In article <43E8885F.6040403 at yahoo.co.uk>, Jules Richardson <julesrichardsonuk at yahoo.co.uk> writes: I remember that they had a feature called a "Z-blit" that was useful for rendering large complex ball-and-stick molecular models. Essentially it was a 2D blt operation but also included a blt to the Z-buffer with a Z compare during the blt. So you could pre-render an awesome looking sphere into a color buffer and z buffer pair and then blt these all over the screen to put a sphere anywhere you wanted/needed. Now that I think about it, there must have been some sort of Z transformation done on the associated Z-buffer as well, or it wouldn't have worked well for complex scenes. I never got the engineering details on it, but I did see a demo and it was pretty impressive for the time. Nowadays you'd just brute force render everything. -- "The Direct3D Graphics Pipeline"-- code samples, sample chapter, FAQ: <http://www.xmission.com/~legalize/book/> Pilgrimage: Utah's annual demoparty <http://pilgrimage.scene.org>