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PC-SIG: World of Games
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PC-SIG World of Games (CDRM1080710) (1993).iso
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GAMES.ZOO
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hypocycl.pas
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Pascal/Delphi Source File
|
1989-06-04
|
2KB
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57 lines
program hypocycloid;
{
A hypocycloid is a figure created by rolling a circle inside another.
this program is adapted from a program on p.97 of MS quickC manual.
This source will produce the same program as HYPOCYCL.EXE, except
this version will require the appropriate .BGI file.
stephen peter 1988
}
uses Crt, Graph, Dos;
var
Graphdriver, GraphMode : integer;
x0, y0, maxx, maxy, x, y, i : integer;
colour, start_colour : word;
ratio, a, b, h, penpos, ang : real;
{-------------------------------------------------------------------}
begin
GraphDriver := detect;
initgraph (GraphDriver,GraphMode,'');
maxx := GetMaxX;
maxy := GetMaxY;
x0 := trunc(maxx/2 -1);
y0 := trunc(maxy/2 -1);
repeat
ClearDevice;
randomize;
ratio := random*10 + 1;
penpos := random*10 +1;
a := 0.5 * ratio * maxy / (ratio + penpos -1);
b := a / ratio;
h := penpos * b;
start_colour := trunc(random*7)+1;
ang := 0;
while not keypressed do
for i := 1 to 20 do
begin
ang := ang + 2*pi/100;
x := trunc (x0 + (a-b)*cos(ang) + h*cos(ang*(a-b)/b));
y := trunc (y0 - (a-b)*sin(ang) + h*sin(ang*(a-b)/b));
colour := getpixel (x,y);
if colour <> 0 then
begin
inc (colour);
if colour = 15 then colour := 1;
end
else colour := start_colour;
putpixel (x,y,colour);
end;
until ReadKey in ['Q','q',#27];
closegraph;
end.