Fix T96205: Active shape key gets lost upon edit mode undo

Regression in d961adb866cc2d7a95e4c6a7f06c49e346ec1abe,
it's important that for the Mesh used for undo storage matches
the shape-key instead of using the coordinates of the Basis key.

Prior to bfdbc78466ac14d45f353db9aa39cb21bb962701 a different method of
restoring the basis shape-key coordinates was used (restoring from the
input `Mesh.mvert` array). When undo wrote the edit-mesh into the mesh
this was always NULL so the basis shape keys coordinates were never
used.

Now a parameter has been added so undo can use the active shape for the
meshes vertex coordinates.

Reviewed By: sergey

Maniphest Tasks: T96205

Ref D14258

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/bmesh/intern/bmesh_mesh_convert.h b/source/blender/bmesh/intern/bmesh_mesh_convert.h
index 07ffc8b43df..6da5412a81c 100644
--- a/source/blender/bmesh/intern/bmesh_mesh_convert.h
+++ b/source/blender/bmesh/intern/bmesh_mesh_convert.h
@@ -69,6 +69,11 @@ struct BMeshToMeshParams {
    * that have become invalid from updating the shape-key, see T71865.
    */
   uint update_shapekey_indices : 1;
+  /**
+   * Instead of copying the basis shape-key into the #MVert array,
+   * copy the #BMVert.co directly to #MVert.co (used for reading undo data).
+   */
+  uint active_shapekey_to_mvert : 1;
   struct CustomData_MeshMasks cd_mask_extra;
 };
 /**