rust-game-ch2.rs

use std::{rc::Rc, sync::Mutex};

use rand::Rng;
use wasm_bindgen::prelude::*;

fn draw_triangle(context: &web_sys::CanvasRenderingContext2d, points: [(f64, f64); 3], color: (u8, u8, u8)) {
    let [top, left, right] = points;
    let color_str = format!("rgb({},{},{})", color.0, color.1, color.2);
    context.set_fill_style(&wasm_bindgen::JsValue::from_str(&color_str));
    context.move_to(top.0, top.1);
    context.begin_path();
    context.line_to(left.0, left.1);
    context.line_to(right.0, right.1);
    context.line_to(top.0, top.1);
    context.close_path();
    context.stroke();
    context.fill();
}

fn midpoint(p1: (f64, f64), p2: (f64, f64)) -> (f64, f64) {
    let (x1, y1) = p1;
    let (x2, y2) = p2;
    ((x1 + x2) / 2.0, (y1 + y2) / 2.0)
}

fn sierpinski(context: &web_sys::CanvasRenderingContext2d, points: [(f64, f64); 3], color: (u8, u8, u8), depth: u8) {
    let [top, left, right] = points;
    draw_triangle(&context, [
        top, left, right
    ], color);

    let depth = depth - 1;
    if depth > 0 {
        let left_mid = midpoint(top, left);
        let right_mid = midpoint(top, right);
        let bottom_mid = midpoint(left, right);

        let mut rng = rand::thread_rng();
        let next_color = (
            rng.gen_range(0..255),
            rng.gen_range(0..255),
            rng.gen_range(0..255)
        );
        sierpinski(context, [top, left_mid, right_mid], next_color, depth);
        sierpinski(context, [left_mid, left, bottom_mid], next_color, depth);
        sierpinski(context, [right_mid, bottom_mid, right], next_color, depth);
    }
}

pub fn main() -> Result<(), JsValue> {
    #[cfg(debug_assertions)]
    console_error_panic_hook::set_once();
    #[cfg(debug_assertions)]
    wasm_logger::init(wasm_logger::Config::default());

    log::debug!("Hello, world!");

    let window = web_sys::window().unwrap();
    let document = window.document().unwrap();
    let canvas = document.get_element_by_id("canvas").unwrap().dyn_into::<web_sys::HtmlCanvasElement>().unwrap();
    let context = canvas.get_context("2d")?.unwrap().dyn_into::<web_sys::CanvasRenderingContext2d>().unwrap();

    sierpinski(&context, [
        (300.0, 0.0),
        (0.0, 600.0),
        (600.0, 600.0)
    ], (0,255,0), 5);


    wasm_bindgen_futures::spawn_local(async move {
        let image = web_sys::HtmlImageElement::new().unwrap();
        let (success_tx, success_rx) = futures::channel::oneshot::channel::<Result<(), JsValue>>();
        let success_tx = Rc::new(Mutex::new(Some(success_tx)));
        let error_tx = Rc::clone(&success_tx);

        let callback = Closure::once(move || {
            log::debug!("Loaded");
            if let Some(success_tx) = success_tx.lock().unwrap().take() {
                success_tx.send(Ok(())).unwrap();
            }
        });
        let error_callback = Closure::once(move |err| {
            log::debug!("Error");
            if let Some(error_tx) = error_tx.lock().ok().and_then(|mut opt| opt.take()) {
                error_tx.send(Err(err)).unwrap();
            }
        });
        image.set_onload(Some(callback.as_ref().unchecked_ref()));
        image.set_onerror(Some(error_callback.as_ref().unchecked_ref()));

        callback.forget();
        error_callback.forget();
        image.set_src("/assets/resized/rhb/Idle (1).png");
        let _ = success_rx.await.unwrap();
        context.draw_image_with_html_image_element(&image, 0.0, 0.0).unwrap();            
    });
    Ok(())
}