OpenRL
OpenRL™ is a flexible low level interactive ray tracing API, available for download as an SDK for accelerating ray tracing in both graphics and non-graphics applications. OpenRL was developed by the Caustic Professional division of Imagination Technologies. A free perpetual license of OpenRL is available for integration, with either commercial or non-commercial applications.
In OpenRL, acceleration structures are built and maintained transparently, behind the scenes, and this eliminates the need for the client application to write any code to create or traverse them. This also allows for ray tracing hardware acceleration of the acceleration structure assembly.