SPIR-V Built-In
BaseInstance
First instance being rendered
BaseInstance
Decorating a variable with the BaseInstance built-in will make that
variable contain the integer value corresponding to the first instance that
was passed to the command that invoked the current vertex shader invocation.
BaseInstance is the firstInstance parameter to a direct drawing
command or the firstInstance member of a structure consumed by an
indirect drawing command.
Valid Usage
VUID-BaseInstance-BaseInstance-04181
The BaseInstance decoration must be used only within the
Vertex Execution Model
VUID-BaseInstance-BaseInstance-04182
The variable decorated with BaseInstance must be declared using
the Input Storage Class
VUID-BaseInstance-BaseInstance-04183
The variable decorated with BaseInstance must be declared as a
scalar 32-bit integer value