wgpu/naga/tests/in/dualsource.wgsl

/* Simple test for multiple output sources from fragment shaders */
struct FragmentOutput{
    @location(0) color: vec4<f32>,
    @location(0) @second_blend_source mask: vec4<f32>,
}
@fragment
fn main(@builtin(position) position: vec4<f32>) -> FragmentOutput {
    var color = vec4(0.4,0.3,0.2,0.1);
    var mask = vec4(0.9,0.8,0.7,0.6);
    return FragmentOutput(color, mask);
}