/* ClutBlitShader.frag -- Brute force CLUT animation.
 * Shader for application of a color lookup table to a texture image.
 * Reads each texels color index from red/luminance channel of texture
 * 'Image', does a index -> color lookup in lookup table texture 'clut'.
 * Assigns looked up color RGB to output fragment color RGB. Copies alpha
 * channels value unmodified.
 * This shader is used by moglClutBlit.m to implement CLUT animation caps.
 *
 * (w)2006 by Mario Kleiner. Licensed under MIT license.
*/

#extension GL_ARB_texture_rectangle : enable

uniform sampler2DRect Image;
uniform sampler2DRect clut;

void main()
{
    vec4 incolor = texture2DRect(Image, gl_TexCoord[0].st);
    float index = incolor.r * 255.0 + 0.5;
    gl_FragColor.rgb = texture2DRect(clut, vec2(index, 0)).rgb;
    gl_FragColor.a = incolor.a;
}