Added example: Intersection

Programs/Intersection.Mod

@@ -0,0 +1,167 @@
+MODULE Intersection;
+IMPORT G := Graph, Random, Int;
+CONST eps = 0.001;
+
+TYPE
+  Point = RECORD
+    x, y: REAL
+  END;
+  Line = RECORD
+    s, v: Point
+  END;
+
+VAR W, H: INTEGER;
+  f: G.Font;
+  YY: INTEGER;
+
+PROCEDURE Intersect(A, B: Line; VAR t, T: REAL; VAR P: Point): BOOLEAN;
+VAR z: REAL;
+BEGIN
+  z := A.v.x * B.v.y - A.v.y * B.v.x;
+  IF (z < -eps) OR (z > eps) THEN
+    t := ((B.s.x - A.s.x) * B.v.y - (B.s.y - A.s.y) * B.v.x) / z;
+    P.x := A.s.x + A.v.x * t;
+    P.y := A.s.y + A.v.y * t;
+    IF (B.v.x < -eps) OR (B.v.x > eps) THEN
+      T := (A.s.x - B.s.x + A.v.x * t) / B.v.x
+    ELSE
+      T := (A.s.y - B.s.y + A.v.y * t) / B.v.y
+    END
+  END
+RETURN (z < -eps) OR (z > eps) END Intersect;
+
+PROCEDURE SpreadLine(VAR A: Line);
+VAR B, C: Line;
+    t1, t2, T: REAL;
+    P1, P2, E: Point;
+    c: G.Color;
+    ZZ: ARRAY 100 OF CHAR;
+BEGIN
+  B.s.x := 10.0;
+  B.s.y := FLT(H) - 10.0;
+  C.s.x := 10.0;
+  C.s.y := 10.0;
+  B.v.x := FLT(W) - 20.0;
+  B.v.y := 0.0;
+  C.v.x := FLT(W) - 20.0;
+  C.v.y := 0.0;
+
+  IF Intersect(A, B, t1, T, P1) & Intersect(A, C, t2, T, P2) THEN
+    G.MakeCol(c, 0, 255, 0);
+    G.FillRect(FLOOR(P1.x) - 3, FLOOR(P1.y) - 3, FLOOR(P1.x) + 3, FLOOR(P1.y) + 3, c);
+    G.MakeCol(c, 255, 0, 0);
+    G.FillRect(FLOOR(P2.x) - 3, FLOOR(P2.y) - 3, FLOOR(P2.x) + 3, FLOOR(P2.y) + 3, c);
+
+    A.s := P1;
+    A.v.x := P2.x - P1.x;
+    A.v.y := P2.y - P1.y
+  END;
+
+  B.s.x := 10.0;
+  B.s.y := 10.0;
+  C.s.x := FLT(W) - 10.0;
+  C.s.y := 10.0;
+  B.v.x := 0.0;
+  B.v.y := FLT(H) - 20.0;
+  C.v.x := 0.0;
+  C.v.y := FLT(H) - 20.0;
+
+  IF Intersect(A, B, t1, T, P1) & Intersect(A, C, t2, T, P2) THEN
+    G.MakeCol(c, 0, 255, 255);
+    G.FillRect(FLOOR(P1.x) - 3, FLOOR(P1.y) - 3, FLOOR(P1.x) + 3, FLOOR(P1.y) + 3, c);
+    G.MakeCol(c, 255, 0, 255);
+    G.FillRect(FLOOR(P2.x) - 3, FLOOR(P2.y) - 3, FLOOR(P2.x) + 3, FLOOR(P2.y) + 3, c);
+
+    Int.Str(FLOOR(t1 * 100), ZZ);
+    G.DrawString(ZZ, 20, H - 50 + YY, f, c);
+    Int.Str(FLOOR(t2 * 100), ZZ);
+    G.DrawString(ZZ, 150, H - 50 + YY, f, c);
+    INC(YY, 16);
+
+    IF (t1 >= 0) & (t1 <= 1) THEN
+      IF t1 < t2 THEN
+        E.x := A.s.x + A.v.x;
+        E.y := A.s.y + A.v.y;
+        A.s := P1;
+        A.v.x := E.x - A.s.x;
+        A.v.y := E.y - A.s.y
+      ELSE
+        A.v.x := P1.x - A.s.x;
+        A.v.y := P1.y - A.s.y
+      END
+    END;
+    IF (t2 >= 0) & (t2 <= 1) THEN
+      IF t1 < t2 THEN
+        A.v.x := P2.x - A.s.x;
+        A.v.y := P2.y - A.s.y
+      ELSE
+        E.x := A.s.x + A.v.x;
+        E.y := A.s.y + A.v.y;
+        A.s := P2;
+        A.v.x := E.x - A.s.x;
+        A.v.y := E.y - A.s.y
+      END
+    END
+  END
+END SpreadLine;
+
+PROCEDURE Do;
+VAR A, B: Line;
+    c: G.Color;
+    P: Point;
+    t, T: REAL;
+BEGIN
+  YY := 0;
+  G.ClearScreen;
+
+  A.s.x := Random.Uniform() * W;
+  A.s.y := Random.Uniform() * H;
+  B.s.x := Random.Uniform() * W;
+  B.s.y := Random.Uniform() * H;
+  A.v.x := Random.Uniform() * W - A.s.x;
+  A.v.y := Random.Uniform() * H - A.s.y;
+  B.v.x := Random.Uniform() * W - B.s.x;
+  B.v.y := Random.Uniform() * H - B.s.y;
+
+  G.MakeCol(c, 155, 0, 0);
+  G.ThickLine(FLOOR(A.s.x), FLOOR(A.s.y), FLOOR(A.s.x + A.v.x), FLOOR(A.s.y + A.v.y), c, 7);
+  G.Rect(FLOOR(A.s.x) - 9, FLOOR(A.s.y) - 9, FLOOR(A.s.x) + 9, FLOOR(A.s.y) + 9, c);
+  G.MakeCol(c, 155, 155, 0);
+  G.ThickLine(FLOOR(B.s.x), FLOOR(B.s.y), FLOOR(B.s.x + B.v.x), FLOOR(B.s.y + B.v.y), c, 7);
+  G.Rect(FLOOR(B.s.x) - 9, FLOOR(B.s.y) - 9, FLOOR(B.s.x) + 9, FLOOR(B.s.y) + 9, c);
+
+  SpreadLine(A);
+  SpreadLine(B);
+
+  G.MakeCol(c, 255, 0, 0);
+  G.Line(FLOOR(A.s.x), FLOOR(A.s.y), FLOOR(A.s.x + A.v.x), FLOOR(A.s.y + A.v.y), c);
+  G.MakeCol(c, 255, 255, 0);
+  G.Line(FLOOR(B.s.x), FLOOR(B.s.y), FLOOR(B.s.x + B.v.x), FLOOR(B.s.y + B.v.y), c);
+  IF Intersect(A, B, t, T, P) THEN
+    G.MakeCol(c, 0, 255, 255);
+    G.Rect(FLOOR(P.x) - 9, FLOOR(P.y) - 9, FLOOR(P.x) + 9, FLOOR(P.y) + 9, c);
+    G.MakeCol(c, 255, 255, 255);
+    G.Rect(FLOOR(P.x) - 7, FLOOR(P.y) - 7, FLOOR(P.x) + 7, FLOOR(P.y) + 7, c)
+  END;
+
+  G.MakeCol(c, 0, 50, 255);
+  G.Rect(10, 10, W - 10, H - 10, c)
+END Do;
+
+PROCEDURE Do2;
+VAR ch: CHAR;
+BEGIN
+  G.Init;
+  f := G.LoadFont('../Data/Fonts/Main');
+  G.GetScreenSize(W, H);
+  REPEAT
+    Do;
+    G.Flip;
+    ch := G.ReadKey();
+  UNTIL ch = CHR(27);
+  G.Close
+END Do2;
+
+BEGIN
+  Do2
+END Intersection.