discard!

Discards the current fragment. In WGSL this emits discard;; on CPU it sets a thread-local flag.

Syntax

#![allow(unused)]
fn main() {
discard!();
}

Behavior

• In WGSL, transpiles to discard; and stops further output for the fragment.
• On CPU, sets a thread-local flag that dispatch_fragments checks; execution continues after the call, matching WGSL’s helper-invocation semantics.

Reachable From

discard!() may be called from any function reachable from a #[fragment] entry point, including helper functions.

Example

#![allow(unused)]
fn main() {
#[wgsl]
pub mod alpha {
    use wgsl_rs::std::*;

    texture!(group(0), binding(0), MASK: Texture2D<f32>);
    sampler!(group(0), binding(1), LIN: Sampler);

    pub fn threshold(uv: Vec2f, min: f32) {
        let a = texture_sample(MASK, LIN, uv).x();
        if a < min {
            discard!();
        }
    }

    #[fragment]
    pub fn fs_main(#[location(0)] uv: Vec2f) -> Vec4f {
        threshold(uv, 0.5);
        vec4f(1.0, 0.0, 0.0, 1.0)
    }
}
}

Notes

• Execution after discard!() continues on the CPU side, so code following the call still runs. Guard any side effects accordingly.
• discard!() is only valid inside fragment shaders. Calling it from a compute or vertex entry point is a validation error.