Method SetClipping

Rendering/ContextOpenGL2/vtkOpenGLContextDevice2D.cxx:2079–2131

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//------------------------------------------------------------------------------
void vtkOpenGLContextDevice2D::SetClipping(int* dim)
{
  // If the window is using tile scaling, we need to update the clip coordinates
  // relative to the tile being rendered.
  // (see paraview/paraview#17308)
  double tileViewPort[4];
  this->Renderer->GetVTKWindow()->GetTileViewport(tileViewPort);
  this->Renderer->NormalizedDisplayToDisplay(tileViewPort[0], tileViewPort[1]);
  this->Renderer->NormalizedDisplayToDisplay(tileViewPort[2], tileViewPort[3]);

  vtkRecti tileRect{ vtkContext2D::FloatToInt(tileViewPort[0]),
    vtkContext2D::FloatToInt(tileViewPort[1]), 0, 0 };
  tileRect.AddPoint(
    vtkContext2D::FloatToInt(tileViewPort[2]), vtkContext2D::FloatToInt(tileViewPort[3]));
  // tileRect is the tile being rendered in the current RenderWindow in pixels.

  double viewport[4];
  this->Renderer->GetViewport(viewport);
  this->Renderer->NormalizedDisplayToDisplay(viewport[0], viewport[1]);
  this->Renderer->NormalizedDisplayToDisplay(viewport[2], viewport[3]);
  vtkRecti rendererRect{ vtkContext2D::FloatToInt(viewport[0]),
    vtkContext2D::FloatToInt(viewport[1]), 0, 0 };
  rendererRect.AddPoint(
    vtkContext2D::FloatToInt(viewport[2]), vtkContext2D::FloatToInt(viewport[3]));
  // rendererRect is the viewport in pixels.

  // `dim` is specified as (x,y,width,height) relative to the viewport that this
  // prop is rendering in. So let's fit it in the viewport rect i.e.
  // rendererRect
  vtkRecti clipRect{ dim[0], dim[1], dim[2], dim[3] };
  clipRect.MoveTo(clipRect.GetX() + rendererRect.GetX(), clipRect.GetY() + rendererRect.GetY());
  clipRect.Intersect(rendererRect);

  // Now, clamp the clipRect to the region being shown on the current tile. This
  // generally has no effect since clipRect is wholly contained in tileRect
  // unless tile scaling was being used. In either case, this method will return
  // true as long as the rectangle intersection will produce a valid rectangle.
  if (clipRect.Intersect(tileRect))
  {
    // offset clipRect relative to current tile i.e. window.
    clipRect.MoveTo(clipRect.GetX() - tileRect.GetX(), clipRect.GetY() - tileRect.GetY());
  }
  else
  {
    // clipping region results in empty region, just set to empty.
    clipRect = vtkRecti{ 0, 0, 0, 0 };
  }

  assert(clipRect.GetWidth() >= 0 && clipRect.GetHeight() >= 0);

  this->RenderWindow->GetState()->vtkglScissor(
    clipRect.GetX(), clipRect.GetY(), clipRect.GetWidth(), clipRect.GetHeight());
}

//------------------------------------------------------------------------------
void vtkOpenGLContextDevice2D::EnableClipping(bool enable)