/*
 * Copyright (C) 2005 Oliver Hunt <ojh16@student.canterbury.ac.nz>.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

kernel vec4 diffuseLighting(sampler normalVectors, sampler lightVectors, __color lightingColor, 
    float surfaceScale, float diffuseConstant, float kernelLengthX, float kernelLengthY)
{
    vec2 pos = samplerCoord(lightVectors);
    vec2 posn = samplerCoord(normalVectors);
    vec4 l4 = sample(lightVectors, pos);
    vec3 l = l4.xyz;
    l = normalize(l);
    vec3 n = sample(normalVectors, posn).xyz;
    float nl = dot(l, n) * diffuseConstant;
    vec4 res = vec4(lightingColor.r * nl, lightingColor.g * nl, lightingColor.b * nl, 1.0);
    res.xyz *= l4.w;
    return res;
}