/* Shader for weighted summing of input texture layers into
 * a scalar output value which is replicated into all four output
 * components.
 *
 * (c) 2014 by Mario Kleiner. Licensed under MIT license.
 */

#extension GL_ARB_texture_rectangle : enable

uniform sampler2DRect Image;
varying vec4 mixWeights;

void main()
{
    vec4 incolor = texture2DRect(Image, gl_TexCoord[0].st);
    float sum = dot(incolor, mixWeights);
    gl_FragColor.rgba = vec4(sum);
}