圆形切割遮罩模板

**
* 裁剪圆模板  by xuao 2018/03/28
* @param str                  图片
* @param Radius               半径
* @param lineWidth            线宽
* @param pos                  位置
* @returns {cc.Sprite}
*/
cc.Node.prototype.addClippingCircle = function(str, Radius, lineWidth, pos){
var size = this.getContentSize();

//圆层实现代码
var stencil = new cc.DrawNode();
stencil.drawCircle(cc.p(0, 0), Radius, 0, 1000, false, lineWidth, cc.color(0, 0, 0));

var layer = new cc.LayerColor(cc.color(0, 0, 0), size.width, size.height);
//层透明度
layer.opacity = 0;

var clippingPanel = new cc.ClippingNode();
clippingPanel.stencil = stencil;
clippingPanel.addChild(layer);
clippingPanel.setPosition(pos);
this.addChild(clippingPanel);

var spImg = new cc.Sprite(str);
spImg.setAnchorPoint(cc.p(0.5, 0.5));
layer.addChild(spImg);

return spImg;
};