//=============================================================================
//
// Project:   SharpImage
// Module:    shader-vt-copy.frag
// Language:  OpenGL Shading Language (GLSL)
// Author:    Dan Mueller
// Date:      $Date$
// Revision:  $Revision$
//
// Copyright (c) Queensland University of Technology (QUT) 2007.
// All rights reserved.
//
// This software is distributed WITHOUT ANY WARRANTY; without even
// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
// PURPOSE.  See the copyright notices for more information.
//
//=============================================================================

uniform sampler3D sam3Tex0;  // Sampler for transfer function
uniform sampler3D sam3Tex1;  // Sampler for value image
uniform sampler3D sam3Tex2;  // Not used
uniform sampler3D sam3Tex3;  // Sampler for tag image
uniform float fFactor1;	     // Enhancement factor
uniform float fFactor2;	     // Enhancement factor
uniform float fFactor3;	     // Enhancement factor

void main()
{
    // Interpolate images
    float value = vec4( texture3D(sam3Tex1, gl_TexCoord[1]) ).a;
    float tag   = vec4( texture3D(sam3Tex3, gl_TexCoord[3]) ).a;
    
    // Weight based on tag
    const float TAG0 = 0.0 / 255.0;
    const float TAG1 = 1.0 / 255.0;
    const float TAG2 = 2.0 / 255.0;
    const float TAG3 = 3.0 / 255.0;
    const float TAG4 = 4.0 / 255.0;
    float fWeightedValue = float( tag == TAG0 ) * value * clamp( fFactor1, 0.0, 1.0 )
                         + float( tag == TAG1 ) * value * clamp( fFactor2, 0.0, 1.0 )
                         + float( tag == TAG2 ) * value * clamp( fFactor3, 0.0, 1.0 );
    
    // Set color
    gl_FragColor = vec4( fWeightedValue, fWeightedValue, fWeightedValue, 1.0 );
}