Viewport: Disable Clipping For EEVEE and External Renderers
Currently it is possible that, when using viewport clipping, the display and tools communicate
different information to the user then the renderer does. The reason is
that the renderer does not support viewport clipping. Both EEVEE and
Cycles do not support it.
This patch will disable the clipping in all the tools and drawing code
when the viewport drawing mode is Material Preview or Rendered.
This patch introduces a RV3D_CLIPPING_ENABLED util that checks if
clipping is enabled for the given rv3d and v3d. Also in places where
it was needed we added the ViewContext as a carrier for the View3D
and RegionView3D.
There are a few areas in the tooling (select, projection painting) that
still needs to be tackled after this patch.