text: /*************************************************************************/
  /*  parallax_layer.cpp                                                   */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2018 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 "parallax_layer.h"
  
  #include "engine.h"
  #include "parallax_background.h"
  
  void ParallaxLayer::set_motion_scale(const Size2 &p_scale) {
  
  	motion_scale = p_scale;
  
  	ParallaxBackground *pb = Object::cast_to<ParallaxBackground>(get_parent());
  	if (pb && is_inside_tree()) {
  		Vector2 ofs = pb->get_final_offset();
  		float scale = pb->get_scroll_scale();
  		set_base_offset_and_scale(ofs, scale, screen_offset);
  	}
  }
  
  Size2 ParallaxLayer::get_motion_scale() const {
  
  	return motion_scale;
  }
  
  void ParallaxLayer::set_motion_offset(const Size2 &p_offset) {
  
  	motion_offset = p_offset;
  
  	ParallaxBackground *pb = Object::cast_to<ParallaxBackground>(get_parent());
  	if (pb && is_inside_tree()) {
  		Vector2 ofs = pb->get_final_offset();
  		float scale = pb->get_scroll_scale();
  		set_base_offset_and_scale(ofs, scale, screen_offset);
  	}
  }
  
  Size2 ParallaxLayer::get_motion_offset() const {
  
  	return motion_offset;
  }
  
  void ParallaxLayer::_update_mirroring() {
  
  	ParallaxBackground *pb = Object::cast_to<ParallaxBackground>(get_parent());
  	if (pb) {
  
  		RID c = pb->get_world_2d()->get_canvas();
  		RID ci = get_canvas_item();
  		Point2 mirrorScale = mirroring * get_scale();
  		VisualServer::get_singleton()->canvas_set_item_mirroring(c, ci, mirrorScale);
  	}
  }
  
  void ParallaxLayer::set_mirroring(const Size2 &p_mirroring) {
  
  	mirroring = p_mirroring;
  	if (mirroring.x < 0)
  		mirroring.x = 0;
  	if (mirroring.y < 0)
  		mirroring.y = 0;
  
  	_update_mirroring();
  }
  
  Size2 ParallaxLayer::get_mirroring() const {
  
  	return mirroring;
  }
  
  void ParallaxLayer::_notification(int p_what) {
  
  	switch (p_what) {
  
  		case NOTIFICATION_ENTER_TREE: {
  
  			orig_offset = get_position();
  			orig_scale = get_scale();
  			_update_mirroring();
  		} break;
  	}
  }
  
  void ParallaxLayer::set_base_offset_and_scale(const Point2 &p_offset, float p_scale, const Point2 &p_screen_offset) {
  	screen_offset = p_screen_offset;
  
  	if (!is_inside_tree())
  		return;
  	if (Engine::get_singleton()->is_editor_hint())
  		return;
  
  	Point2 new_ofs = (screen_offset + (p_offset - screen_offset) * motion_scale) + motion_offset * p_scale + orig_offset * p_scale;
  
  	if (mirroring.x) {
  		double den = mirroring.x * p_scale;
  		double before = new_ofs.x;
  		new_ofs.x -= den * ceil(new_ofs.x / den);
  	}
  
  	if (mirroring.y) {
  		double den = mirroring.y * p_scale;
  		new_ofs.y -= den * ceil(new_ofs.y / den);
  	}
  
  	set_position(new_ofs);
  	set_scale(Vector2(1, 1) * p_scale * orig_scale);
  
  	_update_mirroring();
  }
  
  String ParallaxLayer::get_configuration_warning() const {
  
  	if (!Object::cast_to<ParallaxBackground>(get_parent())) {
  		return "ParallaxLayer node only works when set as child of a ParallaxBackground node.";
  	}
  
  	return String();
  }
  
  void ParallaxLayer::_bind_methods() {
  
  	ClassDB::bind_method(D_METHOD("set_motion_scale", "scale"), &ParallaxLayer::set_motion_scale);
  	ClassDB::bind_method(D_METHOD("get_motion_scale"), &ParallaxLayer::get_motion_scale);
  	ClassDB::bind_method(D_METHOD("set_motion_offset", "offset"), &ParallaxLayer::set_motion_offset);
  	ClassDB::bind_method(D_METHOD("get_motion_offset"), &ParallaxLayer::get_motion_offset);
  	ClassDB::bind_method(D_METHOD("set_mirroring", "mirror"), &ParallaxLayer::set_mirroring);
  	ClassDB::bind_method(D_METHOD("get_mirroring"), &ParallaxLayer::get_mirroring);
  
  	ADD_GROUP("Motion", "motion_");
  	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "motion_scale"), "set_motion_scale", "get_motion_scale");
  	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "motion_offset"), "set_motion_offset", "get_motion_offset");
  	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "motion_mirroring"), "set_mirroring", "get_mirroring");
  }
  
  ParallaxLayer::ParallaxLayer() {
  	motion_scale = Size2(1, 1);
  }
  