Made low level changes to the Skeleton3D class and Skeleton3D inspector. Changes listed below:

* Added helper functions to Skeleton3D for converting transforms from bone space to global space, and vice versa.
* Updated the Skeleton3D class reference.
* Changed the icon used for bones in the Skeleton3D inspector to use BoneAttachement3D's icon.
* Changed the Skeleton3D inspector to use EditorPropertyTransform and EditorPropertyVector3 when possible.
* Placed the Transform/Matrix for each bone in a sub-section, so it is visually similar to the Node3D inspector.

2 files changed, 23 insertions, 5 deletions

diff --git a/scene/3d/skeleton_3d.cpp b/scene/3d/skeleton_3d.cpp
index a09424fa17..6723ca04b9 100644
--- a/scene/3d/skeleton_3d.cpp
+++ b/scene/3d/skeleton_3d.cpp
@@ -67,6 +67,8 @@ SkinReference::~SkinReference() {
 	RS::get_singleton()->free(skeleton);
 }
 
+///////////////////////////////////////
+
 bool Skeleton3D::_set(const StringName &p_path, const Variant &p_value) {
 	String path = p_path;
 
@@ -853,6 +855,15 @@ Ref<SkinReference> Skeleton3D::register_skin(const Ref<Skin> &p_skin) {
 	return skin_ref;
 }
 
+// helper functions
+Transform Skeleton3D::bone_transform_to_world_transform(Transform p_bone_transform) {
+	return get_global_transform() * p_bone_transform;
+}
+
+Transform Skeleton3D::world_transform_to_bone_transform(Transform p_world_transform) {
+	return get_global_transform().affine_inverse() * p_world_transform;
+}
+
 void Skeleton3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_bone_process_orders"), &Skeleton3D::get_bone_process_orders);
 	ClassDB::bind_method(D_METHOD("add_bone", "name"), &Skeleton3D::add_bone);
@@ -892,6 +903,9 @@ void Skeleton3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_bone_custom_pose", "bone_idx"), &Skeleton3D::get_bone_custom_pose);
 	ClassDB::bind_method(D_METHOD("set_bone_custom_pose", "bone_idx", "custom_pose"), &Skeleton3D::set_bone_custom_pose);
 
+	ClassDB::bind_method(D_METHOD("bone_transform_to_world_transform", "bone_transform"), &Skeleton3D::bone_transform_to_world_transform);
+	ClassDB::bind_method(D_METHOD("world_transform_to_bone_transform", "world_transform"), &Skeleton3D::world_transform_to_bone_transform);
+
 #ifndef _3D_DISABLED
 
 	ClassDB::bind_method(D_METHOD("set_animate_physical_bones"), &Skeleton3D::set_animate_physical_bones);
diff --git a/scene/3d/skeleton_3d.h b/scene/3d/skeleton_3d.h
index 66706a9450..a21891a32e 100644
--- a/scene/3d/skeleton_3d.h
+++ b/scene/3d/skeleton_3d.h
@@ -71,10 +71,6 @@ class Skeleton3D : public Node3D {
 private:
 	friend class SkinReference;
 
-	Set<SkinReference *> skin_bindings;
-
-	void _skin_changed();
-
 	struct Bone {
 		String name;
 
@@ -116,6 +112,10 @@ private:
 		}
 	};
 
+	Set<SkinReference *> skin_bindings;
+
+	void _skin_changed();
+
 	bool animate_physical_bones;
 	Vector<Bone> bones;
 	Vector<int> process_order;
@@ -200,6 +200,10 @@ public:
 
 	Ref<SkinReference> register_skin(const Ref<Skin> &p_skin);
 
+	// Helper functions
+	Transform bone_transform_to_world_transform(Transform p_transform);
+	Transform world_transform_to_bone_transform(Transform p_transform);
+
 #ifndef _3D_DISABLED
 	// Physical bone API
 
@@ -213,7 +217,7 @@ public:
 	PhysicalBone3D *get_physical_bone_parent(int p_bone);
 
 private:
-	/// This is a slow API os it's cached
+	/// This is a slow API, so it's cached
 	PhysicalBone3D *_get_physical_bone_parent(int p_bone);
 	void _rebuild_physical_bones_cache();