Blender Git Loki

Make falloff function external to reuse

Move the calculation of falloff factor to a separated function to be reused in transformations.

Fix update of non-scene owned layer collections

We are using NC_SCENE | ND_LAYER_CONTENT for the shader, however this does not work for groups
unless we manually handle the notifiers.

Otherwise the group id is passed, and the listener never gets the notification since a scene id
is expected, or no id at all.

Groups and collection: editing group collections

Allow users to edit either the object group active collection or view layer one

We can't support users selecting the group collections from the outliner group
because that would be imply having an active group for the scene or workspace.

But the way it is now allows to see and edit the collection values after the
group is instanced.

Groups and collection: create group from collection

You could still create groups as before, with Ctl + G. This will create a group
with a single visible collection.

However you can also create a group from an existing collection. Just go to
the menu you get in the outliner when clicking in a collection and pick
"Create Group".

Remember to instance the group afterwards, or link it into a new scene or file.

The group and the collection are not kept in sync afterwards. You need to manually
edit the group for further changes.

Groups and collection: initial integration

Since we are ditching layers from Blender (2.8) we need a replacement to
control groups visibility. This commit introduces collections as the building
blocks for groups, allowing users to control visibility as well as overrides
for groups.

Features
========

* Groups now have collections
This way you can change the visibility of a collection inside a group, and add
overrides which are part of the group and are prioritized over other overrides.

* Outliner
Groups can inspect their collections, change visibility, and add/remove members.

To change an override of a group collection, you need to select an instance of
the group, and then you can choose "group" in the collection properties editor
to edit this group active collection instead of the view layer one.

* Dupli groups overrides
We can now have multiple instances of the same group with an original "override"
and different overrides depending on the collection the instanced object is part
of.

Technical
=========

* Layers
We use the same api for groups and scene as much as possible.

Reviewers: sergey (depsgraph), mont29 (read/write and user count)
Differential Revision: https://developer.blender.org/D2892

fix for particle caching and also added more sanity checks in particle getters

Workspaces: Store an active view-layer per scene

Instead of storing a single active view-layer in the workspace, one is
stored for each scene the workspace showed before.
With this, some things become possible:
* Multiple windows in the same workspace but showing different scenes.
* Toggling back and forth scene keeps same active view-layer for each scene.
* Activating workspace which didn't show current scene before, the current view-layer is kept.

A necessary evil for this is that accessing view-layer and object mode
from .py can't be done via workspace directly anymore. It has to be done
through the window, so RNA can use the correct scene.
So instead of `workspace.view_layer`, it's `window.view_layer` now (same
with mode) even though it's still workspace data.

Fixes T53432.

Depsgraph: Cleanup, simplify evaluation flush function

Also avoid once queue push for cases when current operation has multiple
outgoing relations.

Merge branch 'blender2.8' into greasepencil-object

Fix falloff error when layer has no active frame

Silence warning from object_relations.c

Various cleanup and minor fixes.

Depsgraph: Remove legacy recalc flag from DNA

Merge branch 'blender2.8' into asset-engine

Depsgraph: Remove clear of legacy unused flag

Depsgraph: Move away from setting old deprecated object recalc flags

Those shouldn't be used anywhere for real now.

Depsgraph: Don't use legacy flags in versioning code

Wondering whether files from 2.37 are still working fine.
Don't have that version of Blender running here, so can't test :(

Depsgraph: Use per-ID flags to see whether update is needed

This is actually functions which needs bigger reconsideration, but for now let's
try to keep them working as much as possible.

Depsgraph: Use new per-ID tags to see whether object in a group needs an update

This wouldn't be less precise than object level flag in theory, and we need to
move away from such a duplicating flags.

Transform: Avoid attempt to bypass dependency graph update

It's not possible to bypass new depsgraph, but also flush to other CoW copies
might be needed here.