// Measures the per-frame cost at several canvas sizes, isolating the readback
// path from windowing.
use dr_gpu::{GpuContext, RenderTarget};
use std::time::Instant;

fn main() {
    env_logger::init();
    let ctx = pollster::block_on(GpuContext::new_headless()).unwrap();
    println!("adapter: {}\n", ctx.adapter_name());
    println!(
        "{:>12}  {:>10}  {:>10}  {:>8}",
        "size", "compute", "+readback", "fps"
    );

    for &(w, h) in &[
        (840u32, 692u32),
        (1280, 720),
        (1920, 1080),
        (2048, 1152),
        (3840, 2160),
    ] {
        let rt = RenderTarget::new(&ctx, w, h).unwrap();
        // warm
        for i in 0..10 {
            rt.render(i as f32 * 0.01);
            let _ = pollster::block_on(rt.read_pixels());
        }

        let n = 40;
        let t0 = Instant::now();
        for i in 0..n {
            rt.render(i as f32 * 0.01);
        }
        ctx.device
            .poll(wgpu::PollType::wait_indefinitely())
            .expect("poll");
        let compute = t0.elapsed().as_secs_f64() / n as f64;

        let t1 = Instant::now();
        for i in 0..n {
            rt.render(i as f32 * 0.01);
            let _ = pollster::block_on(rt.read_pixels()).unwrap();
        }
        let full = t1.elapsed().as_secs_f64() / n as f64;

        println!(
            "{:>5}x{:<6}  {:>8.2}ms  {:>8.2}ms  {:>8.0}",
            w,
            h,
            compute * 1000.0,
            full * 1000.0,
            1.0 / full
        );
    }
}