Configure the Alpha Blending Mixer

Hi,guys

I find the root cause: the background is not the 1st layer:-P

you don't need to congfigue the background,because it is on default.

mixer.set_layer_position(0, 150, 0);//the 1st layer

mixer.set_layer_enabled(0,true);

mixer.set_layer_position(1, 600, 0);//the 2nd layer

mixer.set_layer_enabled(1,true);

---there are 3 layers.

Thanks!:D