Pataz-Gooseberry Request: Limits on Volume Preservation for Spline IK

This commit adds a new type of volume preservation mode to Spline IK
which makes it possible to set limits on the minimum and maximum
scaling of bone "fatness".

* The old volume preseving mode has been kept but renamed, to avoid
  breaking old rigs. "Volume Presevation" uses the new method, while
  "Inverse Preservation" is the old one.

* The code and settings for this new xz scale mode are directly lifted
  from the improved Stretch To constraint

1 files changed, 18 insertions, 6 deletions

diff --git a/source/blender/makesdna/DNA_constraint_types.h b/source/blender/makesdna/DNA_constraint_types.h
index fb33879e2c1..86991245068 100644
--- a/source/blender/makesdna/DNA_constraint_types.h
+++ b/source/blender/makesdna/DNA_constraint_types.h
@@ -173,6 +173,12 @@ typedef struct bSplineIKConstraint {
 		/* settings */
 	short flag;				/* general settings for constraint */
 	short xzScaleMode;		/* method used for determining the x & z scaling of the bones */
+	
+		/* volume preservation settings */
+	float		bulge;
+	float		bulge_min;
+	float		bulge_max;
+	float		bulge_smooth;
 } bSplineIKConstraint;
 
 
@@ -680,15 +686,19 @@ typedef enum eKinematic_Flags {
 /* bSplineIKConstraint->flag */
 typedef enum eSplineIK_Flags {
 	/* chain has been attached to spline */
-	CONSTRAINT_SPLINEIK_BOUND			= (1<<0),
+	CONSTRAINT_SPLINEIK_BOUND			= (1 << 0),
 	/* root of chain is not influenced by the constraint */
-	CONSTRAINT_SPLINEIK_NO_ROOT			= (1<<1),
+	CONSTRAINT_SPLINEIK_NO_ROOT			= (1 << 1),
 	/* bones in the chain should not scale to fit the curve */
-	CONSTRAINT_SPLINEIK_SCALE_LIMITED	= (1<<2),
+	CONSTRAINT_SPLINEIK_SCALE_LIMITED	= (1 << 2),
 	/* evenly distribute the bones along the path regardless of length */
-	CONSTRAINT_SPLINEIK_EVENSPLITS		= (1<<3),
+	CONSTRAINT_SPLINEIK_EVENSPLITS		= (1 << 3),
 	/* don't adjust the x and z scaling of the bones by the curve radius */
-	CONSTRAINT_SPLINEIK_NO_CURVERAD	= (1<<4)
+	CONSTRAINT_SPLINEIK_NO_CURVERAD		= (1 << 4),
+	
+	/* for "volumetric" xz scale mode, limit the minimum or maximum scale values */
+	CONSTRAINT_SPLINEIK_USE_BULGE_MIN 	= (1 << 5),
+	CONSTRAINT_SPLINEIK_USE_BULGE_MAX 	= (1 << 6),
 } eSplineIK_Flags;
 
 /* bSplineIKConstraint->xzScaleMode */
@@ -698,7 +708,9 @@ typedef enum eSplineIK_XZScaleModes {
 	/* bones in the chain should take their x/z scales from the original scaling */
 	CONSTRAINT_SPLINEIK_XZS_ORIGINAL		= 1,
 	/* x/z scales are the inverse of the y-scale */
-	CONSTRAINT_SPLINEIK_XZS_VOLUMETRIC		= 2
+	CONSTRAINT_SPLINEIK_XZS_INVERSE			= 2,
+	/* x/z scales are computed using a volume preserving technique (from Stretch To constraint) */
+	CONSTRAINT_SPLINEIK_XZS_VOLUMETRIC		= 3
 } eSplineIK_XZScaleModes;
 
 /* MinMax (floor) flags */