Fix T92815: Incorrect handling of evaluated meshes from curves

Evaluated meshes from curves are presented to render engines as
separate instance objects now, just like evaluated meshes from other
object types like point clouds and volumes. For that reason, cycles
should not consider curve objects as geometry (previously it did,
meaning it retrieved a second mesh from the curve object as well
as the temporary evaluated mesh geometry).

Further, avoid adding a curve object's evaluated mesh as data_eval,
since that is special behavior for meshes that is arbitrary. Adding an
evaluated mesh there but not an evalauted pointcloud is arbitrary,
for example. Retrieve the evaluated mesh in from the geometry set
in BKE_object_get_evaluated_mesh now, to support that change.

This gets us closer to a place where all of an object's evaluated data
is stored in geometry_set_eval, and we just have helper functions
to access specific geometry components.

Differential Revision: https://developer.blender.org/D13118

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/DerivedMesh.cc b/source/blender/blenkernel/intern/DerivedMesh.cc
index 4b1332d5b84..ced9076bbfd 100644
--- a/source/blender/blenkernel/intern/DerivedMesh.cc
+++ b/source/blender/blenkernel/intern/DerivedMesh.cc
@@ -1896,9 +1896,9 @@ static void mesh_build_data(struct Depsgraph *depsgraph,
   const bool is_mesh_eval_owned = (mesh_eval != mesh->runtime.mesh_eval);
   BKE_object_eval_assign_data(ob, &mesh_eval->id, is_mesh_eval_owned);
 
-  /* Add the final mesh as read-only non-owning component to the geometry set. */
+  /* Add the final mesh as a non-owning component to the geometry set. */
   MeshComponent &mesh_component = geometry_set_eval->get_component_for_write<MeshComponent>();
-  mesh_component.replace(mesh_eval, GeometryOwnershipType::ReadOnly);
+  mesh_component.replace(mesh_eval, GeometryOwnershipType::Editable);
   ob->runtime.geometry_set_eval = geometry_set_eval;
 
   ob->runtime.mesh_deform_eval = mesh_deform_eval;