var<function>

var<function> declares a mutable variable in the function address-space.

A var<function> can only be declared within a function.

A var<function> declaration must have an explicit type, an initializer, or both type and initializer:

1
2
3

var<function> var_with_explicit_type : i32;
var<function> var_with_type_inferred_from_initializer = 42;
var<function> var_with_explicit_type_and_initializer : i32 = 42;

A var<function> with no initializer will be automatically initialized with the zero value for the variable’s type.

There are no restrictions for the evaluation stage of the initializer of a var<function>.

A var declared within a function has the default address-space of function, and so most developers will simply omit the <function> and just type var:

1

var this_is_more_common : i32;

Each shader invocation will have a unique instance of a var in function address-space.

Uses of a var<function> will always result in a runtime expression.