/*************************************************************************/
/*  mesh_instance.cpp                                                    */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
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/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
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/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
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/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
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/*************************************************************************/

#include "mesh_instance.h"

#include "collision_shape.h"
#include "core/core_string_names.h"
#include "core/project_settings.h"
#include "physics_body.h"
#include "scene/resources/material.h"
#include "scene/scene_string_names.h"
#include "servers/visual/visual_server_globals.h"
#include "skeleton.h"

bool MeshInstance::_set(const StringName &p_name, const Variant &p_value) {
	//this is not _too_ bad performance wise, really. it only arrives here if the property was not set anywhere else.
	//add to it that it's probably found on first call to _set anyway.

	if (!get_instance().is_valid()) {
		return false;
	}

	Map<StringName, BlendShapeTrack>::Element *E = blend_shape_tracks.find(p_name);
	if (E) {
		E->get().value = p_value;
		VisualServer::get_singleton()->instance_set_blend_shape_weight(get_instance(), E->get().idx, E->get().value);
		return true;
	}

	if (p_name.operator String().begins_with("material/")) {
		int idx = p_name.operator String().get_slicec('/', 1).to_int();
		if (idx >= materials.size() || idx < 0) {
			return false;
		}

		set_surface_material(idx, p_value);
		return true;
	}

	return false;
}

bool MeshInstance::_get(const StringName &p_name, Variant &r_ret) const {
	if (!get_instance().is_valid()) {
		return false;
	}

	const Map<StringName, BlendShapeTrack>::Element *E = blend_shape_tracks.find(p_name);
	if (E) {
		r_ret = E->get().value;
		return true;
	}

	if (p_name.operator String().begins_with("material/")) {
		int idx = p_name.operator String().get_slicec('/', 1).to_int();
		if (idx >= materials.size() || idx < 0) {
			return false;
		}
		r_ret = materials[idx];
		return true;
	}
	return false;
}

void MeshInstance::_get_property_list(List<PropertyInfo> *p_list) const {
	List<String> ls;
	for (const Map<StringName, BlendShapeTrack>::Element *E = blend_shape_tracks.front(); E; E = E->next()) {
		ls.push_back(E->key());
	}

	ls.sort();

	for (List<String>::Element *E = ls.front(); E; E = E->next()) {
		p_list->push_back(PropertyInfo(Variant::REAL, E->get(), PROPERTY_HINT_RANGE, "-1,1,0.00001"));
	}

	if (mesh.is_valid()) {
		for (int i = 0; i < mesh->get_surface_count(); i++) {
			p_list->push_back(PropertyInfo(Variant::OBJECT, "material/" + itos(i), PROPERTY_HINT_RESOURCE_TYPE, "ShaderMaterial,SpatialMaterial"));
		}
	}
}

void MeshInstance::set_mesh(const Ref<Mesh> &p_mesh) {
	if (mesh == p_mesh) {
		return;
	}

	if (mesh.is_valid()) {
		mesh->disconnect(CoreStringNames::get_singleton()->changed, this, SceneStringNames::get_singleton()->_mesh_changed);
	}

	if (skin_ref.is_valid() && mesh.is_valid() && _is_software_skinning_enabled() && is_visible_in_tree()) {
		ERR_FAIL_COND(!skin_ref->get_skeleton_node());
		skin_ref->get_skeleton_node()->disconnect("skeleton_updated", this, "_update_skinning");
	}

	if (software_skinning) {
		memdelete(software_skinning);
		software_skinning = nullptr;
	}

	mesh = p_mesh;

	blend_shape_tracks.clear();
	if (mesh.is_valid()) {
		for (int i = 0; i < mesh->get_blend_shape_count(); i++) {
			BlendShapeTrack mt;
			mt.idx = i;
			mt.value = 0;
			blend_shape_tracks["blend_shapes/" + String(mesh->get_blend_shape_name(i))] = mt;
		}

		mesh->connect(CoreStringNames::get_singleton()->changed, this, SceneStringNames::get_singleton()->_mesh_changed);
		materials.resize(mesh->get_surface_count());

		_initialize_skinning(false, false);
	} else {
		set_base(RID());
	}

	update_gizmo();

	_change_notify();
}
Ref<Mesh> MeshInstance::get_mesh() const {
	return mesh;
}

void MeshInstance::_resolve_skeleton_path() {
	Ref<SkinReference> new_skin_reference;

	if (!skeleton_path.is_empty()) {
		Skeleton *skeleton = Object::cast_to<Skeleton>(get_node(skeleton_path));
		if (skeleton) {
			new_skin_reference = skeleton->register_skin(skin_internal);
			if (skin_internal.is_null()) {
				//a skin was created for us
				skin_internal = new_skin_reference->get_skin();
				_change_notify();
			}
		}
	}

	if (skin_ref.is_valid() && mesh.is_valid() && _is_software_skinning_enabled() && is_visible_in_tree()) {
		ERR_FAIL_COND(!skin_ref->get_skeleton_node());
		skin_ref->get_skeleton_node()->disconnect("skeleton_updated", this, "_update_skinning");
	}

	skin_ref = new_skin_reference;

	software_skinning_flags &= ~SoftwareSkinning::FLAG_BONES_READY;

	_initialize_skinning();
}

bool MeshInstance::_is_global_software_skinning_enabled() {
	// Check if forced in project settings.
	if (GLOBAL_GET("rendering/quality/skinning/force_software_skinning")) {
		return true;
	}

	// Check if enabled in project settings.
	if (!GLOBAL_GET("rendering/quality/skinning/software_skinning_fallback")) {
		return false;
	}

	// Check if requested by renderer settings.
	return VSG::storage->has_os_feature("skinning_fallback");
}

bool MeshInstance::_is_software_skinning_enabled() const {
	// Using static local variable which will be initialized only once,
	// so _is_global_software_skinning_enabled can be only called once on first use.
	static bool global_software_skinning = _is_global_software_skinning_enabled();
	return global_software_skinning;
}

void MeshInstance::_initialize_skinning(bool p_force_reset, bool p_call_attach_skeleton) {
	if (mesh.is_null()) {
		return;
	}

	VisualServer *visual_server = VisualServer::get_singleton();

	bool update_mesh = false;

	if (skin_ref.is_valid()) {
		if (_is_software_skinning_enabled()) {
			if (is_visible_in_tree()) {
				ERR_FAIL_COND(!skin_ref->get_skeleton_node());
				if (!skin_ref->get_skeleton_node()->is_connected("skeleton_updated", this, "_update_skinning")) {
					skin_ref->get_skeleton_node()->connect("skeleton_updated", this, "_update_skinning");
				}
			}

			if (p_force_reset && software_skinning) {
				memdelete(software_skinning);
				software_skinning = nullptr;
			}

			if (!software_skinning) {
				software_skinning = memnew(SoftwareSkinning);

				if (mesh->get_blend_shape_count() > 0) {
					ERR_PRINT("Blend shapes are not supported for software skinning.");
				}

				Ref<ArrayMesh> software_mesh;
				software_mesh.instance();
				RID mesh_rid = software_mesh->get_rid();

				// Initialize mesh for dynamic update.
				int surface_count = mesh->get_surface_count();
				software_skinning->surface_data.resize(surface_count);
				for (int surface_index = 0; surface_index < surface_count; ++surface_index) {
					ERR_CONTINUE(Mesh::PRIMITIVE_TRIANGLES != mesh->surface_get_primitive_type(surface_index));

					SoftwareSkinning::SurfaceData &surface_data = software_skinning->surface_data[surface_index];
					surface_data.transform_tangents = false;
					surface_data.ensure_correct_normals = false;

					uint32_t format = mesh->surface_get_format(surface_index);
					ERR_CONTINUE(0 == (format & Mesh::ARRAY_FORMAT_VERTEX));
					ERR_CONTINUE(0 == (format & Mesh::ARRAY_FORMAT_BONES));
					ERR_CONTINUE(0 == (format & Mesh::ARRAY_FORMAT_WEIGHTS));

					format |= Mesh::ARRAY_FLAG_USE_DYNAMIC_UPDATE;
					format &= ~Mesh::ARRAY_COMPRESS_VERTEX;
					format &= ~Mesh::ARRAY_COMPRESS_WEIGHTS;
					format &= ~Mesh::ARRAY_FLAG_USE_16_BIT_BONES;

					Array write_arrays = mesh->surface_get_arrays(surface_index);
					Array read_arrays;
					read_arrays.resize(Mesh::ARRAY_MAX);

					read_arrays[Mesh::ARRAY_VERTEX] = write_arrays[Mesh::ARRAY_VERTEX];
					read_arrays[Mesh::ARRAY_BONES] = write_arrays[Mesh::ARRAY_BONES];
					read_arrays[Mesh::ARRAY_WEIGHTS] = write_arrays[Mesh::ARRAY_WEIGHTS];

					write_arrays[Mesh::ARRAY_BONES] = Variant();
					write_arrays[Mesh::ARRAY_WEIGHTS] = Variant();

					if (software_skinning_flags & SoftwareSkinning::FLAG_TRANSFORM_NORMALS) {
						ERR_CONTINUE(0 == (format & Mesh::ARRAY_FORMAT_NORMAL));
						format &= ~Mesh::ARRAY_COMPRESS_NORMAL;

						read_arrays[Mesh::ARRAY_NORMAL] = write_arrays[Mesh::ARRAY_NORMAL];

						Ref<Material> mat = get_active_material(surface_index);
						if (mat.is_valid()) {
							Ref<SpatialMaterial> spatial_mat = mat;
							if (spatial_mat.is_valid()) {
								// Spatial material, check from material settings.
								surface_data.transform_tangents = spatial_mat->get_feature(SpatialMaterial::FEATURE_NORMAL_MAPPING);
								surface_data.ensure_correct_normals = spatial_mat->get_flag(SpatialMaterial::FLAG_ENSURE_CORRECT_NORMALS);
							} else {
								// Custom shader, must check for compiled flags.
								surface_data.transform_tangents = VSG::storage->material_uses_tangents(mat->get_rid());
								surface_data.ensure_correct_normals = VSG::storage->material_uses_ensure_correct_normals(mat->get_rid());
							}
						}

						if (surface_data.transform_tangents) {
							ERR_CONTINUE(0 == (format & Mesh::ARRAY_FORMAT_TANGENT));
							format &= ~Mesh::ARRAY_COMPRESS_TANGENT;

							read_arrays[Mesh::ARRAY_TANGENT] = write_arrays[Mesh::ARRAY_TANGENT];
						}
					}

					// 1. Temporarily add surface with bone data to create the read buffer.
					software_mesh->add_surface_from_arrays(Mesh::PRIMITIVE_TRIANGLES, read_arrays, Array(), format);

					PoolByteArray buffer_read = visual_server->mesh_surface_get_array(mesh_rid, surface_index);
					surface_data.source_buffer.append_array(buffer_read);
					surface_data.source_format = software_mesh->surface_get_format(surface_index);

					software_mesh->surface_remove(surface_index);

					// 2. Create the surface again without the bone data for the write buffer.
					software_mesh->add_surface_from_arrays(Mesh::PRIMITIVE_TRIANGLES, write_arrays, Array(), format);

					Ref<Material> material = mesh->surface_get_material(surface_index);
					software_mesh->surface_set_material(surface_index, material);

					surface_data.buffer = visual_server->mesh_surface_get_array(mesh_rid, surface_index);
					surface_data.buffer_write = surface_data.buffer.write();
				}

				software_skinning->mesh_instance = software_mesh;
				update_mesh = true;
			}

			if (p_call_attach_skeleton) {
				visual_server->instance_attach_skeleton(get_instance(), RID());
			}

			if (is_visible_in_tree() && (software_skinning_flags & SoftwareSkinning::FLAG_BONES_READY)) {
				// Initialize from current skeleton pose.
				_update_skinning();
			}
		} else {
			ERR_FAIL_COND(!skin_ref->get_skeleton_node());
			if (skin_ref->get_skeleton_node()->is_connected("skeleton_updated", this, "_update_skinning")) {
				skin_ref->get_skeleton_node()->disconnect("skeleton_updated", this, "_update_skinning");
			}

			if (p_call_attach_skeleton) {
				visual_server->instance_attach_skeleton(get_instance(), skin_ref->get_skeleton());
			}

			if (software_skinning) {
				memdelete(software_skinning);
				software_skinning = nullptr;
				update_mesh = true;
			}
		}
	} else {
		if (p_call_attach_skeleton) {
			visual_server->instance_attach_skeleton(get_instance(), RID());
		}
		if (software_skinning) {
			memdelete(software_skinning);
			software_skinning = nullptr;
			update_mesh = true;
		}
	}

	RID render_mesh = software_skinning ? software_skinning->mesh_instance->get_rid() : mesh->get_rid();
	if (update_mesh || (render_mesh != get_base())) {
		set_base(render_mesh);

		// Update instance materials after switching mesh.
		int surface_count = mesh->get_surface_count();
		for (int surface_index = 0; surface_index < surface_count; ++surface_index) {
			if (materials[surface_index].is_valid()) {
				visual_server->instance_set_surface_material(get_instance(), surface_index, materials[surface_index]->get_rid());
			}
		}
	}
}

void MeshInstance::_update_skinning() {
	ERR_FAIL_COND(!_is_software_skinning_enabled());
#if defined(TOOLS_ENABLED) && defined(DEBUG_ENABLED)
	ERR_FAIL_COND(!is_visible_in_tree());
#else
	ERR_FAIL_COND(!is_visible());
#endif

	ERR_FAIL_COND(!software_skinning);
	Ref<Mesh> software_skinning_mesh = software_skinning->mesh_instance;
	ERR_FAIL_COND(!software_skinning_mesh.is_valid());
	RID mesh_rid = software_skinning_mesh->get_rid();
	ERR_FAIL_COND(!mesh_rid.is_valid());

	ERR_FAIL_COND(!mesh.is_valid());
	RID source_mesh_rid = mesh->get_rid();
	ERR_FAIL_COND(!source_mesh_rid.is_valid());

	ERR_FAIL_COND(skin_ref.is_null());
	RID skeleton = skin_ref->get_skeleton();
	ERR_FAIL_COND(!skeleton.is_valid());

	VisualServer *visual_server = VisualServer::get_singleton();

	// Prepare bone transforms.
	const int num_bones = visual_server->skeleton_get_bone_count(skeleton);
	ERR_FAIL_COND(num_bones <= 0);
	Transform *bone_transforms = (Transform *)alloca(sizeof(Transform) * num_bones);
	for (int bone_index = 0; bone_index < num_bones; ++bone_index) {
		bone_transforms[bone_index] = visual_server->skeleton_bone_get_transform(skeleton, bone_index);
	}

	// Apply skinning.
	int surface_count = software_skinning_mesh->get_surface_count();
	for (int surface_index = 0; surface_index < surface_count; ++surface_index) {
		ERR_CONTINUE((uint32_t)surface_index >= software_skinning->surface_data.size());
		const SoftwareSkinning::SurfaceData &surface_data = software_skinning->surface_data[surface_index];
		const bool transform_tangents = surface_data.transform_tangents;
		const bool ensure_correct_normals = surface_data.ensure_correct_normals;

		const uint32_t format_write = software_skinning_mesh->surface_get_format(surface_index);

		const int vertex_count_write = software_skinning_mesh->surface_get_array_len(surface_index);
		const int index_count_write = software_skinning_mesh->surface_get_array_index_len(surface_index);

		uint32_t array_offsets_write[Mesh::ARRAY_MAX];
		uint32_t array_strides_write[Mesh::ARRAY_MAX];
		visual_server->mesh_surface_make_offsets_from_format(format_write, vertex_count_write, index_count_write, array_offsets_write, array_strides_write);
		ERR_FAIL_COND(array_strides_write[Mesh::ARRAY_VERTEX] != array_strides_write[Mesh::ARRAY_NORMAL])
		const uint32_t stride_write = array_strides_write[Mesh::ARRAY_VERTEX];
		const uint32_t offset_vertices_write = array_offsets_write[Mesh::ARRAY_VERTEX];
		const uint32_t offset_normals_write = array_offsets_write[Mesh::ARRAY_NORMAL];
		const uint32_t offset_tangents_write = array_offsets_write[Mesh::ARRAY_TANGENT];

		PoolByteArray buffer_source = surface_data.source_buffer;
		PoolByteArray::Read buffer_read = buffer_source.read();

		const uint32_t format_read = surface_data.source_format;

		ERR_CONTINUE(0 == (format_read & Mesh::ARRAY_FORMAT_BONES));
		ERR_CONTINUE(0 == (format_read & Mesh::ARRAY_FORMAT_WEIGHTS));

		const int vertex_count = mesh->surface_get_array_len(surface_index);
		const int index_count = mesh->surface_get_array_index_len(surface_index);

		ERR_CONTINUE(vertex_count != vertex_count_write);

		uint32_t array_offsets[Mesh::ARRAY_MAX];
		uint32_t array_strides[Mesh::ARRAY_MAX];
		visual_server->mesh_surface_make_offsets_from_format(format_read, vertex_count, index_count, array_offsets, array_strides);
		ERR_FAIL_COND(array_strides[Mesh::ARRAY_VERTEX] != array_strides[Mesh::ARRAY_NORMAL])
		const uint32_t stride = array_strides[Mesh::ARRAY_VERTEX];
		const uint32_t offset_vertices = array_offsets[Mesh::ARRAY_VERTEX];
		const uint32_t offset_normals = array_offsets[Mesh::ARRAY_NORMAL];
		const uint32_t offset_tangents = array_offsets[Mesh::ARRAY_TANGENT];
		const uint32_t offset_bones = array_offsets[Mesh::ARRAY_BONES];
		const uint32_t offset_weights = array_offsets[Mesh::ARRAY_WEIGHTS];

		PoolByteArray buffer = surface_data.buffer;
		PoolByteArray::Write buffer_write = surface_data.buffer_write;

		for (int vertex_index = 0; vertex_index < vertex_count; ++vertex_index) {
			const uint32_t vertex_offset = vertex_index * stride;
			const uint32_t vertex_offset_write = vertex_index * stride_write;

			float bone_weights[4];
			const float *weight_ptr = (const float *)(buffer_read.ptr() + offset_weights + vertex_offset);
			bone_weights[0] = weight_ptr[0];
			bone_weights[1] = weight_ptr[1];
			bone_weights[2] = weight_ptr[2];
			bone_weights[3] = weight_ptr[3];

			const uint8_t *bones_ptr = buffer_read.ptr() + offset_bones + vertex_offset;
			const int b0 = bones_ptr[0];
			const int b1 = bones_ptr[1];
			const int b2 = bones_ptr[2];
			const int b3 = bones_ptr[3];

			Transform transform;
			transform.origin =
					bone_weights[0] * bone_transforms[b0].origin +
					bone_weights[1] * bone_transforms[b1].origin +
					bone_weights[2] * bone_transforms[b2].origin +
					bone_weights[3] * bone_transforms[b3].origin;

			transform.basis =
					bone_transforms[b0].basis * bone_weights[0] +
					bone_transforms[b1].basis * bone_weights[1] +
					bone_transforms[b2].basis * bone_weights[2] +
					bone_transforms[b3].basis * bone_weights[3];

			const Vector3 &vertex_read = (const Vector3 &)buffer_read[vertex_offset + offset_vertices];
			Vector3 &vertex = (Vector3 &)buffer_write[vertex_offset_write + offset_vertices_write];
			vertex = transform.xform(vertex_read);

			if (software_skinning_flags & SoftwareSkinning::FLAG_TRANSFORM_NORMALS) {
				if (ensure_correct_normals) {
					transform.basis.invert();
					transform.basis.transpose();
				}

				const Vector3 &normal_read = (const Vector3 &)buffer_read[vertex_offset + offset_normals];
				Vector3 &normal = (Vector3 &)buffer_write[vertex_offset_write + offset_normals_write];
				normal = transform.basis.xform(normal_read);

				if (transform_tangents) {
					const Vector3 &tangent_read = (const Vector3 &)buffer_read[vertex_offset + offset_tangents];
					Vector3 &tangent = (Vector3 &)buffer_write[vertex_offset_write + offset_tangents_write];
					tangent = transform.basis.xform(tangent_read);
				}
			}
		}

		visual_server->mesh_surface_update_region(mesh_rid, surface_index, 0, buffer);
	}

	software_skinning_flags |= SoftwareSkinning::FLAG_BONES_READY;
}

void MeshInstance::set_skin(const Ref<Skin> &p_skin) {
	skin_internal = p_skin;
	skin = p_skin;
	if (!is_inside_tree()) {
		return;
	}
	_resolve_skeleton_path();
}

Ref<Skin> MeshInstance::get_skin() const {
	return skin;
}

void MeshInstance::set_skeleton_path(const NodePath &p_skeleton) {
	skeleton_path = p_skeleton;
	if (!is_inside_tree()) {
		return;
	}
	_resolve_skeleton_path();
}

NodePath MeshInstance::get_skeleton_path() {
	return skeleton_path;
}

AABB MeshInstance::get_aabb() const {
	if (!mesh.is_null()) {
		return mesh->get_aabb();
	}

	return AABB();
}

PoolVector<Face3> MeshInstance::get_faces(uint32_t p_usage_flags) const {
	if (!(p_usage_flags & (FACES_SOLID | FACES_ENCLOSING))) {
		return PoolVector<Face3>();
	}

	if (mesh.is_null()) {
		return PoolVector<Face3>();
	}

	return mesh->get_faces();
}

Node *MeshInstance::create_trimesh_collision_node() {
	if (mesh.is_null()) {
		return nullptr;
	}

	Ref<Shape> shape = mesh->create_trimesh_shape();
	if (shape.is_null()) {
		return nullptr;
	}

	StaticBody *static_body = memnew(StaticBody);
	CollisionShape *cshape = memnew(CollisionShape);
	cshape->set_shape(shape);
	static_body->add_child(cshape);
	return static_body;
}

void MeshInstance::create_trimesh_collision() {
	StaticBody *static_body = Object::cast_to<StaticBody>(create_trimesh_collision_node());
	ERR_FAIL_COND(!static_body);
	static_body->set_name(String(get_name()) + "_col");

	add_child(static_body);
	if (get_owner()) {
		CollisionShape *cshape = Object::cast_to<CollisionShape>(static_body->get_child(0));
		static_body->set_owner(get_owner());
		cshape->set_owner(get_owner());
	}
}

Node *MeshInstance::create_multiple_convex_collisions_node() {
	if (mesh.is_null()) {
		return nullptr;
	}

	Vector<Ref<Shape>> shapes = mesh->convex_decompose();
	if (!shapes.size()) {
		return nullptr;
	}

	StaticBody *static_body = memnew(StaticBody);
	for (int i = 0; i < shapes.size(); i++) {
		CollisionShape *cshape = memnew(CollisionShape);
		cshape->set_shape(shapes[i]);
		static_body->add_child(cshape);
	}
	return static_body;
}

void MeshInstance::create_multiple_convex_collisions() {
	StaticBody *static_body = Object::cast_to<StaticBody>(create_multiple_convex_collisions_node());
	ERR_FAIL_COND(!static_body);
	static_body->set_name(String(get_name()) + "_col");

	add_child(static_body);
	if (get_owner()) {
		static_body->set_owner(get_owner());
		int count = static_body->get_child_count();
		for (int i = 0; i < count; i++) {
			CollisionShape *cshape = Object::cast_to<CollisionShape>(static_body->get_child(i));
			cshape->set_owner(get_owner());
		}
	}
}

Node *MeshInstance::create_convex_collision_node(bool p_clean, bool p_simplify) {
	if (mesh.is_null()) {
		return nullptr;
	}

	Ref<Shape> shape = mesh->create_convex_shape(p_clean, p_simplify);
	if (shape.is_null()) {
		return nullptr;
	}

	StaticBody *static_body = memnew(StaticBody);
	CollisionShape *cshape = memnew(CollisionShape);
	cshape->set_shape(shape);
	static_body->add_child(cshape);
	return static_body;
}

void MeshInstance::create_convex_collision(bool p_clean, bool p_simplify) {
	StaticBody *static_body = Object::cast_to<StaticBody>(create_convex_collision_node(p_clean, p_simplify));
	ERR_FAIL_COND(!static_body);
	static_body->set_name(String(get_name()) + "_col");

	add_child(static_body);
	if (get_owner()) {
		CollisionShape *cshape = Object::cast_to<CollisionShape>(static_body->get_child(0));
		static_body->set_owner(get_owner());
		cshape->set_owner(get_owner());
	}
}

void MeshInstance::_notification(int p_what) {
	if (p_what == NOTIFICATION_ENTER_TREE) {
		_resolve_skeleton_path();
	}

	if (p_what == NOTIFICATION_VISIBILITY_CHANGED) {
		if (skin_ref.is_valid() && mesh.is_valid() && _is_software_skinning_enabled()) {
			ERR_FAIL_COND(!skin_ref->get_skeleton_node());
			if (is_visible_in_tree()) {
				skin_ref->get_skeleton_node()->connect("skeleton_updated", this, "_update_skinning");
			} else {
				skin_ref->get_skeleton_node()->disconnect("skeleton_updated", this, "_update_skinning");
			}
		}
	}
}

int MeshInstance::get_surface_material_count() const {
	return materials.size();
}

void MeshInstance::set_surface_material(int p_surface, const Ref<Material> &p_material) {
	ERR_FAIL_INDEX(p_surface, materials.size());

	materials.write[p_surface] = p_material;

	if (materials[p_surface].is_valid()) {
		VS::get_singleton()->instance_set_surface_material(get_instance(), p_surface, materials[p_surface]->get_rid());
	} else {
		VS::get_singleton()->instance_set_surface_material(get_instance(), p_surface, RID());
	}

	if (software_skinning) {
		_initialize_skinning(true);
	}
}

Ref<Material> MeshInstance::get_surface_material(int p_surface) const {
	ERR_FAIL_INDEX_V(p_surface, materials.size(), Ref<Material>());

	return materials[p_surface];
}

Ref<Material> MeshInstance::get_active_material(int p_surface) const {
	Ref<Material> material_override = get_material_override();
	if (material_override.is_valid()) {
		return material_override;
	}

	Ref<Material> surface_material = get_surface_material(p_surface);
	if (surface_material.is_valid()) {
		return surface_material;
	}

	Ref<Mesh> mesh = get_mesh();
	if (mesh.is_valid()) {
		return mesh->surface_get_material(p_surface);
	}

	return Ref<Material>();
}

void MeshInstance::set_material_override(const Ref<Material> &p_material) {
	if (p_material == get_material_override()) {
		return;
	}

	GeometryInstance::set_material_override(p_material);

	if (software_skinning) {
		_initialize_skinning(true);
	}
}

void MeshInstance::set_software_skinning_transform_normals(bool p_enabled) {
	if (p_enabled == is_software_skinning_transform_normals_enabled()) {
		return;
	}

	if (p_enabled) {
		software_skinning_flags |= SoftwareSkinning::FLAG_TRANSFORM_NORMALS;
	} else {
		software_skinning_flags &= ~SoftwareSkinning::FLAG_TRANSFORM_NORMALS;
	}

	if (software_skinning) {
		_initialize_skinning(true);
	}
}

bool MeshInstance::is_software_skinning_transform_normals_enabled() const {
	return 0 != (software_skinning_flags & SoftwareSkinning::FLAG_TRANSFORM_NORMALS);
}

void MeshInstance::_mesh_changed() {
	ERR_FAIL_COND(mesh.is_null());
	materials.resize(mesh->get_surface_count());

	if (software_skinning) {
		_initialize_skinning(true);
	}
}

void MeshInstance::create_debug_tangents() {
	Vector<Vector3> lines;
	Vector<Color> colors;

	Ref<Mesh> mesh = get_mesh();
	if (!mesh.is_valid()) {
		return;
	}

	for (int i = 0; i < mesh->get_surface_count(); i++) {
		Array arrays = mesh->surface_get_arrays(i);
		Vector<Vector3> verts = arrays[Mesh::ARRAY_VERTEX];
		Vector<Vector3> norms = arrays[Mesh::ARRAY_NORMAL];
		if (norms.size() == 0) {
			continue;
		}
		Vector<float> tangents = arrays[Mesh::ARRAY_TANGENT];
		if (tangents.size() == 0) {
			continue;
		}

		for (int j = 0; j < verts.size(); j++) {
			Vector3 v = verts[j];
			Vector3 n = norms[j];
			Vector3 t = Vector3(tangents[j * 4 + 0], tangents[j * 4 + 1], tangents[j * 4 + 2]);
			Vector3 b = (n.cross(t)).normalized() * tangents[j * 4 + 3];

			lines.push_back(v); //normal
			colors.push_back(Color(0, 0, 1)); //color
			lines.push_back(v + n * 0.04); //normal
			colors.push_back(Color(0, 0, 1)); //color

			lines.push_back(v); //tangent
			colors.push_back(Color(1, 0, 0)); //color
			lines.push_back(v + t * 0.04); //tangent
			colors.push_back(Color(1, 0, 0)); //color

			lines.push_back(v); //binormal
			colors.push_back(Color(0, 1, 0)); //color
			lines.push_back(v + b * 0.04); //binormal
			colors.push_back(Color(0, 1, 0)); //color
		}
	}

	if (lines.size()) {
		Ref<SpatialMaterial> sm;
		sm.instance();

		sm->set_flag(SpatialMaterial::FLAG_UNSHADED, true);
		sm->set_flag(SpatialMaterial::FLAG_SRGB_VERTEX_COLOR, true);
		sm->set_flag(SpatialMaterial::FLAG_ALBEDO_FROM_VERTEX_COLOR, true);

		Ref<ArrayMesh> am;
		am.instance();
		Array a;
		a.resize(Mesh::ARRAY_MAX);
		a[Mesh::ARRAY_VERTEX] = lines;
		a[Mesh::ARRAY_COLOR] = colors;

		am->add_surface_from_arrays(Mesh::PRIMITIVE_LINES, a);
		am->surface_set_material(0, sm);

		MeshInstance *mi = memnew(MeshInstance);
		mi->set_mesh(am);
		mi->set_name("DebugTangents");
		add_child(mi);
#ifdef TOOLS_ENABLED

		if (is_inside_tree() && this == get_tree()->get_edited_scene_root()) {
			mi->set_owner(this);
		} else {
			mi->set_owner(get_owner());
		}
#endif
	}
}

bool MeshInstance::is_mergeable_with(const MeshInstance &p_other) {
	if (!get_mesh().is_valid() || !p_other.get_mesh().is_valid()) {
		return false;
	}

	Ref<Mesh> rmesh_a = get_mesh();
	Ref<Mesh> rmesh_b = p_other.get_mesh();

	int num_surfaces = rmesh_a->get_surface_count();
	if (num_surfaces != rmesh_b->get_surface_count()) {
		return false;
	}

	for (int n = 0; n < num_surfaces; n++) {
		// materials must match
		if (get_active_material(n) != p_other.get_active_material(n)) {
			return false;
		}

		// formats must match
		uint32_t format_a = rmesh_a->surface_get_format(n);
		uint32_t format_b = rmesh_b->surface_get_format(n);

		if (format_a != format_b) {
			return false;
		}
	}

	// NOTE : These three commented out sections below are more conservative
	// checks for whether to allow mesh merging. I am not absolutely sure a priori
	// how conservative we need to be, so we can further enable this if testing
	// shows they are required.

	//	if (get_surface_material_count() != p_other.get_surface_material_count()) {
	//		return false;
	//	}

	//	for (int n = 0; n < get_surface_material_count(); n++) {
	//		if (get_surface_material(n) != p_other.get_surface_material(n)) {
	//			return false;
	//		}
	//	}

	// test only allow identical meshes
	//	if (get_mesh() != p_other.get_mesh()) {
	//		return false;
	//	}

	return true;
}

void MeshInstance::_merge_into_mesh_data(const MeshInstance &p_mi, int p_surface_id, PoolVector<Vector3> &r_verts, PoolVector<Vector3> &r_norms, PoolVector<real_t> &r_tangents, PoolVector<Color> &r_colors, PoolVector<Vector2> &r_uvs, PoolVector<Vector2> &r_uv2s, PoolVector<int> &r_inds) {
	_merge_log("\t\t\tmesh data from " + p_mi.get_name());

	// get the mesh verts in local space
	Ref<Mesh> rmesh = p_mi.get_mesh();

	if (rmesh->get_surface_count() <= p_surface_id) {
		return;
	}

	Array arrays = rmesh->surface_get_arrays(p_surface_id);

	PoolVector<Vector3> verts = arrays[VS::ARRAY_VERTEX];
	PoolVector<Vector3> normals = arrays[VS::ARRAY_NORMAL];
	PoolVector<real_t> tangents = arrays[VS::ARRAY_TANGENT];
	PoolVector<Color> colors = arrays[VS::ARRAY_COLOR];
	PoolVector<Vector2> uvs = arrays[VS::ARRAY_TEX_UV];
	PoolVector<Vector2> uv2s = arrays[VS::ARRAY_TEX_UV2];
	PoolVector<int> indices = arrays[VS::ARRAY_INDEX];

	// NEW .. the checking for valid triangles should be on WORLD SPACE vertices,
	// NOT model space

	// special case, if no indices, create some
	int num_indices_before = indices.size();
	if (!_ensure_indices_valid(indices, verts)) {
		_merge_log("\tignoring INVALID TRIANGLES (duplicate indices or zero area triangle) detected in " + p_mi.get_name() + ", num inds before / after " + itos(num_indices_before) + " / " + itos(indices.size()));
	}

	// the first index of this mesh is offset from the verts we already have stored in the merged mesh
	int first_index = r_verts.size();

	// transform verts to world space
	Transform tr = p_mi.get_global_transform();

	// to transform normals
	Basis normal_basis = tr.basis.inverse();
	normal_basis.transpose();

	for (int n = 0; n < verts.size(); n++) {
		Vector3 pt_world = tr.xform(verts[n]);
		r_verts.push_back(pt_world);

		if (normals.size()) {
			Vector3 pt_norm = normal_basis.xform(normals[n]);
			pt_norm.normalize();
			r_norms.push_back(pt_norm);
		}

		if (tangents.size()) {
			int tstart = n * 4;
			Vector3 pt_tangent = Vector3(tangents[tstart], tangents[tstart + 1], tangents[tstart + 2]);
			real_t fourth = tangents[tstart + 3];

			pt_tangent = normal_basis.xform(pt_tangent);
			pt_tangent.normalize();
			r_tangents.push_back(pt_tangent.x);
			r_tangents.push_back(pt_tangent.y);
			r_tangents.push_back(pt_tangent.z);
			r_tangents.push_back(fourth);
		}

		if (colors.size()) {
			r_colors.push_back(colors[n]);
		}

		if (uvs.size()) {
			r_uvs.push_back(uvs[n]);
		}

		if (uv2s.size()) {
			r_uv2s.push_back(uv2s[n]);
		}
	}

	// indices
	for (int n = 0; n < indices.size(); n++) {
		int ind = indices[n] + first_index;
		r_inds.push_back(ind);
	}
}

bool MeshInstance::_ensure_indices_valid(PoolVector<int> &r_indices, const PoolVector<Vector3> &p_verts) {
	// no indices? create some
	if (!r_indices.size()) {
		_merge_log("\t\t\t\tindices are blank, creating...");

		// indices are blank!! let's create some, assuming the mesh is using triangles
		r_indices.resize(p_verts.size());
		PoolVector<int>::Write write = r_indices.write();
		int *pi = write.ptr();

		// this is assuming each triangle vertex is unique
		for (int n = 0; n < p_verts.size(); n++) {
			*pi = n;
			pi++;
		}
	}

	if (!_check_for_valid_indices(r_indices, p_verts, nullptr)) {
		LocalVector<int, int32_t> new_inds;
		_check_for_valid_indices(r_indices, p_verts, &new_inds);

		// copy the new indices
		r_indices.resize(new_inds.size());
		PoolVector<int>::Write write = r_indices.write();
		int *pi = write.ptr();

		for (int n = 0; n < new_inds.size(); n++) {
			pi[n] = new_inds[n];
		}

		return false;
	}

	return true;
}

// check for invalid tris, or make a list of the valid triangles, depending on whether r_inds is set
bool MeshInstance::_check_for_valid_indices(const PoolVector<int> &p_inds, const PoolVector<Vector3> &p_verts, LocalVector<int, int32_t> *r_inds) {
	int nTris = p_inds.size();
	nTris /= 3;
	int indCount = 0;

	for (int t = 0; t < nTris; t++) {
		int i0 = p_inds[indCount++];
		int i1 = p_inds[indCount++];
		int i2 = p_inds[indCount++];

		bool ok = true;

		// if the indices are the same, the triangle is invalid
		if (i0 == i1) {
			ok = false;
		}
		if (i1 == i2) {
			ok = false;
		}
		if (i0 == i2) {
			ok = false;
		}

		// check positions
		if (ok) {
			// vertex positions
			const Vector3 &p0 = p_verts[i0];
			const Vector3 &p1 = p_verts[i1];
			const Vector3 &p2 = p_verts[i2];

			// if the area is zero, the triangle is invalid (and will crash xatlas if we use it)
			if (_triangle_is_degenerate(p0, p1, p2, 0.00001)) {
				_merge_log("\t\tdetected zero area triangle, ignoring");
				ok = false;
			}
		}

		if (ok) {
			// if the triangle is ok, we will output it if we are outputting
			if (r_inds) {
				r_inds->push_back(i0);
				r_inds->push_back(i1);
				r_inds->push_back(i2);
			}
		} else {
			// if triangle not ok, return failed check if we are not outputting
			if (!r_inds) {
				return false;
			}
		}
	}

	return true;
}

bool MeshInstance::_triangle_is_degenerate(const Vector3 &p_a, const Vector3 &p_b, const Vector3 &p_c, real_t p_epsilon) {
	// not interested in the actual area, but numerical stability
	Vector3 edge1 = p_b - p_a;
	Vector3 edge2 = p_c - p_a;

	// for numerical stability keep these values reasonably high
	edge1 *= 1024.0;
	edge2 *= 1024.0;

	Vector3 vec = edge1.cross(edge2);
	real_t sl = vec.length_squared();

	if (sl <= p_epsilon) {
		return true;
	}

	return false;
}

bool MeshInstance::create_by_merging(Vector<MeshInstance *> p_list) {
	// must be at least 2 meshes to merge
	if (p_list.size() < 2) {
		// should not happen but just in case
		return false;
	}

	// use the first mesh instance to get common data like number of surfaces
	const MeshInstance *first = p_list[0];

	Ref<ArrayMesh> am;
	am.instance();

	for (int s = 0; s < first->get_mesh()->get_surface_count(); s++) {
		PoolVector<Vector3> verts;
		PoolVector<Vector3> normals;
		PoolVector<real_t> tangents;
		PoolVector<Color> colors;
		PoolVector<Vector2> uvs;
		PoolVector<Vector2> uv2s;
		PoolVector<int> inds;

		for (int n = 0; n < p_list.size(); n++) {
			_merge_into_mesh_data(*p_list[n], s, verts, normals, tangents, colors, uvs, uv2s, inds);
		} // for n through source meshes

		if (!verts.size()) {
			WARN_PRINT_ONCE("No vertices for surface");
		}

		// sanity check on the indices
		for (int n = 0; n < inds.size(); n++) {
			int i = inds[n];
			if (i >= verts.size()) {
				WARN_PRINT_ONCE("Mesh index out of range, invalid mesh, aborting");
				return false;
			}
		}

		Array arr;
		arr.resize(Mesh::ARRAY_MAX);
		arr[Mesh::ARRAY_VERTEX] = verts;
		if (normals.size()) {
			arr[Mesh::ARRAY_NORMAL] = normals;
		}
		if (tangents.size()) {
			arr[Mesh::ARRAY_TANGENT] = tangents;
		}
		if (colors.size()) {
			arr[Mesh::ARRAY_COLOR] = colors;
		}
		if (uvs.size()) {
			arr[Mesh::ARRAY_TEX_UV] = uvs;
		}
		if (uv2s.size()) {
			arr[Mesh::ARRAY_TEX_UV2] = uv2s;
		}
		arr[Mesh::ARRAY_INDEX] = inds;

		am->add_surface_from_arrays(Mesh::PRIMITIVE_TRIANGLES, arr, Array(), Mesh::ARRAY_COMPRESS_DEFAULT);
	} // for s through surfaces

	// set all the surfaces on the mesh
	set_mesh(am);

	// set merged materials
	int num_surfaces = first->get_mesh()->get_surface_count();
	for (int n = 0; n < num_surfaces; n++) {
		set_surface_material(n, first->get_active_material(n));
	}

	return true;
}

void MeshInstance::_merge_log(String p_string) {
	print_verbose(p_string);
}

void MeshInstance::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_mesh", "mesh"), &MeshInstance::set_mesh);
	ClassDB::bind_method(D_METHOD("get_mesh"), &MeshInstance::get_mesh);
	ClassDB::bind_method(D_METHOD("set_skeleton_path", "skeleton_path"), &MeshInstance::set_skeleton_path);
	ClassDB::bind_method(D_METHOD("get_skeleton_path"), &MeshInstance::get_skeleton_path);
	ClassDB::bind_method(D_METHOD("set_skin", "skin"), &MeshInstance::set_skin);
	ClassDB::bind_method(D_METHOD("get_skin"), &MeshInstance::get_skin);

	ClassDB::bind_method(D_METHOD("get_surface_material_count"), &MeshInstance::get_surface_material_count);
	ClassDB::bind_method(D_METHOD("set_surface_material", "surface", "material"), &MeshInstance::set_surface_material);
	ClassDB::bind_method(D_METHOD("get_surface_material", "surface"), &MeshInstance::get_surface_material);
	ClassDB::bind_method(D_METHOD("get_active_material", "surface"), &MeshInstance::get_active_material);

	ClassDB::bind_method(D_METHOD("set_software_skinning_transform_normals", "enabled"), &MeshInstance::set_software_skinning_transform_normals);
	ClassDB::bind_method(D_METHOD("is_software_skinning_transform_normals_enabled"), &MeshInstance::is_software_skinning_transform_normals_enabled);

	ClassDB::bind_method(D_METHOD("create_trimesh_collision"), &MeshInstance::create_trimesh_collision);
	ClassDB::set_method_flags("MeshInstance", "create_trimesh_collision", METHOD_FLAGS_DEFAULT);
	ClassDB::bind_method(D_METHOD("create_multiple_convex_collisions"), &MeshInstance::create_multiple_convex_collisions);
	ClassDB::set_method_flags("MeshInstance", "create_multiple_convex_collisions", METHOD_FLAGS_DEFAULT);
	ClassDB::bind_method(D_METHOD("create_convex_collision", "clean", "simplify"), &MeshInstance::create_convex_collision, DEFVAL(true), DEFVAL(false));
	ClassDB::set_method_flags("MeshInstance", "create_convex_collision", METHOD_FLAGS_DEFAULT);
	ClassDB::bind_method(D_METHOD("_mesh_changed"), &MeshInstance::_mesh_changed);
	ClassDB::bind_method(D_METHOD("_update_skinning"), &MeshInstance::_update_skinning);

	ClassDB::bind_method(D_METHOD("create_debug_tangents"), &MeshInstance::create_debug_tangents);
	ClassDB::set_method_flags("MeshInstance", "create_debug_tangents", METHOD_FLAGS_DEFAULT | METHOD_FLAG_EDITOR);

	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "mesh", PROPERTY_HINT_RESOURCE_TYPE, "Mesh"), "set_mesh", "get_mesh");
	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "skin", PROPERTY_HINT_RESOURCE_TYPE, "Skin"), "set_skin", "get_skin");
	ADD_PROPERTY(PropertyInfo(Variant::NODE_PATH, "skeleton", PROPERTY_HINT_NODE_PATH_VALID_TYPES, "Skeleton"), "set_skeleton_path", "get_skeleton_path");

	ADD_GROUP("Software Skinning", "software_skinning");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "software_skinning_transform_normals"), "set_software_skinning_transform_normals", "is_software_skinning_transform_normals_enabled");
}

MeshInstance::MeshInstance() {
	skeleton_path = NodePath("..");
	software_skinning = nullptr;
	software_skinning_flags = SoftwareSkinning::FLAG_TRANSFORM_NORMALS;
}

MeshInstance::~MeshInstance() {
	if (software_skinning) {
		memdelete(software_skinning);
		software_skinning = nullptr;
	}
}