[example:webgl_materials_blending_custom materials / blending / custom ]
这个常量可以用于所有的材质类型。首先将材质的混合模式设置为THREE.CustomBlending,然后设置所需要的混合方程、源因子和目标因子。
		var material = new THREE.MeshBasicMaterial( {color: 0x00ff00} );
		material.blending = THREE.CustomBlending;
		material.blendEquation = THREE.AddEquation; //default
		material.blendSrc = THREE.SrcAlphaFactor; //default
		material.blendDst = THREE.OneMinusSrcAlphaFactor; //default
		
		
		THREE.AddEquation
		THREE.SubtractEquation
		THREE.ReverseSubtractEquation
		THREE.MinEquation
		THREE.MaxEquation
		
		
		THREE.ZeroFactor
		THREE.OneFactor
		THREE.SrcColorFactor
		THREE.OneMinusSrcColorFactor
		THREE.SrcAlphaFactor
		THREE.OneMinusSrcAlphaFactor
		THREE.DstAlphaFactor
		THREE.OneMinusDstAlphaFactor
		THREE.DstColorFactor
		THREE.OneMinusDstColorFactor
		THREE.SrcAlphaSaturateFactor
		
		
			所有的源因子的值,在目标因子中都是有效的。除了:THREE.SrcAlphaSaturateFactor
		
[link:https://github.com/mrdoob/three.js/blob/master/src/constants.js src/constants.js]