ospray unstructured volume render limited to tets and float and point aligned arrays
opening it up to other word types should be easy. For any type that ospray doesn't have a match for we should just convert as we send over.
cell aligned data is a little tricker, a cell to point filter type averaging would work
other cell types should eventually be supported by ospray. We could tetrahedralize until then at some cost in both time and memory.