Method BuildShaders

Rendering/OpenGL2/vtkOpenGLPolyDataMapper.cxx:284–334

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//------------------------------------------------------------------------------
void vtkOpenGLPolyDataMapper::BuildShaders(
  std::map<vtkShader::Type, vtkShader*> shaders, vtkRenderer* ren, vtkActor* actor)
{
  this->GetShaderTemplate(shaders, ren, actor);

  // user specified pre replacements
  vtkOpenGLShaderProperty* sp = vtkOpenGLShaderProperty::SafeDownCast(actor->GetShaderProperty());
  vtkOpenGLShaderProperty::ReplacementMap repMap = sp->GetAllShaderReplacements();
  for (const auto& i : repMap)
  {
    if (i.first.ReplaceFirst)
    {
      std::string ssrc = shaders[i.first.ShaderType]->GetSource();
      vtkShaderProgram::Substitute(
        ssrc, i.first.OriginalValue, i.second.Replacement, i.second.ReplaceAll);
      shaders[i.first.ShaderType]->SetSource(ssrc);
    }
  }

  this->ReplaceShaderValues(shaders, ren, actor);

  // user specified post replacements
  for (const auto& i : repMap)
  {
    if (!i.first.ReplaceFirst)
    {
      std::string ssrc = shaders[i.first.ShaderType]->GetSource();
      vtkShaderProgram::Substitute(
        ssrc, i.first.OriginalValue, i.second.Replacement, i.second.ReplaceAll);
      shaders[i.first.ShaderType]->SetSource(ssrc);
    }
  }

  // Fix gl_PrimitiveID in fragment shader after all shader replacements.
  // When oglRenderWindow->IsPrimIDBugPresent() returns true, the geometry shader
  // ignores values written into gl_PrimitiveID and increments it per output primitive.
  // So, here, undo the two increments per line segment with a divide-by-2.
  std::string FSSource = shaders[vtkShader::Fragment]->GetSource();
  if (this->HaveWideLines(ren, actor))
  {
    if (auto oglRenderWindow = vtkOpenGLRenderWindow::SafeDownCast(ren->GetRenderWindow()))
    {
      if (oglRenderWindow->IsPrimIDBugPresent())
      {
        vtkShaderProgram::Substitute(FSSource, "gl_PrimitiveID", "gl_PrimitiveID / 2");
      }
    }
  }

  shaders[vtkShader::Fragment]->SetSource(FSSource);
}

//------------------------------------------------------------------------------
bool vtkOpenGLPolyDataMapper::HaveWideLines(vtkRenderer* ren, vtkActor* actor)