//
// Fragment shader for producing a marble effect
//
// Author: Randi Rost
//
// Copyright (c) 2002-2005 3Dlabs Inc. Ltd. 
//
// See 3Dlabs-License.txt for license information
//

varying float LightIntensity; 
varying vec3  MCposition;

uniform sampler3D Noise;
uniform vec3 MarbleColor;
uniform vec3 VeinColor;

void main()
{
    vec4 noisevec   = texture3D(Noise, MCposition);

    float intensity = abs(noisevec[0] - 0.25) +
                      abs(noisevec[1] - 0.125) +
                      abs(noisevec[2] - 0.0625) +
                      abs(noisevec[3] - 0.03125);

    float sineval = sin(MCposition.y * 6.0 + intensity * 12.0) * 0.5 + 0.5;
    vec3 color    = mix(VeinColor, MarbleColor, sineval) * LightIntensity;
    gl_FragColor  = vec4(color, 1.0);
}