== Constraints System ==

After just over a week of coding, I've finished doing a major refactor/cleanup of the constraints code. In the process, quite a few old kludges and ugly hacks have been removed. Also, some new features which will greatly benefit riggers have been implemented.

=== What's New ===
* The long-awaited ``ChildOf Constraint'':
This allows you to animate parent influences, and choose which transformation channels the parent affects the child on (i.e. no translation/rotation/scaling). It should be noted that disabling some combinations may not totally work as expected. Also, the 'Set Inverse' and 'Clear Inverse' buttons at the bottom of this constraint's panel set/clear the inverse correction for the parent's effects. Use these to make the owner not stick/be glued to the parent.
* Constraint/Target Evaluation Spaces:
In some constraints, there are now 1-2 combo boxes at the bottom of their panel, which allows you to pick which `co-ordinate space' they are evaluated in. This is much more flexible than the old 'local' options for bones only were.
* Action Constraint - Loc/Rot/Size Inputs
The Action Constraint can finally use the target's location/rotation/scaling transforms as input, to control the owner of the constraint. This should work much more reliably than it used to. The target evaluation should now also be more accurate due to the new space conversion stuff.
* Transform - No longer in Crazy Space (TM)
Transforming objects/bones with constraints applied should no longer occur in Crazy Space. They are now correctly inverse-corrected. This also applies to old-style object tracking.

=== General Code Changes ===
* solve_constraints is now in constraints.c. I've removed the old `blend consecutive constraints of same type' junk, which made the code more complex than it needed to be.
* evaluate_constraint is now only passed the constraint, and two matrices. A few unused variables have been removed from here.
* A tempolary struct, bConstraintOb, is now passed to solve_constraints instead of relying on an ugly, static workobject in some cases. This works much better.
* Made the formatting of constraint code consistent
* There's a version patch for older files so that constraint settings are correctly converted to the new system. This is currently done for MajorVersion <= 244, and SubVersion < 3. I've bumped up the subversion to 3 for this purpose. However, with the imminent 2.45 release, this may need to be adjusted accordingly.
* LocEulSizeToMat4 and LocQuatSizeToMat4 now work in the order Size, Rot, Location. I've also added a few other math functions.
* Mat4BlendMat4 is now in arithb. I've modified it's method slightly, to use other arithb functions, instead of its crazy blending scheme. 
* Moved some of the RigidBodyJoint constraint's code out of blenkernel, and into src. It shouldn't be setting its target in its data initialisation function based + accessing scene stuff where it was doing so.

=== Future Work ===
* Geometry to act as targets for constraints. A space has been reserved for this already. 
* Tidy up UI buttons of constraints

1 files changed, 43 insertions, 30 deletions

diff --git a/source/blender/src/editconstraint.c b/source/blender/src/editconstraint.c
index 7e1178de377..248b7196b8f 100644
--- a/source/blender/src/editconstraint.c
+++ b/source/blender/src/editconstraint.c
@@ -671,21 +671,21 @@ void add_constraint(int only_IK)
 	else {
 		if(pchanact) {
 			if(pchansel)
-				nr= pupmenu("Add Constraint to Active Bone%t|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Stretch To%x7|Action%x16|%l|Script%x18");
+				nr= pupmenu("Add Constraint to Active Bone%t|Child Of%x19|%l|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Stretch To%x7|%l|Action%x16|Script%x18");
 			else if(obsel && obsel->type==OB_CURVE)
-				nr= pupmenu("Add Constraint to Active Object%t|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Follow Path%x6|Clamp To%x17|Stretch To%x7|Action%x16|%l|Script%x18");
+				nr= pupmenu("Add Constraint to Active Object%t|Child Of%x19|%l|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Follow Path%x6|Clamp To%x17|Stretch To%x7|%l|Action%x16|Script%x18");
 			else if(obsel)
-				nr= pupmenu("Add Constraint to Active Object%t|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Stretch To%x7|Action%x16|%l|Script%x18");
+				nr= pupmenu("Add Constraint to Active Object%t|Child Of%x19|%l|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Stretch To%x7|%l|Action%x16|Script%x18");
 			else
-				nr= pupmenu("Add Constraint to New Empty Object%t|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Stretch To%x7|%l|Script%x18");
+				nr= pupmenu("Add Constraint to New Empty Object%t|Child Of%x19|%l|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Stretch To%x7|%l|Script%x18");
 		}
 		else {
 			if(obsel && obsel->type==OB_CURVE)
-				nr= pupmenu("Add Constraint to Active Object%t|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Follow Path%x6|Clamp To%x17|%l|Script%x18");
+				nr= pupmenu("Add Constraint to Active Object%t|Child Of%x19|%l|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|Follow Path%x6|Clamp To%x17|%l|Script%x18");
 			else if(obsel)
-				nr= pupmenu("Add Constraint to Active Object%t|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|%l|Script%x18");
+				nr= pupmenu("Add Constraint to Active Object%t|Child Of%x19|%l|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|%l|Script%x18");
 			else
-				nr= pupmenu("Add Constraint to New Empty Object%t|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|%l|Script%x18");
+				nr= pupmenu("Add Constraint to New Empty Object%t|Child Of%x19|%l|Copy Location%x1|Copy Rotation%x2|Copy Scale%x8|%l|Limit Location%x13|Limit Rotation%x14|Limit Scale%x15|%l|Track To%x3|Floor%x4|Locked Track%x5|%l|Script%x18");
 		}
 	}
 	
@@ -724,28 +724,31 @@ void add_constraint(int only_IK)
 	}
 	else {
 		
-		if(nr==1) con = add_new_constraint(CONSTRAINT_TYPE_LOCLIKE);
-		else if(nr==2) con = add_new_constraint(CONSTRAINT_TYPE_ROTLIKE);
-		else if(nr==3) con = add_new_constraint(CONSTRAINT_TYPE_TRACKTO);
-		else if(nr==4) con = add_new_constraint(CONSTRAINT_TYPE_MINMAX);
-		else if(nr==5) con = add_new_constraint(CONSTRAINT_TYPE_LOCKTRACK);
-		else if(nr==6) {
+		if (nr==1) con = add_new_constraint(CONSTRAINT_TYPE_LOCLIKE);
+		else if (nr==2) con = add_new_constraint(CONSTRAINT_TYPE_ROTLIKE);
+		else if (nr==3) con = add_new_constraint(CONSTRAINT_TYPE_TRACKTO);
+		else if (nr==4) con = add_new_constraint(CONSTRAINT_TYPE_MINMAX);
+		else if (nr==5) con = add_new_constraint(CONSTRAINT_TYPE_LOCKTRACK);
+		else if (nr==6) {
 			Curve *cu= obsel->data;
 			cu->flag |= CU_PATH;
 			con = add_new_constraint(CONSTRAINT_TYPE_FOLLOWPATH);
 		}
-		else if(nr==7) con = add_new_constraint(CONSTRAINT_TYPE_STRETCHTO);
-		else if(nr==8) con = add_new_constraint(CONSTRAINT_TYPE_SIZELIKE);
-		else if(nr==13) con = add_new_constraint(CONSTRAINT_TYPE_LOCLIMIT);
-		else if(nr==14) con = add_new_constraint(CONSTRAINT_TYPE_ROTLIMIT);
-		else if(nr==15) con = add_new_constraint(CONSTRAINT_TYPE_SIZELIMIT);
-		else if(nr==16) con = add_new_constraint(CONSTRAINT_TYPE_ACTION);
-		else if(nr==17) {
+		else if (nr==7) con = add_new_constraint(CONSTRAINT_TYPE_STRETCHTO);
+		else if (nr==8) con = add_new_constraint(CONSTRAINT_TYPE_SIZELIKE);
+		else if (nr==13) con = add_new_constraint(CONSTRAINT_TYPE_LOCLIMIT);
+		else if (nr==14) con = add_new_constraint(CONSTRAINT_TYPE_ROTLIMIT);
+		else if (nr==15) con = add_new_constraint(CONSTRAINT_TYPE_SIZELIMIT);
+		else if (nr==16) {
+			/* TODO: add a popup-menu to display list of available actions to use (like for pyconstraints) */
+			con = add_new_constraint(CONSTRAINT_TYPE_ACTION);
+		}
+		else if (nr==17) {
 			Curve *cu= obsel->data;
 			cu->flag |= CU_PATH;
 			con = add_new_constraint(CONSTRAINT_TYPE_CLAMPTO);
 		}
-		else if(nr==18) {	
+		else if (nr==18) {	
 			char *menustr;
 			int scriptint= 0, dummy_int=0;
 			float dummy_matrix[4][4];
@@ -769,10 +772,21 @@ void add_constraint(int only_IK)
 				}
 			}
 		}
+		else if (nr==19) {
+			con= add_new_constraint(CONSTRAINT_TYPE_CHILDOF);
+			
+			/* if this constraint is being added to a posechannel, make sure
+			 * the constraint gets evaluated in pose-space
+			 */
+			if (pchanact) {
+				con->ownspace = CONSTRAINT_SPACE_POSE;
+				con->flag |= CONSTRAINT_SPACEONCE;
+			}
+		}
 		
-		if(con==NULL) return;	/* paranoia */
+		if (con==NULL) return;	/* paranoia */
 		
-		if(pchanact) {
+		if (pchanact) {
 			BLI_addtail(&pchanact->constraints, con);
 			unique_constraint_name(con, &pchanact->constraints);
 			pchanact->constflag |= PCHAN_HAS_CONST;	/* for draw */
@@ -784,13 +798,13 @@ void add_constraint(int only_IK)
 	}
 	
 	/* set the target */
-	if(pchansel) {
+	if (pchansel) {
 		set_constraint_target(con, ob, pchansel->name);
 	}
 	else if(obsel) {
 		set_constraint_target(con, obsel, NULL);
 	}
-	else if(ELEM4(nr, 11, 13, 14, 15)==0) {	/* add new empty as target */
+	else if (ELEM4(nr, 11, 13, 14, 15)==0) {	/* add new empty as target */
 		Base *base= BASACT, *newbase;
 		Object *obt;
 		
@@ -801,7 +815,7 @@ void add_constraint(int only_IK)
 		obt->lay= newbase->lay;
 		
 		/* transform cent to global coords for loc */
-		if(pchanact) {
+		if (pchanact) {
 			if(only_IK)
 				VecMat4MulVecfl(obt->loc, ob->obmat, pchanact->pose_tail);
 			else
@@ -816,8 +830,7 @@ void add_constraint(int only_IK)
 		BASACT= base;
 		base->flag |= SELECT;
 	}
-
-
+	
 	/* active flag */
 	con->flag |= CONSTRAINT_ACTIVE;
 	for(con= con->prev; con; con= con->prev)
@@ -825,7 +838,7 @@ void add_constraint(int only_IK)
 
 	DAG_scene_sort(G.scene);		// sort order of objects
 	
-	if(pchanact) {
+	if (pchanact) {
 		ob->pose->flag |= POSE_RECALC;	// sort pose channels
 		DAG_object_flush_update(G.scene, ob, OB_RECALC_DATA);	// and all its relations
 	}
@@ -836,7 +849,7 @@ void add_constraint(int only_IK)
 	allqueue (REDRAWBUTSOBJECT, 0);
 	allqueue (REDRAWOOPS, 0);
 	
-	if(only_IK)
+	if (only_IK)
 		BIF_undo_push("Add IK Constraint");
 	else
 		BIF_undo_push("Add Constraint");