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

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uniform sampler2D spritea;
uniform sampler2D spriteb;
uniform sampler2D palette;
uniform vec4 fog;
varying float blend;
varying vec4 colora, colorb;
varying vec2 sta, stb;
float
sqr (float x)
{
return x * x;
}
vec4
fogBlend (vec4 color)
{
float f;
vec4 fog_color = vec4 (fog.rgb, 1.0);
f = exp (-sqr (fog.a * gl_FragCoord.z / gl_FragCoord.w));
return vec4 (mix (fog_color.rgb, color.rgb, f), color.a);
}
void
main (void)
{
float pixa, pixb;
vec4 cola, colb;
vec4 col;
pixa = texture2D (spritea, sta).r;
pixb = texture2D (spriteb, stb).r;
if (pixa == 1.0 && pixb == 1.0)
discard;
cola = texture2D (palette, vec2 (pixa, 0.0)) * colora;
colb = texture2D (palette, vec2 (pixb, 0.0)) * colorb;
col = mix (cola, colb, blend);
if (col.a == 0.0)
discard;
gl_FragColor = fogBlend (col);
}