//
// Fragment shader for Gooch shading
//
// Author: Randi Rost
//
// Copyright (c) 2002-2004 3Dlabs Inc. Ltd. 
//
// See 3Dlabs-License.txt for license information
//

uniform vec3  SurfaceColor; // (0.75, 0.75, 0.75)
uniform vec3  WarmColor;    // (0.6, 0.6, 0.0)
uniform vec3  CoolColor;    // (0.0, 0.0, 0.6)
uniform float DiffuseWarm;  // 0.45
uniform float DiffuseCool;  // 0.45

varying float NdotL;
varying vec3  ReflectVec;
varying vec3  ViewVec;

void main (void)
{
    vec3 kcool    = min(CoolColor + DiffuseCool * SurfaceColor, 1.0);
    vec3 kwarm    = min(WarmColor + DiffuseWarm * SurfaceColor, 1.0); 
    vec3 kfinal   = mix(kcool, kwarm, NdotL);

    vec3 nreflect = normalize(ReflectVec);
    vec3 nview    = normalize(ViewVec);

    float spec    = max(dot(nreflect, nview), 0.0);
    spec          = pow(spec, 32.0);

    gl_FragColor = vec4 (min(kfinal + spec, 1.0), 1.0);
}
