Code was assuming frustrum planes are symmetrical which is not the case for shifting. This lead to a shrinking region if shift was negative (and a growing region if shift was positive) So instead of only keeping track of plane on one side (and mirroring over in code) get the actual planes after shifting and use these instead. This code corrects this for ortho and perspective cameras, it does not touch panoramic cameras. Reviewed By: brecht Maniphest Tasks: T69911 Differential Revision: https://developer.blender.org/D9342