Blender Git Loki

Fix T78392: [2.83.5, 2.90, 2.91] Crash on undo/ redo after changing modes.

During undo/redo read code is expected to clear the `OB_MODE_EDIT`
bitflag of `Object.mode`, for some reasons.

This was not done anymore for re-used Objects, we need to add a special
handling case for that too.

Should be backported to 2.90 and 2.83 (will probably not be straight
forward for the latter).

Fix T77584: Edit Mode crash with shape keys created on blank mesh

Entering edit-mode after creating shape keys on a blank mesh would crash.

Regression in 9b9f84b317fef which prevented initializing empty
shape keys when there is no shape key offset data available.

Fix T79737: ERROR ACCESS VIOLATION when switching to eevee rendered view

This prevents Blender from crashing when switching
to rendered view and the grid_data is NULL in the
lightcache (due to possible corruption), by switching
to the fallback lightcache. The fix extends the solution
for possible corruption in the cube_data as well.

Fix T79737

Reviewed By: fclem
Differential Revision: https://developer.blender.org/D8835

Fix T80603 Workbench: Inverted alpha when rendering

The state of the passes was not set back after the first sample.

This is a simpler fix than rBecfbc5fb55d5 which needs the new draw manager
features from 2.90.

Fix T75061 Grease Pencil: MacOS: broken Gradient and Texture

There is a driver bug that makes all the end of the structure unreadable.
Workaround this by just declaring a vec4 an unpacking manually.

Version Blender 2.83.7 Beta

MTLWriter: overwrite the file instead of appending to it.

Prepend importer_ to mesh_utils; parser_ to string_utils.

Move MTLMaterial & float3_to_string to exporter files.

Keeping the branch in sync with D8754 and D8753.

Merge branch 'exporter_n' into soc-2020-io-performance

Merge remote-tracking branch 'origin/master' into lanpr-under-gp

# Conflicts:
# source/blender/makesdna/DNA_collection_types.h
# source/blender/makesrna/intern/rna_collection.c

Move vertex index Vector resize to OBJMesh.

Corrections: correct wrong assert, remove cast.

Simplify material group calculation.

Simplify vertex group calculation.

Add smooth group constants, use "0" instead of "off".

Add polygon element writer selector to OBJWriter.

Add polygon normal indices calculation method to OBJMesh.

Remove depsgraph member variable; use const variables.

Material: Disambiguate mat_nr + 1.