Engine reserved blit modes. Blit mode capabilities should be queried from XRDisplaySubsystemDescriptor.GetAvailableMirrorBlitModeCount and XRDisplaySubsystemDescriptor.GetMirrorBlitModeByIndex.
| Distort | Mirror view pass should blit after distortion pass image to the mirror target. |
| LeftEye | Mirror view pass should blit left eye image to the mirror target. |
| None | Mirror view pass should not be performed. |
| RightEye | Mirror view pass should blit right eye image to the mirror target. |
| SideBySide | Mirror view pass should blit left eye image and right eye image in a side-by-side fashion to the mirror target. |
| SideBySideOcclusionMesh | Mirror view pass should blit similar to side-by-side mode, but also showing not rendered pixels saved by the occlusion mesh. |