@vertex
fn vs_main(@builtin(vertex_index) in_vertex_index: u32) -> @builtin(position) vec4<f32>{
    let a: f32 = 0.0;
    let b: i32 = 20;
    let c = a + b;

    let x = f32(i32(in_vertex_index) - 1);
    let y = f32(i32(in_vertex_index & 1u) * 2 - 1);
    return vec4<f32>(x, y, 0.0, 1.0);
}


@fragment
fn fs_main() -> @location(0) vec4<f32>{
    return vec4<f32>(1.0, 0.0, 0.0, 1.0);
}