text: /*************************************************************************/
  /*  navigation_mesh.cpp                                                  */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
  /*                                                                       */
  /* 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   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* 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.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #include "navigation_mesh.h"
  #include "mesh_instance.h"
  #include "navigation.h"
  
  void NavigationMesh::create_from_mesh(const Ref<Mesh> &p_mesh) {
  
  	vertices = PoolVector<Vector3>();
  	clear_polygons();
  
  	for (int i = 0; i < p_mesh->get_surface_count(); i++) {
  
  		if (p_mesh->surface_get_primitive_type(i) != Mesh::PRIMITIVE_TRIANGLES)
  			continue;
  		Array arr = p_mesh->surface_get_arrays(i);
  		PoolVector<Vector3> varr = arr[Mesh::ARRAY_VERTEX];
  		PoolVector<int> iarr = arr[Mesh::ARRAY_INDEX];
  		if (varr.size() == 0 || iarr.size() == 0)
  			continue;
  
  		int from = vertices.size();
  		vertices.append_array(varr);
  		int rlen = iarr.size();
  		PoolVector<int>::Read r = iarr.read();
  
  		for (int j = 0; j < rlen; j += 3) {
  			Vector<int> vi;
  			vi.resize(3);
  			vi.write[0] = r[j + 0] + from;
  			vi.write[1] = r[j + 1] + from;
  			vi.write[2] = r[j + 2] + from;
  
  			add_polygon(vi);
  		}
  	}
  }
  
  void NavigationMesh::set_sample_partition_type(int p_value) {
  	ERR_FAIL_COND(p_value >= SAMPLE_PARTITION_MAX);
  	partition_type = static_cast<SamplePartitionType>(p_value);
  }
  
  int NavigationMesh::get_sample_partition_type() const {
  	return static_cast<int>(partition_type);
  }
  
  void NavigationMesh::set_cell_size(float p_value) {
  	cell_size = p_value;
  }
  
  float NavigationMesh::get_cell_size() const {
  	return cell_size;
  }
  
  void NavigationMesh::set_cell_height(float p_value) {
  	cell_height = p_value;
  }
  
  float NavigationMesh::get_cell_height() const {
  	return cell_height;
  }
  
  void NavigationMesh::set_agent_height(float p_value) {
  	agent_height = p_value;
  }
  
  float NavigationMesh::get_agent_height() const {
  	return agent_height;
  }
  
  void NavigationMesh::set_agent_radius(float p_value) {
  	agent_radius = p_value;
  }
  
  float NavigationMesh::get_agent_radius() {
  	return agent_radius;
  }
  
  void NavigationMesh::set_agent_max_climb(float p_value) {
  	agent_max_climb = p_value;
  }
  
  float NavigationMesh::get_agent_max_climb() const {
  	return agent_max_climb;
  }
  
  void NavigationMesh::set_agent_max_slope(float p_value) {
  	agent_max_slope = p_value;
  }
  
  float NavigationMesh::get_agent_max_slope() const {
  	return agent_max_slope;
  }
  
  void NavigationMesh::set_region_min_size(float p_value) {
  	region_min_size = p_value;
  }
  
  float NavigationMesh::get_region_min_size() const {
  	return region_min_size;
  }
  
  void NavigationMesh::set_region_merge_size(float p_value) {
  	region_merge_size = p_value;
  }
  
  float NavigationMesh::get_region_merge_size() const {
  	return region_merge_size;
  }
  
  void NavigationMesh::set_edge_max_length(float p_value) {
  	edge_max_length = p_value;
  }
  
  float NavigationMesh::get_edge_max_length() const {
  	return edge_max_length;
  }
  
  void NavigationMesh::set_edge_max_error(float p_value) {
  	edge_max_error = p_value;
  }
  
  float NavigationMesh::get_edge_max_error() const {
  	return edge_max_error;
  }
  
  void NavigationMesh::set_verts_per_poly(float p_value) {
  	verts_per_poly = p_value;
  }
  
  float NavigationMesh::get_verts_per_poly() const {
  	return verts_per_poly;
  }
  
  void NavigationMesh::set_detail_sample_distance(float p_value) {
  	detail_sample_distance = p_value;
  }
  
  float NavigationMesh::get_detail_sample_distance() const {
  	return detail_sample_distance;
  }
  
  void NavigationMesh::set_detail_sample_max_error(float p_value) {
  	detail_sample_max_error = p_value;
  }
  
  float NavigationMesh::get_detail_sample_max_error() const {
  	return detail_sample_max_error;
  }
  
  void NavigationMesh::set_filter_low_hanging_obstacles(bool p_value) {
  	filter_low_hanging_obstacles = p_value;
  }
  
  bool NavigationMesh::get_filter_low_hanging_obstacles() const {
  	return filter_low_hanging_obstacles;
  }
  
  void NavigationMesh::set_filter_ledge_spans(bool p_value) {
  	filter_ledge_spans = p_value;
  }
  
  bool NavigationMesh::get_filter_ledge_spans() const {
  	return filter_ledge_spans;
  }
  
  void NavigationMesh::set_filter_walkable_low_height_spans(bool p_value) {
  	filter_walkable_low_height_spans = p_value;
  }
  
  bool NavigationMesh::get_filter_walkable_low_height_spans() const {
  	return filter_walkable_low_height_spans;
  }
  
  void NavigationMesh::set_vertices(const PoolVector<Vector3> &p_vertices) {
  
  	vertices = p_vertices;
  }
  
  PoolVector<Vector3> NavigationMesh::get_vertices() const {
  
  	return vertices;
  }
  
  void NavigationMesh::_set_polygons(const Array &p_array) {
  
  	polygons.resize(p_array.size());
  	for (int i = 0; i < p_array.size(); i++) {
  		polygons.write[i].indices = p_array[i];
  	}
  }
  
  Array NavigationMesh::_get_polygons() const {
  
  	Array ret;
  	ret.resize(polygons.size());
  	for (int i = 0; i < ret.size(); i++) {
  		ret[i] = polygons[i].indices;
  	}
  
  	return ret;
  }
  
  void NavigationMesh::add_polygon(const Vector<int> &p_polygon) {
  
  	Polygon polygon;
  	polygon.indices = p_polygon;
  	polygons.push_back(polygon);
  }
  int NavigationMesh::get_polygon_count() const {
  
  	return polygons.size();
  }
  Vector<int> NavigationMesh::get_polygon(int p_idx) {
  
  	ERR_FAIL_INDEX_V(p_idx, polygons.size(), Vector<int>());
  	return polygons[p_idx].indices;
  }
  void NavigationMesh::clear_polygons() {
  
  	polygons.clear();
  }
  
  Ref<Mesh> NavigationMesh::get_debug_mesh() {
  
  	if (debug_mesh.is_valid())
  		return debug_mesh;
  
  	PoolVector<Vector3> vertices = get_vertices();
  	PoolVector<Vector3>::Read vr = vertices.read();
  	List<Face3> faces;
  	for (int i = 0; i < get_polygon_count(); i++) {
  		Vector<int> p = get_polygon(i);
  
  		for (int j = 2; j < p.size(); j++) {
  			Face3 f;
  			f.vertex[0] = vr[p[0]];
  			f.vertex[1] = vr[p[j - 1]];
  			f.vertex[2] = vr[p[j]];
  
  			faces.push_back(f);
  		}
  	}
  
  	Map<_EdgeKey, bool> edge_map;
  	PoolVector<Vector3> tmeshfaces;
  	tmeshfaces.resize(faces.size() * 3);
  
  	{
  		PoolVector<Vector3>::Write tw = tmeshfaces.write();
  		int tidx = 0;
  
  		for (List<Face3>::Element *E = faces.front(); E; E = E->next()) {
  
  			const Face3 &f = E->get();
  
  			for (int j = 0; j < 3; j++) {
  
  				tw[tidx++] = f.vertex[j];
  				_EdgeKey ek;
  				ek.from = f.vertex[j].snapped(Vector3(CMP_EPSILON, CMP_EPSILON, CMP_EPSILON));
  				ek.to = f.vertex[(j + 1) % 3].snapped(Vector3(CMP_EPSILON, CMP_EPSILON, CMP_EPSILON));
  				if (ek.from < ek.to)
  					SWAP(ek.from, ek.to);
  
  				Map<_EdgeKey, bool>::Element *F = edge_map.find(ek);
  
  				if (F) {
  
  					F->get() = false;
  
  				} else {
  
  					edge_map[ek] = true;
  				}
  			}
  		}
  	}
  	List<Vector3> lines;
  
  	for (Map<_EdgeKey, bool>::Element *E = edge_map.front(); E; E = E->next()) {
  
  		if (E->get()) {
  			lines.push_back(E->key().from);
  			lines.push_back(E->key().to);
  		}
  	}
  
  	PoolVector<Vector3> varr;
  	varr.resize(lines.size());
  	{
  		PoolVector<Vector3>::Write w = varr.write();
  		int idx = 0;
  		for (List<Vector3>::Element *E = lines.front(); E; E = E->next()) {
  			w[idx++] = E->get();
  		}
  	}
  
  	debug_mesh = Ref<ArrayMesh>(memnew(ArrayMesh));
  
  	Array arr;
  	arr.resize(Mesh::ARRAY_MAX);
  	arr[Mesh::ARRAY_VERTEX] = varr;
  
  	debug_mesh->add_surface_from_arrays(Mesh::PRIMITIVE_LINES, arr);
  
  	return debug_mesh;
  }
  
  void NavigationMesh::_bind_methods() {
  	ClassDB::bind_method(D_METHOD("set_sample_partition_type", "sample_partition_type"), &NavigationMesh::set_sample_partition_type);
  	ClassDB::bind_method(D_METHOD("get_sample_partition_type"), &NavigationMesh::get_sample_partition_type);
  
  	ClassDB::bind_method(D_METHOD("set_cell_size", "cell_size"), &NavigationMesh::set_cell_size);
  	ClassDB::bind_method(D_METHOD("get_cell_size"), &NavigationMesh::get_cell_size);
  
  	ClassDB::bind_method(D_METHOD("set_cell_height", "cell_height"), &NavigationMesh::set_cell_height);
  	ClassDB::bind_method(D_METHOD("get_cell_height"), &NavigationMesh::get_cell_height);
  
  	ClassDB::bind_method(D_METHOD("set_agent_height", "agent_height"), &NavigationMesh::set_agent_height);
  	ClassDB::bind_method(D_METHOD("get_agent_height"), &NavigationMesh::get_agent_height);
  
  	ClassDB::bind_method(D_METHOD("set_agent_radius", "agent_radius"), &NavigationMesh::set_agent_radius);
  	ClassDB::bind_method(D_METHOD("get_agent_radius"), &NavigationMesh::get_agent_radius);
  
  	ClassDB::bind_method(D_METHOD("set_agent_max_climb", "agent_max_climb"), &NavigationMesh::set_agent_max_climb);
  	ClassDB::bind_method(D_METHOD("get_agent_max_climb"), &NavigationMesh::get_agent_max_climb);
  
  	ClassDB::bind_method(D_METHOD("set_agent_max_slope", "agent_max_slope"), &NavigationMesh::set_agent_max_slope);
  	ClassDB::bind_method(D_METHOD("get_agent_max_slope"), &NavigationMesh::get_agent_max_slope);
  
  	ClassDB::bind_method(D_METHOD("set_region_min_size", "region_min_size"), &NavigationMesh::set_region_min_size);
  	ClassDB::bind_method(D_METHOD("get_region_min_size"), &NavigationMesh::get_region_min_size);
  
  	ClassDB::bind_method(D_METHOD("set_region_merge_size", "region_merge_size"), &NavigationMesh::set_region_merge_size);
  	ClassDB::bind_method(D_METHOD("get_region_merge_size"), &NavigationMesh::get_region_merge_size);
  
  	ClassDB::bind_method(D_METHOD("set_edge_max_length", "edge_max_length"), &NavigationMesh::set_edge_max_length);
  	ClassDB::bind_method(D_METHOD("get_edge_max_length"), &NavigationMesh::get_edge_max_length);
  
  	ClassDB::bind_method(D_METHOD("set_edge_max_error", "edge_max_error"), &NavigationMesh::set_edge_max_error);
  	ClassDB::bind_method(D_METHOD("get_edge_max_error"), &NavigationMesh::get_edge_max_error);
  
  	ClassDB::bind_method(D_METHOD("set_verts_per_poly", "verts_per_poly"), &NavigationMesh::set_verts_per_poly);
  	ClassDB::bind_method(D_METHOD("get_verts_per_poly"), &NavigationMesh::get_verts_per_poly);
  
  	ClassDB::bind_method(D_METHOD("set_detail_sample_distance", "detail_sample_dist"), &NavigationMesh::set_detail_sample_distance);
  	ClassDB::bind_method(D_METHOD("get_detail_sample_distance"), &NavigationMesh::get_detail_sample_distance);
  
  	ClassDB::bind_method(D_METHOD("set_detail_sample_max_error", "detail_sample_max_error"), &NavigationMesh::set_detail_sample_max_error);
  	ClassDB::bind_method(D_METHOD("get_detail_sample_max_error"), &NavigationMesh::get_detail_sample_max_error);
  
  	ClassDB::bind_method(D_METHOD("set_filter_low_hanging_obstacles", "filter_low_hanging_obstacles"), &NavigationMesh::set_filter_low_hanging_obstacles);
  	ClassDB::bind_method(D_METHOD("get_filter_low_hanging_obstacles"), &NavigationMesh::get_filter_low_hanging_obstacles);
  
  	ClassDB::bind_method(D_METHOD("set_filter_ledge_spans", "filter_ledge_spans"), &NavigationMesh::set_filter_ledge_spans);
  	ClassDB::bind_method(D_METHOD("get_filter_ledge_spans"), &NavigationMesh::get_filter_ledge_spans);
  
  	ClassDB::bind_method(D_METHOD("set_filter_walkable_low_height_spans", "filter_walkable_low_height_spans"), &NavigationMesh::set_filter_walkable_low_height_spans);
  	ClassDB::bind_method(D_METHOD("get_filter_walkable_low_height_spans"), &NavigationMesh::get_filter_walkable_low_height_spans);
  
  	ClassDB::bind_method(D_METHOD("set_vertices", "vertices"), &NavigationMesh::set_vertices);
  	ClassDB::bind_method(D_METHOD("get_vertices"), &NavigationMesh::get_vertices);
  
  	ClassDB::bind_method(D_METHOD("add_polygon", "polygon"), &NavigationMesh::add_polygon);
  	ClassDB::bind_method(D_METHOD("get_polygon_count"), &NavigationMesh::get_polygon_count);
  	ClassDB::bind_method(D_METHOD("get_polygon", "idx"), &NavigationMesh::get_polygon);
  	ClassDB::bind_method(D_METHOD("clear_polygons"), &NavigationMesh::clear_polygons);
  
  	ClassDB::bind_method(D_METHOD("create_from_mesh", "mesh"), &NavigationMesh::create_from_mesh);
  
  	ClassDB::bind_method(D_METHOD("_set_polygons", "polygons"), &NavigationMesh::_set_polygons);
  	ClassDB::bind_method(D_METHOD("_get_polygons"), &NavigationMesh::_get_polygons);
  
  	BIND_CONSTANT(SAMPLE_PARTITION_WATERSHED);
  	BIND_CONSTANT(SAMPLE_PARTITION_MONOTONE);
  	BIND_CONSTANT(SAMPLE_PARTITION_LAYERS);
  
  	ADD_PROPERTY(PropertyInfo(Variant::POOL_VECTOR3_ARRAY, "vertices", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NOEDITOR | PROPERTY_USAGE_INTERNAL), "set_vertices", "get_vertices");
  	ADD_PROPERTY(PropertyInfo(Variant::ARRAY, "polygons", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NOEDITOR | PROPERTY_USAGE_INTERNAL), "_set_polygons", "_get_polygons");
  
  	ADD_PROPERTY(PropertyInfo(Variant::INT, "sample_partition_type/sample_partition_type", PROPERTY_HINT_ENUM, "Watershed,Monotone,Layers"), "set_sample_partition_type", "get_sample_partition_type");
  
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "cell/size", PROPERTY_HINT_RANGE, "0.1,1.0,0.01"), "set_cell_size", "get_cell_size");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "cell/height", PROPERTY_HINT_RANGE, "0.1,1.0,0.01"), "set_cell_height", "get_cell_height");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "agent/height", PROPERTY_HINT_RANGE, "0.1,5.0,0.01"), "set_agent_height", "get_agent_height");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "agent/radius", PROPERTY_HINT_RANGE, "0.1,5.0,0.01"), "set_agent_radius", "get_agent_radius");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "agent/max_climb", PROPERTY_HINT_RANGE, "0.1,5.0,0.01"), "set_agent_max_climb", "get_agent_max_climb");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "agent/max_slope", PROPERTY_HINT_RANGE, "0.0,90.0,0.1"), "set_agent_max_slope", "get_agent_max_slope");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "region/min_size", PROPERTY_HINT_RANGE, "0.0,150.0,0.01"), "set_region_min_size", "get_region_min_size");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "region/merge_size", PROPERTY_HINT_RANGE, "0.0,150.0,0.01"), "set_region_merge_size", "get_region_merge_size");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "edge/max_length", PROPERTY_HINT_RANGE, "0.0,50.0,0.01"), "set_edge_max_length", "get_edge_max_length");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "edge/max_error", PROPERTY_HINT_RANGE, "0.1,3.0,0.01"), "set_edge_max_error", "get_edge_max_error");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "polygon/verts_per_poly", PROPERTY_HINT_RANGE, "3.0,12.0,1.0"), "set_verts_per_poly", "get_verts_per_poly");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "detail/sample_distance", PROPERTY_HINT_RANGE, "0.0,16.0,0.01"), "set_detail_sample_distance", "get_detail_sample_distance");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "detail/sample_max_error", PROPERTY_HINT_RANGE, "0.0,16.0,0.01"), "set_detail_sample_max_error", "get_detail_sample_max_error");
  
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "filter/low_hanging_obstacles"), "set_filter_low_hanging_obstacles", "get_filter_low_hanging_obstacles");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "filter/ledge_spans"), "set_filter_ledge_spans", "get_filter_ledge_spans");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "filter/filter_walkable_low_height_spans"), "set_filter_walkable_low_height_spans", "get_filter_walkable_low_height_spans");
  }
  
  NavigationMesh::NavigationMesh() {
  	cell_size = 0.3f;
  	cell_height = 0.2f;
  	agent_height = 2.0f;
  	agent_radius = 0.6f;
  	agent_max_climb = 0.9f;
  	agent_max_slope = 45.0f;
  	region_min_size = 8.0f;
  	region_merge_size = 20.0f;
  	edge_max_length = 12.0f;
  	edge_max_error = 1.3f;
  	verts_per_poly = 6.0f;
  	detail_sample_distance = 6.0f;
  	detail_sample_max_error = 1.0f;
  
  	partition_type = SAMPLE_PARTITION_WATERSHED;
  
  	filter_low_hanging_obstacles = false;
  	filter_ledge_spans = false;
  	filter_walkable_low_height_spans = false;
  }
  
  void NavigationMeshInstance::set_enabled(bool p_enabled) {
  
  	if (enabled == p_enabled)
  		return;
  	enabled = p_enabled;
  
  	if (!is_inside_tree())
  		return;
  
  	if (!enabled) {
  
  		if (nav_id != -1) {
  			navigation->navmesh_remove(nav_id);
  			nav_id = -1;
  		}
  	} else {
  
  		if (navigation) {
  
  			if (navmesh.is_valid()) {
  
  				nav_id = navigation->navmesh_add(navmesh, get_relative_transform(navigation), this);
  			}
  		}
  	}
  
  	if (debug_view) {
  		MeshInstance *dm = Object::cast_to<MeshInstance>(debug_view);
  		if (is_enabled()) {
  			dm->set_material_override(get_tree()->get_debug_navigation_material());
  		} else {
  			dm->set_material_override(get_tree()->get_debug_navigation_disabled_material());
  		}
  	}
  
  	update_gizmo();
  }
  
  bool NavigationMeshInstance::is_enabled() const {
  
  	return enabled;
  }
  
  /////////////////////////////
  
  void NavigationMeshInstance::_notification(int p_what) {
  
  	switch (p_what) {
  		case NOTIFICATION_ENTER_TREE: {
  
  			Spatial *c = this;
  			while (c) {
  
  				navigation = Object::cast_to<Navigation>(c);
  				if (navigation) {
  
  					if (enabled && navmesh.is_valid()) {
  
  						nav_id = navigation->navmesh_add(navmesh, get_relative_transform(navigation), this);
  					}
  					break;
  				}
  
  				c = c->get_parent_spatial();
  			}
  
  			if (navmesh.is_valid() && get_tree()->is_debugging_navigation_hint()) {
  
  				MeshInstance *dm = memnew(MeshInstance);
  				dm->set_mesh(navmesh->get_debug_mesh());
  				if (is_enabled()) {
  					dm->set_material_override(get_tree()->get_debug_navigation_material());
  				} else {
  					dm->set_material_override(get_tree()->get_debug_navigation_disabled_material());
  				}
  				add_child(dm);
  				debug_view = dm;
  			}
  
  		} break;
  		case NOTIFICATION_TRANSFORM_CHANGED: {
  
  			if (navigation && nav_id != -1) {
  				navigation->navmesh_set_transform(nav_id, get_relative_transform(navigation));
  			}
  
  		} break;
  		case NOTIFICATION_EXIT_TREE: {
  
  			if (navigation) {
  
  				if (nav_id != -1) {
  					navigation->navmesh_remove(nav_id);
  					nav_id = -1;
  				}
  			}
  
  			if (debug_view) {
  				debug_view->queue_delete();
  				debug_view = NULL;
  			}
  			navigation = NULL;
  		} break;
  	}
  }
  
  void NavigationMeshInstance::set_navigation_mesh(const Ref<NavigationMesh> &p_navmesh) {
  
  	if (p_navmesh == navmesh)
  		return;
  
  	if (navigation && nav_id != -1) {
  		navigation->navmesh_remove(nav_id);
  		nav_id = -1;
  	}
  	navmesh = p_navmesh;
  
  	if (navigation && navmesh.is_valid() && enabled) {
  		nav_id = navigation->navmesh_add(navmesh, get_relative_transform(navigation), this);
  	}
  
  	if (debug_view && navmesh.is_valid()) {
  		Object::cast_to<MeshInstance>(debug_view)->set_mesh(navmesh->get_debug_mesh());
  	}
  
  	update_gizmo();
  	update_configuration_warning();
  }
  
  Ref<NavigationMesh> NavigationMeshInstance::get_navigation_mesh() const {
  
  	return navmesh;
  }
  
  String NavigationMeshInstance::get_configuration_warning() const {
  
  	if (!is_visible_in_tree() || !is_inside_tree())
  		return String();
  
  	if (!navmesh.is_valid()) {
  		return TTR("A NavigationMesh resource must be set or created for this node to work.");
  	}
  	const Spatial *c = this;
  	while (c) {
  
  		if (Object::cast_to<Navigation>(c))
  			return String();
  
  		c = Object::cast_to<Spatial>(c->get_parent());
  	}
  
  	return TTR("NavigationMeshInstance must be a child or grandchild to a Navigation node. It only provides navigation data.");
  }
  
  void NavigationMeshInstance::_bind_methods() {
  
  	ClassDB::bind_method(D_METHOD("set_navigation_mesh", "navmesh"), &NavigationMeshInstance::set_navigation_mesh);
  	ClassDB::bind_method(D_METHOD("get_navigation_mesh"), &NavigationMeshInstance::get_navigation_mesh);
  
  	ClassDB::bind_method(D_METHOD("set_enabled", "enabled"), &NavigationMeshInstance::set_enabled);
  	ClassDB::bind_method(D_METHOD("is_enabled"), &NavigationMeshInstance::is_enabled);
  
  	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "navmesh", PROPERTY_HINT_RESOURCE_TYPE, "NavigationMesh"), "set_navigation_mesh", "get_navigation_mesh");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "enabled"), "set_enabled", "is_enabled");
  }
  
  NavigationMeshInstance::NavigationMeshInstance() {
  
  	debug_view = NULL;
  	navigation = NULL;
  	nav_id = -1;
  	enabled = true;
  	set_notify_transform(true);
  }
  