Rigging Goodies: Spline IK Constraint

At last, this commit introduces the Spline IK Constraint to Blender. Spline IK is a constraint that makes n bones follow the shape of a specified curve. 

Simply add a chain of bones, add a curve, add a Spline IK Constraint to the tip bone and set the number of bones in the chain to make it work. Or, try the following test file:
http://download.blender.org/ftp/incoming/250_splineik_spine01.blend

Screenshots of this in action (as proof):
http://download.blender.org/ftp/incoming/b250_splineik_001_before.png
http://download.blender.org/ftp/incoming/b250_splineik_001_after.png

I've implemented this in a similar way to how standard IK solvers are done. However, this code is currently not an IK plugin, since I imagine that it would be useful to be able to combine the 2 types of IK. This can be easily changed though :)

Finally, a few notes on what to expect still:
* Constraint blending currently doesn't affect this. Getting that to work correctly will take a bit more work still.
* Options for not affecting the root joint (to make it easier to attach the chain to a stump or whatever), and non-uniform scaling options have yet to be added. I've marked the places where they can be added though
* Control over the twisting of the chain still needs investigation. 

Have fun!

1 files changed, 5 insertions, 2 deletions

diff --git a/source/blender/blenkernel/BKE_armature.h b/source/blender/blenkernel/BKE_armature.h
index 19c2662054b..03f23f07c8c 100644
--- a/source/blender/blenkernel/BKE_armature.h
+++ b/source/blender/blenkernel/BKE_armature.h
@@ -55,11 +55,14 @@ typedef struct PoseTarget
 typedef struct PoseTree
 {
 	struct PoseTree *next, *prev;
-
+	
+	int 	type;					/* type of IK that this serves (CONSTRAINT_TYPE_KINEMATIC or ..._SPLINEIK) */
+	int		totchannel;				/* number of pose channels */
+	
 	struct ListBase targets;		/* list of targets of the tree */
 	struct bPoseChannel	**pchan;	/* array of pose channels */
 	int		*parent;				/* and their parents */
-	int		totchannel;				/* number of pose channels */
+	
 	float	(*basis_change)[3][3]; 	/* basis change result from solver */
 	int		iterations;				/* iterations from the constraint */
 	int     stretch;				/* disable stretching */