Patch #7767: Constraint Subtargets can now target anywhere on a bone, not just the head or tail

Patch by: Roland Hess (harkyman)

For example, a constraint can be sub-targeted at the 50% (or 31.2% or 85% etc.) point of its target bone, giving you enormous rigging flexibility and removing the need for complex contraptions to do such things as:

- A bone whose base slides only between to points on a rig (CopyLoc with a variable, animated subtarget point)
- Bones that attach to multiple points along another bone (CopyLocs, each with a different head/tail percentage)
- Bones that need to stretch to a point midway between specific spots on two other bones (old way: too crazy to mention; new way: stretch bone between points on end bones, then another stretch to the midpoint of the first stretch)

It is only used for the constraint types for which it is relevant: CopyLoc, TrackTo, StretchTo and MinMax, TrackTo, and Floor.

Notes:
- This is accessed by the Head/Tail number-slider. 
- This value can be animated per constraint
- The old "Copy Bone Tail" option for the CopyLoc constraint has been automatically converted to 1.0 Head/Bone values for the affected constraints
- In the code, this value is in the bConstraint struct, so it is available for all constraints, even though only a few implement it.

1 files changed, 5 insertions, 2 deletions

diff --git a/source/blender/makesdna/DNA_ipo_types.h b/source/blender/makesdna/DNA_ipo_types.h
index 1fca73b576c..2b943c2c23e 100644
--- a/source/blender/makesdna/DNA_ipo_types.h
+++ b/source/blender/makesdna/DNA_ipo_types.h
@@ -319,10 +319,11 @@ typedef short IPO_Channel;
 #define AC_QUAT_Z	28
 
 /* ******************** */
-#define CO_TOTIPO	1	/* Constraint Ipos */
-#define CO_TOTNAM	1
+#define CO_TOTIPO	2	/* Constraint Ipos */
+#define CO_TOTNAM	2
 
 #define CO_ENFORCE	1
+#define CO_HEADTAIL	2
 /*
 #define	CO_TIME		2
 #define CO_OFFSET_X	3
@@ -399,3 +400,5 @@ typedef short IPO_Channel;
 
 #endif
 
+
+