Targeting shader models and GPU features in HLSL

You can use #pragma directives to indicate that a shader requires certain GPU features. At runtime, Unity uses this information to determine whether a shader program is compatible with the current hardware.

You can specify individual GPU features with the #pragma require directive, or specify a shader model with the #pragma target directive. A shader model is a shorthand for a group of GPU features; internally, it is the same as a #pragma require directive with the same list of features.

It is important to correctly describe the GPU features that your shader requires. If your shader uses features that are not included in the list of requirements, this can result in either compile time errors, or in devices failing to support shaders at runtime.

Default behavior

By default, Unity compiles shaders with #pragma require derivatives, which corresponds to #pragma target 2.5.

Special requirements for shader stages

If your shader defines certain shader stages, Unity automatically adds items to the list of requirements.

• If a shader defines a geometry stage (with #pragma geometry), Unity automatically adds geometry to the list of requirements.
• If a shader defines a tessellation stage (with #pragma hull or #pragma domain), Unity automatically adds tessellation to the list of requirements.

If the list of requirements (or the equivalent target value) does not already include these values, Unity displays a warning message when it compiles the shader, to indicate that it has added these requirements. To avoid seeing this warning message, explicitly add the requirements or use an appropriate target value in your code.

Specifying GPU features or a shader model

To specify required features, use the #pragma require directive, followed by a list of space-delimited values. For example:

#pragma require integers mrt8

You can also use the #pragma require directive followed by a colon and a list of space-delimited shader keywords. This means that the requirement applies only to variants that are used when any of the given keywords are enabled.

例如：

#pragma require integers mrt8 : EXAMPLE_KEYWORD OTHER_EXAMPLE_KEYWORD

You can use multiple #pragma require lines. In this example, the shader requires integers in all cases, and mrt8 if EXAMPLE_KEYWORD is enabled.

#pragma require integers
#pragma require integers mrt8 : EXAMPLE_KEYWORD

To specify a shader model, use #pragma target directive. For example:

#pragma target 4.0

You can also use the #pragma target directive followed by a list of space-delimited shader keywords. This means that the requirement applies only to variants that are used when any of the given keywords are enabled.

例如：

#pragma target 4.0 EXAMPLE_KEYWORD OTHER_EXAMPLE_KEYWORD

Note: The syntax for specifying keywords for #pragma require and #pragma target is slightly different. When you specify keywords for #pragma require, you use a colon. When you specify keywords for #pragma target, you do not use a colon.

List of ‘#pragma target’ values

Here is the list of shader models that Unity uses, and the combination of #pragma require values that each corresponds to.

Note: Unity’s shader models are similar to DirectX shader models and OpenGL version requirements, but they do not correspond exactly. Read the descriptions carefully to ensure that you understand the differences.

For information on shader model support for console platforms, see the platform-specific documentation.

注意：

• In the DirectX definitions, shader model 4.0 includes mrt8, and shader model 5.0 includes interpolators32 and cubearray. Unity does not include these, for broader compatibility. To require these features, use an explicit #pragma require directive.
• If you use a target that requires geometry but your shader does not define a geometry stage, Unity removes geometry from the list of requirements at compile time.
• If you use a target that requires tessellation but your shader does not define a hull or domain stage, Unity removes tessellation from the list of requirements at compile time.

List of ‘#pragma require’ values

Here are all the valid values for the #pragma require directive.