Metaball: Evaluate metaball objects as mesh components

With the ultimate goal of simplifying drawing and evaluation,
this patch makes the following changes and removes code:
- Use `Mesh` instead of `DispList` for evaluated basis metaballs.
- Remove all `DispList` drawing code, which is now unused.
- Simplify code that converts evaluated metaballs to meshes.
- Store the evaluated mesh in the evaluated geometry set.

This has the following indirect benefits:
- Evaluated meshes from metaball objects can be used in geometry nodes.
- Renderers can ignore evaluated metaball objects completely
- Cycles rendering no longer has to convert to mesh from `DispList`.
- We get closer to removing `DispList` completely.
- Optimizations to mesh rendering will also apply to metaball objects.

The vertex normals on the evaluated mesh are technically invalid;
the regular calculation wouldn't reproduce them. Metaball objects
don't support modifiers though, so it shouldn't be a problem.
Eventually we can support per-vertex custom normals (T93551).

Differential Revision: https://developer.blender.org/D14593

1 files changed, 0 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_mesh.h b/source/blender/blenkernel/BKE_mesh.h
index b9f6b4b73f3..8cf973b785c 100644
--- a/source/blender/blenkernel/BKE_mesh.h
+++ b/source/blender/blenkernel/BKE_mesh.h
@@ -193,7 +193,6 @@ void BKE_mesh_orco_ensure(struct Object *ob, struct Mesh *mesh);
 
 struct Mesh *BKE_mesh_from_object(struct Object *ob);
 void BKE_mesh_assign_object(struct Main *bmain, struct Object *ob, struct Mesh *me);
-void BKE_mesh_from_metaball(struct ListBase *lb, struct Mesh *me);
 void BKE_mesh_to_curve_nurblist(const struct Mesh *me,
                                 struct ListBase *nurblist,
                                 int edge_users_test);