Multires: Unsubdivide and Rebuild Subdivisions

This implements the main unsubdivide algorithm which rebuilds a base mesh and extracts the grid's data from a high resolution mesh.
It includes the Rebuild Subdivisions operator, which generates all subdivision levels down to the level 0 base mesh.

It supports:
- Rebuilding an arbitrary number of levels (Unsubdivide) or as many levels as possible down to level 0 in a single step (Rebuild Subdivisions).
- Rebuilding with already existing grids.
- Meshes with n-gons and triangles
- Meshes with more than 2 faces per edge
- Base mesh made completely out of triangles
- Meshes without poles
- Meshes with multiple disconnected elements at the same subdivision level

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D7372

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_multires.h b/source/blender/blenkernel/BKE_multires.h
index e55d050a533..62366f7952b 100644
--- a/source/blender/blenkernel/BKE_multires.h
+++ b/source/blender/blenkernel/BKE_multires.h
@@ -110,6 +110,11 @@ void multiresModifier_del_levels(struct MultiresModifierData *mmd,
 void multiresModifier_base_apply(struct Depsgraph *depsgraph,
                                  struct Object *object,
                                  struct MultiresModifierData *mmd);
+int multiresModifier_rebuild_subdiv(struct Depsgraph *depsgraph,
+                                    struct Object *object,
+                                    struct MultiresModifierData *mmd,
+                                    int rebuild_limit,
+                                    bool switch_view_to_lower_level);
 void multiresModifier_subdivide_legacy(struct MultiresModifierData *mmd,
                                        struct Scene *scene,
                                        struct Object *ob,