Implement built-in classes Vector4, Vector4i and Projection.
* Two versions of Vector4 (float and integer).
* A Projection class, which is a 4x4 matrix specialized in projection types.
These types have been requested for a long time, but given they were very corner case they were not added before.
Because in Godot 4, reimplementing parts of the rendering engine is now possible, access to these types (heavily used by the rendering code) becomes a necessity.
**Q**: Why Projection and not Matrix4?
**A**: Godot does not use Matrix2, Matrix3, Matrix4x3, etc. naming convention because, within the engine, these types always have a *purpose*. As such, Godot names them: Transform2D, Transform3D or Basis. In this case, this 4x4 matrix is _always_ used as a _Projection_, hence the naming.
* Added a function to ignore subsequent commands if they don't fall within the slice.
* This will be used by the new TileMap to properly provide animated tiles.
It turns out the calculation of the bounding rect for canvas items has a nasty bug. When a transform is applied (especially in a custom draw), in the renderer this extra matrix is applied to all later commands in the canvas item. However in the calculation of the bound, the transform is only applied to the first command following the transform.
This PR fixes this inconsistency.
-Mesh2D now works
-MultiMesh2D now works
-Polygon2D now works
-Added hooks for processing 2D particles
-Skeleton2D now works
2D particles still not working, but stuff needed for it is now implemented.
Happy new year to the wonderful Godot community!
2020 has been a tough year for most of us personally, but a good year for
Godot development nonetheless with a huge amount of work done towards Godot
4.0 and great improvements backported to the long-lived 3.2 branch.
We've had close to 400 contributors to engine code this year, authoring near
7,000 commit! (And that's only for the `master` branch and for the engine code,
there's a lot more when counting docs, demos and other first-party repos.)
Here's to a great year 2021 for all Godot users 🎆
