Xref: news2.mv.net comp.os.msdos.djgpp:2969
From: jasonk AT direct DOT ca (Jason Keddie)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Allegro + pallete fades
Date: Tue, 23 Apr 1996 00:24:58 GMT
Organization: Keddie Enterprises
Lines: 71
Message-ID: <4lh7is$t62@orb.direct.ca>
References: <317561DD DOT A86 AT gl DOT umbc DOT edu> <4la5q0$6rg AT news DOT wco DOT com>
Reply-To: jasonk AT direct DOT ca
NNTP-Posting-Host: vic-as-01a13.direct.ca
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

This is my function for fading out the color palette. I don't claim
that it's great or anything but it works so maybe it will help. I like
to use the fractional approach because if you just subtract one from
r/g/b dark screens will fade out too fast. You could pass it a number
to use instead of 18643 if you want to be able to control the speed of
the fade. 


/*This is what colorType is*/
struct colorType
{
  unsigned char r:6;
  unsigned char g:6;
  unsigned char b:6;
};

void fadePaletteOut(void)
{
  colorType
    savedPalette[256];
  unsigned long
    index,
    lastTime,
    intensityIndex;

  /*Save the palette*/
  for(index=0;index<256;index++)
  {
    outportb(0x3c7,index);
    savedPalette[index].r = inportb(0x3c9);
    savedPalette[index].g = inportb(0x3c9);
    savedPalette[index].b = inportb(0x3c9); 
  }

  /*slowly lower palette to black*/
  lastTime = clock();
  for(intensityIndex=64;intensityIndex>0;intensityIndex--)
  {
    do{}while ((lastTime + 18643) > uclock());
    lastTime = uclock();
    for(index=0;index<256;index++)
    {
      outportb(0x3c6,0xff);
      outportb(0x3c8,index);
      outportb(0x3c9,((savedPalette[index].r << 4) *
intensityIndex)>>10);
      outportb(0x3c9,((savedPalette[index].g << 4) *
intensityIndex)>>10);
      outportb(0x3c9,((savedPalette[index].b << 4) *
intensityIndex)>>10);
    }
  }

  /*clear screen and reload saved palette*/
  clearVideoBuffer();
  writeVideoBuffer();
  for(index=0;index<256;index++)
    {
      outportb(0x3c6,0xff);
      outportb(0x3c8,index);
      outportb(0x3c9,savedPalette[index].r);
      outportb(0x3c9,savedPalette[index].g);
      outportb(0x3c9,savedPalette[index].b);
    }

}

jasonk AT tnet DOT net