text: /*************************************************************************/
  /*  path.cpp                                                             */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2022 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 "path.h"
  
  #include "core/engine.h"
  #include "scene/scene_string_names.h"
  
  void Path::_notification(int p_what) {
  }
  
  void Path::_curve_changed() {
  	if (is_inside_tree() && Engine::get_singleton()->is_editor_hint()) {
  		update_gizmo();
  	}
  	if (is_inside_tree()) {
  		emit_signal("curve_changed");
  	}
  
  	// update the configuration warnings of all children of type PathFollow
  	// previously used for PathFollowOriented (now enforced orientation is done in PathFollow)
  	if (is_inside_tree()) {
  		for (int i = 0; i < get_child_count(); i++) {
  			PathFollow *child = Object::cast_to<PathFollow>(get_child(i));
  			if (child) {
  				child->update_configuration_warning();
  			}
  		}
  	}
  }
  
  void Path::set_curve(const Ref<Curve3D> &p_curve) {
  	if (curve.is_valid()) {
  		curve->disconnect("changed", this, "_curve_changed");
  	}
  
  	curve = p_curve;
  
  	if (curve.is_valid()) {
  		curve->connect("changed", this, "_curve_changed");
  	}
  	_curve_changed();
  }
  
  Ref<Curve3D> Path::get_curve() const {
  	return curve;
  }
  
  void Path::_bind_methods() {
  	ClassDB::bind_method(D_METHOD("set_curve", "curve"), &Path::set_curve);
  	ClassDB::bind_method(D_METHOD("get_curve"), &Path::get_curve);
  	ClassDB::bind_method(D_METHOD("_curve_changed"), &Path::_curve_changed);
  
  	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve3D"), "set_curve", "get_curve");
  
  	ADD_SIGNAL(MethodInfo("curve_changed"));
  }
  
  Path::Path() {
  	set_curve(Ref<Curve3D>(memnew(Curve3D))); //create one by default
  }
  
  //////////////
  
  void PathFollow::_update_transform(bool p_update_xyz_rot) {
  	if (!path) {
  		return;
  	}
  
  	Ref<Curve3D> c = path->get_curve();
  	if (!c.is_valid()) {
  		return;
  	}
  
  	float bl = c->get_baked_length();
  	if (bl == 0.0) {
  		return;
  	}
  	float bi = c->get_bake_interval();
  	float o_next = offset + bi;
  	float o_prev = offset - bi;
  
  	if (loop) {
  		o_next = Math::fposmod(o_next, bl);
  		o_prev = Math::fposmod(o_prev, bl);
  	} else if (rotation_mode == ROTATION_ORIENTED) {
  		if (o_next >= bl) {
  			o_next = bl;
  		}
  		if (o_prev <= 0) {
  			o_prev = 0;
  		}
  	}
  
  	Vector3 pos = c->interpolate_baked(offset, cubic);
  	Transform t = get_transform();
  	// Vector3 pos_offset = Vector3(h_offset, v_offset, 0); not used in all cases
  	// will be replaced by "Vector3(h_offset, v_offset, 0)" where it was formerly used
  
  	if (rotation_mode == ROTATION_ORIENTED) {
  		Vector3 forward = c->interpolate_baked(o_next, cubic) - pos;
  
  		// Try with the previous position
  		if (forward.length_squared() < CMP_EPSILON2) {
  			forward = pos - c->interpolate_baked(o_prev, cubic);
  		}
  
  		if (forward.length_squared() < CMP_EPSILON2) {
  			forward = Vector3(0, 0, 1);
  		} else {
  			forward.normalize();
  		}
  
  		Vector3 up = c->interpolate_baked_up_vector(offset, true);
  
  		if (o_next < offset) {
  			Vector3 up1 = c->interpolate_baked_up_vector(o_next, true);
  			Vector3 axis = up.cross(up1);
  
  			if (axis.length_squared() < CMP_EPSILON2) {
  				axis = forward;
  			} else {
  				axis.normalize();
  			}
  
  			up.rotate(axis, up.angle_to(up1) * 0.5f);
  		}
  
  		Vector3 scale = t.basis.get_scale();
  		Vector3 sideways = up.cross(forward).normalized();
  		up = forward.cross(sideways).normalized();
  
  		t.basis.set(sideways, up, forward);
  		t.basis.scale_local(scale);
  
  		t.origin = pos + sideways * h_offset + up * v_offset;
  	} else if (rotation_mode != ROTATION_NONE) {
  		// perform parallel transport
  		//
  		// see C. Dougan, The Parallel Transport Frame, Game Programming Gems 2 for example
  		// for a discussion about why not Frenet frame.
  
  		t.origin = pos;
  
  		if (p_update_xyz_rot && delta_offset != 0) { // Only update rotation if some parameter has changed - i.e. not on addition to scene tree.
  			Vector3 t_prev = (pos - c->interpolate_baked(offset - delta_offset, cubic)).normalized();
  			Vector3 t_cur = (c->interpolate_baked(offset + delta_offset, cubic) - pos).normalized();
  
  			Vector3 axis = t_prev.cross(t_cur);
  			float dot = t_prev.dot(t_cur);
  			float angle = Math::acos(CLAMP(dot, -1, 1));
  
  			if (likely(!Math::is_zero_approx(angle))) {
  				if (rotation_mode == ROTATION_Y) {
  					// assuming we're referring to global Y-axis. is this correct?
  					axis.x = 0;
  					axis.z = 0;
  				} else if (rotation_mode == ROTATION_XY) {
  					axis.z = 0;
  				} else if (rotation_mode == ROTATION_XYZ) {
  					// all components are allowed
  				}
  
  				if (likely(!Math::is_zero_approx(axis.length()))) {
  					t.rotate_basis(axis.normalized(), angle);
  				}
  			}
  
  			// do the additional tilting
  			float tilt_angle = c->interpolate_baked_tilt(offset);
  			Vector3 tilt_axis = t_cur; // not sure what tilt is supposed to do, is this correct??
  
  			if (likely(!Math::is_zero_approx(Math::abs(tilt_angle)))) {
  				if (rotation_mode == ROTATION_Y) {
  					tilt_axis.x = 0;
  					tilt_axis.z = 0;
  				} else if (rotation_mode == ROTATION_XY) {
  					tilt_axis.z = 0;
  				} else if (rotation_mode == ROTATION_XYZ) {
  					// all components are allowed
  				}
  
  				if (likely(!Math::is_zero_approx(tilt_axis.length()))) {
  					t.rotate_basis(tilt_axis.normalized(), tilt_angle);
  				}
  			}
  		}
  
  		t.translate(Vector3(h_offset, v_offset, 0));
  	} else {
  		t.origin = pos + Vector3(h_offset, v_offset, 0);
  	}
  
  	set_transform(t);
  }
  
  void PathFollow::_notification(int p_what) {
  	switch (p_what) {
  		case NOTIFICATION_ENTER_TREE: {
  			Node *parent = get_parent();
  			if (parent) {
  				path = Object::cast_to<Path>(parent);
  				if (path) {
  					_update_transform(false);
  				}
  			}
  
  		} break;
  		case NOTIFICATION_EXIT_TREE: {
  			path = nullptr;
  		} break;
  	}
  }
  
  void PathFollow::set_cubic_interpolation(bool p_enable) {
  	cubic = p_enable;
  }
  
  bool PathFollow::get_cubic_interpolation() const {
  	return cubic;
  }
  
  void PathFollow::_validate_property(PropertyInfo &property) const {
  	if (property.name == "offset") {
  		float max = 10000;
  		if (path && path->get_curve().is_valid()) {
  			max = path->get_curve()->get_baked_length();
  		}
  
  		property.hint_string = "0," + rtos(max) + ",0.01,or_lesser,or_greater";
  	}
  }
  
  String PathFollow::get_configuration_warning() const {
  	if (!is_visible_in_tree() || !is_inside_tree()) {
  		return String();
  	}
  
  	String warning = Spatial::get_configuration_warning();
  	if (!Object::cast_to<Path>(get_parent())) {
  		if (warning != String()) {
  			warning += "\n\n";
  		}
  		warning += TTR("PathFollow only works when set as a child of a Path node.");
  	} else {
  		Path *path = Object::cast_to<Path>(get_parent());
  		if (path->get_curve().is_valid() && !path->get_curve()->is_up_vector_enabled() && rotation_mode == ROTATION_ORIENTED) {
  			if (warning != String()) {
  				warning += "\n\n";
  			}
  			warning += TTR("PathFollow's ROTATION_ORIENTED requires \"Up Vector\" to be enabled in its parent Path's Curve resource.");
  		}
  	}
  
  	return warning;
  }
  
  void PathFollow::_bind_methods() {
  	ClassDB::bind_method(D_METHOD("set_offset", "offset"), &PathFollow::set_offset);
  	ClassDB::bind_method(D_METHOD("get_offset"), &PathFollow::get_offset);
  
  	ClassDB::bind_method(D_METHOD("set_h_offset", "h_offset"), &PathFollow::set_h_offset);
  	ClassDB::bind_method(D_METHOD("get_h_offset"), &PathFollow::get_h_offset);
  
  	ClassDB::bind_method(D_METHOD("set_v_offset", "v_offset"), &PathFollow::set_v_offset);
  	ClassDB::bind_method(D_METHOD("get_v_offset"), &PathFollow::get_v_offset);
  
  	ClassDB::bind_method(D_METHOD("set_unit_offset", "unit_offset"), &PathFollow::set_unit_offset);
  	ClassDB::bind_method(D_METHOD("get_unit_offset"), &PathFollow::get_unit_offset);
  
  	ClassDB::bind_method(D_METHOD("set_rotation_mode", "rotation_mode"), &PathFollow::set_rotation_mode);
  	ClassDB::bind_method(D_METHOD("get_rotation_mode"), &PathFollow::get_rotation_mode);
  
  	ClassDB::bind_method(D_METHOD("set_cubic_interpolation", "enable"), &PathFollow::set_cubic_interpolation);
  	ClassDB::bind_method(D_METHOD("get_cubic_interpolation"), &PathFollow::get_cubic_interpolation);
  
  	ClassDB::bind_method(D_METHOD("set_loop", "loop"), &PathFollow::set_loop);
  	ClassDB::bind_method(D_METHOD("has_loop"), &PathFollow::has_loop);
  
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "offset", PROPERTY_HINT_RANGE, "0,10000,0.01,or_lesser,or_greater"), "set_offset", "get_offset");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "unit_offset", PROPERTY_HINT_RANGE, "0,1,0.0001,or_lesser,or_greater", PROPERTY_USAGE_EDITOR), "set_unit_offset", "get_unit_offset");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "h_offset"), "set_h_offset", "get_h_offset");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "v_offset"), "set_v_offset", "get_v_offset");
  	ADD_PROPERTY(PropertyInfo(Variant::INT, "rotation_mode", PROPERTY_HINT_ENUM, "None,Y,XY,XYZ,Oriented"), "set_rotation_mode", "get_rotation_mode");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "cubic_interp"), "set_cubic_interpolation", "get_cubic_interpolation");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "loop"), "set_loop", "has_loop");
  
  	BIND_ENUM_CONSTANT(ROTATION_NONE);
  	BIND_ENUM_CONSTANT(ROTATION_Y);
  	BIND_ENUM_CONSTANT(ROTATION_XY);
  	BIND_ENUM_CONSTANT(ROTATION_XYZ);
  	BIND_ENUM_CONSTANT(ROTATION_ORIENTED);
  }
  
  void PathFollow::set_offset(float p_offset) {
  	delta_offset = p_offset - offset;
  	offset = p_offset;
  
  	if (path) {
  		if (path->get_curve().is_valid()) {
  			float path_length = path->get_curve()->get_baked_length();
  
  			if (loop) {
  				offset = Math::fposmod(offset, path_length);
  				if (!Math::is_zero_approx(p_offset) && Math::is_zero_approx(offset)) {
  					offset = path_length;
  				}
  			} else {
  				offset = CLAMP(offset, 0, path_length);
  			}
  		}
  
  		_update_transform();
  	}
  	_change_notify("offset");
  	_change_notify("unit_offset");
  }
  
  void PathFollow::set_h_offset(float p_h_offset) {
  	h_offset = p_h_offset;
  	if (path) {
  		_update_transform();
  	}
  }
  
  float PathFollow::get_h_offset() const {
  	return h_offset;
  }
  
  void PathFollow::set_v_offset(float p_v_offset) {
  	v_offset = p_v_offset;
  	if (path) {
  		_update_transform();
  	}
  }
  
  float PathFollow::get_v_offset() const {
  	return v_offset;
  }
  
  float PathFollow::get_offset() const {
  	return offset;
  }
  
  void PathFollow::set_unit_offset(float p_unit_offset) {
  	if (path && path->get_curve().is_valid() && path->get_curve()->get_baked_length()) {
  		set_offset(p_unit_offset * path->get_curve()->get_baked_length());
  	}
  }
  
  float PathFollow::get_unit_offset() const {
  	if (path && path->get_curve().is_valid() && path->get_curve()->get_baked_length()) {
  		return get_offset() / path->get_curve()->get_baked_length();
  	} else {
  		return 0;
  	}
  }
  
  void PathFollow::set_rotation_mode(RotationMode p_rotation_mode) {
  	rotation_mode = p_rotation_mode;
  
  	update_configuration_warning();
  	_update_transform();
  }
  
  PathFollow::RotationMode PathFollow::get_rotation_mode() const {
  	return rotation_mode;
  }
  
  void PathFollow::set_loop(bool p_loop) {
  	loop = p_loop;
  }
  
  bool PathFollow::has_loop() const {
  	return loop;
  }
  
  PathFollow::PathFollow() {
  	offset = 0;
  	delta_offset = 0;
  	h_offset = 0;
  	v_offset = 0;
  	path = nullptr;
  	rotation_mode = ROTATION_XYZ;
  	cubic = true;
  	loop = true;
  }
  