>> I also wonder whether the extra memory would be of particular benefit. > >Yes, at least if you're drawing in Mode 4. Do you remember a demo >called DWC (Dead Wild Cat) by Marc Broster on Fred 50? It drew rotating >3D wireframe objects and usually kept up to 50 fps. He used most of the >Sam's memory to hold pre-calculated line drawing routines.
You mean, if he had been able to go to extremes, having 256*192 * 256*192 routines, one for each possible [clipped] slope and position of line? Anyway, one of the benefits of an Elite type game is that the trig table requirements are miniscule - when I wrote a clone of the Elite engine (slightly cheekily, since it was after I'd played with the Elite:TNK source) for the Atari Lynx (4Mhz 6502, but with a coprocessor offering hardware multiply and divide, and another offering line drawing and display clearing and so on) I got away with only storing trig for +/- 5 degrees or so. But that was using orthonomal basis' (bases?) to retain orientation information - you'd obviously have a much rougher time with quaternions. Not that I reckon they'd be a good choice - you'd gain on compositions but lose massively on frame rendering. I always thought a good way to attack a vector renderer on the SAM Coupé would be to stick in black and white, but to take advantage of the 16 colour palette and the scanline interrupts to clear 1/16ths of scanlines which are not reused very cheaply. Or possibly to clear 16x16 blocks of pixels, depending on how much you want to expend on interrupt palette things. Otherwise, it always strikes me that clearing the display costs almost as much as drawing it in the first place which is a stupid situation to be in. Or perhaps I am too fanciful? -Thomas When words aren't enough - Vodafone live! A new world of colour, sounds, picture messages and information on your mobile. <a href="http://ad.doubleclick.net/clk;4909903;7724245;q?http://www.vodafone.co.uk/live";> Click here</a> to find out more.
