ShaderLab混合命令 - rockf91/ShaderWiki GitHub Wiki
//正常(Normal) Blend SrcAlpha OneMinusSrcAlpha
//柔和相加(Soft Addtive) Blend OneMinusDstAlpha One
//正片叠底(Multiply),即相乘 Blend DstColor Zero
//两倍相乘(2x Multiply) Blend DstColor SrcColor
//变暗(Darken) BlendOp Min Blend One One
//变亮(Lighten) BlendOp Max Blend One One
//滤色(Screen) Blend OneMinusDstColor One
//线性减淡(Linear Dodge) Blend One One