叠加 Blend SrcAlpha OneMinusSrcAlpha
柔和相加 Blend OneMinuseDstColor One
正片叠加 Blend DstColor Zero
两倍相乘 Blend DstColor SrcColor
变暗 BlendOp Min Blend One One
变亮 BlendOp Max Blend One One
滤色 Blend OneMinuseDstColor One
Beldn One OneMinusSrcColor
线性减淡 Blend One One