Blender Git Loki

Merge branch 'master' into temp-abc-features

Merge branch 'master' into temp-abc-features

Fix UI.

Remove attribute regexes.

This was too cumbersome to use.

Use panels to organize buttons in the modifier.

Fix missing null-terminator in BLI_string_join_arrayN

Although the documentation says so, the null-terminator was missing.
This could cause crashes when logging shader linking errors as shader
sources are empty in this case.

Merge branch 'master' into temp-abc-features

Generic structures to handle attributes, handle sculpt vcol as regular
color.

Prepare ground for bool and int attributes.

Separate attribute and VBO types for the conversion.

Also do not promote readily all attributes to float4.

Merge branch 'master' into temp-abc-features

Fix compile error on Windows

Merge branch 'master' into abc-features

Viewport: support rendering point attributes.

This adds support for rendering arbitrary attributes on point domains.
For now only float, float2, and float3 attributes are supported. For
more attribute types, and domains, a more flexible system to gather
needed attributes will be required, as we are currently running out of
bits.

Merge branch 'master' into abc-features

Fix missing draw updates when modifying the layers.

Fix unitialized layer flag.

Alembic: use GeometrySets in the modifier

This uses GeometrySets to import data from Alembic cache. The main idea
is to easily extend the modifier's capabilities by directly generating
an object of the right type instead of always outputing a Mesh.

This will also make it much easier to use Alembic objects from Geometry
nodes until a Alembic node is available there, and can be considered a
first step to supporting such a node.

For meshes, nothing really changes.

For points, a PointCloud object is generated, which can also be used
inside of Geometry nodes. The radius information is also read now, as
well as arbitrary attributes.

For curves, the CurveEval is directly modified if the data did not
change. Otherwise, we keep the current behavior of modifying the
original Curve object and create a new CurveEval from it.

Alembic: generic attribute import

This adds support for reading arbitrary attributes from Alembic
archives.

This is for now only supported for meshes and point clouds (as it reuses
the CDStreamConfig from the Mesh), although it is being made generic
with the usage of an ID and Blender's attribute API. Attributes are
added either on points, face corners, or faces depending on their
original scope.

In order to choose which attributes to load, parameters are added to let
users input the names of the attributes. The names have to be comma
separated, and are segregated by domain (point, face, face corners). A
wildcard (*) can be used to load every attribute of the domain.

Since some software export vector or color attributes as a flat array of
floats, a mechanism to remap attributes is added and accessible through
the user interface. Remapping is only available for float and double
types. The arrays can be remapped to UV maps, vertex colors, float2,
float3, color types, and vertex groups.

Supported attribute types are bool, int, float, 2D & 3D vectors, uvs,
and colors, as well as double precision versions of those.

Alembic: add support for archive layers

This adds support for Alembic archive layers for the Blender CacheFile
and the Cycles Alembic procedural.

Layers are a feature of the Alembic library in which an archive can be
opened from a list of archives or file paths, and where archives
override data from the others. The order of the files matter since
latter files override data from former ones (i.e. a stack).

This feature is useful to, for example, replace a UV map or the
animation of an object without having to re-export the entire scene;
only the affected hierarchy needs to be re-exported, and "imported" as a
layer.

This adds a UI list for adding layers to the CacheFile, with buttons to
change their relative order. The filepath of the CacheFile is
implicitely considered as the bottom layer, although it is not shown as
such in the UI.

In the future, maybe with T68933, this could be the basis for a non-
destructive workflow where edits to an Alembic archive are exported as
layers.