Crate wesl_quote 

Write shaders inline with the quote_module macro

This crate provides the quote_*! macros which let one write WGSL shaders directly in source code. This is experimental work.

Writing shaders inline in Rust code has a few advantages:

• Like quote, it supports local variable injection. This can be used e.g. to customize a shader module at runtime.
• The module is parsed at build-time, and syntax errors will be reported at the right location in the macro invocation.
• WGSL and Rust have a similar syntax. Your Rust syntax highlighter will also highlight injected WGSL code.

use wesl::syntax::*; // this is necessary for the quote_module macro

// this i64 value is computed at runtime and injected into the shader.
let num_iterations = 8i64;

// the following variable has type `TranslationUnit`.
let wgsl = quote_module! {
    @fragment
    fn fs_main(@location(0) in_color: vec4<f32>) -> @location(0) vec4<f32> {
        for (let i = 0; i < #num_iterations; i++) {
            // ...
        }
        return in_color;
    }
};

One can inject variables into the following places by prefixing the name with a # symbol:

Code location	Injected type	Indirectly supported injection type with Into
name of a global declaration	GlobalDeclaration	Declaration TypeAlias Struct Function ConstAssert
name of a struct member	StructMember
name of an attribute, after @	Attribute	BuiltinValue InterpolateAttribute WorkgroupSizeAttribute TypeConstraint CustomAttribute
type or identifier expression	Expression	LiteralExpression ParenthesizedExpression NamedComponentExpression IndexingExpression UnaryExpression BinaryExpression FunctionCallExpression TypeOrIdentifierExpression and transitively: bool i64 (AbstractInt) f64 (AbstractFloat) i32 u32 f32 Ident
name of an attribute preceding and empty block statement	Statement	CompoundStatement AssignmentStatement IncrementStatement DecrementStatement IfStatement SwitchStatement LoopStatement ForStatement WhileStatement BreakStatement ContinueStatement ReturnStatement DiscardStatement FunctionCallStatement ConstAssertStatement DeclarationStatement

use wesl::syntax::*; // this is necessary for the quote_module macro

let inject_struct = Struct::new(Ident::new("mystruct".to_string()));
let inject_func = Function::new(Ident::new("myfunc".to_string()));
let inject_stmt = Statement::Void;
let inject_expr = 1f32;
let wgsl = quote_module! {
    struct #inject_struct { dummy: u32 } // structs cannot be empty
    fn #inject_func() {}
    fn foo() {
        @#inject_stmt {}
        let x: f32 = #inject_expr;
    }
};

Macros

quote_declaration

quote_directive

quote_expression

quote_import

quote_literal

quote_module

quote_statement