boku2d.js

window.Boku2D = (function() {
	// RDC
	var RDC = (function() {
		var Entity = function (type, pos, obj) {
			this.type = type;
			this.pos = pos;
			this.obj = obj;
		};

		var RDC = function (collide) {
			this.collide = collide;
		};
		RDC.SUBDIVISION_THRESHOLD = 4;
		RDC.CONTACT_THRESHOLD = 0.001;

		RDC.prototype.bruteForce = function (group) {
			for (var i=0,l=group.length; i<l; i++) {
				for (var j=i+1; j<l; j++) {
					this.collide(group[i], group[j]);
				}
			}
		};
		RDC.prototype.recursiveClustering = function (group, axis1, axis2) {
			if (axis1 === -1 || group.length < RDC.SUBDIVISION_THRESHOLD) {
				this.bruteForce(group);
			} else {
				var boundaries = this.getOpenCloseBounds(group, axis1);		
				boundaries.sort(function (a, b) {
					return a.pos - b.pos;
				});
				
				var newAxis1 = axis2,
					newAxis2 = -1,
					groupSubdivided = false,
					subgroup = [],
					count = 0,
					l = boundaries.length;
				for (var i=0; i<l; i++)
				{
					var b = boundaries[i];
					if (b.type === "open") {
						count++;
						subgroup.push(b.obj);
					} else {
						count--;
						if (count === 0) {
							if (i !== (l - 1)) {
								groupSubdivided = true;
							}
							
							if (groupSubdivided) {
								if (axis1 === 0) {
									newAxis1 = 1;
								} else if (axis1 === 1) {
									newAxis1 = 0;
								}
							}
							
							this.recursiveClustering(subgroup, newAxis1, newAxis2);
							subgroup = [];
						}
					}
				}
			}
		};
		RDC.prototype.getOpenCloseBounds = function (group, axis) {
			var l = group.length,
				boundaries = [];
			
			switch(axis)
			{
				case 0:
					for (i=0; i<l; i++) {
						o = group[i];
						boundaries.push(new Entity("open", o.center.x - o.size.x + RDC.CONTACT_THRESHOLD, o));
						boundaries.push(new Entity("close", o.center.x + o.size.x - RDC.CONTACT_THRESHOLD, o));
					}
					break;
				case 1:
					for (i=0; i<l; i++) {
						o = group[i];
						boundaries.push(new Entity("open", o.center.y - o.size.y + RDC.CONTACT_THRESHOLD, o));
						boundaries.push(new Entity("close", o.center.y + o.size.y - RDC.CONTACT_THRESHOLD, o));
					}
			}
			return boundaries;
		};
		
		return RDC;
	})();
	
	var IsNumber = function(num) {
		return typeof num === "number";
	};
	
	var Extend = function(option) {
		if (!option) {
			return;
		}
		 
		var key;
		for (key in option) {
			if (option.hasOwnProperty(key)) {
				this[key] = option[key];
			}
		}
	};
	
	var Vec = function(x, y) {
		this.x = (IsNumber(x) ? x : parseInt(x, 10)) || 0;
		this.y = (IsNumber(y) ? y : parseInt(y, 10)) || 0;
	};
	Vec.prototype = {
		copy: function() {
			return new Vec(this.x, this.y);
		},
		add: function(v, y) {
			if (y !== undefined) {
				v = new Vec(v, y);
			}
			
			var x = this.x + v.x,
				y = this.y + v.y;
			return new Vec(x, y);
		},
		subtract: function(v, y) {
			if (y !== undefined) {
				v = new Vec(v, y);
			}
			
			var x = this.x - v.x,
				y = this.y - v.y;
			return new Vec(x, y);
		},
		multiply: function(i) {
			var x = this.x * i,
				y = this.y * i;
			return new Vec(x, y);
		},
		divide: function(i) {
			var x = this.x / i,
				y = this.y / i;
			return new Vec(x, y);
		},
		dot: function(v) {
			return this.x * v.x + this.y * v.y;
		},
		length: function() {
			return Math.sqrt(this.x*this.x + this.y*this.y);
		},
		normalize: function() {
			var length = this.length();
			return this.divide(length);
		}
	};
	
	var SPRING = 10;
	var DAMP = 1;
	
	var Manifold = function(object, opponent) {
		this.object = object;
		this.opponent = opponent;
		this.normal = new Vec();
	};
	Manifold.prototype = {
		solve: function() {
			var move = this.object,
				fixed = this.opponent;
			
			if (move.fixed) {
				return false;
			}
			
			// 衝突ソルバー
			var diff,
				relSpeed = move.speed.subtract(fixed.speed),
				adj = 0;
			
			this.normal = new Vec();
			if (this.direction.x < 0) {
				diff = move.maxPos().x - fixed.minPos().x;
				adj = SPRING * diff + DAMP * relSpeed.x;
				this.normal = this.normal.add(-adj, 0);
			} else if (this.direction.x > 0) {
				diff = fixed.maxPos().x - move.minPos().x;
				adj = SPRING * diff - DAMP * relSpeed.x;
				this.normal = this.normal.add(adj, 0);
			}
			if (this.direction.y < 0) {
				diff = move.maxPos().y - fixed.minPos().y;
				adj = SPRING * diff + DAMP * relSpeed.y;
				this.normal = this.normal.add(0, -adj);
			} else if (this.direction.y > 0) {
				diff = fixed.maxPos().y - move.minPos().y;
				adj = SPRING * diff - DAMP * relSpeed.y;
				this.normal = this.normal.add(0, adj);
			}
			move.applyForce(this.normal);
			
			// 摩擦
			var n = this.normal.length(),
				friction = Math.sqrt(move.friction*fixed.friction),
				force = new Vec(n, n).multiply(friction);
			if (force.x > Math.abs(move.force.x)) {
				force.x = Math.abs(move.force.x);
			}
			if (force.y > Math.abs(move.force.y)) {
				force.y = Math.abs(move.force.y);
			}
			if (this.direction.y !== 0) {
				if (relSpeed.x > 0) {
					force.x = -force.x;
				}
			} else {
				force.x = 0;
			}
			if (this.direction.x !== 0) {
				if (relSpeed.y > 0) {
					force.y = -force.y;
				}
			} else {
				force.y = 0;
			}
			move.applyForce(force);
			!fixed.fixed && fixed.applyForce(force.multiply(-1));
		}
	};
	
	var Contact = function(object1, object2) {
		var direction1 = new Vec(),
			direction2 = new Vec();
		
		// 前回の位置から衝突方向を調べる
		if (object1.maxTmpPos().x <= object2.minTmpPos().x && 
			object1.maxPos().x >= object2.minPos().x) {
			direction1 = direction1.add(-1, 0);
		} else if (object1.minTmpPos().x >= object2.maxTmpPos().x && 
			object1.minPos().x <= object2.maxPos().x) {
			direction1 = direction1.add(1, 0);
		}
		if (object1.maxTmpPos().y <= object2.minTmpPos().y &&
			object1.maxPos().y >= object2.minPos().y) {
			direction1 = direction1.add(0, -1);
		} else if (object1.minTmpPos().y >= object2.maxTmpPos().y && 
			object1.minPos().y <= object2.maxPos().y) {
			direction1 = direction1.add(0, 1);
		}
		
		
		if (direction1.x === 0 && direction1.y === 0) {
			// 最小分離距離を計る
			var normals = [],
				d,
				normal;
			
			if (object2.minPos().x <= object1.minPos().x && 
				object1.minPos().x <= object2.maxPos().x) {
				// 左衝突
				d = (object2.maxPos().x - object1.minPos().x)/2;
				normal = new Vec(d, 0);
				normal.direction = new Vec(1, 0);
				normals.push(normal);
			} else if (object2.minPos().x <= object1.maxPos().x && 
				object1.maxPos().x <= object2.maxPos().x) {
				// 右衝突
				d = (object2.minPos().x - object1.maxPos().x)/2;
				normal = new Vec(d, 0);
				normal.direction = new Vec(-1, 0);
				normals.push(normal);
			}
			if (object2.minPos().y <= object1.minPos().y && 
				object1.minPos().y <= object2.maxPos().y) {
				// 上衝突
				d = (object2.maxPos().y - object1.minPos().y)/2;
				normal = new Vec(0, d);
				normal.direction = new Vec(0, 1);
				normals.push(normal);
			} else if (object2.minPos().y <= object1.maxPos().y && 
				object1.maxPos().y <= object2.maxPos().y) {
				// 下衝突
				d = (object2.minPos().y - object1.maxPos().y)/2;
				normal = new Vec(0, d);
				normal.direction = new Vec(0, -1);
				normals.push(normal);
			}
			
			normal = normals[0];
			for (var i=0,l=normals.length;i<l;i++) {
				normal = normal.length() > normals[i].length() ? 
					normals[i] : 
					normal;
			}
			direction1 = normal.direction;
		}
		
		direction2 = direction1.multiply(-1);
		
		var manifold1 = new Manifold(object1, object2),
			manifold2 = new Manifold(object2, object1);
		manifold1.direction = direction1;
		manifold2.direction = direction2;
		
		this.manifolds = [manifold1, manifold2];
		this.timeStep = 0;
		this.world = object1.world;
		this.object1 = object1;
		this.object2 = object2;
		this.update();
		
		var manifolds = this.manifolds;
		for (var i=0,l=manifolds.length;i<l;i++) {
			var manifold = manifolds[i];
			manifold.object.createContact(this, manifold);
		}
	};
	Contact.prototype = {
		update: function() {
			this.timeStep = this.world.timeStep;
			
			var manifolds = this.manifolds;
			for (var i=0,l=manifolds.length;i<l;i++) {
				var manifold = manifolds[i];
				manifold.object.updateContact(this, manifold);
			}
		},
		solve: function() {
			var manifolds = this.manifolds;
			for (var i=0,l=manifolds.length;i<l;i++) {
				var manifold = manifolds[i];
				manifold.object.beforeSolve(this, manifold);
				manifold.solve();
				manifold.object.afterSolve(this, manifold);
			}
		},
		destroy: function() {
			this._removeFromList(this.world.contacts);
			this._removeFromList(this.object1.contacts);
			this._removeFromList(this.object2.contacts);
			
			var manifolds = this.manifolds;
			for (var i=0,l=manifolds.length;i<l;i++) {
				var manifold = manifolds[i];
				manifold.object.destroyContact(this, manifold);
			}
		},
		_removeFromList: function(contacts) {
			for (var i=0,l=contacts.length;i<l;i++) {
				if (contacts[i] == this) {
					contacts.splice(i, 1);
				}
			}
		}
	};
	
	var Collide = function(object1, object2) {
		if (!CheckContact(object1, object2)) {
			return;
		}
		
		var list = object1.contacts,
			contact = null;
		for (var i=0,l=list.length;i<l;i++) {
			var c = list[i];
			if (c.manifolds[0].opponent === object2 || 
				c.manifolds[1].opponent === object2) {
				contact = c;
				break;
			}
		}
		
		if (contact) {
			contact.update();
		} else {
			contact = new Contact(object1, object2);
			object1.contacts.push(contact);
			object2.contacts.push(contact);
			object1.world.contacts.push(contact);
		}
	};
	
	var CheckContact = function(object1, object2) {
		return object1.maxPos().x >= object2.minPos().x && 
			object1.minPos().x <= object2.maxPos().x &&
			object1.maxPos().y >= object2.minPos().y && 
			object1.minPos().y <= object2.maxPos().y;
	};
	
	var Model = function() {
		var newObject = function(option) {
			this._init(option);
		};
		
		/*
			object <- object.prototype 
				<- object.prototype.prototype( = Model.prototype)
		*/
		var newModel = function() {};
		newModel.prototype = Model.defaults;
		newObject.prototype = new newModel();
		
		return newObject;
	};
	Model.defaults = {
		speed: new Vec(),
		force: new Vec(),
		accel: new Vec(),
		center: new Vec(),
		centerTmp: new Vec(),
		size: new Vec(0, 0),
		gravity: new Vec(0, 10),
		weight: 1, // 質量
		restitution: 0.7, // 反発係数
		friction: 0.1, // 摩擦係数
		fixed: false,
		contacts: [],
		init: function() {},
		beforeStep: function(time) {},
		afterStep: function(time) {},
		createContact: function(contact, manifold) {},
		destroyContact: function(contact, manifold) {},
		updateContact: function(contact, manifold) {},
		beforeSolve: function(contact, manifold) {},
		afterSolve: function(contact, manifold) {},
		_init: function(option) {
			this.speed = this.speed.copy();
			this.accel = this.accel.copy();
			this.center = this.center.copy();
			this.centerTmp = this.center.copy();
			this.size = this.size.copy();
			this.gravity = this.gravity.copy();
			this.contacts = [];
			Extend.call(this, option);
			
			this.init(option);
		},
		_move: function(time) {
			this.centerTmp = this.center.copy();
			this.center = this.center.add(this.speed.multiply(time));
		},
		_step: function(time) {
			this.beforeStep(time);
			
			this.applyForce(this.gravity.multiply(this.weight));
			this.speed = this.speed.add(this.accel.multiply(time));
			this._move(time);
			
			this.afterStep(time);
			
			this.resetForce();
		},
		maxTmpPos: function() {
			return this.centerTmp.add(this.size.divide(2));
		},
		minTmpPos: function() {
			return this.centerTmp.subtract(this.size.divide(2));
		},
		maxPos: function() {
			return this.center.add(this.size.divide(2));
		},
		minPos: function() {
			return this.center.subtract(this.size.divide(2));
		},
		applyForce: function(force) {
			this.force = this.force.add(force);
			this.accel = this.accel.add(force.divide(this.weight));
		},
		resetForce: function() {
			this.accel = new Vec();
		}
	};
	
	var Rdc = new RDC(Collide);
	
	var World = function(option) {
		this.objects = [];
		this.size = new Vec(0, 0);
		this.timeStep = 0;
		this.contacts = [];
		
		Extend.call(this, option);
		
		this.init(option);
	};
	World.prototype = {
		step: function(time) {
			this.beforeStep(time);
			
			this.timeStep += time;
			
			// 衝突情報取得
			Rdc.recursiveClustering(this.objects, 0, 1);
			
			// 衝突処理
			var contacts = this.contacts;
			for (var i=0;i<contacts.length;i++) {
				var contact = contacts[i];
				if (contact.timeStep !== this.timeStep) {
					contact.destroy();
					i--;
				} else {
					contact.solve();
				}
			}
			
			// 各アイテムの進行
			for (var i=0,l=this.objects.length;i<l;i++) {
				var object = this.objects[i];
				object._step(time);
			}
			
			this.afterStep(time);
			
			return this;
		},
		createObject: function(object) {
			object.world = this;
			this.objects.push(object);
		},
		destroyObject: function(object) {
			for (var i=0,l=this.objects.length;i<l;i++) {
				if (this.objects[i] === object) {
					this.objects.splice(i, 1);
				}
			}
			delete object;
		},
		init: function(option) {},
		beforeStep: function(time) {},
		afterStep: function(time) {}
	};
	
	return {
		Vec: Vec,
		World: World,
		Model: Model
	};
})();