quakeforge/libs/video/renderer/glsl/quakebsp.frag

uniform sampler2D colormap;
uniform sampler2D texture;
uniform sampler2D lightmap;

varying vec2 tst;
varying vec2 lst;
varying vec4 color;

void
main (void)
{
	float       pix = texture2D (texture, tst).r;
	float       light = texture2D (lightmap, lst).r;
	float       col;

	gl_FragColor = texture2D (colormap, vec2 (pix, light * 4.0)) * color;
}