Set a shader to require a shader model or GPU feature

You can use #pragma directives to indicate that a shaderA program that runs on the GPU. More info
See in Glossary 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.

For example:

#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.

For example:

#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.

DirectX12 (DX12), Vulkan and Metal graphics APIs features

Note: If you use the following shader keywords, Unity compiles shaders using the DXC compiler. DXC support in Unity is experimental, not supported on all platforms, and not ready for production use.

If you use the DirectX12 (DX12), Vulkan or Metal graphics APIs, you can use a shader keyword to target the following GPU features:

• Support for 16-bit data types.
• Support for wave operations in compute shaders.

Use the following syntax:

#pragma multi_compile _ <keyword>

You don’t need to add a pragma require directive.

Unity then does the following:

• Uses a compatible shader compiler and turns on compiler flags related to the feature.
• Automatically compiles both a shader variant with the keyword on and a shader variant with the keyword off.
• At runtime, automatically checks if the hardware supports the feature and selects the correct variant.

You can use an #if statement to make parts of your shader code conditional on whether the GPU supports the feature.

Keywords

If you use a keyword that targets a specific wave size, Unity sets a UNITY_HW_WAVE_SIZE define to the same wave size so you can use it in shader code.

Refer to Declaring and using shader keywords in HLSL for more information.

Additional resources

• HLSL pragma directives reference
• HLSL pragma target command reference
• HLSL pragma require command reference