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, 2 insertions, 1 deletions

diff --git a/source/blender/editors/object/object_modifier.cc b/source/blender/editors/object/object_modifier.cc
index 010a01f9d30..75f9fdd485e 100644
--- a/source/blender/editors/object/object_modifier.cc
+++ b/source/blender/editors/object/object_modifier.cc
@@ -50,6 +50,7 @@
 #include "BKE_lib_id.h"
 #include "BKE_main.h"
 #include "BKE_material.h"
+#include "BKE_mball.h"
 #include "BKE_mesh.h"
 #include "BKE_mesh_mapping.h"
 #include "BKE_mesh_runtime.h"
@@ -111,7 +112,7 @@ static void object_force_modifier_update_for_bind(Depsgraph *depsgraph, Object *
     BKE_lattice_modifiers_calc(depsgraph, scene_eval, ob_eval);
   }
   else if (ob->type == OB_MBALL) {
-    BKE_displist_make_mball(depsgraph, scene_eval, ob_eval);
+    BKE_mball_data_update(depsgraph, scene_eval, ob_eval);
   }
   else if (ELEM(ob->type, OB_CURVES_LEGACY, OB_SURF, OB_FONT)) {
     BKE_displist_make_curveTypes(depsgraph, scene_eval, ob_eval, false);