[[block]]
struct PushConstants {
    index: u32;
    double: vec2<f64>;
};
var<push_constant> pc: PushConstants;

struct FragmentIn {
    [[location(0)]] color: vec4<f32>;
    [[builtin(primitive_index)]] primitive_index: u32;
};

[[stage(fragment)]]
fn main(in: FragmentIn) -> [[location(0)]] vec4<f32> {
    if (in.primitive_index % 2u == 0u) {
        return in.color;
    } else {
        return vec4<f32>(vec3<f32>(1.0) - in.color.rgb, in.color.a);
    }
}