From dd1591f76d2810480a85f4016d8170d28887078b Mon Sep 17 00:00:00 2001
From: Svjatoslav Agejenko <svjatoslav@svjatoslav.eu>
Date: Thu, 26 Jun 2025 16:52:38 +0300
Subject: [PATCH] Better code readability.

---
 2D GFX/Presentations/AI/AI demo.bas | 80 +++++++++++++++--------------
 1 file changed, 41 insertions(+), 39 deletions(-)

diff --git a/2D GFX/Presentations/AI/AI demo.bas b/2D GFX/Presentations/AI/AI demo.bas
index 306e0bc..be9f839 100644
--- a/2D GFX/Presentations/AI/AI demo.bas	
+++ b/2D GFX/Presentations/AI/AI demo.bas	
@@ -141,55 +141,57 @@ SUB DrawRoundedBox (xOne, yOne, xTwo, yTwo)
 END SUB
 
 
-SUB FillPolygon (xCoordOne, yCoordOne, xCoordTwo, yCoordTwo, xCoordThree, yCoordThree, colorValue)
+SUB FillPolygon (x1, y1, x2, y2, x3, y3, fillColor)
 '
-' Fills a triangular region using a simple scanline approach.
-'   1) Draw lines between points to find intersections on each horizontal row.
-'   2) Use the pairs of intersection points to draw horizontal lines in colorValue.
+' Fills a triangular area using a scanline algorithm.
+' 1. Finds intersection points between edges and horizontal scanlines
+' 2. Draws horizontal lines between pairs of intersections
 '
     DIM scanIntersection(-100 TO 300)
 
-    localX1 = xCoordOne
-    localY1 = yCoordOne
-    localX2 = xCoordTwo
-    localY2 = yCoordTwo
-    GOSUB fillLines
-
-    localX1 = xCoordOne
-    localY1 = yCoordOne
-    localX2 = xCoordThree
-    localY2 = yCoordThree
-    GOSUB fillLines
-
-    localX1 = xCoordThree
-    localY1 = yCoordThree
-    localX2 = xCoordTwo
-    localY2 = yCoordTwo
-    GOSUB fillLines
-
-    GOTO polygonDone
-
-fillLines:
-    ' If the second point is above the first, swap them
-    IF localY2 < localY1 THEN
-        SWAP localY1, localY2
-        SWAP localX1, localX2
+    startPointX = x1
+    startPointY = y1
+    endPointX = x2
+    endPointY = y2
+    GOSUB drawEdges
+
+    startPointX = x1
+    startPointY = y1
+    endPointX = x3
+    endPointY = y3
+    GOSUB drawEdges
+
+    startPointX = x3
+    startPointY = y3
+    endPointX = x2
+    endPointY = y2
+    GOSUB drawEdges
+
+    GOTO finishPolygon
+
+drawEdges:
+    ' Swap points if needed to ensure we draw from top to bottom
+    IF endPointY < startPointY THEN
+        SWAP startPointY, endPointY
+        SWAP startPointX, endPointX
     END IF
 
-    ' Walk through rows from localY1 up to localY2
-    FOR yFill = localY1 TO localY2 - 1
-        xFill = localX1 + (localX2 - localX1) * ((yFill - localY1) / (localY2 - localY1))
-        IF scanIntersection(yFill) = 0 THEN
-            ' This is the first intersection discovered on this row
-            scanIntersection(yFill) = xFill
+    ' For each scanline between the two points
+    FOR yScan = startPointY TO endPointY - 1
+        ' Calculate x position along the edge
+        xScan = startPointX + (endPointX - startPointX) * ((yScan - startPointY) / (endPointY - startPointY))
+
+        ' Store first intersection point
+        IF scanIntersection(yScan) = 0 THEN
+            scanIntersection(yScan) = xScan
         ELSE
-            ' Second intersection found -> draw horizontal line to the first intersection
-            LINE (xFill, yFill)-(scanIntersection(yFill), yFill), colorValue
+            ' Draw horizontal line between intersections
+            LINE (xScan, yScan)-(scanIntersection(yScan), yScan), fillColor
         END IF
-    NEXT yFill
+    NEXT yScan
     RETURN
 
-polygonDone:
+finishPolygon:
 END SUB
 
 
-- 
2.20.1