Nvidia OptiX (OptiX Application Acceleration Engine) is a ray tracing API that was first developed around 2009. The computations are offloaded to the GPUs through either the low-level or the high-level API introduced with CUDA. CUDA is only available for Nvidia's graphics products. Nvidia OptiX is part of Nvidia GameWorks. OptiX is a high-level, or "to-the-algorithm" API, meaning that it is designed to encapsulate the entire algorithm of which ray tracing is a part, not just the ray tracing itself. This is meant to allow the OptiX engine to execute the larger algorithm with great flexibility without application-side changes.

Commonly, video games use rasterization rather than ray tracing for their rendering.

According to Nvidia, OptiX is designed to be flexible enough for "procedural definitions and hybrid rendering approaches". Aside from computer graphics rendering, OptiX also helps in optical and acoustical design, radiation and electromagnetic research, artificial intelligence queries and collision analysis.

OptiX works by using user-supplied instructions (in the form of CUDA kernels) regarding what a ray should do in particular circumstances to simulate a complete tracing process.

A light ray (or perhaps another kind of ray) might have a different behavior when hitting a particular surface rather than another one, OptiX allows to customize these hit conditions with user-provided programs. These programs are written in CUDA C or directly in PTX code and are linked together when used by the OptiX engine.

In order to use OptiX a CUDA-capable GPU must be available on the system and the CUDA toolkit must be installed.

Using the OptiX engine in a ray tracing application usually involves the following steps:

Several examples for these programs are available with the program's SDK