Mesh: Tag normals dirty instead of calculating

Because mesh vertex and face normals are just derived data, they can
be calculated lazily instead of eagerly. Often normal calculation is
a relatively expensive task, and the calculation is often redundant
if the mesh is deformed afterwards anyway.

Instead, normals should be calculated only when they are needed. This
commit moves in that direction by adding a new function to tag a mesh's
normals dirty and replacing normal calculation with it in some places.

Differential Revision: https://developer.blender.org/D12107

4 files changed, 5 insertions, 7 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_convex_hull.cc b/source/blender/nodes/geometry/nodes/node_geo_convex_hull.cc
index 4286db52115..91d569282c3 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_convex_hull.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_convex_hull.cc
@@ -150,7 +150,7 @@ static Mesh *hull_from_bullet(const Mesh *mesh, Span<float3> coords)
 
   plConvexHullDelete(hull);
 
-  BKE_mesh_calc_normals(result);
+  BKE_mesh_normals_tag_dirty(result);
   return result;
 }
 
diff --git a/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc
index 925ed0f8da8..d46ea2d2050 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc
@@ -299,7 +299,7 @@ Mesh *create_cylinder_or_cone_mesh(const float radius_top,
     mesh->medge[0].v1 = 0;
     mesh->medge[0].v2 = 1;
     mesh->medge[0].flag |= ME_LOOSEEDGE;
-    BKE_mesh_calc_normals(mesh);
+    BKE_mesh_normals_tag_dirty(mesh);
     return mesh;
   }
 
@@ -534,12 +534,10 @@ Mesh *create_cylinder_or_cone_mesh(const float radius_top,
     }
   }
 
-  BKE_mesh_calc_normals(mesh);
+  BKE_mesh_normals_tag_dirty(mesh);
 
   calculate_uvs(mesh, top_is_point, bottom_is_point, verts_num, fill_type);
 
-  BLI_assert(BKE_mesh_is_valid(mesh));
-
   return mesh;
 }
 
diff --git a/source/blender/nodes/geometry/nodes/node_geo_mesh_subdivide.cc b/source/blender/nodes/geometry/nodes/node_geo_mesh_subdivide.cc
index 245d7800621..165da8ec9f2 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_mesh_subdivide.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_mesh_subdivide.cc
@@ -88,7 +88,7 @@ static void geo_node_mesh_subdivide_exec(GeoNodeExecParams params)
   }
 
   Mesh *mesh_out = BKE_subdiv_to_mesh(subdiv, &mesh_settings, mesh_in);
-  BKE_mesh_calc_normals(mesh_out);
+  BKE_mesh_normals_tag_dirty(mesh_out);
 
   MeshComponent &mesh_component = geometry_set.get_component_for_write<MeshComponent>();
   mesh_component.replace(mesh_out);
diff --git a/source/blender/nodes/geometry/nodes/node_geo_subdivision_surface.cc b/source/blender/nodes/geometry/nodes/node_geo_subdivision_surface.cc
index f0f032ed8f4..a2c10af9c4d 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_subdivision_surface.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_subdivision_surface.cc
@@ -93,7 +93,7 @@ static void geo_node_subdivision_surface_exec(GeoNodeExecParams params)
   }
 
   Mesh *mesh_out = BKE_subdiv_to_mesh(subdiv, &mesh_settings, mesh_in);
-  BKE_mesh_calc_normals(mesh_out);
+  BKE_mesh_normals_tag_dirty(mesh_out);
 
   MeshComponent &mesh_component = geometry_set.get_component_for_write<MeshComponent>();
   mesh_component.replace(mesh_out);