2 sided faces aren't supported and will cause problems in many areas
of Blender's code.
Removing (implied) support for faces with fewer than 3 sides
means the total number of triangles is known ahead of time.
This simplifies adding support for multi-threading and partial updates
to an existing tessellation - as the face and loop indices can be used
to access the range of triangles associated with a face.
Also correct outdated comments.
This allows us to remove a callback from the modifier type info struct.
In the future the these modifiers might just be replaced by nodes
internally anyway, but in the meantime it's nice to unify the handling
of evaluated geometry a bit.
Differential Revision: https://developer.blender.org/D11080
This fixes T87666 and T83252.
The boolean modifier and geometry nodes can depend on the geometry
of an entire collection. Before, the modifiers had to manually create relations
to all the objects in the collection. This worked for the most part, but was
cumbersome and did not solve all issues. For example, the modifiers were not
properly updated when objects were added/removed from the referenced collection.
This commit introduces the concept of "collection geometry" in the depsgraph.
The geometry of a collection depends on the transforms and geometry of all
the objects in it. The boolean modifier and geometry nodes can now just depend
on the collection geometry instead of creating all the dependencies themselves.
Differential Revision: https://developer.blender.org/D11053
The main goal here is to remove the need for a C API to the code in
`mesh_boolean_convert.cc`. This is achieved by moving `MOD_boolean.c`
to C++ and making the necessary changes for it to compile. On top of
that there are some other slight simplifications possible to the
direct mesh boolean code: it doesn't need to copy the material
remaps, and the modifier code can use some other C++ types directly.
