Version: 2020.3
ShaderLab command: AlphaToMask
ShaderLab command: BlendOp

ShaderLab command: Blend

Determines how the GPU combines the output of the fragment shader with the render target.

The functionality of this command depends on the blending operation, which you can set using the BlendOp command. Note that while blending itself is supported on all graphics APIs and hardware, some blending operations have more limited support.

Enabling blending disables some optimizations on the GPU (mostly hidden surface removal/Early-Z), which can lead to increased GPU frame times.

レンダリングパイプラインの互換性

Feature name Built-in Render Pipeline Universal Render Pipeline (URP) HD レンダーパイプライン (HDRP) Custom SRP
Blend

使用法

This command makes a change to the render state. Use it in a Pass block to set the render state for that Pass, or use it in a SubShader block to set the render state for all Passes in that SubShader.

If blending is enabled, the following occurs:

  • If the BlendOp command is used, the blending operation is set to that value. Otherwise, the blending operation defaults to Add.
  • If the blending operation is Add, Sub, RevSub, Min, or Max, the GPU multiplies the value of the output of the fragment shader by the source factor.
  • If the blending operation is Add, Sub, RevSub, Min, or Max, the GPU multiplies the value that is already in the render target by the destination factor.
  • The GPU performs the blending operation on the resulting values.

The blending equation is:

finalValue = sourceFactor * sourceValue operation destinationFactor * destinationValue

In this equation:

  • finalValue is the value that the GPU writes to the destination buffer.
  • sourceFactor is defined in the Blend command.
  • sourceValue is the value output by the fragment shader.
  • operation is the blending operation.
  • destinationFactor is defined in the Blend command.
  • destinationValue is the value already in the destination buffer.
Signature Example syntax 機能
Blend <state> Blend Off Disables blending for the default render target. This is the default value.
Blend <render target> <state> Blend 1 Off As above, but for a given render target. (1)
Blend <source factor> <destination factor> Blend One Zero Enables blending for the default render target. Sets blend factors for RGBA values.
Blend <render target> <source factor> <destination factor> Blend 1 One Zero As above, but for a given render target. (1)
Blend <source factor RGB> <destination factor RGB>, <source factor alpha> <destination factor alpha> Blend One Zero, Zero One Enables blending the default render target. Sets separate blend factors for RGB and alpha values. (2)
Blend <render target> <source factor RGB> <destination factor RGB>, <source factor alpha> <destination factor alpha> Blend 1 One Zero, Zero One As above, but for a given render target. (1) (2)

ノート:

  1. Any signature that specifies a render target requires OpenGL 4.0+, GL_ARB_draw_buffers_blend, or OpenGL ES 3.2.
  2. Separate RGB and alpha blending is not compatible with advanced OpenGL blending operations.

Valid parameter values

パラメーター   機能
render target Integer, range 0 through 7 The render target index.
state Off Disables blending.
factor One The value of this input is one. Use this to use the value of the source or the destination color.
Zero The value of this input is zero. Use this to remove either the source or the destination values.
SrcColor The GPU multiplies the value of this input by the source color value.
SrcAlpha The GPU multiplies the value of this input by the source alpha value.
DstColor The GPU multiplies the value of this input by the frame buffer source color value.
DstAlpha The GPU multiplies the value of this input by the frame buffer source alpha value.
OneMinusSrcColor The GPU multiplies the value of this input by (1 - source color).
OneMinusSrcAlpha The GPU multiplies the value of this input by (1 - source alpha).
OneMinusDstColor The GPU multiplies the value of this input by (1 - destination color).
OneMinusDstAlpha The GPU multiplies the value of this input by (1 - destination alpha).

Common blend types

Here is the syntax for the most common blend types:

Blend SrcAlpha OneMinusSrcAlpha // Traditional transparency
Blend One OneMinusSrcAlpha // Premultiplied transparency
Blend One One // Additive
Blend OneMinusDstColor One // Soft additive
Blend DstColor Zero // Multiplicative
Blend DstColor SrcColor // 2x multiplicative

Shader "Examples/CommandExample"
{
    SubShader
    {
         // The rest of the code that defines the SubShader goes here.

        Pass
        {    
              // Enable regular alpha blending for this Pass
      Blend SrcAlpha OneMinusSrcAlpha
            
              // The rest of the code that defines the Pass goes here.
        }
    }
}

This example code demonstrates the syntax for using this command in a SubShader block.

Shader "Examples/CommandExample"
{
    SubShader
    {
         // Enable regular alpha blending for this SubShader
         Blend SrcAlpha OneMinusSrcAlpha

         // The rest of the code that defines the SubShader goes here.        

        Pass
        {    
              // The rest of the code that defines the Pass goes here.
        }
    }
}
ShaderLab command: AlphaToMask
ShaderLab command: BlendOp