Ours was an Onyx Reality Engine. The size of a *very* big fridge, Purple, IIRC.
It was for the SRMH (Single Role Mine Hunter) sonar simulation trainer.
There was going to be an OpenGL virtual rendering of the view from a "Yellow Submarine" ROV fitted with a cable cutter and capable of dropping a demolition charge, whilst simultaneously generating a simulated feed into the sonar display. The latter was to be done on a rack of TI TMS 320C40 DSPs.
Ours was definitely powered up and used for development. One memory is of having to optimise the loop unrolling of the C compiler to match the size of cache on a processor.