Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

  ◄Example► ◄Contents► ◄Index►                                    ◄Back►
 
PROGRAM horizon;
 
{ HORIZON.PAS : Demonstrates VGA graphics with cycling of 256 colors }
 
USES
    Crt, MSGraph;
 
CONST
    Red  = $00002a;
    grn  = $002a00;
    blu  = $2a0000;
    wht  = $2a2a2a;
    step = 21;
 
VAR
    vc        : _VideoConfig;
    rainbow   : ARRAY [1..512] OF LongInt;
    i, a      : Integer;
    col, gray : LongInt;
    rec       : _XYCoord;
 
BEGIN    { Begin main program }
 
    a := _SetVideoMode( _MRes256Color );
    IF (a = 0) THEN
        BEGIN
        Writeln( 'This program requires a VGA or MCGA card' );
        Halt( 0 );
        END;
 
    FOR col := 0 TO 63 DO
        BEGIN
        gray := col OR (col SHL 8) OR (col SHL 16);
        rainbow[col] :=   blu AND gray;
        rainbow[col + 256] := blu AND gray;
        rainbow[col + 64] := blu OR gray;
        rainbow[col + 64 + 256] := blu OR gray;
        rainbow[col + 128] := Red OR (wht AND NOT gray);
        rainbow[col + 128 + 256] := Red  OR (wht AND NOT gray);
        rainbow[col + 192] := Red OR NOT gray;
        rainbow[col + 192 + 256] := Red OR NOT gray;
        END;
 
    _SetViewOrg( 160, 85, rec );
 
    FOR i := 0 TO 254 DO
        BEGIN
        _SetColor( 255 - i );
        _MoveTo( i, i - 255 );
        _LineTo( -i, 255 - i );
        _MoveTo( -i, i - 255 );
        _LineTo( i, 255 - i );
        _Ellipse( _GBorder, -i, -i DIV 2, i, i DIV 2 );
        END;
 
    i := 0;
    WHILE NOT KeyPressed DO
        BEGIN
        _RemapAllPalette( rainbow[i] );
        i := i + step;
        IF (i >= 256) THEN i := 0;
        END;
 
    a := _SetVideoMode( _DefaultMode );
 
END.