3DLDF might be interesting to some of you. I have not tested it, but it seems to use a similar language to MetaPost (but with 3D coordinates) and generates real MetaPost.
| My primary purpose in writing 3DLDF was to make it possible to use MetaPost for | three-dimensional drawing. I've always enjoyed using MetaPost, and thought it was | a shame that I could only use it for making two-dimensional drawings. 3DLDF is a | front-end that operates on three-dimensional data, performs the necessary | calculations for the projection onto two dimensions, and writes its output in the form | of MetaPost code. | | While 3DLDF's data types and operations are modelled on those of Metafont and | MetaPost, and while the only form of output 3DLDF currently produces is MetaPost | code, it is nonetheless not in principle tied to MetaPost. It could be modified to | produce PostScript code directly, or output in other formats. It would also be possible | to modify 3DLDF so that it could be used for creating graphics interactively on a | terminal, by means of an appropriate interface to the computer's graphics hardware.