From: leathm AT solwarra DOT gbrmpa DOT gov DOT au (Leath Muller)
Message-Id: <199703052352.JAA14542@solwarra.gbrmpa.gov.au>
Subject: Re: Lighting Techniques
To: sly AT aussie DOT net (Sly)
Date: Thu, 6 Mar 1997 09:52:27 +1000 (EST)
Cc: djgpp AT delorie DOT com
In-Reply-To: <01bc290e$ccc6e8c0$8a081ecb@sly> from "Sly" at Mar 5, 97 02:38:10 am
Content-Type: text

> > If you want to tint the sprites to some color other than black, pass a
> > color other than "0, 0, 0" to the create_light_table() routine, eg.
> > "255, 255, 255" to tint the images to white. If you want to tint them in
> > both directions, you could (a bit more work) use the
> > create_color_table() function to build a lookup table which will treat
> > light level 128 as the original color, 0 as black, and 255 as white.
 
> When I read this, I started thinking how this would be achieved (the lookup
> table to treat light level 128 as the original colour, 0 as black, and 255
> as white).  But I can't think of how it would be done.  Any tips?

Well, for true colour stuff I use this sort of setup...

	char *brightness = (char *)malloc(256 * 256));

	for (i = 0; i < 256; i++)
		for (j = 0; j < 256; j++)
		{
			val = (i / 128) * j;
			brightness[i][j] = (unsigned char) val;
		}

You get the point.... :) You should make sure you do correct int/float
conversions etc, but otherwise, this is extremely effective for me...

Leathal.