RNA: expose access to B-Bone shape data from Python.

B-Bone shape is a non-trivial computation, so access to
the results would be useful for Python scripts working with
B-Bones, e.g. rig generation.

This exposes both final segment matrices, and the tangent
vectors computed from the custom handle bones.

Since the handle tangents use the axis+roll orientation math
of edit bones, add matrix conversion static methods to Bone.

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D3983

1 files changed, 71 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_pose_api.c b/source/blender/makesrna/intern/rna_pose_api.c
index 04ecdd497f6..f4463e0f7d8 100644
--- a/source/blender/makesrna/intern/rna_pose_api.c
+++ b/source/blender/makesrna/intern/rna_pose_api.c
@@ -59,6 +59,45 @@ static float rna_PoseBone_do_envelope(bPoseChannel *chan, float *vec)
 	return distfactor_to_bone(vec, chan->pose_head, chan->pose_tail, bone->rad_head * scale,
 	                          bone->rad_tail * scale, bone->dist * scale);
 }
+
+static void rna_PoseBone_bbone_segment_matrix(bPoseChannel *pchan, ReportList *reports, float mat_ret[16], int index, bool rest)
+{
+	if (!pchan->bone || pchan->bone->segments <= 1) {
+		BKE_reportf(reports, RPT_ERROR, "Bone '%s' is not a B-Bone!", pchan->name);
+		return;
+	}
+	if (pchan->runtime.bbone_segments != pchan->bone->segments) {
+		BKE_reportf(reports, RPT_ERROR, "Bone '%s' has out of date B-Bone segment data!", pchan->name);
+		return;
+	}
+	if (index < 0 || index >= pchan->runtime.bbone_segments) {
+		BKE_reportf(reports, RPT_ERROR, "Invalid index %d for B-Bone segments of '%s'!", index, pchan->name);
+		return;
+	}
+
+	if (rest) {
+		copy_m4_m4((float (*)[4])mat_ret, pchan->runtime.bbone_rest_mats[index].mat);
+	}
+	else {
+		copy_m4_m4((float (*)[4])mat_ret, pchan->runtime.bbone_pose_mats[index].mat);
+	}
+}
+
+static void rna_PoseBone_compute_bbone_handles(
+        bPoseChannel *pchan, ReportList *reports,
+        float ret_h1[3], float *ret_roll1, float ret_h2[3], float *ret_roll2,
+        bool rest, bool ease, bool offsets)
+{
+	if (!pchan->bone || pchan->bone->segments <= 1) {
+		BKE_reportf(reports, RPT_ERROR, "Bone '%s' is not a B-Bone!", pchan->name);
+		return;
+	}
+
+	BBoneSplineParameters params;
+
+	BKE_pchan_get_bbone_spline_parameters(pchan, rest, &params);
+	BKE_compute_b_bone_handles(&params, ret_h1, ret_roll1, ret_h2, ret_roll2, ease || offsets, offsets);
+}
 #else
 
 void RNA_api_pose(StructRNA *UNUSED(srna))
@@ -80,6 +119,38 @@ void RNA_api_pose_channel(StructRNA *srna)
 	/* return value */
 	parm = RNA_def_float(func, "factor", 0, -FLT_MAX, FLT_MAX, "Factor", "Envelope factor", -FLT_MAX, FLT_MAX);
 	RNA_def_function_return(func, parm);
+
+	/* B-Bone segment matrices */
+	func = RNA_def_function(srna, "bbone_segment_matrix", "rna_PoseBone_bbone_segment_matrix");
+	RNA_def_function_ui_description(func, "Retrieve the matrix of the B-Bone segment if available");
+	RNA_def_function_flag(func, FUNC_USE_REPORTS);
+	parm = RNA_def_property(func, "matrix_return", PROP_FLOAT, PROP_MATRIX);
+	RNA_def_property_multi_array(parm, 2, rna_matrix_dimsize_4x4);
+	RNA_def_property_ui_text(parm, "", "The resulting matrix in bone local space");
+	RNA_def_function_output(func, parm);
+	parm = RNA_def_int(func, "index", 0, 0, INT_MAX, "", "Index of the segment", 0, 10000);
+	RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+	parm = RNA_def_boolean(func, "rest", false, "", "Return the rest pose matrix");
+
+	/* B-Bone custom handle positions */
+	func = RNA_def_function(srna, "compute_bbone_handles", "rna_PoseBone_compute_bbone_handles");
+	RNA_def_function_ui_description(func, "Retrieve the vectors and rolls coming from B-Bone custom handles");
+	RNA_def_function_flag(func, FUNC_USE_REPORTS);
+	parm = RNA_def_property(func, "handle1", PROP_FLOAT, PROP_XYZ);
+	RNA_def_property_array(parm, 3);
+	RNA_def_property_ui_text(parm, "", "The direction vector of the start handle in bone local space");
+	RNA_def_function_output(func, parm);
+	parm = RNA_def_float(func, "roll1", 0, -FLT_MAX, FLT_MAX, "", "Roll of the start handle", -FLT_MAX, FLT_MAX);
+	RNA_def_function_output(func, parm);
+	parm = RNA_def_property(func, "handle2", PROP_FLOAT, PROP_XYZ);
+	RNA_def_property_array(parm, 3);
+	RNA_def_property_ui_text(parm, "", "The direction vector of the end handle in bone local space");
+	RNA_def_function_output(func, parm);
+	parm = RNA_def_float(func, "roll2", 0, -FLT_MAX, FLT_MAX, "", "Roll of the end handle", -FLT_MAX, FLT_MAX);
+	RNA_def_function_output(func, parm);
+	parm = RNA_def_boolean(func, "rest", false, "", "Return the rest pose state");
+	parm = RNA_def_boolean(func, "ease", false, "", "Apply scale from ease values");
+	parm = RNA_def_boolean(func, "offsets", false, "", "Apply roll and curve offsets from bone properties");
 }