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/intern/multires_reshape.h b/source/blender/blenkernel/intern/multires_reshape.h
index bf5b03f51d9..3b06e126f15 100644
--- a/source/blender/blenkernel/intern/multires_reshape.h
+++ b/source/blender/blenkernel/intern/multires_reshape.h
@@ -156,6 +156,11 @@ bool multires_reshape_context_create_from_object(MultiresReshapeContext *reshape
                                                  struct Object *object,
                                                  struct MultiresModifierData *mmd);
 
+bool multires_reshape_context_create_from_base_mesh(MultiresReshapeContext *reshape_context,
+                                                    struct Depsgraph *depsgraph,
+                                                    struct Object *object,
+                                                    struct MultiresModifierData *mmd);
+
 bool multires_reshape_context_create_from_ccg(MultiresReshapeContext *reshape_context,
                                               struct SubdivCCG *subdiv_ccg,
                                               struct Mesh *base_mesh,