README.md

rustray

The rustray project is a pure-rust ray tracer. It is capable of optimizing material-related computions, by using highly composable material building blocks.

Usage

Currently, rustray virtual 3d scenes can only be constructed by a user program. Implementing a simple scene format is on the todo list.

To see the built-in demo scene render, run:

# note: --release is important!
# ray tracing is *painfully slow* in debug mode
cargo run --release

If this is your first time running rustray, some Creative Commons textures will be downloaded from ambientcg.com. These will be cached for future runs.

After rustray has run, take a look at output.png

xdg-open output.png

Programming rustray scenes

Basic types

All of rustray features user-selectable floating-point number type. This is reflected in the api, with names such as Point<F>, Vector<F>, Color<F>, etc.

The <F> in these type names have to implement the Float trait. This trait is already implemented for the standard f32 and f64 types.

Tracer

The main starting point for rustray is the Tracer. It is supplied with:

• A virtual camera (Camera<F>)
• A list of objects in the scene (Geometry<F>)
• A list of lights (Light<F>)

like so:

let tracer = tracer::Tracer::new(
    camera,
    objects,
    lights,
);

After this setup, the tracer is ready to generate output. See src/main.rs for a practical example.

Objects

The parameter objects is a list of things that all implement Geometry<F>

Each Geometry<F> can test itself for intersection with a ray. If so, they return a Hit<F> describing the hit point where the intersection took place, and the direction of the ray.

The next step is to resolve the material properties at this point. In addition to the intersection point, and ray direction, the Hit<F> struct also contains a HitTarget<F> reference.

The HitTarget<F> can compute material properties at the hit point, such as texture coordinates, surface normals, etc. Calling resolve(...) returns a Maxel<F> ("Material Pixel").

The Maxel<F> depends on the geometry being hit, but is unrelated to the desired material simulation.

To get a color contribution from a Maxel, we call render(...) on the referenced Material.

Thus, the pipeline is Ray -> Hit -> Maxel -> Color.

Demo images

Glassy material, demonstrating Fresnel behavior.

Untextured glass spheres, demonstrating Fresnel behavior. Index of refraction is set much higher than real glass, to get a more metallic reflective surface.

Glassy-metallic material showing refraction and reflection.

Utah Teapot made from glass.

Classic shiny spheres.

Experimental test of colored shadow material. This proof-of-concept material casts red shadows. Since the main material (teapot) is transparent, this is of course highly unrealistic, but is demonstrates the possibility.