1 /** 2 * The Render Engine 3 * ArrivalBehavior 4 * 5 * @fileoverview Arrival behavior, based on Craig Reynolds "Autonomous Steering Behaviors" article. 6 * The arrival behavior is similar to the seek behavior, where a vehicle will navigate 7 * to a target. However, the arrival behavior will slow as it approaches the target. 8 * 9 * @author: Brett Fattori (brettf@renderengine.com) 10 * @author: $Author: bfattori $ 11 * @version: $Revision: 1555 $ 12 * 13 * Copyright (c) 2011 Brett Fattori (brettf@renderengine.com) 14 * 15 * Permission is hereby granted, free of charge, to any person obtaining a copy 16 * of this software and associated documentation files (the "Software"), to deal 17 * in the Software without restriction, including without limitation the rights 18 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 19 * copies of the Software, and to permit persons to whom the Software is 20 * furnished to do so, subject to the following conditions: 21 * 22 * The above copyright notice and this permission notice shall be included in 23 * all copies or substantial portions of the Software. 24 * 25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 30 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 31 * THE SOFTWARE 32 */ 33 34 // Load all required engine components 35 R.Engine.define({ 36 "class":"R.components.logic.behaviors.Arrival", 37 "requires":[ 38 "R.components.logic.behaviors.BaseBehavior" 39 ] 40 }); 41 42 // Add behavior options 43 if (R.Engine.options.behaviors === undefined) { 44 R.Engine.options.behaviors = {}; 45 } 46 47 $.extend(R.Engine.options.behaviors, { 48 "arrivalSlowingDistance":50 49 }); 50 51 52 /** 53 * @class The arrival behavior component. Causes the vehicle to seek the destination, but slow as it 54 * approaches it. 55 * @param destination The point to seek 56 * @param [slowingDistance] The distance (in pixels) at which slowing should occur. The velocity 57 * will be scaled as it nears the destination and stop when it is at, or almost at, the 58 * destination. 59 * @extends R.components.logic.behaviors.BaseBehavior 60 * @constructor 61 */ 62 R.components.logic.behaviors.Arrival = function () { 63 "use strict"; 64 return R.components.logic.behaviors.BaseBehavior.extend(/** @scope R.components.logic.behaviors.Arrival.prototype */{ 65 66 slowDist:0, 67 arrived:false, 68 target:null, 69 70 /** @private */ 71 constructor:function (target, slowingDistance) { 72 this.base("arrival"); 73 this.arrived = false; 74 this.setTarget(target); 75 this.slowDist = slowingDistance || R.Engine.options.behaviors.arrivalSlowingDistance; 76 }, 77 78 destroy:function () { 79 this.base(); 80 this.destPt.destroy(); 81 }, 82 83 reset:function () { 84 this.arrived = false; 85 this.base(); 86 }, 87 88 /** 89 * Set the target to seek. 90 * @param target {R.math.Point2D|R.objects.Object2D} The point, or object, 91 * to seek. 92 */ 93 setTarget:function (target) { 94 this.target = target; 95 }, 96 97 /** 98 * This method is called by the game object to run the component, 99 * updating its state. 100 * 101 * @param renderContext {R.rendercontexts.AbstractRenderContext} The context the component will render within. 102 * @param time {Number} The global engine time 103 * @param dt {Number} The delta between the world time and the last time the world was updated 104 * in milliseconds. 105 */ 106 execute:function (time, dt) { 107 var destPt = R.math.Vector2D.create(0, 0); 108 if (this.target.__POINT2D) { 109 destPt.set(this.target); 110 } else if (this.target instanceof R.objects.Object2D && !this.target.isDestroyed()) { 111 destPt.set(this.target.getOriginPosition()); 112 } else { 113 // Not a point or object, return zero steering 114 return R.math.Vector2D.ZERO; 115 } 116 117 var gO = this.getGameObject(), mC = this.getTransformComponent(), pt = R.clone(gO.getOriginPosition()), 118 offs = R.clone(destPt).sub(pt), distance = offs.len(), steering = R.math.Vector2D.create(0, 0); 119 120 if (!this.getGameObject() || this.getGameObject().isDestroyed()) { 121 return steering; 122 } 123 124 if (distance > 5) { 125 offs.normalize(); 126 127 if (distance < this.slowDist) { 128 offs.mul(mC.getMaxSpeed() * (distance / this.slowDist)); 129 } else { 130 offs.mul(mC.getMaxSpeed()); 131 } 132 steering.set(offs.sub(mC.getVelocity())); 133 } else { 134 steering.set(R.math.Vector2D.ZERO); 135 this.arrived = true; 136 } 137 138 offs.destroy(); 139 pt.destroy(); 140 destPt.destroy(); 141 142 return steering; 143 }, 144 145 /** 146 * True if the vehicle has "arrived" at it's destination 147 * @return {Boolean} 148 */ 149 isArrived:function () { 150 return this.arrived; 151 } 152 153 }, /** @scope R.components.logic.behaviors.Arrival.prototype */{ 154 getClassName:function () { 155 return "R.components.logic.behaviors.Arrival"; 156 } 157 }); 158 }; 159