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

6 files changed, 5 insertions, 7 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_engine.c b/source/blender/draw/engines/eevee/eevee_engine.c
index ffe0863fb9f..cc7d0c6b22e 100644
--- a/source/blender/draw/engines/eevee/eevee_engine.c
+++ b/source/blender/draw/engines/eevee/eevee_engine.c
@@ -109,7 +109,7 @@ void EEVEE_cache_populate(void *vedata, Object *ob)
   }
 
   if (DRW_object_is_renderable(ob) && (ob_visibility & OB_VISIBLE_SELF)) {
-    if (ELEM(ob->type, OB_MESH, OB_SURF, OB_MBALL)) {
+    if (ELEM(ob->type, OB_MESH, OB_SURF)) {
       EEVEE_materials_cache_populate(vedata, sldata, ob, &cast_shadow);
     }
     else if (ob->type == OB_CURVES) {
diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index efd27c19654..94f29d64628 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -806,7 +806,7 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
                          !DRW_state_is_image_render();
 
   /* First get materials for this mesh. */
-  if (ELEM(ob->type, OB_MESH, OB_SURF, OB_MBALL)) {
+  if (ELEM(ob->type, OB_MESH, OB_SURF)) {
     const int materials_len = DRW_cache_object_material_count_get(ob);
 
     EeveeMaterialCache *matcache = BLI_array_alloca(matcache, materials_len);
diff --git a/source/blender/draw/engines/eevee/eevee_render.c b/source/blender/draw/engines/eevee/eevee_render.c
index 82944f237ea..3e268758076 100644
--- a/source/blender/draw/engines/eevee/eevee_render.c
+++ b/source/blender/draw/engines/eevee/eevee_render.c
@@ -224,7 +224,7 @@ void EEVEE_render_cache(void *vedata,
   }
 
   if (ob_visibility & OB_VISIBLE_SELF) {
-    if (ELEM(ob->type, OB_MESH, OB_SURF, OB_MBALL)) {
+    if (ELEM(ob->type, OB_MESH, OB_SURF)) {
       EEVEE_materials_cache_populate(vedata, sldata, ob, &cast_shadow);
       if (do_cryptomatte) {
         EEVEE_cryptomatte_cache_populate(data, sldata, ob);
diff --git a/source/blender/draw/engines/eevee_next/eevee_instance.cc b/source/blender/draw/engines/eevee_next/eevee_instance.cc
index 6665b3a7c9b..eb32ebe9555 100644
--- a/source/blender/draw/engines/eevee_next/eevee_instance.cc
+++ b/source/blender/draw/engines/eevee_next/eevee_instance.cc
@@ -144,8 +144,7 @@ void Instance::object_sync(Object *ob)
       case OB_MESH:
       case OB_CURVES_LEGACY:
       case OB_SURF:
-      case OB_FONT:
-      case OB_MBALL: {
+      case OB_FONT: {
         sync.sync_mesh(ob, ob_handle);
         break;
       }
diff --git a/source/blender/draw/engines/overlay/overlay_engine.c b/source/blender/draw/engines/overlay/overlay_engine.c
index 5edd68bffff..6e2da95e405 100644
--- a/source/blender/draw/engines/overlay/overlay_engine.c
+++ b/source/blender/draw/engines/overlay/overlay_engine.c
@@ -320,7 +320,6 @@ static void OVERLAY_cache_populate(void *vedata, Object *ob)
                                 OB_MESH,
                                 OB_CURVES_LEGACY,
                                 OB_SURF,
-                                OB_MBALL,
                                 OB_FONT,
                                 OB_GPENCIL,
                                 OB_CURVES,
diff --git a/source/blender/draw/engines/workbench/workbench_engine.c b/source/blender/draw/engines/workbench/workbench_engine.c
index 9eb35c25bf4..ad32618e636 100644
--- a/source/blender/draw/engines/workbench/workbench_engine.c
+++ b/source/blender/draw/engines/workbench/workbench_engine.c
@@ -409,7 +409,7 @@ void workbench_cache_populate(void *ved, Object *ob)
     return;
   }
 
-  if (ELEM(ob->type, OB_MESH, OB_SURF, OB_MBALL, OB_POINTCLOUD)) {
+  if (ELEM(ob->type, OB_MESH, OB_SURF, OB_POINTCLOUD)) {
     bool use_sculpt_pbvh, use_texpaint_mode, draw_shadow, has_transp_mat = false;
     eV3DShadingColorType color_type = workbench_color_type_get(
         wpd, ob, &use_sculpt_pbvh, &use_texpaint_mode, &draw_shadow);