Method ReadDepthComponent

Rendering/OpenGL2/vtkOpenGLRenderWindow.cxx:1781–1819

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
bool vtkOpenGLRenderWindow::ReadDepthComponent(int depthSize)
{
  bool readDepthBuffer = false;
  if (!this->DepthReadQuad)
  {
    std::string shader = DepthReadShader;
    std::ostringstream os;
    os << "int depthSize = " << depthSize << ';';
    vtkShaderProgram::Substitute(shader, "//VTK::DepthSize::Impl", os.str());
    this->DepthReadQuad = new vtkOpenGLQuadHelper(this, nullptr, shader.c_str(), "");
    if (!this->DepthReadQuad->Program || !this->DepthReadQuad->Program->GetCompiled())
    {
      vtkErrorMacro("Couldn't build the shader program for reading depth component.");
    }
  }
  else
  {
    this->GetShaderCache()->ReadyShaderProgram(this->DepthReadQuad->Program);
  }

  if (this->DepthReadQuad->Program && this->DepthReadQuad->Program->GetCompiled())
  {
    auto ostate = this->GetState();
    vtkOpenGLState::ScopedglEnableDisable depthTestSaver(ostate, GL_DEPTH_TEST);
    ostate->vtkglDisable(GL_DEPTH_TEST);
    vtkOpenGLState::ScopedglEnableDisable blendSaver(ostate, GL_BLEND);
    ostate->vtkglDisable(GL_BLEND);
    auto tex = this->GetBufferNeedsResolving()
      ? this->ResolveFramebuffer->GetDepthAttachmentAsTextureObject()
      : this->RenderFramebuffer->GetDepthAttachmentAsTextureObject();
    tex->Activate();
    this->DepthReadQuad->Program->SetUniformi("tex", tex->GetTextureUnit());
    this->DepthReadQuad->Render();
    tex->Deactivate();
    readDepthBuffer = true;
  }

  return readDepthBuffer;
}

//------------------------------------------------------------------------------
void vtkOpenGLRenderWindow::BlitDisplayFramebuffersToHardware()