Summary:
Use PyTorch3D's new faster sample_pdf function instead of local Python implementation.
Also clarify deps for the Python implementation.
Reviewed By: gkioxari
Differential Revision: D30512109
fbshipit-source-id: 84cfdc00313fada37a6b29837de96f6a4646434f
Summary: Change doc references to master branch to its new name main.
Reviewed By: nikhilaravi
Differential Revision: D30303018
fbshipit-source-id: cfdbb207dfe3366de7e0ca759ed56f4b8dd894d1