Bendy Bones: Advanced B-Bones for Easier + Simple Rigging

This commit/patch/branch brings a bunch of powerful new options for B-Bones and
for working with B-Bones, making it easier for animators to create their own
rigs, using fewer bones (which also means hopefully lighter + faster rigs ;)
This functionality was first demoed by Daniel at BConf15

Some highlights from this patch include:
* You can now directly control the shape of B-Bones using a series of properties
  instead of being restricted to trying to indirectly control them through the
  neighbouring bones.  See the "Bendy Bones" panel...

* B-Bones can be shaped in EditMode to define a "curved rest pose" for the bone.
  This is useful for things like eyebrows and mouths/eyelids

* You can now make B-Bones use custom bones as their reference bone handles,
  instead of only using the parent/child bones. To do so, enable the
  "Use Custom Reference Handles" toggle. If none are specified, then the BBone will
  only use the Bendy Bone properties.

* Constraints Head/Tail option can now slide along the B-Bone shape, instead of
  just linearly interpolating between the endpoints of the bone.

For more details, see:
* http://aligorith.blogspot.co.nz/2016/05/bendy-bones-dev-update.html
* http://aligorith.blogspot.co.nz/2016/05/an-in-depth-look-at-how-b-bones-work.html



-- Credits --
Original Idea: Daniel M Lara (pepeland)
Original Patch/Research: Jose Molina
Additional Development + Polish: Joshua Leung (aligorith)
Testing/Feedback: Daniel M Lara (pepeland), Juan Pablo Bouza (jpbouza)

1 files changed, 23 insertions, 32 deletions

diff --git a/source/blender/makesrna/intern/rna_constraint.c b/source/blender/makesrna/intern/rna_constraint.c
index 0b5d0f3d41d..98560bf3452 100644
--- a/source/blender/makesrna/intern/rna_constraint.c
+++ b/source/blender/makesrna/intern/rna_constraint.c
@@ -483,6 +483,21 @@ static EnumPropertyItem constraint_distance_items[] = {
 };
 
 
+static void rna_def_constraint_headtail_common(StructRNA *srna)
+{
+	PropertyRNA *prop;
+	
+	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
+	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
+	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
+	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	
+	prop = RNA_def_property(srna, "use_bbone_shape", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, "bConstraint", "flag", CONSTRAINT_BBONE_SHAPE);
+	RNA_def_property_ui_text(prop, "Follow B-Bone", "Follow shape of B-Bone segments when calculating Head/Tail position");
+	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+}
+
 static void rna_def_constrainttarget(BlenderRNA *brna)
 {
 	StructRNA *srna;
@@ -787,10 +802,7 @@ static void rna_def_constraint_track_to(BlenderRNA *brna)
 	srna = RNA_def_struct(brna, "TrackToConstraint", "Constraint");
 	RNA_def_struct_ui_text(srna, "Track To Constraint", "Aim the constrained object toward the target");
 
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	rna_def_constraint_headtail_common(srna);
 
 	RNA_def_struct_sdna_from(srna, "bTrackToConstraint", "data");
 
@@ -831,10 +843,7 @@ static void rna_def_constraint_locate_like(BlenderRNA *brna)
 	srna = RNA_def_struct(brna, "CopyLocationConstraint", "Constraint");
 	RNA_def_struct_ui_text(srna, "Copy Location Constraint", "Copy the location of the target");
 
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	rna_def_constraint_headtail_common(srna);
 
 	RNA_def_struct_sdna_from(srna, "bLocateLikeConstraint", "data");
 
@@ -1022,10 +1031,7 @@ static void rna_def_constraint_transform_like(BlenderRNA *brna)
 	srna = RNA_def_struct(brna, "CopyTransformsConstraint", "Constraint");
 	RNA_def_struct_ui_text(srna, "Copy Transforms Constraint", "Copy all the transforms of the target");
 	
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	rna_def_constraint_headtail_common(srna);
 
 	RNA_def_struct_sdna_from(srna, "bTransLikeConstraint", "data");
 
@@ -1200,10 +1206,7 @@ static void rna_def_constraint_locked_track(BlenderRNA *brna)
 	RNA_def_struct_ui_text(srna, "Locked Track Constraint",
 	                       "Point toward the target along the track axis, while locking the other axis");
 	
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	rna_def_constraint_headtail_common(srna);
 	
 	RNA_def_struct_sdna_from(srna, "bLockTrackConstraint", "data");
 
@@ -1327,10 +1330,7 @@ static void rna_def_constraint_stretch_to(BlenderRNA *brna)
 	srna = RNA_def_struct(brna, "StretchToConstraint", "Constraint");
 	RNA_def_struct_ui_text(srna, "Stretch To Constraint", "Stretch to meet the target object");
 
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	rna_def_constraint_headtail_common(srna);
 
 	RNA_def_struct_sdna_from(srna, "bStretchToConstraint", "data");
 
@@ -2122,10 +2122,7 @@ static void rna_def_constraint_distance_limit(BlenderRNA *brna)
 	srna = RNA_def_struct(brna, "LimitDistanceConstraint", "Constraint");
 	RNA_def_struct_ui_text(srna, "Limit Distance Constraint", "Limit the distance from target object");
 	
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	rna_def_constraint_headtail_common(srna);
 	
 	RNA_def_struct_sdna_from(srna, "bDistLimitConstraint", "data");
 
@@ -2236,10 +2233,7 @@ static void rna_def_constraint_damped_track(BlenderRNA *brna)
 	RNA_def_struct_ui_text(srna, "Damped Track Constraint",
 	                       "Point toward target by taking the shortest rotation path");
 	
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+rna_def_constraint_headtail_common(srna);
 	
 	RNA_def_struct_sdna_from(srna, "bDampTrackConstraint", "data");
 
@@ -2396,10 +2390,7 @@ static void rna_def_constraint_pivot(BlenderRNA *brna)
 	srna = RNA_def_struct(brna, "PivotConstraint", "Constraint");
 	RNA_def_struct_ui_text(srna, "Pivot Constraint", "Rotate around a different point");
 	
-	prop = RNA_def_property(srna, "head_tail", PROP_FLOAT, PROP_FACTOR);
-	RNA_def_property_float_sdna(prop, "bConstraint", "headtail");
-	RNA_def_property_ui_text(prop, "Head/Tail", "Target along length of bone: Head=0, Tail=1");
-	RNA_def_property_update(prop, NC_OBJECT | ND_CONSTRAINT, "rna_Constraint_update");
+	rna_def_constraint_headtail_common(srna);
 	
 	RNA_def_struct_sdna_from(srna, "bPivotConstraint", "data");