Armature: convert the length Python property of bones to a RNA property.

This allows accessing it from drivers and using it in UI, as
demonstrated by adding it to the transform panel of 3D View.

As an aside, properly mark transform-related properties of Bone
read-only, as they can only be changed correctly in edit mode.

1 files changed, 39 insertions, 7 deletions

diff --git a/source/blender/makesrna/intern/rna_armature.c b/source/blender/makesrna/intern/rna_armature.c
index cfcc37adf6c..4dc383a2460 100644
--- a/source/blender/makesrna/intern/rna_armature.c
+++ b/source/blender/makesrna/intern/rna_armature.c
@@ -36,6 +36,8 @@
 
 #ifdef RNA_RUNTIME
 
+#  include "BLI_math_vector.h"
+
 #  include "BKE_action.h"
 #  include "BKE_context.h"
 #  include "BKE_global.h"
@@ -483,6 +485,22 @@ static void rna_EditBone_matrix_set(PointerRNA *ptr, const float *values)
   ED_armature_ebone_from_mat4(ebone, (float(*)[4])values);
 }
 
+static float rna_EditBone_length_get(PointerRNA *ptr)
+{
+  EditBone *ebone = (EditBone *)(ptr->data);
+  return len_v3v3(ebone->head, ebone->tail);
+}
+
+static void rna_EditBone_length_set(PointerRNA *ptr, float length)
+{
+  EditBone *ebone = (EditBone *)(ptr->data);
+  float delta[3];
+
+  sub_v3_v3v3(delta, ebone->tail, ebone->head);
+  normalize_v3(delta);
+  madd_v3_v3v3fl(ebone->tail, ebone->head, delta, length);
+}
+
 static void rna_Bone_bbone_handle_update(Main *bmain, Scene *scene, PointerRNA *ptr)
 {
   bArmature *arm = (bArmature *)ptr->owner_id;
@@ -1141,27 +1159,28 @@ static void rna_def_bone(BlenderRNA *brna)
   prop = RNA_def_property(srna, "matrix", PROP_FLOAT, PROP_MATRIX);
   RNA_def_property_float_sdna(prop, NULL, "bone_mat");
   RNA_def_property_multi_array(prop, 2, rna_matrix_dimsize_3x3);
-  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
   RNA_def_property_ui_text(prop, "Bone Matrix", "3x3 bone matrix");
 
   prop = RNA_def_property(srna, "matrix_local", PROP_FLOAT, PROP_MATRIX);
   RNA_def_property_float_sdna(prop, NULL, "arm_mat");
   RNA_def_property_multi_array(prop, 2, rna_matrix_dimsize_4x4);
-  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
   RNA_def_property_ui_text(
       prop, "Bone Armature-Relative Matrix", "4x4 bone matrix relative to armature");
 
   prop = RNA_def_property(srna, "tail", PROP_FLOAT, PROP_TRANSLATION);
   RNA_def_property_float_sdna(prop, NULL, "tail");
   RNA_def_property_array(prop, 3);
-  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
-  RNA_def_property_ui_text(prop, "Tail", "Location of tail end of the bone");
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_ui_text(
+      prop, "Tail", "Location of tail end of the bone relative to its parent");
   RNA_def_property_ui_range(prop, -FLT_MAX, FLT_MAX, 1, RNA_TRANSLATION_PREC_DEFAULT);
 
   prop = RNA_def_property(srna, "tail_local", PROP_FLOAT, PROP_TRANSLATION);
   RNA_def_property_float_sdna(prop, NULL, "arm_tail");
   RNA_def_property_array(prop, 3);
-  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
   RNA_def_property_ui_text(
       prop, "Armature-Relative Tail", "Location of tail end of the bone relative to armature");
   RNA_def_property_ui_range(prop, -FLT_MAX, FLT_MAX, 1, RNA_TRANSLATION_PREC_DEFAULT);
@@ -1169,7 +1188,7 @@ static void rna_def_bone(BlenderRNA *brna)
   prop = RNA_def_property(srna, "head", PROP_FLOAT, PROP_TRANSLATION);
   RNA_def_property_float_sdna(prop, NULL, "head");
   RNA_def_property_array(prop, 3);
-  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
   RNA_def_property_ui_text(
       prop, "Head", "Location of head end of the bone relative to its parent");
   RNA_def_property_ui_range(prop, -FLT_MAX, FLT_MAX, 1, RNA_TRANSLATION_PREC_DEFAULT);
@@ -1177,11 +1196,16 @@ static void rna_def_bone(BlenderRNA *brna)
   prop = RNA_def_property(srna, "head_local", PROP_FLOAT, PROP_TRANSLATION);
   RNA_def_property_float_sdna(prop, NULL, "arm_head");
   RNA_def_property_array(prop, 3);
-  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
   RNA_def_property_ui_text(
       prop, "Armature-Relative Head", "Location of head end of the bone relative to armature");
   RNA_def_property_ui_range(prop, -FLT_MAX, FLT_MAX, 1, RNA_TRANSLATION_PREC_DEFAULT);
 
+  prop = RNA_def_property(srna, "length", PROP_FLOAT, PROP_DISTANCE);
+  RNA_def_property_float_sdna(prop, NULL, "length");
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_ui_text(prop, "Length", "Length of the bone");
+
   RNA_api_bone(srna);
 }
 
@@ -1227,6 +1251,14 @@ static void rna_def_edit_bone(BlenderRNA *brna)
   RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
   RNA_def_property_update(prop, 0, "rna_Armature_editbone_transform_update");
 
+  prop = RNA_def_property(srna, "length", PROP_FLOAT, PROP_DISTANCE);
+  RNA_def_property_float_funcs(prop, "rna_EditBone_length_get", "rna_EditBone_length_set", NULL);
+  RNA_def_property_range(prop, 0, FLT_MAX);
+  RNA_def_property_ui_range(prop, 0, FLT_MAX, 1, RNA_TRANSLATION_PREC_DEFAULT);
+  RNA_def_property_ui_text(prop, "Length", "Length of the bone. Changing moves the tail end");
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_update(prop, 0, "rna_Armature_editbone_transform_update");
+
   rna_def_bone_common(srna, 1);
   rna_def_bone_curved_common(srna, false, true);