Bendy Bones: Option to treat disconnected bbone start/end reference locations as relative

This is an experimental option for use with the previous commit. It's an attempt
at making these bone references more useful when there's a big gap between the
reference bone being used, and the bone it's controlling.

4 files changed, 67 insertions, 10 deletions

diff --git a/release/scripts/startup/bl_ui/properties_data_bone.py b/release/scripts/startup/bl_ui/properties_data_bone.py
index 2c22259d518..4ac10f2050b 100644
--- a/release/scripts/startup/bl_ui/properties_data_bone.py
+++ b/release/scripts/startup/bl_ui/properties_data_bone.py
@@ -212,6 +212,11 @@ class BONE_PT_curved(BoneButtonsPanel, Panel):
             row.prop_search(pchan, "bbone_custom_handle_start", ob.pose, "bones", text="In")
             row.prop_search(pchan, "bbone_custom_handle_end", ob.pose, "bones", text="Out")
 
+            row = col.row()
+            row.active = pchan.use_bbone_custom_handles
+            row.prop(pchan, "use_bbone_relative_start_handle", text="Relative")
+            row.prop(pchan, "use_bbone_relative_end_handle", text="Relative")
+
 
 
 
diff --git a/source/blender/blenkernel/intern/armature.c b/source/blender/blenkernel/intern/armature.c
index 90fc88db37a..0cd63cd2314 100644
--- a/source/blender/blenkernel/intern/armature.c
+++ b/source/blender/blenkernel/intern/armature.c
@@ -533,10 +533,27 @@ void b_bone_spline_setup(bPoseChannel *pchan, int rest, Mat4 result_array[MAX_BB
 		float difmat[4][4], result[3][3], imat3[3][3];
 
 		/* transform previous point inside this bone space */
-		if (rest)
-			copy_v3_v3(h1, prev->bone->arm_head);
-		else
-			copy_v3_v3(h1, prev->pose_head);
+		if ((pchan->bboneflag & PCHAN_BBONE_CUSTOM_HANDLES) &&
+		    (pchan->bboneflag & PCHAN_BBONE_CUSTOM_START_REL))
+		{
+			/* Use delta movement (from restpose), and apply this relative to the current bone's head */
+			if (rest) {
+				/* in restpose, arm_head == pose_head */
+				h1[0] = h1[1] = h1[2] = 0.0f;
+			}
+			else {
+				float delta[3];
+				sub_v3_v3v3(delta, prev->pose_head, prev->bone->arm_head);
+				sub_v3_v3v3(h1, pchan->pose_head, delta);
+			}
+		}
+		else {
+			/* Use bone head as absolute position */
+			if (rest)
+				copy_v3_v3(h1, prev->bone->arm_head);
+			else
+				copy_v3_v3(h1, prev->pose_head);
+		}
 		mul_m4_v3(imat, h1);
 
 		if (prev->bone->segments > 1) {
@@ -572,10 +589,27 @@ void b_bone_spline_setup(bPoseChannel *pchan, int rest, Mat4 result_array[MAX_BB
 		float difmat[4][4], result[3][3], imat3[3][3];
 
 		/* transform next point inside this bone space */
-		if (rest)
-			copy_v3_v3(h2, next->bone->arm_tail);
-		else
-			copy_v3_v3(h2, next->pose_tail);
+		if ((pchan->bboneflag & PCHAN_BBONE_CUSTOM_HANDLES) &&
+		    (pchan->bboneflag & PCHAN_BBONE_CUSTOM_END_REL))
+		{
+			/* Use delta movement (from restpose), and apply this relative to the current bone's tail */
+			if (rest) {
+				/* in restpose, arm_tail == pose_tail */
+				h2[0] = h2[1] = h2[2] = 0.0f;
+			}
+			else {
+				float delta[3];
+				sub_v3_v3v3(delta, next->pose_tail, next->bone->arm_tail);
+				add_v3_v3v3(h2, pchan->pose_tail, delta);
+			}
+		}
+		else {
+			/* Use bone tail as absolute position */
+			if (rest)
+				copy_v3_v3(h2, next->bone->arm_tail);
+			else
+				copy_v3_v3(h2, next->pose_tail);
+		}
 		mul_m4_v3(imat, h2);
 
 		/* if next bone is B-bone too, use average handle direction */
diff --git a/source/blender/makesdna/DNA_action_types.h b/source/blender/makesdna/DNA_action_types.h
index 1c8832fa552..4d82e4528d6 100644
--- a/source/blender/makesdna/DNA_action_types.h
+++ b/source/blender/makesdna/DNA_action_types.h
@@ -332,6 +332,10 @@ typedef enum ePchan_DrawFlag {
 typedef enum ePchan_BBoneFlag {
 	/* Use custom reference bones (for roll and handle alignment), instead of immediate neighbours */
 	PCHAN_BBONE_CUSTOM_HANDLES    = (1 << 1),
+	/* Evaluate start handle as being "relative" */
+	PCHAN_BBONE_CUSTOM_START_REL  = (1 << 2),
+	/* Evaluate end handle as being "relative" */
+	PCHAN_BBONE_CUSTOM_END_REL    = (1 << 3),
 } ePchan_BBoneFlag;
 
 /* PoseChannel->rotmode and Object->rotmode */
diff --git a/source/blender/makesrna/intern/rna_pose.c b/source/blender/makesrna/intern/rna_pose.c
index 9e1bde70370..fb7d5141a6d 100644
--- a/source/blender/makesrna/intern/rna_pose.c
+++ b/source/blender/makesrna/intern/rna_pose.c
@@ -881,8 +881,8 @@ static void rna_def_pose_channel(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Use Custom Handle References", 
 	                         "Use custom reference bones as handles for B-Bones instead of next/previous bones, "
 	                         "leave these blank to use only B-Bone offset properties to control the shape");
-	//RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
-	RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_IK_update");
+	RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
+	RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
 	
 	prop = RNA_def_property(srna, "bbone_custom_handle_start", PROP_POINTER, PROP_NONE);
 	RNA_def_property_pointer_sdna(prop, NULL, "bbone_prev");
@@ -893,6 +893,13 @@ static void rna_def_pose_channel(BlenderRNA *brna)
 	RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
 	RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
 	
+	prop = RNA_def_property(srna, "use_bbone_relative_start_handle", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "bboneflag", PCHAN_BBONE_CUSTOM_START_REL);
+	RNA_def_property_ui_text(prop, "Relative B-Bone Start Handle", 
+	                         "Use treat custom start handle position as a relative value");
+	RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
+	RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
+	
 	prop = RNA_def_property(srna, "bbone_custom_handle_end", PROP_POINTER, PROP_NONE);
 	RNA_def_property_pointer_sdna(prop, NULL, "bbone_next");
 	RNA_def_property_struct_type(prop, "PoseBone");
@@ -902,6 +909,13 @@ static void rna_def_pose_channel(BlenderRNA *brna)
 	RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
 	RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
 	
+	prop = RNA_def_property(srna, "use_bbone_relative_end_handle", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "bboneflag", PCHAN_BBONE_CUSTOM_END_REL);
+	RNA_def_property_ui_text(prop, "Relative B-Bone End Handle", 
+	                         "Use treat custom end handle position as a relative value");
+	RNA_def_property_editable_func(prop, "rna_PoseChannel_proxy_editable");
+	RNA_def_property_update(prop, NC_OBJECT | ND_POSE, "rna_Pose_update");
+	
 	/* transform matrices - should be read-only since these are set directly by AnimSys evaluation */
 	prop = RNA_def_property(srna, "matrix_channel", PROP_FLOAT, PROP_MATRIX);
 	RNA_def_property_float_sdna(prop, NULL, "chan_mat");