Method SetCameraShaderParameters

Rendering/OpenGL2/vtkOpenGLPolyDataMapper2D.cxx:434–516

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//------------------------------------------------------------------------------
void vtkOpenGLPolyDataMapper2D::SetCameraShaderParameters(
  vtkOpenGLHelper& cellBO, vtkViewport* viewport, vtkActor2D* actor)
{
  vtkShaderProgram* program = cellBO.Program;

  if (!program)
  {
    vtkErrorWithObjectMacro(this, " got null shader program, cannot set parameters.");
    return;
  }

  // Get the position of the actor
  int size[2];
  size[0] = viewport->GetSize()[0];
  size[1] = viewport->GetSize()[1];

  double* vport = viewport->GetViewport();
  int* actorPos = actor->GetPositionCoordinate()->GetComputedViewportValue(viewport);

  // get window info
  double* tileViewPort = viewport->GetVTKWindow()->GetTileViewport();
  double visVP[4];
  visVP[0] = (vport[0] >= tileViewPort[0]) ? vport[0] : tileViewPort[0];
  visVP[1] = (vport[1] >= tileViewPort[1]) ? vport[1] : tileViewPort[1];
  visVP[2] = (vport[2] <= tileViewPort[2]) ? vport[2] : tileViewPort[2];
  visVP[3] = (vport[3] <= tileViewPort[3]) ? vport[3] : tileViewPort[3];
  if (visVP[0] >= visVP[2])
  {
    return;
  }
  if (visVP[1] >= visVP[3])
  {
    return;
  }
  size[0] = static_cast<int>(std::round(size[0] * (visVP[2] - visVP[0]) / (vport[2] - vport[0])));
  size[1] = static_cast<int>(std::round(size[1] * (visVP[3] - visVP[1]) / (vport[3] - vport[1])));

  const int* winSize = viewport->GetVTKWindow()->GetSize();

  int xoff = static_cast<int>(actorPos[0] - (visVP[0] - vport[0]) * winSize[0]);
  int yoff = static_cast<int>(actorPos[1] - (visVP[1] - vport[1]) * winSize[1]);

  // set ortho projection
  float left = -xoff;
  float right = -xoff + size[0];
  float bottom = -yoff;
  float top = -yoff + size[1];

  // it's an error to call glOrtho with
  // either left==right or top==bottom
  if (left == right)
  {
    right = left + 1.0;
  }
  if (bottom == top)
  {
    top = bottom + 1.0;
  }