How does ray tracing differ from rasterisation?

Rasterisation maps 3-D geometry onto a 2-D screen triangle-by-triangle — fast, but physically approximate. Ray tracing fires rays from the camera through every pixel, finding which object each ray hits and following secondary rays for shadows, reflections and refractions. The result is physically accurate light transport, at the cost of many more calculations per pixel.

What is path tracing?

Path tracing is a Monte Carlo extension of ray tracing. Instead of evaluating all light paths analytically, the renderer importance-samples a random path through the scene for each pixel sample and averages the results over many samples. With enough samples-per-pixel the image converges to a reference-quality solution with physically correct global illumination, caustics and colour bleeding.

What is the Fresnel effect?

The Fresnel equations describe how much light is reflected versus transmitted at a dielectric boundary. At grazing angles almost all light reflects; at normal incidence most transmits. The Schlick approximation r0 + (1–r0)(1–cos?)5 is used in real-time graphics for glass, water and car paint.

Why does the image look noisy at first?

Path tracing estimates each pixel with random samples. Early samples are few, so variance (noise) is high. As the sample count — shown as 'spp' (samples per pixel) — increases, the Monte Carlo estimate converges and noise decreases proportional to 1/vspp. This progressive refinement is exactly how professional offline renderers like Blender Cycles work.

Home▸Rendering & Computer Graphics▸Ray Tracing Simulator

🧪 Ray Tracing Simulator

Explore ray tracing and path tracing in real time. Visualise reflections, refractions, soft shadows, and global illumination with an interactive browser-based renderer.

Rendering & Computer Graphics2DModerate60 FPS

⚙ Under the hood

This simulation demonstrates the principles of ray tracing, a core technique in computer graphics. Users can observe how light interacts with objects and surfaces to create realistic images.

Ray TracingPath Tracer

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install