// -*-c-*-
// shader for luminance data
// and texture rectangles

#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect textureY;
uniform sampler2DRect textureX;
uniform float alpha;

void main(void) {
    float y = texture2DRect(
            textureY,
            gl_TexCoord[0].st).x;
    float x = texture2DRect(
            textureX,
            gl_TexCoord[0].st).x;
    gl_FragColor.x =
            y + alpha*x;
}