{> Cut here. FileName= COS.PAS }
{Plasma Caleidoscope Demo [320x200x256]
 by Alexey Monastyrenko <aamonster@mail.ru>
          11 Mar 1998
}
procedure SetPalette;
var   N:Integer;
begin
  Port[$3C8] := 0;
  for N := 0 to 256*3-1 do
    Port[$3C9] := Round(Sqr(Sin(N*21167.0{PI*257/3/256}))*63);
end; {of SetPalette}

procedure VIDMode(Mode : Byte);assembler;
  asm mov ah,$00;  mov al,mode; int 10h; end;

type TScr = array[0..199,0..319] of Byte;
type TScr_ = array[0..63999] of Byte;
var Scr: TScr absolute $A000:$0000;
var Scr_: TScr_ absolute Scr;
var Scr_2: TScr_;

label M1;
var SinTable:array[Byte] of Integer;
    I,J,Q:Integer;
    X,Y,Z,Z0,ZC,DZDX,DZDY,A:Word;
begin
  for I:=0 to 255 do SinTable[I]:=Round(Sin(I*2*PI/256)*64);
  VIDMode($13);
  SetPalette;
  for J:=0 to 1000 do begin
    FillChar(Scr_2,64000,0);
    for Q:=0 to 4 do begin
      Z0:=J*1000;
      DZDX:=Round(2000*Cos(Q*2*PI/5+J/100));
      DZDY:=Round(2400*Sin(Q*2*PI/5+J/100));
      Z0:=Z0-100*DZDY-160*DZDX;
      A:=0;
      for Y:=0 to 199 do begin
        Z:=Z0;
        Inc(Z0,DZDY);
        for X:=0 to 319 do begin
          Inc(Scr_2[A],SinTable[Hi(Z)]);
          Inc(Z,DZDX);
          Inc(A);
        end;
      end;
    end;
    Scr_:=Scr_2;
    if Port[$60]<128 then Break;
  end;
  asm mov ah,0;
      int 16h
  end; {readkey}
  asm mov ah,0;
      int 16h
  end; {readkey}
  VIDMode($3);
end.