Blender Git Loki

Fix T92608: Image Editor does not display stereo images

Caused by own {rB5aa3167e48b2}.
Related commit: {rBebaa3fcedd23}.

For stereo renders, `BKE_image_is_multilayer` is true, however we seem
to get to down to `space_image_gpu_texture_get` [where this is called]
from `IMAGE_cache_init` with a NULL Image->RenderResult.

So what then happens is that `BKE_image_multilayer_index` is called and
even though it has an appropriate codepath for stereo, it earlies out
and does not set multi_index correctly.

Still a bit puzzled why RenderResult is NULL for a render, but since
other places also check for a valid RenderResult before going down the
_multilayer_ route (and doing _multiview_ instead), now do the same
thing, BKE_image_multiview_index is now called in these cases (and seems
to behave correctly, checked with layers and passes and all seems to
display correctly, either in stereo or choosing individual eyes).

thx @jbakker & @brecht for double-checking.

Maniphest Tasks: T92608

Differential Revision: https://developer.blender.org/D13063