Hans Goudey
1ea169d90e
As part of T95966, this patch moves loose edge information out of the flag on each edge and into a new lazily calculated cache in mesh runtime data. The number of loose edges is also cached, so further processing can be skipped completely when there are no loose edges. Previously the `ME_LOOSEEDGE` flag was updated on a "best effort" basis. In order to be sure that it was correct, you had to be sure to call `BKE_mesh_calc_edges_loose` first. Now the loose edge tag is always correct. It also doesn't have to be calculated eagerly in various places like the screw modifier where the complexity wasn't worth the theoretical performance benefit. The patch also adds a function to eagerly set the number of loose edges to zero to avoid building the cache. This is used by various primitive nodes, with the goal of improving drawing performance. This results in a few ms shaved off extracting draw data for some large meshes in my tests. In the Python API, `MeshEdge.is_loose` is no longer editable. No built-in addons set the value anyway. The upside is that addons can be sure the data is correct based on the mesh. **Tests** There is one test failure in the Python OBJ exporter: `export_obj_cube` that happens because of existing incorrect versioning. Opening the file in master, all the edges were set to "loose", which is fixed by this patch. Differential Revision: https://developer.blender.org/D16504