Raytracer on MoonZoon

Raytracer is implemented according to the tutorial Ray Tracing in One Weekend. It's a bit slow and single-threaded, but useful for learning.

MoonZoon is a Rust Fullstack Framework. It renders the HTML canvas and provides a server with auto-reloading for fast dev iteration loop.

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How to start it

1. Check you've installed Rust and wasm-pack:

   rustc -V # rustc 1.52.1 (9bc8c42bb 2021-05-09)
   wasm-pack -V # wasm-pack 0.9.1

   • Note: wasm-pack will be installed automatically in the future.

2. Install mzoon to cargo_install_root:

   cargo install mzoon --git https://github.com/MoonZoon/MoonZoon --rev a6f5070 --root cargo_install_root --locked

   • Note: cargo install mzoon will be enough in the future. And there will be a faster way with pre-compiled binaries.

3. Build and run:

   cargo_install_root/bin/mzoon start

   • Note: The app is much faster when built in the release mode (-r).

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Problems in the tutorial

1. Rotated image in some tutorial steps. Replace

   for j in 0..IMAGE_HEIGHT {
       eprintln!("Scanlines remaining: {}", IMAGE_HEIGHT - j - 1);

   with

   for j in (0..IMAGE_HEIGHT).rev() {
       eprintln!("Scanlines remaining: {}", j + 1);

2. Missing Vec3 impl:

   impl Mul<Vec3> for Vec3 {
       type Output = Vec3;
   
       fn mul(self, other: Vec3) -> Vec3 {
           Vec3 {
               e: [self[0] * other[0], self[1] * other[1], self[2] * other[2]]
           }
       }
   }

3. r0 * (1.0 - r0) corrected to r0 + (1.0 - r0):

   fn reflectance(cosine: f64, ref_idx: f64) -> f64 {
       // Use Schlick's approximation for reflectance
       let r0 = ((1.0 - ref_idx) / (1.0 + ref_idx)).powi(2);
       r0 + (1.0 - r0) * (1.0 - cosine).powi(5)
   }

4. Change the value in const MAX_DEPTH: u64 = 5; to 50. (This and the previous correction fix black bubbles).

5. There are some other problems in the tutorial but all of them should be easily fixed by the Rust compiler suggestions.

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Notes

• The random_scene function has been moved to scene.rs and renamed to scene.

• The ray_color function has been moved to ray.rs as Ray::color.

• main.rs rewritten to lib.rs.

• There is an alternative raytracer described in the wasm-bindgen docs. I assume the raytracer is based on this tutorial: Writing a Raytracer in Rust.