mask在canves不支持inverted有别的处理方法吗

[matt (matt789)]

var stencil = this.mask._clippingStencil;
var color = cc.color(255, 255, 255, 0);
stencil.drawPoly(this.mask._calculateCircle(point,cc.p(15,15), 64), color, 0, color);

现在是用mask画遮罩，但在canves不支付反向，请问怎么处理