three.js 源码注释（六十六）objects/Sprite.js

/** * @author mikael emtinger / http://gomo.se/ * @author alteredq / http://alteredqualia.com/ */ /* ///Sprite对象,点精灵对象,对应粒子对象,具体的实现是通过BufferGeometry创建1个总是面对相机的平面. /// 用法:var map = THREE.ImageUtils.loadTexture("sprite.png"); //加载image对象 /// var material = new THREE.SpriteMaterial({map:map,color: 0xffffff,fog: true}); //创建材质对象,这里有专门适用于Sprite对象的材质对象SpriteMaterial. /// var sprite = new THREE.Sprite( material); //创建精灵对象. /// scene.add(line); //将精灵添加到场景中. */ ///<summary>Sprite</summary> ///<param name ="material" type="THREE.SpriteMaterial">可选参数,SpriteMaterial对象(点精灵对象专用的材质对象)</param> ///<returns type="Sprite">返回Sprite对象</returns> THREE.Sprite = ( function () { var vertices = new Float32Array( [ - 0.5, - 0.5, 0, 0.5, - 0.5, 0, 0.5, 0.5, 0 ] ); var geometry = new THREE.BufferGeometry(); //使用buffergeometry对象 geometry.addAttribute( 'position', new THREE.BufferAttribute( vertices, 3 ) ); //为geometry对象添加position属性.这里可以看考BufferGeometry对象的源码注释. return function ( material ) { THREE.Object3D.call( this ); //调用Object3D对象的call方法,将本来属于Object3D的方法交给当前对象Sprite来使用. this.geometry = geometry; this.material = ( material !== undefined ) ? material : new THREE.SpriteMaterial(); }; } )(); /************************************************* ****下面是Sprite对象的方法属性定义,继承自Object3D **************************************************/ THREE.Sprite.prototype = Object.create( THREE.Object3D.prototype ); /* ///raycast方法用来取得当前对象与射线（参数raycaster）的交点.raycaster.intersectObject会调用这个方法。主要是用来进行碰撞检测, /// 在选择场景中的对象时常常会用到,判断当前鼠标是不是与对象重适用来选择对象. /// NOTE：raycast方法中参数intersects参数用来存储交点的集合，格式以下 /// intersects.push( { /// /// distance: distance, /// point: this.position, /// face: null, /// object: this /// /// } ); /// *////<summary>raycast</summary> ///<param name ="raycaster" type="THREE.Raycaster">射线对象</param> ///<param name ="intersects" type="ObjectArray">交点的属性集合</param> ///<returns type="ObjectArray">交点的属性集合</returns> THREE.Sprite.prototype.raycast = ( function () { var matrixPosition = new THREE.Vector3(); return function ( raycaster, intersects ) { matrixPosition.setFromMatrixPosition( this.matrixWorld ); var distance = raycaster.ray.distanceToPoint( matrixPosition ); if ( distance > this.scale.x ) { return; } intersects.push( { distance: distance, point: this.position, face: null, object: this } ); }; }() ); /*updateMatrix方法 ///updateMatrix方法更新场景中当前精灵的平移、旋转和缩放属性. */ ///<summary>updateMatrix</summary> ///<returns type="Skeleton">返回新的Sprite精灵对象.</returns> THREE.Sprite.prototype.updateMatrix = function () { this.matrix.compose( this.position, this.quaternion, this.scale ); //compose方法利用变换矩阵的平移、旋转和缩放设置 this.matrixWorldNeedsUpdate = true; //Sprite对象matrixWorldNeedsUpdate属性,设置为true. }; /*clone方法 ///clone方法克隆1个Sprite精灵对象. */ ///<summary>clone</summary> ///<param name ="object" type="Sprite">接收克隆的Sprite对象</param> ///<returns type="Sprite">返回克隆的Sprite精灵对象.</returns> THREE.Sprite.prototype.clone = function ( object ) { if ( object === undefined ) object = new THREE.Sprite( this.material ); THREE.Object3D.prototype.clone.call( this, object ); return object; //返回克隆的Sprite精灵对象 }; // Backwards compatibility 向后兼容,粒子被更名为精灵. THREE.Particle = THREE.Sprite;