Fix T96308: Mesh to BMesh conversion doesn't calculate vertex normals

Currently there is a "calc_face_normal" argument to mesh to bmesh
conversion, but vertex normals had always implicitly inherited whatever
dirty state the mesh input's vertex normals were in. Probably they were
most often assumed to not be dirty, but this was never really correct in
the general case.

Ever since the refactor to move vertex normals out of mesh vertices,
cfa53e0fbeed7178c7, the copying logic has been explicit: copy the
normals when they are not dirty. But it turns out that more control is
needed, and sometimes normals should be calculated for the resulting
BMesh.

This commit adds an option to the conversion to calculate vertex
normals, true by default. In almost all places except the decimate
and edge split modifiers, I just copied the value of the
"calc_face_normals" argument.

Differential Revision: https://developer.blender.org/D14406

4 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
index 61a02e10063..72cacd2bf85 100644
--- a/source/blender/blenkernel/intern/mesh.cc
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -1172,6 +1172,7 @@ BMesh *BKE_mesh_to_bmesh(Mesh *me,
 {
   BMeshFromMeshParams bmesh_from_mesh_params{};
   bmesh_from_mesh_params.calc_face_normal = false;
+  bmesh_from_mesh_params.calc_vert_normal = false;
   bmesh_from_mesh_params.add_key_index = add_key_index;
   bmesh_from_mesh_params.use_shapekey = true;
   bmesh_from_mesh_params.active_shapekey = ob->shapenr;
diff --git a/source/blender/blenkernel/intern/mesh_mirror.c b/source/blender/blenkernel/intern/mesh_mirror.c
index ec3655ac491..4b529ccf3a8 100644
--- a/source/blender/blenkernel/intern/mesh_mirror.c
+++ b/source/blender/blenkernel/intern/mesh_mirror.c
@@ -62,6 +62,7 @@ Mesh *BKE_mesh_mirror_bisect_on_mirror_plane_for_modifier(MirrorModifierData *mm
                             &(struct BMeshCreateParams){0},
                             &(struct BMeshFromMeshParams){
                                 .calc_face_normal = true,
+                                .calc_vert_normal = true,
                                 .cd_mask_extra = {.vmask = CD_MASK_ORIGINDEX,
                                                   .emask = CD_MASK_ORIGINDEX,
                                                   .pmask = CD_MASK_ORIGINDEX},
@@ -108,6 +109,7 @@ void BKE_mesh_mirror_apply_mirror_on_axis(struct Main *bmain,
                                    },
                                    &(struct BMeshFromMeshParams){
                                        .calc_face_normal = true,
+                                       .calc_vert_normal = true,
                                        .cd_mask_extra =
                                            {
                                                .vmask = CD_MASK_SHAPEKEY,
diff --git a/source/blender/blenkernel/intern/mesh_remesh_voxel.cc b/source/blender/blenkernel/intern/mesh_remesh_voxel.cc
index 50464da86e9..ea06385b07d 100644
--- a/source/blender/blenkernel/intern/mesh_remesh_voxel.cc
+++ b/source/blender/blenkernel/intern/mesh_remesh_voxel.cc
@@ -416,6 +416,7 @@ struct Mesh *BKE_mesh_remesh_voxel_fix_poles(const Mesh *mesh)
 
   BMeshFromMeshParams bmesh_from_mesh_params{};
   bmesh_from_mesh_params.calc_face_normal = true;
+  bmesh_from_mesh_params.calc_vert_normal = true;
   BM_mesh_bm_from_me(bm, mesh, &bmesh_from_mesh_params);
 
   BMVert *v;
diff --git a/source/blender/blenkernel/intern/multires_unsubdivide.c b/source/blender/blenkernel/intern/multires_unsubdivide.c
index 643e1a50fd5..543ff244538 100644
--- a/source/blender/blenkernel/intern/multires_unsubdivide.c
+++ b/source/blender/blenkernel/intern/multires_unsubdivide.c
@@ -885,6 +885,7 @@ static BMesh *get_bmesh_from_mesh(Mesh *mesh)
                      mesh,
                      (&(struct BMeshFromMeshParams){
                          .calc_face_normal = true,
+                         .calc_vert_normal = true,
                      }));
 
   return bm;