Thomas wrote: > like only using 4 colours and using > palette switching so that the frame buffer only needs to be 'cleared' > every fourth frame. Or only a quarter needs to be cleared each frame, > if you prefer.
What I did on Stratosphere to clear the previous frame was to draw over the previous set of vectors. What I did when a frame was drawn was to store all the line co-ordinates in a table, and then when clearing simply rattle through the table and draw over the lines with palette 0 and not bothering about pixel accuracy, just clear the full byte. Far quicker than attempting to clear the whole game area. > Attempt at "low framerate" 3d (with Freescape-style interaction). > Obviously I've just been studying the Freescape engine, but I don't > think it's the optimal way of doing things on the Sam — 3d graphics > are a classic time/space trade-off and the Sam has at least 5 times as > much RAM as the old Spectrum 48 kB, Easier to ignore programming for the 256K SAM if that's what you thinking with 'at least 5 times', always just assume the machine has the full 512K memory as that's what the sheer majority of software was written to use. Although saying that, 256K memory upgrades still sell so there is probably a fair few machines still tucked away with just 256K. > In reality, I'll probably just think about it all for a long time and > do nothing. But I'd love to hear other's comments/thoughts in case I > do manage to push through. Oh don't say that! Give it a go if you have the time :) Out of the two ideas you came up with, I think the 2nd option - a freescape sytle system - with coloured solid walls in MODE4 would look really spectacular and would be something new on the SAM. > Incidentally, what are good timings for multiply and divide on a z80? > If I can stick to something relatively compact like 8.8 fixed point > then multiplication doesn't seem to be a problem as I can just use one > of those (x^2)/4 table solutions reducing it all to a couple of table > lookups and two or three adds and subtracts, but dividing looks like > it'll eat quite a few cycles. I used a lot of data tables and 8.8 fixed point maths on Stratosphere, and was going to do the same with Chrome. I'll have to hunt out old routines and see what I did come up with back then. Colin ====== Quazar : Hardware, Software, Spares and Repairs for the Sam Coupe 1995-2008 - Celebrating 14 Years of developing for the Sam Coupe Website: http://www.samcoupe.com/
