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FRACTAL2.PAS
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Pascal/Delphi Source File
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1995-02-14
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1KB
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51 lines
{$g+,n+,e-}
{ Reals : -1 -0.1 0.3 -1.139
Complex : 0 0.8 -0.5 0.238 }
program julia; { FRACTAL2.PAS }
{ Julia Fractal (uses SVGA256.BGI), by Bas van Gaalen }
uses u_vga,graph,u_pal,u_kb; { VGA BEFORE GRAPH! }
const speed=2; { ei: 1=slow and accurate; 5=fast and inaccurate }
type real=double;
var cx,cy,xo,yo,x1,y1,xdiv,ydiv:real; mx,my,a,b,i,orb:word;
procedure setvid;
var grmd,grdr:integer;
{$f+} function detectvga:integer; begin detectvga:=2; end; {$f-}
begin
grdr:=installuserdriver('svga256',@detectvga); grdr := 0;
initgraph(grdr,grmd,'');
end;
begin
write('Real part: '); readln(cx);
write('Imaginary part: '); readln(cy);
setvid;
for i:=1 to 64 do setrgb(i,15+i div 3,15+i div 3,15+round(i/1.306122449));
mx:=639; my:=479; xdiv:=mx/4; ydiv:=my/4;
a:=1;
while a<mx do begin
b:=1;
while b<my do begin
xo:=-2+a/xdiv; { X complex plane coordinate }
yo:=2-b/ydiv; { Y complex plane coordinate }
i:=0;
repeat
x1:=xo*xo-yo*yo+cx;
y1:=2*xo*yo+cy;
xo:=x1;
yo:=y1;
inc(i);
until (i=64) or (x1*x1+y1*y1>4) or (abs(x1)>2) or (abs(y1)>2);
if i<64 then orb:=i else orb:=63;
putpixel(a,b,orb); { Plot orbit }
inc(b,speed);
end;
inc(a,speed);
end;
while not keypressed do;
setvideo(u_lm);
end.