Fix T43204: Shrinkwrap constraint, project mode: Space ignored in bone case.

Own fault in rBb154aa8c060a60d to fix T42447... Reverted that commit, and added
kind of not-so-nice hack instead.

Note root of the issue comes from the special case we are doing here re 'Local'
space of parent-less objects. In that case, local space should be the same as
world one, but instead we apply the object rotation to it... This is inconsistent
with all other cases and could very well lead to other issues as T42447, but afraid
fixing that properly would be rather hairy - not to mention it would likely break
all existing riggings etc. :(

Should be safe for a 2.73a, shall we need it.

4 files changed, 39 insertions, 28 deletions

diff --git a/source/blender/blenkernel/BKE_constraint.h b/source/blender/blenkernel/BKE_constraint.h
index 87da74dc119..82ae4930526 100644
--- a/source/blender/blenkernel/BKE_constraint.h
+++ b/source/blender/blenkernel/BKE_constraint.h
@@ -141,7 +141,8 @@ bool BKE_constraints_proxylocked_owner(struct Object *ob, struct bPoseChannel *p
 struct bConstraintOb *BKE_constraints_make_evalob(struct Scene *scene, struct Object *ob, void *subdata, short datatype);
 void                  BKE_constraints_clear_evalob(struct bConstraintOb *cob);
 
-void BKE_constraint_mat_convertspace(struct Object *ob, struct bPoseChannel *pchan, float mat[4][4], short from, short to);
+void BKE_constraint_mat_convertspace(
+        struct Object *ob, struct bPoseChannel *pchan, float mat[4][4], short from, short to, const bool keep_scale);
 
 void BKE_constraint_target_matrix_get(struct Scene *scene, struct bConstraint *con, int n, short ownertype, void *ownerdata, float mat[4][4], float ctime);
 void BKE_constraint_targets_for_solving_get(struct bConstraint *con, struct bConstraintOb *ob, struct ListBase *targets, float ctime);
diff --git a/source/blender/blenkernel/intern/constraint.c b/source/blender/blenkernel/intern/constraint.c
index 8fedf37fb95..9072acd8b02 100644
--- a/source/blender/blenkernel/intern/constraint.c
+++ b/source/blender/blenkernel/intern/constraint.c
@@ -229,7 +229,8 @@ void BKE_constraints_clear_evalob(bConstraintOb *cob)
  * of a matrix from one space to another for constraint evaluation.
  * For now, this is only implemented for Objects and PoseChannels.
  */
-void BKE_constraint_mat_convertspace(Object *ob, bPoseChannel *pchan, float mat[4][4], short from, short to)
+void BKE_constraint_mat_convertspace(
+        Object *ob, bPoseChannel *pchan, float mat[4][4], short from, short to, const bool keep_scale)
 {
 	float diff_mat[4][4];
 	float imat[4][4];
@@ -252,7 +253,7 @@ void BKE_constraint_mat_convertspace(Object *ob, bPoseChannel *pchan, float mat[
 				/* use pose-space as stepping stone for other spaces... */
 				if (ELEM(to, CONSTRAINT_SPACE_LOCAL, CONSTRAINT_SPACE_PARLOCAL)) {
 					/* call self with slightly different values */
-					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, to);
+					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, to, keep_scale);
 				}
 				break;
 			}
@@ -288,7 +289,7 @@ void BKE_constraint_mat_convertspace(Object *ob, bPoseChannel *pchan, float mat[
 				/* use pose-space as stepping stone for other spaces */
 				if (ELEM(to, CONSTRAINT_SPACE_WORLD, CONSTRAINT_SPACE_PARLOCAL)) {
 					/* call self with slightly different values */
-					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, to);
+					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, to, keep_scale);
 				}
 				break;
 			}
@@ -303,7 +304,7 @@ void BKE_constraint_mat_convertspace(Object *ob, bPoseChannel *pchan, float mat[
 				/* use pose-space as stepping stone for other spaces */
 				if (ELEM(to, CONSTRAINT_SPACE_WORLD, CONSTRAINT_SPACE_LOCAL)) {
 					/* call self with slightly different values */
-					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, to);
+					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, to, keep_scale);
 				}
 				break;
 			}
@@ -323,8 +324,17 @@ void BKE_constraint_mat_convertspace(Object *ob, bPoseChannel *pchan, float mat[
 				/* Local space in this case will have to be defined as local to the owner's 
 				 * transform-property-rotated axes. So subtract this rotation component.
 				 */
+				/* XXX This is actually an ugly hack, local space of a parent-less object *is* the same as
+				 *     global space!
+				 *     Think what we want actually here is some kind of 'Final Space', i.e. once transformations
+				 *     are applied - users are often confused about this too, this is not consistent with bones
+				 *     local space either... Meh :|
+				 *     --mont29
+				 */
 				BKE_object_to_mat4(ob, diff_mat);
-				normalize_m4(diff_mat);
+				if (!keep_scale) {
+					normalize_m4(diff_mat);
+				}
 				zero_v3(diff_mat[3]);
 				
 				invert_m4_m4_safe(imat, diff_mat);
@@ -342,8 +352,11 @@ void BKE_constraint_mat_convertspace(Object *ob, bPoseChannel *pchan, float mat[
 				/* Local space in this case will have to be defined as local to the owner's 
 				 * transform-property-rotated axes. So add back this rotation component.
 				 */
+				/* XXX See comment above for world->local case... */
 				BKE_object_to_mat4(ob, diff_mat);
-				normalize_m4(diff_mat);
+				if (!keep_scale) {
+					normalize_m4(diff_mat);
+				}
 				zero_v3(diff_mat[3]);
 				
 				mul_m4_m4m4(mat, diff_mat, mat);
@@ -511,7 +524,7 @@ static void constraint_target_to_mat4(Object *ob, const char *substring, float m
 	/*	Case OBJECT */
 	if (!strlen(substring)) {
 		copy_m4_m4(mat, ob->obmat);
-		BKE_constraint_mat_convertspace(ob, NULL, mat, from, to);
+		BKE_constraint_mat_convertspace(ob, NULL, mat, from, to, false);
 	}
 	/*  Case VERTEXGROUP */
 	/* Current method just takes the average location of all the points in the
@@ -524,11 +537,11 @@ static void constraint_target_to_mat4(Object *ob, const char *substring, float m
 	 */
 	else if (ob->type == OB_MESH) {
 		contarget_get_mesh_mat(ob, substring, mat);
-		BKE_constraint_mat_convertspace(ob, NULL, mat, from, to);
+		BKE_constraint_mat_convertspace(ob, NULL, mat, from, to, false);
 	}
 	else if (ob->type == OB_LATTICE) {
 		contarget_get_lattice_mat(ob, substring, mat);
-		BKE_constraint_mat_convertspace(ob, NULL, mat, from, to);
+		BKE_constraint_mat_convertspace(ob, NULL, mat, from, to, false);
 	}
 	/*	Case BONE */
 	else {
@@ -561,7 +574,7 @@ static void constraint_target_to_mat4(Object *ob, const char *substring, float m
 			copy_m4_m4(mat, ob->obmat);
 			
 		/* convert matrix space as required */
-		BKE_constraint_mat_convertspace(ob, pchan, mat, from, to);
+		BKE_constraint_mat_convertspace(ob, pchan, mat, from, to, false);
 	}
 }
 
@@ -3461,16 +3474,13 @@ static void shrinkwrap_get_tarmat(bConstraint *con, bConstraintOb *cob, bConstra
 					}
 					
 					/* transform normal into requested space */
-					/* We cannot use BKE_constraint_mat_convertspace here, it does not take into account scaling...
-					 * In theory we would not need it, but in this case we'd have to tweak SpaceTransform to also
-					 * optionally ignore scaling when handling normals - simpler to directly call BKE_object_to_mat4
-					 * if needed! See T42447. */
-					if (scon->projAxisSpace == CONSTRAINT_SPACE_WORLD) {
-						BKE_object_to_mat4(cob->ob, mat);
-						invert_m4(mat);
-						mul_mat3_m4_v3(mat, no);
-					}
-					/* Else, we remain in local space, nothing to do. */
+					/* Note that in this specific case, we need to keep scaling in non-parented 'local2world' object
+					 * case, because SpaceTransform also takes it into account when handling normals. See T42447. */
+					unit_m4(mat);
+					BKE_constraint_mat_convertspace(cob->ob, cob->pchan, mat,
+					                                CONSTRAINT_SPACE_LOCAL, scon->projAxisSpace, true);
+					invert_m4(mat);
+					mul_mat3_m4_v3(mat, no);
 
 					if (normalize_v3(no) < FLT_EPSILON) {
 						fail = true;
@@ -4816,7 +4826,7 @@ void BKE_constraints_solve(ListBase *conlist, bConstraintOb *cob, float ctime)
 		copy_m4_m4(oldmat, cob->matrix);
 		
 		/* move owner matrix into right space */
-		BKE_constraint_mat_convertspace(cob->ob, cob->pchan, cob->matrix, CONSTRAINT_SPACE_WORLD, con->ownspace);
+		BKE_constraint_mat_convertspace(cob->ob, cob->pchan, cob->matrix, CONSTRAINT_SPACE_WORLD, con->ownspace, false);
 		
 		/* prepare targets for constraint solving */
 		BKE_constraint_targets_for_solving_get(con, cob, &targets, ctime);
@@ -4834,7 +4844,7 @@ void BKE_constraints_solve(ListBase *conlist, bConstraintOb *cob, float ctime)
 		
 		/* move owner back into worldspace for next constraint/other business */
 		if ((con->flag & CONSTRAINT_SPACEONCE) == 0) 
-			BKE_constraint_mat_convertspace(cob->ob, cob->pchan, cob->matrix, con->ownspace, CONSTRAINT_SPACE_WORLD);
+			BKE_constraint_mat_convertspace(cob->ob, cob->pchan, cob->matrix, con->ownspace, CONSTRAINT_SPACE_WORLD, false);
 			
 		/* Interpolate the enforcement, to blend result of constraint into final owner transform 
 		 *  - all this happens in worldspace to prevent any weirdness creeping in ([#26014] and [#25725]),
diff --git a/source/blender/blenkernel/intern/fcurve.c b/source/blender/blenkernel/intern/fcurve.c
index 64300ad6f52..b50e563775e 100644
--- a/source/blender/blenkernel/intern/fcurve.c
+++ b/source/blender/blenkernel/intern/fcurve.c
@@ -1283,7 +1283,7 @@ static float dvar_eval_locDiff(ChannelDriver *driver, DriverVar *dvar)
 					
 					/* extract transform just like how the constraints do it! */
 					copy_m4_m4(mat, pchan->pose_mat);
-					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, CONSTRAINT_SPACE_LOCAL);
+					BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, CONSTRAINT_SPACE_LOCAL, false);
 					
 					/* ... and from that, we get our transform */
 					copy_v3_v3(tmp_loc, mat[3]);
@@ -1308,7 +1308,7 @@ static float dvar_eval_locDiff(ChannelDriver *driver, DriverVar *dvar)
 					
 					/* extract transform just like how the constraints do it! */
 					copy_m4_m4(mat, ob->obmat);
-					BKE_constraint_mat_convertspace(ob, NULL, mat, CONSTRAINT_SPACE_WORLD, CONSTRAINT_SPACE_LOCAL);
+					BKE_constraint_mat_convertspace(ob, NULL, mat, CONSTRAINT_SPACE_WORLD, CONSTRAINT_SPACE_LOCAL, false);
 					
 					/* ... and from that, we get our transform */
 					copy_v3_v3(tmp_loc, mat[3]);
@@ -1385,7 +1385,7 @@ static float dvar_eval_transChan(ChannelDriver *driver, DriverVar *dvar)
 			if (dtar->flag & DTAR_FLAG_LOCAL_CONSTS) {
 				/* just like how the constraints do it! */
 				copy_m4_m4(mat, pchan->pose_mat);
-				BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, CONSTRAINT_SPACE_LOCAL);
+				BKE_constraint_mat_convertspace(ob, pchan, mat, CONSTRAINT_SPACE_POSE, CONSTRAINT_SPACE_LOCAL, false);
 			}
 			else {
 				/* specially calculate local matrix, since chan_mat is not valid 
@@ -1412,7 +1412,7 @@ static float dvar_eval_transChan(ChannelDriver *driver, DriverVar *dvar)
 			if (dtar->flag & DTAR_FLAG_LOCAL_CONSTS) {
 				/* just like how the constraints do it! */
 				copy_m4_m4(mat, ob->obmat);
-				BKE_constraint_mat_convertspace(ob, NULL, mat, CONSTRAINT_SPACE_WORLD, CONSTRAINT_SPACE_LOCAL);
+				BKE_constraint_mat_convertspace(ob, NULL, mat, CONSTRAINT_SPACE_WORLD, CONSTRAINT_SPACE_LOCAL, false);
 			}
 			else {
 				/* transforms to matrix */
diff --git a/source/blender/makesrna/intern/rna_object_api.c b/source/blender/makesrna/intern/rna_object_api.c
index fa356ed43d0..1b4bc10551b 100644
--- a/source/blender/makesrna/intern/rna_object_api.c
+++ b/source/blender/makesrna/intern/rna_object_api.c
@@ -109,7 +109,7 @@ static void rna_Scene_mat_convert_space(Object *ob, ReportList *reports, bPoseCh
 		}
 	}
 
-	BKE_constraint_mat_convertspace(ob, pchan, (float (*)[4])mat_ret, from, to);
+	BKE_constraint_mat_convertspace(ob, pchan, (float (*)[4])mat_ret, from, to, false);
 }
 
 static void rna_Object_calc_matrix_camera(