SPIR-V Built-In
InstanceIndex
Index of an instance
InstanceIndex
Decorating a variable in a vertex shader with the InstanceIndex
built-in decoration will make that variable contain the index of the
instance that is being processed by the current vertex shader invocation.
InstanceIndex begins at the firstInstance parameter to
vkCmdDraw or vkCmdDrawIndexed or at the firstInstance
member of a structure consumed by vkCmdDrawIndirect or
vkCmdDrawIndexedIndirect.
Valid Usage
VUID-InstanceIndex-InstanceIndex-04263
The InstanceIndex decoration must be used only within the
Vertex Execution Model
VUID-InstanceIndex-InstanceIndex-04264
The variable decorated with InstanceIndex must be declared using
the Input Storage Class
VUID-InstanceIndex-InstanceIndex-04265
The variable decorated with InstanceIndex must be declared as a
scalar 32-bit integer value