SPIR-V Built-In

HelperInvocation

Indication of whether a fragment shader is a helper invocation
HelperInvocation

Decorating a variable with the HelperInvocation built-in decoration will make that variable contain whether the current invocation is a helper invocation. This variable is non-zero if the current fragment being shaded is a helper invocation and zero otherwise. A helper invocation is an invocation of the shader that is produced to satisfy internal requirements such as the generation of derivatives.

It is very likely that a helper invocation will have a value of SampleMask fragment shader input value that is zero.

Valid Usage

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The HelperInvocation decoration must be used only within the Fragment Execution Model

VUID-HelperInvocation-HelperInvocation-04240

The variable decorated with HelperInvocation must be declared using the Input Storage Class

VUID-HelperInvocation-HelperInvocation-04241

The variable decorated with HelperInvocation must be declared as a boolean value