Function ClearBuffers

Rendering/LICOpenGL2/vtkLineIntegralConvolution2D.cxx:250–294

Description: Clear all the buffers used for writing.

  // Description:
  // Clear all the buffers used for writing.
  void ClearBuffers(vtkOpenGLFramebufferObject* fbo, const vtkPixelExtent& viewExt,
    const deque<vtkPixelExtent>& extents, int clearEETex = 0)
  {
    vtkOpenGLState* ostate = fbo->GetContext()->GetState();

    // attach
    fbo->AddColorAttachment(0U, this->LICTexture0);
    fbo->AddColorAttachment(1U, this->SeedTexture0);
    fbo->AddColorAttachment(2U, this->LICTexture1);
    fbo->AddColorAttachment(3U, this->SeedTexture1);
    unsigned int num = 4U;
    if (clearEETex)
    {
      fbo->AddColorAttachment(4U, this->EETexture);
      num = 5U;
    }
    fbo->ActivateDrawBuffers(num);
    DEBUG3CheckFrameBufferStatusMacro(GL_DRAW_FRAMEBUFFER);

    // clear the parts of the screen which we will modify
    // initially mask all fragments
    ostate->vtkglClearColor(0.0, 1.0, 0.0, 0.0);
    ostate->vtkglEnable(GL_SCISSOR_TEST);
    size_t nBlocks = extents.size();
    for (size_t e = 0; e < nBlocks; ++e)
    {
      vtkPixelExtent ext = extents[e];
      // add halo for linear filtering
      // since at most linear filtering requires
      // 4 pixels , clearing an extra 4 here
      // ensures we never access uninitialized
      // memory.
      ext.Grow(4);
      ext &= viewExt;

      unsigned int extSize[2];
      ext.Size(extSize);

      ostate->vtkglScissor(ext[0], ext[2], extSize[0], extSize[1]);
      ostate->vtkglClear(GL_COLOR_BUFFER_BIT);
    }
    ostate->vtkglDisable(GL_SCISSOR_TEST);
    fbo->RemoveColorAttachments(num);
    fbo->DeactivateDrawBuffers();
  }

  // Description:
  // Clear the given buffer