Java Ray Tracer

A 3D ray tracer implemented from scratch in Java, developed as a joint Software Engineering course project by Noa Aizen and Noga Jacobs. It uses no graphics libraries: rays, intersections, lighting and pixels are all computed by the project's own code.

Features

• Geometry: ray intersection for spheres, planes, triangles, polygons and circles
• Lighting: ambient, directional, point (distance attenuation) and spot lights
• Shading: Phong model with diffuse, specular, shininess and emission
• Shadows: hard shadows, lighter shadows behind transparent objects, and optional soft shadows
• Global effects: recursive reflection and transparency, with a depth limit and a contribution cutoff
• Image quality: anti-aliasing (multiple rays per pixel) and adaptive super sampling that subdivides only pixels whose samples differ
• Performance: multithreaded rendering with a shared pixel work queue and a progress indicator
• Scenes: fluent Java builder API, plus basic XML scene loading
• Tests: JUnit 5 tests for the math core and intersection algorithms

How It Works

1. Camera casts a ray through each pixel (or several rays per pixel, when sampling is enabled).
2. RayTracerBasic finds the closest intersection among the scene's geometries.
3. Local effects add emission and, for each light, diffuse and specular terms, scaled by a shadow-ray transparency factor.
4. Global effects trace reflected and transmitted rays recursively, up to 10 levels, stopping early when the contribution drops below 0.001.
5. ImageWriter writes the final colors to a PNG.

Package	Responsibility
primitives	Point, Vector, Ray, Color, Material, and floating-point helpers
geometries	Intersectable base class, the Geometries composite, and the shapes
lighting	Ambient, directional, point and spot lights
renderer	Camera, RayTracerBasic, ImageWriter, and Pixel (thread work distribution)
Scene, parser	Scene with its SceneBuilder, and the XML scene descriptor

Design patterns used: Builder (SceneBuilder), Composite (Geometries), Template Method (findGeoIntersections → findGeoIntersectionsHelper), and fluent setters.

Example Renders

Without improvements	Soft shadows and anti-aliasing

Reflection	Transparency and shadow	Spot light	Soft shadows

Running

There is no build tool yet. The project targets Java 17, and the JUnit 5 jars are in lib/. In IntelliJ IDEA:

1. Open the folder as a project.
2. Mark src/ as Sources Root and unitTests/ as Test Sources Root.
3. Add lib/ as a project library.
4. Run a test class. Renders are written to images/.

Testing

unitTests/ contains 53 JUnit 5 test methods:

• Math core: VectorTest and PointTest.
• Geometry: SphereTest, PlaneTest, TriangleTest, PolygonTests, TubeTest and GeometriesTests, covering normals and intersections with equivalence-partition and boundary cases.
• Camera: CameraTests and IntegrationTests check ray construction and intersection counts.
• Rendering: the rendering tests generate images for visual inspection. They do not assert on pixel values.

Project Structure

src/         primitives, geometries, lighting, renderer, Scene, parser
unitTests/   JUnit 5 tests
lib/         JUnit 5 jars
docs/images/ showcase renders
images/      render output (git-ignored)

Known Limitations

This project was developed as an academic Software Engineering project and some components remain incomplete:

• Tube and Cylinder ray intersections are not implemented.
• Some rendering and sampling components have known limitations that can be improved in future iterations.
• Some original course tests require environment-specific adjustments.
• The project currently uses local JUnit dependencies rather than Maven or Gradle.

Credits

• Noa Aizen and Noga Jacobs: design and implementation, developed together.
• Dan Zilberstein (course lecturer): the course starter code, including Main.java, the original Polygon class, and the base test scenes in PolygonTests, CameraTests, RenderTests, LightsTests, ShadowTests and ReflectionRefractionTests, which the authors extended.

Created for the Introduction to Software Engineering course.