This is the correct versioning for new MeshDescription objects.
The original versioning (in ReleaseObjectVersion) clashes with changes being brought over from 4.26. MeshDescription objects already saved in UE5 will only be valid for precisely FReleaseObjectVersion::MeshDescriptionNewFormat; subsequent version numbers belong to assets from 4.26 (and derived streams) which have been resaved and merged into UE5, and do *not* have the new MeshDescription format.
Going forward, UE5MainStreamObjectVersion holds the latest version for MeshDescription objects.
#rb Steve.Robb, Marc.Audy
[CL 14377658 by Richard TalbotWatkin in ue5-main branch]
- Removed hardcoded element type arrays (Vertices, Edges, Triangles etc.). Mesh element types can now be arbitrarily added, with any number of channels.
- Mesh element containers have a much leaner format; instead of sparse arrays, they are now represented by a simple bitarray, determining whether an index is used or not. Consequently, mesh topology is now entirely described with the attribute system, e.g. edge start and end vertices, triangle vertices, etc.
- Support added for attributes of arbitrary dimensions, e.g. float[4] or int[2].
- Support added for attributes which index into another mesh element container.
- Added FMeshElementIndexer: this is an efficient container for maintaining backward references from one element type to another; for example, edges have an attribute specifying which vertices are at each end (an attribute of type FVertexID[2]). With an indexer, it is possible to look up which edges contain a given vertex, even though this is not explicitly stored. Indexers are designed to do minimal allocations and update lazily and in batch when necessary.
- Added support for preserving UV topology in static meshes. UVs are now a first-class element type which may be indexed directly from triangles.
- Added the facility to access the underlying array in an attribute array directly.
- Triangles now directly reference their vertex, edge and UV IDs. Vertex instances are to be deprecated.
- Changed various systems to be triangle-centric rather than polygon-centric, as this is faster. Triangles are presumed to be the elementary face type in a MeshDescription, even if polygons are still supported. The concept of polygons will be somewhat shifted to mean a group of triangles which should be treated collectively for editing purposes.
- Optimised normal/tangent generation and FBX import.
- Deprecated EditableMesh, MeshEditor and StaticMeshEditorExtension plugins - these are to be removed, but they still have certain hooks in place which need removing.
#rb
[CL 13568702 by Richard TalbotWatkin in ue5-main branch]
#rnx
#rb none
#ROBOMERGE-OWNER: ryan.durand
#ROBOMERGE-AUTHOR: ryan.durand
#ROBOMERGE-SOURCE: CL 10869210 via CL 10869511 via CL 10869900
#ROBOMERGE-BOT: (v613-10869866)
[CL 10870549 by ryan durand in Main branch]
