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https://git.sr.ht/~rabbits/macintosh_cookbook
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99 lines
1.5 KiB
ObjectPascal
99 lines
1.5 KiB
ObjectPascal
program ExampleMandelbrot;
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const
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Nit = 100;
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scale = 0.005;
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R = 10;
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type
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complex = record
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r: Real;
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i: real
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end;
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var
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i, j, k, n, row, col: Integer;
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x, y: Real;
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z, znew, c: complex;
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done, gone: Boolean;
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render: Rect;
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procedure prod (a, b: complex; var c: complex);
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{Does complex multiplication: c = a bullet b}
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begin
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c.r := a.r * b.r - a.i * b.i;
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c.i := a.r * b.i + a.i * b.r;
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end;
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procedure sub (a, b: complex; var c: complex);
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{Does complex subtraction: c = a - b}
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begin
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c.r := a.r - b.r;
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c.i := a.i - b.i;
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end;
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procedure plot (c, r, n: integer);
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{Procedure to pixel (c.r) in color code n.}
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begin
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case n of
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0..4:
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ForeColor(blueColor);
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5:
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ForeColor(cyanColor);
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6:
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ForeColor(greenColor);
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7:
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ForeColor(magentaColor);
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8..11:
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ForeColor(redColor);
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12..20:
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ForeColor(yellowColor);
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21..99:
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ForeColor(whiteColor);
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100:
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ForeColor(blackColor);
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otherwise
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ForeColor(blackColor);
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end;
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Moveto(c, r);
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Lineto(c, r);
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r := 400 - r;
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Moveto(c, r);
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Lineto(c, r);
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end;
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begin
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SetRect(render, 60, 60, 500, 440);
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SetDrawingRect(render);
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ShowDrawing;
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for col := 1 to 400 do
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for row := 1 to 200 do
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begin
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z.r := 0.0;
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z.i := 0.0;
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c.r := (col - 100) * scale;
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c.i := (200 - row) * scale;
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repeat
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n := n + 1;
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prod(z, z, znew);
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sub(znew, c, z);
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done := (n > Nit);
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gone := (z.r * z.r + z.i * z.i > R);
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until done or gone or button;
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plot(col, row, n);
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n := 0;
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end;
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end. |