Glossary/GPU/Ray tracing

Ray tracing

Ray tracing computes lighting by following rays from the camera into the scene to find what each pixel actually sees and how light reaches it.

Also known as RT, hardware ray tracing

Measured by SystemCheck

Part of the four-stage run: a 60-second sustained CPU load reporting throughput, decay and consistency; a memory stage reporting bandwidth and latency; a calibrated GPU raster load reporting frame time, pacing and decay; and a path tracer reporting samples per second. The paragraphs below say which metric carries this term.

Instead of projecting geometry onto pixels, ray tracing asks per pixel what the ray hits, then evaluates lighting at that hit. Reflections, refractions, and shadows fall out of the algorithm rather than being approximated. The cost is that every ray requires traversing an acceleration structure over the scene geometry.

In shipping games, ray tracing is nearly always hybrid: raster handles primary visibility and rays handle specific effects such as reflections or shadows. Dedicated RT hardware accelerates the traversal and intersection tests, which is why generations differ far more in RT performance than in raster performance.

SystemCheck measures a path-traced workload, the full form of ray tracing, through the browser's graphics backend, reporting samples per second and delivery consistency. Because it runs through WebGL2 or WebGPU rather than a native RT API, treat it as a comparative measure of your GPU's ray-throughput capability rather than as a prediction of a specific game's RT frame rate.

Related terms

Path tracingPath tracing is ray tracing that follows light along many random bounce paths per pixel, converging on a physically accurate image as samples accumulate.Read more Global illuminationGlobal illumination is lighting that accounts for light bouncing between surfaces, so a red wall tints a nearby white floor rather than leaving it flat.Read more RasterizationRasterization is the rendering technique that projects triangles onto the screen grid and shades the covered pixels, and it drives nearly all real-time graphics.Read more WebGPUWebGPU is the modern browser graphics and compute API built on Vulkan, Metal, and Direct3D 12, offering lower overhead and compute shaders that WebGL2 lacks.Read more Shader throughputShader throughput is how much arithmetic a GPU's programmable cores complete per second, and it limits performance in shading-heavy modern rendering.Read more

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