Remove REST transform influence in skeleton bones

* Animations and Skeletons are now pose-only.
* Rest transform is kept as reference (when it exists) and for IK
* Improves 3D model compatibility (non uniform transforms will properly work, as well as all animations coming from Autodesk products).

8 files changed, 73 insertions, 156 deletions

diff --git a/scene/3d/bone_attachment_3d.cpp b/scene/3d/bone_attachment_3d.cpp
index afd11482e3..8e89f4fc54 100644
--- a/scene/3d/bone_attachment_3d.cpp
+++ b/scene/3d/bone_attachment_3d.cpp
@@ -215,8 +215,6 @@ void BoneAttachment3D::_transform_changed() {
 			sk->set_bone_global_pose_override(bone_idx, our_trans, 1.0, true);
 		} else if (override_mode == OVERRIDE_MODES::MODE_LOCAL_POSE) {
 			sk->set_bone_local_pose_override(bone_idx, sk->global_pose_to_local_pose(bone_idx, our_trans), 1.0, true);
-		} else if (override_mode == OVERRIDE_MODES::MODE_CUSTOM_POSE) {
-			sk->set_bone_custom_pose(bone_idx, sk->global_pose_to_local_pose(bone_idx, our_trans));
 		}
 	}
 }
@@ -273,8 +271,6 @@ void BoneAttachment3D::set_override_pose(bool p_override) {
 				sk->set_bone_global_pose_override(bone_idx, Transform3D(), 0.0, false);
 			} else if (override_mode == OVERRIDE_MODES::MODE_LOCAL_POSE) {
 				sk->set_bone_local_pose_override(bone_idx, Transform3D(), 0.0, false);
-			} else if (override_mode == OVERRIDE_MODES::MODE_CUSTOM_POSE) {
-				sk->set_bone_custom_pose(bone_idx, Transform3D());
 			}
 		}
 		_transform_changed();
@@ -294,8 +290,6 @@ void BoneAttachment3D::set_override_mode(int p_mode) {
 				sk->set_bone_global_pose_override(bone_idx, Transform3D(), 0.0, false);
 			} else if (override_mode == OVERRIDE_MODES::MODE_LOCAL_POSE) {
 				sk->set_bone_local_pose_override(bone_idx, Transform3D(), 0.0, false);
-			} else if (override_mode == OVERRIDE_MODES::MODE_CUSTOM_POSE) {
-				sk->set_bone_custom_pose(bone_idx, Transform3D());
 			}
 		}
 		override_mode = p_mode;
diff --git a/scene/3d/bone_attachment_3d.h b/scene/3d/bone_attachment_3d.h
index cf681cace8..57b9854e0e 100644
--- a/scene/3d/bone_attachment_3d.h
+++ b/scene/3d/bone_attachment_3d.h
@@ -47,7 +47,6 @@ class BoneAttachment3D : public Node3D {
 	enum OVERRIDE_MODES {
 		MODE_GLOBAL_POSE,
 		MODE_LOCAL_POSE,
-		MODE_CUSTOM_POSE
 	};
 
 	bool use_external_skeleton = false;
diff --git a/scene/3d/mesh_instance_3d.cpp b/scene/3d/mesh_instance_3d.cpp
index 67f4a88228..cfd90e5da0 100644
--- a/scene/3d/mesh_instance_3d.cpp
+++ b/scene/3d/mesh_instance_3d.cpp
@@ -146,11 +146,13 @@ void MeshInstance3D::_resolve_skeleton_path() {
 	if (!skeleton_path.is_empty()) {
 		Skeleton3D *skeleton = Object::cast_to<Skeleton3D>(get_node(skeleton_path));
 		if (skeleton) {
-			new_skin_reference = skeleton->register_skin(skin_internal);
 			if (skin_internal.is_null()) {
+				new_skin_reference = skeleton->register_skin(skeleton->create_skin_from_rest_transforms());
 				//a skin was created for us
 				skin_internal = new_skin_reference->get_skin();
 				notify_property_list_changed();
+			} else {
+				new_skin_reference = skeleton->register_skin(skin_internal);
 			}
 		}
 	}
diff --git a/scene/3d/skeleton_3d.cpp b/scene/3d/skeleton_3d.cpp
index 79504b10bb..9b28d7aff8 100644
--- a/scene/3d/skeleton_3d.cpp
+++ b/scene/3d/skeleton_3d.cpp
@@ -557,18 +557,6 @@ void Skeleton3D::unparent_bone_and_rest(int p_bone) {
 	_make_dirty();
 }
 
-void Skeleton3D::set_bone_disable_rest(int p_bone, bool p_disable) {
-	const int bone_size = bones.size();
-	ERR_FAIL_INDEX(p_bone, bone_size);
-	bones.write[p_bone].disable_rest = p_disable;
-}
-
-bool Skeleton3D::is_bone_rest_disabled(int p_bone) const {
-	const int bone_size = bones.size();
-	ERR_FAIL_INDEX_V(p_bone, bone_size, false);
-	return bones[p_bone].disable_rest;
-}
-
 int Skeleton3D::get_bone_parent(int p_bone) const {
 	const int bone_size = bones.size();
 	ERR_FAIL_INDEX_V(p_bone, bone_size, -1);
@@ -723,23 +711,6 @@ Transform3D Skeleton3D::get_bone_pose(int p_bone) const {
 	return bones[p_bone].pose_cache;
 }
 
-void Skeleton3D::set_bone_custom_pose(int p_bone, const Transform3D &p_custom_pose) {
-	const int bone_size = bones.size();
-	ERR_FAIL_INDEX(p_bone, bone_size);
-	//ERR_FAIL_COND( !is_inside_scene() );
-
-	bones.write[p_bone].custom_pose_enable = (p_custom_pose != Transform3D());
-	bones.write[p_bone].custom_pose = p_custom_pose;
-
-	_make_dirty();
-}
-
-Transform3D Skeleton3D::get_bone_custom_pose(int p_bone) const {
-	const int bone_size = bones.size();
-	ERR_FAIL_INDEX_V(p_bone, bone_size, Transform3D());
-	return bones[p_bone].custom_pose;
-}
-
 void Skeleton3D::_make_dirty() {
 	if (dirty) {
 		return;
@@ -938,59 +909,57 @@ void Skeleton3D::_skin_changed() {
 	_make_dirty();
 }
 
-Ref<SkinReference> Skeleton3D::register_skin(const Ref<Skin> &p_skin) {
-	for (Set<SkinReference *>::Element *E = skin_bindings.front(); E; E = E->next()) {
-		if (E->get()->skin == p_skin) {
-			return Ref<SkinReference>(E->get());
+Ref<Skin> Skeleton3D::create_skin_from_rest_transforms() {
+	Ref<Skin> skin;
+
+	skin.instantiate();
+	skin->set_bind_count(bones.size());
+	_update_process_order(); // Just in case.
+
+	// Pose changed, rebuild cache of inverses.
+	const Bone *bonesptr = bones.ptr();
+	int len = bones.size();
+
+	// Calculate global rests and invert them.
+	LocalVector<int> bones_to_process;
+	bones_to_process = get_parentless_bones();
+	while (bones_to_process.size() > 0) {
+		int current_bone_idx = bones_to_process[0];
+		const Bone &b = bonesptr[current_bone_idx];
+		bones_to_process.erase(current_bone_idx);
+		LocalVector<int> child_bones_vector;
+		child_bones_vector = get_bone_children(current_bone_idx);
+		int child_bones_size = child_bones_vector.size();
+		if (b.parent < 0) {
+			skin->set_bind_pose(current_bone_idx, b.rest);
+		}
+		for (int i = 0; i < child_bones_size; i++) {
+			int child_bone_idx = child_bones_vector[i];
+			const Bone &cb = bonesptr[child_bone_idx];
+			skin->set_bind_pose(child_bone_idx, skin->get_bind_pose(current_bone_idx) * cb.rest);
+			// Add the bone's children to the list of bones to be processed.
+			bones_to_process.push_back(child_bones_vector[i]);
 		}
 	}
 
-	Ref<Skin> skin = p_skin;
-
-	if (skin.is_null()) {
-		// Need to create one from existing code, this is for compatibility only
-		// when skeletons did not support skins. It is also used by gizmo
-		// to display the skeleton.
-
-		skin.instantiate();
-		skin->set_bind_count(bones.size());
-		_update_process_order(); // Just in case.
-
-		// Pose changed, rebuild cache of inverses.
-		const Bone *bonesptr = bones.ptr();
-		int len = bones.size();
-
-		// Calculate global rests and invert them.
-		LocalVector<int> bones_to_process;
-		bones_to_process = get_parentless_bones();
-		while (bones_to_process.size() > 0) {
-			int current_bone_idx = bones_to_process[0];
-			const Bone &b = bonesptr[current_bone_idx];
-			bones_to_process.erase(current_bone_idx);
-			LocalVector<int> child_bones_vector;
-			child_bones_vector = get_bone_children(current_bone_idx);
-			int child_bones_size = child_bones_vector.size();
-			if (b.parent < 0) {
-				skin->set_bind_pose(current_bone_idx, b.rest);
-			}
-			for (int i = 0; i < child_bones_size; i++) {
-				int child_bone_idx = child_bones_vector[i];
-				const Bone &cb = bonesptr[child_bone_idx];
-				skin->set_bind_pose(child_bone_idx, skin->get_bind_pose(current_bone_idx) * cb.rest);
-				// Add the bone's children to the list of bones to be processed.
-				bones_to_process.push_back(child_bones_vector[i]);
-			}
-		}
+	for (int i = 0; i < len; i++) {
+		// The inverse is what is actually required.
+		skin->set_bind_bone(i, i);
+		skin->set_bind_pose(i, skin->get_bind_pose(i).affine_inverse());
+	}
 
-		for (int i = 0; i < len; i++) {
-			// The inverse is what is actually required.
-			skin->set_bind_bone(i, i);
-			skin->set_bind_pose(i, skin->get_bind_pose(i).affine_inverse());
+	return skin;
+}
+
+Ref<SkinReference> Skeleton3D::register_skin(const Ref<Skin> &p_skin) {
+	ERR_FAIL_COND_V(p_skin.is_null(), Ref<SkinReference>());
+
+	for (Set<SkinReference *>::Element *E = skin_bindings.front(); E; E = E->next()) {
+		if (E->get()->skin == p_skin) {
+			return Ref<SkinReference>(E->get());
 		}
 	}
 
-	ERR_FAIL_COND_V(skin.is_null(), Ref<SkinReference>());
-
 	Ref<SkinReference> skin_ref;
 	skin_ref.instantiate();
 
@@ -998,11 +967,11 @@ Ref<SkinReference> Skeleton3D::register_skin(const Ref<Skin> &p_skin) {
 	skin_ref->bind_count = 0;
 	skin_ref->skeleton = RenderingServer::get_singleton()->skeleton_create();
 	skin_ref->skeleton_node = this;
-	skin_ref->skin = skin;
+	skin_ref->skin = p_skin;
 
 	skin_bindings.insert(skin_ref.operator->());
 
-	skin->connect("changed", Callable(skin_ref.operator->(), "_skin_changed"));
+	skin_ref->skin->connect("changed", Callable(skin_ref.operator->(), "_skin_changed"));
 
 	_make_dirty(); // Skin needs to be updated, so update skeleton.
 
@@ -1038,61 +1007,33 @@ void Skeleton3D::force_update_bone_children_transforms(int p_bone_idx) {
 		Bone &b = bonesptr[current_bone_idx];
 		bool bone_enabled = b.enabled && !show_rest_only;
 
-		if (b.disable_rest) {
-			if (bone_enabled) {
-				b.update_pose_cache();
-				Transform3D pose = b.pose_cache;
-				if (b.custom_pose_enable) {
-					pose = b.custom_pose * pose;
-				}
-				if (b.parent >= 0) {
-					b.pose_global = bonesptr[b.parent].pose_global * pose;
-					b.pose_global_no_override = b.pose_global;
-				} else {
-					b.pose_global = pose;
-					b.pose_global_no_override = b.pose_global;
-				}
+		if (bone_enabled) {
+			b.update_pose_cache();
+			Transform3D pose = b.pose_cache;
+
+			if (b.parent >= 0) {
+				b.pose_global = bonesptr[b.parent].pose_global * pose;
+				b.pose_global_no_override = b.pose_global;
 			} else {
-				if (b.parent >= 0) {
-					b.pose_global = bonesptr[b.parent].pose_global;
-					b.pose_global_no_override = b.pose_global;
-				} else {
-					b.pose_global = Transform3D();
-					b.pose_global_no_override = b.pose_global;
-				}
+				b.pose_global = pose;
+				b.pose_global_no_override = b.pose_global;
 			}
-
 		} else {
-			if (bone_enabled) {
-				b.update_pose_cache();
-				Transform3D pose = b.pose_cache;
-				if (b.custom_pose_enable) {
-					pose = b.custom_pose * pose;
-				}
-				if (b.parent >= 0) {
-					b.pose_global = bonesptr[b.parent].pose_global * (b.rest * pose);
-					b.pose_global_no_override = b.pose_global;
-				} else {
-					b.pose_global = b.rest * pose;
-					b.pose_global_no_override = b.pose_global;
-				}
+			if (b.parent >= 0) {
+				b.pose_global = bonesptr[b.parent].pose_global * b.rest;
+				b.pose_global_no_override = b.pose_global;
 			} else {
-				if (b.parent >= 0) {
-					b.pose_global = bonesptr[b.parent].pose_global * b.rest;
-					b.pose_global_no_override = b.pose_global;
-				} else {
-					b.pose_global = b.rest;
-					b.pose_global_no_override = b.pose_global;
-				}
+				b.pose_global = b.rest;
+				b.pose_global_no_override = b.pose_global;
 			}
 		}
 
 		if (b.local_pose_override_amount >= CMP_EPSILON) {
 			Transform3D override_local_pose;
 			if (b.parent >= 0) {
-				override_local_pose = bonesptr[b.parent].pose_global * (b.rest * b.local_pose_override);
+				override_local_pose = bonesptr[b.parent].pose_global * b.local_pose_override;
 			} else {
-				override_local_pose = (b.rest * b.local_pose_override);
+				override_local_pose = b.local_pose_override;
 			}
 			b.pose_global = b.pose_global.interpolate_with(override_local_pose, b.local_pose_override_amount);
 		}
@@ -1133,8 +1074,8 @@ Transform3D Skeleton3D::global_pose_to_local_pose(int p_bone_idx, Transform3D p_
 	ERR_FAIL_INDEX_V(p_bone_idx, bone_size, Transform3D());
 	if (bones[p_bone_idx].parent >= 0) {
 		int parent_bone_idx = bones[p_bone_idx].parent;
-		Transform3D conversion_transform = (bones[parent_bone_idx].pose_global * bones[p_bone_idx].rest);
-		return conversion_transform.affine_inverse() * p_global_pose;
+		Transform3D conversion_transform = bones[parent_bone_idx].pose_global.affine_inverse();
+		return conversion_transform * p_global_pose;
 	} else {
 		return p_global_pose;
 	}
@@ -1145,8 +1086,7 @@ Transform3D Skeleton3D::local_pose_to_global_pose(int p_bone_idx, Transform3D p_
 	ERR_FAIL_INDEX_V(p_bone_idx, bone_size, Transform3D());
 	if (bones[p_bone_idx].parent >= 0) {
 		int parent_bone_idx = bones[p_bone_idx].parent;
-		Transform3D conversion_transform = (bones[parent_bone_idx].pose_global * bones[p_bone_idx].rest);
-		return conversion_transform * p_local_pose;
+		return bones[parent_bone_idx].pose_global * p_local_pose;
 	} else {
 		return p_local_pose;
 	}
@@ -1236,13 +1176,11 @@ void Skeleton3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_bone_rest", "bone_idx"), &Skeleton3D::get_bone_rest);
 	ClassDB::bind_method(D_METHOD("set_bone_rest", "bone_idx", "rest"), &Skeleton3D::set_bone_rest);
 
+	ClassDB::bind_method(D_METHOD("create_skin_from_rest_transforms"), &Skeleton3D::create_skin_from_rest_transforms);
 	ClassDB::bind_method(D_METHOD("register_skin", "skin"), &Skeleton3D::register_skin);
 
 	ClassDB::bind_method(D_METHOD("localize_rests"), &Skeleton3D::localize_rests);
 
-	ClassDB::bind_method(D_METHOD("set_bone_disable_rest", "bone_idx", "disable"), &Skeleton3D::set_bone_disable_rest);
-	ClassDB::bind_method(D_METHOD("is_bone_rest_disabled", "bone_idx"), &Skeleton3D::is_bone_rest_disabled);
-
 	ClassDB::bind_method(D_METHOD("clear_bones"), &Skeleton3D::clear_bones);
 
 	ClassDB::bind_method(D_METHOD("get_bone_pose", "bone_idx"), &Skeleton3D::get_bone_pose);
@@ -1267,9 +1205,6 @@ void Skeleton3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_bone_local_pose_override", "bone_idx", "pose", "amount", "persistent"), &Skeleton3D::set_bone_local_pose_override, DEFVAL(false));
 	ClassDB::bind_method(D_METHOD("get_bone_local_pose_override", "bone_idx"), &Skeleton3D::get_bone_local_pose_override);
 
-	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("force_update_all_bone_transforms"), &Skeleton3D::force_update_all_bone_transforms);
 	ClassDB::bind_method(D_METHOD("force_update_bone_child_transform", "bone_idx"), &Skeleton3D::force_update_bone_children_transforms);
 
diff --git a/scene/3d/skeleton_3d.h b/scene/3d/skeleton_3d.h
index aacee3da4e..f3cf551af7 100644
--- a/scene/3d/skeleton_3d.h
+++ b/scene/3d/skeleton_3d.h
@@ -76,7 +76,6 @@ private:
 		bool enabled;
 		int parent;
 
-		bool disable_rest = false;
 		Transform3D rest;
 
 		_FORCE_INLINE_ void update_pose_cache() {
@@ -95,9 +94,6 @@ private:
 		Transform3D pose_global;
 		Transform3D pose_global_no_override;
 
-		bool custom_pose_enable = false;
-		Transform3D custom_pose;
-
 		real_t global_pose_override_amount = 0.0;
 		bool global_pose_override_reset = false;
 		Transform3D global_pose_override;
@@ -119,8 +115,6 @@ private:
 		Bone() {
 			parent = -1;
 			enabled = true;
-			disable_rest = false;
-			custom_pose_enable = false;
 			global_pose_override_amount = 0;
 			global_pose_override_reset = false;
 #ifndef _3D_DISABLED
@@ -199,9 +193,6 @@ public:
 	void remove_bone_child(int p_bone, int p_child);
 	Vector<int> get_parentless_bones();
 
-	void set_bone_disable_rest(int p_bone, bool p_disable);
-	bool is_bone_rest_disabled(int p_bone) const;
-
 	int get_bone_count() const;
 
 	void set_bone_rest(int p_bone, const Transform3D &p_rest);
@@ -228,9 +219,6 @@ public:
 	Quaternion get_bone_pose_rotation(int p_bone) const;
 	Vector3 get_bone_pose_scale(int p_bone) const;
 
-	void set_bone_custom_pose(int p_bone, const Transform3D &p_custom_pose);
-	Transform3D get_bone_custom_pose(int p_bone) const;
-
 	void clear_bones_global_pose_override();
 	Transform3D get_bone_global_pose_override(int p_bone) const;
 	void set_bone_global_pose_override(int p_bone, const Transform3D &p_pose, real_t p_amount, bool p_persistent = false);
@@ -241,6 +229,8 @@ public:
 
 	void localize_rests(); // used for loaders and tools
 
+	Ref<Skin> create_skin_from_rest_transforms();
+
 	Ref<SkinReference> register_skin(const Ref<Skin> &p_skin);
 
 	void force_update_all_dirty_bones();
diff --git a/scene/animation/animation_tree.cpp b/scene/animation/animation_tree.cpp
index 2ed8268289..dd5fe46223 100644
--- a/scene/animation/animation_tree.cpp
+++ b/scene/animation/animation_tree.cpp
@@ -1360,9 +1360,6 @@ void AnimationTree::_process_graph(real_t p_delta) {
 
 						root_motion_transform = xform;
 
-						if (t->skeleton && t->bone_idx >= 0) {
-							root_motion_transform = (t->skeleton->get_bone_rest(t->bone_idx) * root_motion_transform) * t->skeleton->get_bone_rest(t->bone_idx).affine_inverse();
-						}
 					} else if (t->skeleton && t->bone_idx >= 0) {
 						if (t->loc_used) {
 							t->skeleton->set_bone_pose_position(t->bone_idx, t->loc);
diff --git a/scene/resources/skeleton_modification_3d_fabrik.cpp b/scene/resources/skeleton_modification_3d_fabrik.cpp
index e615615924..20ebbda256 100644
--- a/scene/resources/skeleton_modification_3d_fabrik.cpp
+++ b/scene/resources/skeleton_modification_3d_fabrik.cpp
@@ -168,7 +168,7 @@ void SkeletonModification3DFABRIK::_execute(real_t p_delta) {
 		// Apply magnet positions:
 		if (stack->skeleton->get_bone_parent(fabrik_data_chain[i].bone_idx) >= 0) {
 			int parent_bone_idx = stack->skeleton->get_bone_parent(fabrik_data_chain[i].bone_idx);
-			Transform3D conversion_transform = (stack->skeleton->get_bone_global_pose(parent_bone_idx) * stack->skeleton->get_bone_rest(parent_bone_idx));
+			Transform3D conversion_transform = (stack->skeleton->get_bone_global_pose(parent_bone_idx));
 			local_pose_override.origin += conversion_transform.basis.xform_inv(fabrik_data_chain[i].magnet_position);
 		} else {
 			local_pose_override.origin += fabrik_data_chain[i].magnet_position;
diff --git a/scene/resources/skeleton_modification_3d_twoboneik.cpp b/scene/resources/skeleton_modification_3d_twoboneik.cpp
index ae7a3bab7e..c1a71148a7 100644
--- a/scene/resources/skeleton_modification_3d_twoboneik.cpp
+++ b/scene/resources/skeleton_modification_3d_twoboneik.cpp
@@ -455,7 +455,7 @@ void SkeletonModification3DTwoBoneIK::calculate_joint_lengths() {
 			joint_two_length = 0;
 			for (int i = 0; i < bone_two_children.size(); i++) {
 				joint_two_length += bone_two_rest_trans.origin.distance_to(
-						stack->skeleton->local_pose_to_global_pose(bone_two_children[i], stack->skeleton->get_bone_rest(bone_two_children[i])).origin);
+						stack->skeleton->get_bone_global_pose(bone_two_children[i]).origin);
 			}
 			joint_two_length = joint_two_length / bone_two_children.size();
 		} else {