//VTK::System::Dec

// ============================================================================
//
//  Program:   Visualization Toolkit
//  Module:    vtkOutlineGlowUpscalePassFS.glsl
//
//  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
//  All rights reserved.
//  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
//
//     This software is distributed WITHOUT ANY WARRANTY; without even
//     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
//     PURPOSE.  See the above copyright notice for more information.
//
// ============================================================================

// Fragment shader used by outline glow pass to combine the original scene and the blurred image to form an outline

in vec2 tcoordVC;
uniform sampler2D scene;
uniform sampler2D source;

uniform float outlineIntensity;

// the output of this shader
//VTK::Output::Dec

void main(void)
{
  vec4 color = texture2D(scene, tcoordVC);
  if( length(color.rgb) > 0.0)
  {
    // If the pixel was filled in the original scene it not part of the outline
    gl_FragData[0] = vec4(0.0, 0.0, 0.0, 0.0);
  }
  else
  {
    vec4 blurredColor = texture2D(source,tcoordVC);
    float brightness = max(blurredColor.r, max(blurredColor.g, blurredColor.b));
      gl_FragData[0].rgb = blurredColor.rgb * outlineIntensity;
      gl_FragData[0].a = brightness * outlineIntensity;
    }
}