/* MultiMorphShader.frag.txt
 * A fragment shader that computes a pixel-wise weighted linear combination
 * of many input images, stored in one texture bound to Image:
 * outimage(x,y) = (Image1Weight * Image1(x,y)) + (Image2Weight * Image2(x,y));
 *
 * This one is e.g., used by the new moglmorpher.m for fast shape morphing
 * on the GPU.
 *
 * (c) 2007 by Mario Kleiner, licensed to you under MIT license.
 */

#extension GL_ARB_texture_rectangle : enable

uniform sampler2DRect Image;
uniform sampler2DRect WeightImage;
uniform int Count;
uniform int Stride;

void main()
{
    vec4 imgsum = vec4(0.0);
    int i;
    float weight;

    for (i=0; i < Count; i++) {
        weight = texture2DRect(WeightImage, vec2(float(i), 0.0)).r;
        imgsum+= texture2DRect(Image, gl_FragCoord.xy + vec2(0.0, float(i * Stride))) * weight;
    }

    gl_FragColor = imgsum;
}