ray-tracer

A toy ray-tracing renderer in Rust

Quick start

Download this image and put it under root directory of this repo. It will be used as a texture map in the demo.

cargo run --release --example main > image.png

This will generate book 2's cover image. It takes roughly 1 hour on my i5-3317U.

--release can significantly increase rendering speed.

If you are on windows, just cargo run --release and find a image.png under root directory.

To generate book 1's cover image (random spheres):

cargo run --release --example book-one > image.ppm

This example takes about 10 min on my i5-3317U.

To generate Cornell box:

cargo run --release --example cornell-box > image.ppm

This example takes about 1 hour on my i5-3317U.

Features

• lambertian, metal, dielectric (glass-like), light-emitting materials
• sub-surface scattering inside constant density medium like fog and smoke
• bounding volume hierarchy to speedup ray-object intersection detection
• sphere, rectangle, cube geometry
• perspective camera with depth-of-field blurring effect

Build your own scene

Build a blue smoke sphere with radius 70 and place it at (360, 150, 145):

let sphere = Arc::new(
    Sprite::builder()
        .geometry(ConstantMedium::new(Sphere::new(70.0).into(), 0.2).into())
        .material(Isotropic::new(Vec3::new(0.2, 0.4, 0.9)).into())
        .transform(Mat4::translation(Vec3::new(360.0, 150.0, 145.0)))
        .build(),
);

Speed up ray-object intersection detection by constructing a bounding volume hierarchy:

let sprites: Vec<Arc<dyn Bound<AxisAlignedBoundingBox>>> = unimplemented!();
let bvh = BoundingVolumeHierarchyNode::new(sprites).unwrap();

Set up a perspective camera:

let camera = PerspectiveCamera::new(
    eye, // eye position
    center, // what eye is looking at
    up, // camera's head up direction
    (40.0 as f64).to_radians(), // field of view in radians
    width as f64 / height as f64, // aspect ratio
    10.0, // focus distance
    0.01, // lens radius
);

Get color at image position (x, y) (image coordinate origin is at lower-left corner, +x points rightward, +y points upward):

let world: Arc<dyn Hit> = unimplemented!(); // your scene
let u = (x as f64) / width as f64; // convert to camera coordinate
let v = (y as f64) / height as f64;
let ray = camera.ray(u, v);
let pixel = color(&ray, world.as_ref(), 100); // ray scatters at most 100 times

To-do

• surface/geometry modifiers like bump map
• random noise textures
• GPU parallelism to speedup (real time?)
• port to WebAssembly
• physical realism for wave optics
• mesh/mass triangle rendering
• load from 3D files like .obj

Please feel free to drop an issue or a comment!

References

[book-i]

Ray Tracing in One Weekend

[book-ii]

Ray Tracing: The Next Week

[pbr]

Physically Based Rendering: From Theory to Implementation