArea towerX% + 9, towerY% - 11, towerX% + 11, towerY% - 9, getcol(0, 255, 0), 20
+FillSquareArea towerX% - 11, towerY% + 9, towerX% - 9, towerY% + 11, getcol(0, 0, 255), 20
+FillSquareArea towerX% + 9, towerY% + 9, towerX% + 11, towerY% + 11, getcol(255, 255, 0), 20
+
+END SUB
+
 SUB DisplayFrame
 
 l = 0
 zst = -.0031 * ste
 FOR z = .5 TO -.5 STEP zst
     ' Trace a line from the player's perspective
-    traceline SIN(zmyan + z) * dist + myx, COS(zmyan + z) * dist + myy, l
+    DrawLineFromPlayer SIN(zmyan + z) * dist + myx, COS(zmyan + z) * dist + myy, l
     l = l + ste
 NEXT z
 
@@ -195,36 +216,84 @@ PRINT "Press any key to continue..."
 
 END SUB
 
-DEFSNG A-Y
-FUNCTION getcol (r, g, b)
-IF r < 0 THEN
-    ' Ensure the color value is within bounds
-    r = 0
-END IF
-IF g < 0 THEN
-    g = 0
-END IF
-IF b < 0 THEN
-    b = 0
+SUB DrawLineFromPlayer (x%, y%, xl%)
+
+' Trace a line from the player's perspective
+IF x < 0 THEN
+    ' Calculate the distance to the next point
+    zpr = myx / (myx - x)
+    x = 0
+    y = myy - ((myy - y) * zpr)
 END IF
-IF r > 255 THEN
-    r = 255
+
+IF y < 0 THEN
+    ' Calculate the distance to the next point
+    zpr = myy / (myy - y)
+    y = 0
+    x = myx - ((myx - x) * zpr)
 END IF
-IF g > 255 THEN
-    g = 255
+
+IF x > 180 THEN
+    ' Calculate the distance to the next point
+    zpr = (180 - myx) / (x - myx)
+    x = 180
+    y = myy - ((myy - y) * zpr)
 END IF
-IF b > 255 THEN
-    b = 255
+
+IF y > 180 THEN
+    ' Calculate the distance to the next point
+    zpr = (180 - myy) / (y - myy)
+    y = 180
+    x = myx - ((myx - x) * zpr)
 END IF
-' Calculate the color index
-getcol = INT(r / 43) * 36 + INT(g / 43) * 6 + INT(b / 43)
-END FUNCTION
 
-DEFINT A-Y
+' Calculate the distance to the next point
+lp% = SQR(ABS(myx - x) ^ 2 + ABS(myy - y) ^ 2)
+
+' Save the current player position and orientation
+imyx% = myx
+imyy% = myy
+imyz% = myz
+xp% = x - imyx%
+yp% = y - imyy%
+istem% = stem
+imyan2% = myan2
+
+' Draw the line
+yo% = 200
+FOR a% = 1 TO lp%
+    cx% = xp% * a% / lp% + imyx%
+    cy% = yp% * a% / lp% + imyy%
+    yn% = imyan2% - ((landh(cx%, cy%) - imyz%) / a%) * 300
+
+    ' Draw the line segment
+    IF yn% < yo% THEN
+        LINE (xl%, yn%)-(xl% + istem%, yo% - 1), landc(cx%, cy%), BF
+        yo% = yn%
+    END IF
+NEXT a%
+
+' Draw the final line segment
+LINE (xl%, yo% - 1)-(xl% + istem%, 0), 0, BF
+
+END SUB
+
+SUB FillSquareArea (x1%, y1%, x2%, y2%, c%, h%)
+
+' Fill a square area with the specified color and height
+FOR y = y1 TO y2
+    FOR x = x1 TO x2
+        landh(x, y) = h
+        landc(x, y) = c
+    NEXT x
+NEXT y
+
+END SUB
+
 SUB GenerateLandscape
 
 ' Create a square landscape
-square 0, 0, 180, 180, 15, 0
+FillSquareArea 0, 0, 180, 180, 15, 0
 
 ' Generate the landscape height and color
 FOR y = 0 TO 180
@@ -259,9 +328,9 @@ FOR y = 10 TO 90
 NEXT y
 
 ' Add towers to the landscape
-tower 20, 20
-tower 60, 20
-tower 40, 60
+CreateTower 20, 20
+CreateTower 60, 20
+CreateTower 40, 60
 
 ' Generate a path
 FOR y = 100 TO 150
@@ -287,34 +356,32 @@ NEXT za
 
 END SUB
 
-SUB SetupPalette
-' Initialize the color palette
-c = 0
-FOR r = 0 TO 5
-    FOR g = 0 TO 5
-        FOR b = 0 TO 5
-            OUT &H3C8, c
-            c = c + 1
-            OUT &H3C9, r * 12
-            OUT &H3C9, g * 12
-            OUT &H3C9, b * 12
-        NEXT b
-    NEXT g
-NEXT r
-END SUB
-
-SUB square (x1%, y1%, x2%, y2%, c%, h%)
-
-' Fill a square area with the specified color and height
-FOR y = y1 TO y2
-    FOR x = x1 TO x2
-        landh(x, y) = h
-        landc(x, y) = c
-    NEXT x
-NEXT y
-
-END SUB
+DEFSNG A-Y
+FUNCTION getcol (r, g, b)
+IF r < 0 THEN
+    ' Ensure the color value is within bounds
+    r = 0
+END IF
+IF g < 0 THEN
+    g = 0
+END IF
+IF b < 0 THEN
+    b = 0
+END IF
+IF r > 255 THEN
+    r = 255
+END IF
+IF g > 255 THEN
+    g = 255
+END IF
+IF b > 255 THEN
+    b = 255
+END IF
+' Calculate the color index
+getcol = INT(r / 43) * 36 + INT(g / 43) * 6 + INT(b / 43)
+END FUNCTION
 
+DEFINT A-Y
 SUB InitializeProgram
 ' Set the graphics mode
 SCREEN 13
@@ -336,80 +403,19 @@ zmyz = 20
 
 END SUB
 
-SUB tower (x%, y%)
-
-' Draw a tower at the specified position
-FOR a = 10 TO 0 STEP -1
-    ' Fill each level of the tower with color
-    square x% - a, y% - a, x% + a, y% + a, getcol(100, 0, a * 20), 20 - a
-NEXT a
-
-' Draw the top of the tower
-square x% - 11, y% - 11, x% - 9, y% - 9, getcol(255, 0, 0), 20
-square x% + 9, y% - 11, x% + 11, y% - 9, getcol(0, 255, 0), 20
-square x% - 11, y% + 9, x% - 9, y% + 11, getcol(0, 0, 255), 20
-square x% + 9, y% + 9, x% + 11, y% + 11, getcol(255, 255, 0), 20
-
+SUB SetupPalette
+' Initialize the color palette
+c = 0
+FOR r = 0 TO 5
+    FOR g = 0 TO 5
+        FOR b = 0 TO 5
+            OUT &H3C8, c
+            c = c + 1
+            OUT &H3C9, r * 12
+            OUT &H3C9, g * 12
+            OUT &H3C9, b * 12
+        NEXT b
+    NEXT g
+NEXT r
 END SUB
 
-SUB traceline (x%, y%, xl%)
-
-' Trace a line from the player's perspective
-IF x < 0 THEN
-    ' Calculate the distance to the next point
-    zpr = myx / (myx - x)
-    x = 0
-    y = myy - ((myy - y) * zpr)
-END IF
-
-IF y < 0 THEN
-    ' Calculate the distance to the next point
-    zpr = myy / (myy - y)
-    y = 0
-    x = myx - ((myx - x) * zpr)
-END IF
-
-IF x > 180 THEN
-    ' Calculate the distance to the next point
-    zpr = (180 - myx) / (x - myx)
-    x = 180
-    y = myy - ((myy - y) * zpr)
-END IF
-
-IF y > 180 THEN
-    ' Calculate the distance to the next point
-    zpr = (180 - myy) / (y - myy)
-    y = 180
-    x = myx - ((myx - x) * zpr)
-END IF
-
-' Calculate the distance to the next point
-lp% = SQR(ABS(myx - x) ^ 2 + ABS(myy - y) ^ 2)
-
-' Save the current player position and orientation
-imyx% = myx
-imyy% = myy
-imyz% = myz
-xp% = x - imyx%
-yp% = y - imyy%
-istem% = stem
-imyan2% = myan2
-
-' Draw the line
-yo% = 200
-FOR a% = 1 TO lp%
-    cx% = xp% * a% / lp% + imyx%
-    cy% = yp% * a% / lp% + imyy%
-    yn% = imyan2% - ((landh(cx%, cy%) - imyz%) / a%) * 300
-
-    ' Draw the line segment
-    IF yn% < yo% THEN
-        LINE (xl%, yn%)-(xl% + istem%, yo% - 1), landc(cx%, cy%), BF
-        yo% = yn%
-    END IF
-NEXT a%
-
-' Draw the final line segment
-LINE (xl%, yo% - 1)-(xl% + istem%, 0), 0, BF
-
-END SUB
-- 
2.20.1