Fix T46945: Mesh Deform binding to a cage object with modifiers is unreliable.

Binding code was re-building its own DM for the cage, now it uses given one instead.
I cannot see really any good reason not to use 'visual' modified cage for binding process,
using base mesh instead was breaking any 'advanced' binding as described in the report.

4 files changed, 8 insertions, 6 deletions

diff --git a/source/blender/editors/armature/meshlaplacian.c b/source/blender/editors/armature/meshlaplacian.c
index 6bf75413e81..ce87ffb3494 100644
--- a/source/blender/editors/armature/meshlaplacian.c
+++ b/source/blender/editors/armature/meshlaplacian.c
@@ -1633,7 +1633,9 @@ static void harmonic_coordinates_bind(Scene *UNUSED(scene), MeshDeformModifierDa
 	free_bvhtree_from_mesh(&mdb->bvhdata);
 }
 
-void mesh_deform_bind(Scene *scene, MeshDeformModifierData *mmd, float *vertexcos, int totvert, float cagemat[4][4])
+void mesh_deform_bind(
+        Scene *scene, MeshDeformModifierData *mmd, DerivedMesh *cagedm,
+        float *vertexcos, int totvert, float cagemat[4][4])
 {
 	MeshDeformBind mdb;
 	MVert *mvert;
@@ -1648,7 +1650,7 @@ void mesh_deform_bind(Scene *scene, MeshDeformModifierData *mmd, float *vertexco
 	mdb.vertexcos = MEM_callocN(sizeof(float) * 3 * totvert, "MeshDeformCos");
 	mdb.totvert = totvert;
 	
-	mdb.cagedm = mesh_create_derived_no_deform(scene, mmd->object, NULL, CD_MASK_BAREMESH);
+	mdb.cagedm = cagedm;
 	mdb.totcagevert = mdb.cagedm->getNumVerts(mdb.cagedm);
 	mdb.cagecos = MEM_callocN(sizeof(*mdb.cagecos) * mdb.totcagevert, "MeshDeformBindCos");
 	copy_m4_m4(mdb.cagemat, cagemat);
@@ -1673,7 +1675,6 @@ void mesh_deform_bind(Scene *scene, MeshDeformModifierData *mmd, float *vertexco
 		mul_m4_v3(mmd->object->obmat, mmd->bindcagecos + a * 3);
 
 	/* free */
-	mdb.cagedm->release(mdb.cagedm);
 	MEM_freeN(mdb.vertexcos);
 
 	/* compact weights */
@@ -1682,4 +1683,3 @@ void mesh_deform_bind(Scene *scene, MeshDeformModifierData *mmd, float *vertexco
 	end_progress_bar();
 	waitcursor(0);
 }
-
diff --git a/source/blender/editors/include/ED_armature.h b/source/blender/editors/include/ED_armature.h
index 7d7ee33bde4..15c68378b9a 100644
--- a/source/blender/editors/include/ED_armature.h
+++ b/source/blender/editors/include/ED_armature.h
@@ -42,6 +42,7 @@ struct bPoseChannel;
 struct IDProperty;
 struct ListBase;
 struct MeshDeformModifierData;
+struct DerivedMesh;
 struct Object;
 struct ReportList;
 struct Scene;
@@ -208,6 +209,7 @@ int BDR_drawSketchNames(struct ViewContext *vc);
 /* meshlaplacian.c */
 void mesh_deform_bind(struct Scene *scene,
                       struct MeshDeformModifierData *mmd,
+                      struct DerivedMesh *cagedm,
                       float *vertexcos, int totvert, float cagemat[4][4]);
 	
 #ifdef __cplusplus
diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index 525e267e537..7bd29137aeb 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -698,7 +698,7 @@ typedef struct MeshDeformModifierData {
 	float *bindcos;                 /* deprecated storage of cage coords */
 
 	/* runtime */
-	void (*bindfunc)(struct Scene *scene, struct MeshDeformModifierData *mmd,
+	void (*bindfunc)(struct Scene *scene, struct MeshDeformModifierData *mmd, struct DerivedMesh *cagedm,
 	                 float *vertexcos, int totvert, float cagemat[4][4]);
 } MeshDeformModifierData;
 
diff --git a/source/blender/modifiers/intern/MOD_meshdeform.c b/source/blender/modifiers/intern/MOD_meshdeform.c
index cdf1f85ade5..5f2f51df528 100644
--- a/source/blender/modifiers/intern/MOD_meshdeform.c
+++ b/source/blender/modifiers/intern/MOD_meshdeform.c
@@ -352,7 +352,7 @@ static void meshdeformModifier_do(
 		/* progress bar redraw can make this recursive .. */
 		if (!recursive) {
 			recursive = 1;
-			mmd->bindfunc(md->scene, mmd, (float *)vertexCos, numVerts, cagemat);
+			mmd->bindfunc(md->scene, mmd, cagedm, (float *)vertexCos, numVerts, cagemat);
 			recursive = 0;
 		}
 	}