three.js 源码注释（五十五）Material /SpriteCanvasMaterial.js

/**
* @author mrdoob / http:///
*
* parameters = {
* color: ,
* program: ,
* opacity: ,
* blending: THREE.NormalBlending
* }
*/
/*
///SpriteCanvasMaterial方法根据参数parameters创建适用于canvas渲染器的Sprite(点精灵)的材质类型,
///parameters参数的格式看上面.SpriteCanvasMaterial对象的功能函数采用,定义构造的函数原型对象来实现.大部分属性方法继承自材质的基类Material.
///TODO: SpriteCanvasMaterial和SpriteMaterial除了几个属性不一样,不知道是不是应用场景也不一样?
*/
///SpriteCanvasMaterial
///string类型的JSON格式材质属性参数
///返回SpriteCanvasMaterial,点精灵材质.
THREE.SpriteCanvasMaterial = function ( parameters ) {
THREE.Material.call( this ); //调用Material对象的call方法,将原本属于Material的方法交给当前对象SpriteCanvasMaterial来使用
this.color = new THREE.Color( 0xffffff ); // 颜色,默认初始化为0xffffff,白色
this.program = function ( context, color ) {}; //自定义程序,
//TODO:this.program属性在这里是啥意思???
this.setValues( parameters ); //调用Material类的setValues方法,将参数parameters赋值给当前SpriteCanvasMaterial材质的属性.
};
/*************************************************************
****下面是SpriteCanvasMaterial对象的方法属性定义,继承自Material
*************************************************************/
THREE.SpriteCanvasMaterial.prototype = Object.create( THREE.Material.prototype );
/*clone方法
///clone方法克隆SpriteCanvasMaterial对象,
*/
///clone
///SpriteCanvasMaterial对象,可有可无.
///返回克隆的SpriteCanvasMaterial对象
THREE.SpriteCanvasMaterial.prototype.clone = function () {
//以下是将材质的属性一一进行复制.
var material = new THREE.SpriteCanvasMaterial();
THREE.Material.prototype.clone.call( this, material );
material.color.copy( this.color );
material.program = this.program;
return material; //返回克隆的SpriteMaterial对象
};
// backwards compatibility 向后兼容
/*
///ParticleCanvasMaterial方法被THREE.SpriteCanvasMaterial方法替换.
*/
THREE.ParticleCanvasMaterial = THREE.SpriteCanvasMaterial;
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