wgsl-rs-layout Overview

wgsl-rs-layout computes WGSL memory layout for Rust types, implementing the rules in WGSL spec section 14.4.1 (“Alignment and Size”). It answers a single practical question: where do bytes go in the GPU buffer?

Crates

Quick Start

Annotate a struct with #[derive(Layout)] and assert its WGSL layout constants:

use wgsl_rs_layout::{Layout, WgslLayout};

#[derive(Layout)]
struct Particle {
    pos: [f32; 3],
    velocity: [f32; 3],
    charge: f32,
}

fn main() {
    assert_eq!(Particle::SIZE, 32);
    assert_eq!(Particle::ALIGN, 16);
}

SIZE and ALIGN are the WGSL-spec size and alignment of the struct, not the Rust layout. Use FIELDS to find each field’s offset:

#![allow(unused)]
fn main() {
for field in Particle::FIELDS {
    println!("{:>10} offset={:<3} size={:<3} align={}",
        field.name, field.offset, field.size, field.alignment);
}
}

What It Is Not

The derive computes the WGSL memory layout only. It does not align the Rust CPU-side representation. For example, a struct with #[repr(C)] and a Vec3f field has Rust alignment 4, but WGSL vec3<f32> has alignment 16. To use a struct as a staging buffer that matches WGSL layout, you must separately ensure the Rust layout matches (for example by padding fields manually) or use a serialization step that writes bytes per FieldLayout.

See Traits, Derive, and Field Layout for the details.