From: Steve Cheng <elmert@ipoline.com>
  To  : Christoph Egger <Christoph_Egger@t-online.de>
  Date: Sun, 4 Jul 1999 14:19:06 -0400 (EDT)

Re: Got to be a faster way.

On Sun, 4 Jul 1999, Christoph Egger wrote:

> 
> 
> On Sun, 4 Jul 1999, Club Neon wrote:
> 
> > > How about with this:
> > >
> > > /* generate_332_palette:
> > >  *  Used when loading a truecolor image into an 8 bit bitmap, to generate
> > >  *  a 3.3.2 RGB palette.
> > >  */
> > > void generate_332_palette(ggi_color *pal)
> > > {
> > >    #define PAL_SIZE 256
> > >    ggi_sint c;
> > >
> > >    for (c=0; c < PAL_SIZE; c++) {
> > >       pal[c].r = ((c>>5)&7) * 0xffff/7;
> > >       pal[c].g = ((c>>2)&7) * 0xffff/7;
> > >       pal[c].b = (c&3) * 0xffff/3;
> > >    }
> > >
> > >    pal[0].r = 0xffff;
> > >    pal[0].g = 0;
> > >    pal[0].b = 0xffff;
> > >
> > >    pal[254].r = pal[254].g = pal[254].b = 0;
> > >    #undef PAL_SIZE
> > > } // generate_332_palette
> > >
> > >
> > > Any comments?
> > 
> > How about a question?  Why is pal[0] magenta, and pal[254] black?  Am I
> > missing something?
> > 
> > I was thinking that pal[0] would be black, and I guess pal[254] would be
> > almost white, slightly yellow tinted.
> > 
> 
> Oh - if I am understanding you correctly, you mean ...
> 
> /* generate_332_palette:
>  *  Used when loading a truecolor image into an 8 bit bitmap, to generate
>  *  a 3.3.2 RGB palette.
>  */
> void generate_332_palette(ggi_color *pal)
> {
>    #define PAL_SIZE 256
>    ggi_sint c;
> 
>    for (c=0; c < PAL_SIZE; c++) {
>       pal[c].r = ((c>>5)&7) * 0xffff/7;
>       pal[c].g = ((c>>2)&7) * 0xffff/7;
>       pal[c].b = (c&3) * 0xffff/3;
>    }
> 
>    pal[0].r = 0;
>    pal[0].g = 0;
>    pal[0].b = 0;
> 
>    pal[255].r = pal[255].g = pal[255].b = 0;
>    #undef PAL_SIZE
> } // generate_332_palette
> 
> ... instead the first above, no?
> 
> Christoph Egger
> E-Mail: Christoph_Egger@t-online.de
> 
> 

-- 
Steve Cheng

email: steve@ggi-project.org
www: <http://shell.ipoline.com/~elmert/>;