Function BaseInit

Rendering/VolumeOpenGL2/vtkVolumeShaderComposer.h:385–492

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//--------------------------------------------------------------------------
inline std::string BaseInit(vtkRenderer* vtkNotUsed(ren), vtkVolumeMapper* mapper,
  vtkOpenGLGPUVolumeRayCastMapper::VolumeInputMap& inputs, bool defaultLighting)
{
  vtkOpenGLGPUVolumeRayCastMapper* glMapper = vtkOpenGLGPUVolumeRayCastMapper::SafeDownCast(mapper);
  vtkVolume* vol = inputs.begin()->second.Volume;
  const int numInputs = static_cast<int>(inputs.size());

  std::ostringstream shaderStr;
  if (glMapper->GetCurrentPass() != vtkOpenGLGPUVolumeRayCastMapper::DepthPass &&
    glMapper->GetUseDepthPass() && glMapper->GetBlendMode() == vtkVolumeMapper::COMPOSITE_BLEND)
  {
    shaderStr << "\
        \n  //\
        \n  vec2 fragTexCoord2 = (gl_FragCoord.xy - in_windowLowerLeftCorner) *\
        \n                        in_inverseWindowSize;\
        \n  vec4 depthValue = texture2D(in_depthPassSampler, fragTexCoord2);\
        \n  vec4 rayOrigin = WindowToNDC(gl_FragCoord.x, gl_FragCoord.y, depthValue.x);\
        \n\
        \n  // From normalized device coordinates to eye coordinates.\
        \n  // in_projectionMatrix is inversed because of way VT\
        \n  // From eye coordinates to texture coordinates\
        \n  rayOrigin = in_inverseTextureDatasetMatrix[0] *\
        \n              in_inverseVolumeMatrix[0] *\
        \n              in_inverseModelViewMatrix *\
        \n              in_inverseProjectionMatrix *\
        \n              rayOrigin;\
        \n  rayOrigin /= rayOrigin.w;\
        \n  g_rayOrigin = rayOrigin.xyz;";
  }
  else
  {
    shaderStr << "\
        \n  // Get the 3D texture coordinates for lookup into the in_volume dataset\
        \n  g_rayOrigin = ip_textureCoords.xyz;";
  }

  shaderStr << "\n\
      \n  // Getting the ray marching direction (in dataset space)\
      \n  vec3 rayDir = computeRayDirection();\
      \n\
      \n  // 2D Texture fragment coordinates [0,1] from fragment coordinates.\
      \n  // The frame buffer texture has the size of the plain buffer but \
      \n  // we use a fraction of it. The texture coordinate is less than 1 if\
      \n  // the reduction factor is less than 1.\
      \n  // Device coordinates are between -1 and 1. We need texture\
      \n  // coordinates between 0 and 1. The in_depthSampler\
      \n  // buffer has the original size buffer.\
      \n  vec2 fragTexCoord = (gl_FragCoord.xy - in_windowLowerLeftCorner) *\
      \n                      in_inverseWindowSize;\
      \n\
      \n  // Multiply the raymarching direction with the step size to get the\
      \n  // sub-step size we need to take at each raymarching step\
      \n  g_dirStep = (ip_inverseTextureDataAdjusted *\
      \n              vec4(rayDir, 0.0)).xyz * in_sampleDistance;\
      \n  g_lengthStep = length(g_dirStep);\
      \n";

  shaderStr << "\