>Graphics: >This uses "downgraded" graphics in 16 colours. Because we will spend the >most time on making these look good and touching up the graphics so they >dont look like routine scaled and degraded graphics this will be the >version that has most of the time on it. >Ive tried thinking about how I used to work out downgrading routines on >the AMIGA for HAM, the rules were more complex than the line >modifications that SAM VLSI ( or is it ASIC? ) can give us in mode 4. If >I can get it to work I can hopefully take advantage of it to produce >more colours on screen
Downgrading for the SAM is complicated, because it has 7-bit colour. 2 bits for each of RGB, and the Spectrum handed down its 'half-brightness' bit. Which ever way you split the RGB space, brightness and saturation levels (is this called 'gamma'??) are different, so it looks a tiny bit odd. It's really easy to software-code an interlace mode like the Amiga, making the top resolution 512*284 in MODE 3 (4 colours per scan-line), and the results can be quite nice. On the other hand, ages ago Mike AJ flicked between diffferent palettes to fake new colours. It's not quite as convincing, especially with large blocks of colour. If you're clever with textures, you can get a passable effect. As for breadboarding new graphics chips, I have no idea! >Strangely enough it isnt that hard to provide a game construction kit ( >I know I know ) once you have put together a game engine properly ( >which I never have done before now ). Luckily, Atic-Atac is fairly static, with only a few sprites on-screen at once. But for more more active games (say, Space Harrier), I'd suggest a Sprite Builder. There are two good ones on Fred disks. One's really stable (by Stefan Drissen), and the other's a bit faster (by Marc Broster). They take advantage of the SAM's screen memory (nice and simple) and shortcuts with the chipset to produce a single print program for each sprite frame. There's a few provisos - - you can't clip the sprites on the edge of the screen, it can get memory expensive, it is SAM-specific. But it's useful. >The Isometric, someone pointed out that this would not be true 3d - >correct. I would like to do a limited iteration voxel display. Voxel? Sorry you've lost me. What I meant was that you didn't have a 3D map containing isometric data for a room, 'cos it could be (say) 20x20x20 blocks big, and 8 bytes per block would make a very memory inefficient system. However, if you used a much simpler coordinate system for each room, you could convert it to the first system at display time, which would be really playable. Other 3D isometrics like Inside Outing, Last Ninja 2 and Movie relied on being really flat. It might as well have been a straight aerial projection! Momentum is the only real SAM isometric game I think Dave, and Graham Burtenshaw probably wrote it in BASIC (doesn't mean it's not really good, just really, really slow at swapping screens). >1) hardware expansion port - can it support frame buffers, would it be >worth my while trying to breadboard up a different graphics chip at some >point, are there any examples of this already out there? Yes. Well, no.(!) SAM doesn't support frame buffers, all it has is a video paging system, selectable to 32K segments, even for MODE 1 (Speccy emulation with only 6912 bytes per screen). Since each Mode 3/4 screen is 24K, you can fake one (with a lot of wasted memory), and set up an interrupt call to swap the pages. SamBASIC only caters to opening separate SCREENs up, in the same manner. Interestingly, it does also do non-overlapping windows - sorry, non manual here at work so I can't quote keywords. >4) Is there a SAM Carrier Command/Elite already? Don't start! Long and bitter tales about this - we eventually got a Spectrum port of Elite with patched LOAD and SAVE routines, sold at full price. Brenchley said it wasn't possible to render solid 3D in MODE 4 so he was doing us a favour by 'sticking as closely as possible to the best version' ie the Speccy. (PS I disagree.) >7) Finally, is there a decent GUI project for the SAM? Ages ago Steve Taylor wrote a MODE 3 one, but it never caught on cos it cost too much and was fiddly to convert existing software. And it's word processor was apparantly too slow for real typists. You might try hacking SAMmines by Mnemotech/Andrew Collier, and I like the GI_monitor one, though you can't redefine windows' size and position! I've got a bunch of display routines and graphics for a system I started for O3D. I did a nice robust priority table routine, but the button scanning is atrocious, even when you only scan for live windows and desktop icons. Oh, and it's in Assembler. Cheers! -howard The NTICS Group: providers of Database Services to learndirect and Sheffield TEC. Contract management: Sheffield Libraries, Archives & Information Service. National Training Information Central Support Unit 4 AVEC 1 Sidney Street Sheffield S1 4RG Tel: 0114 275 1046 Fax: 0114 273 0024 Email: [EMAIL PROTECTED] Web: http://www.ntics.org.uk The contents of this e-mail are confidential to the addressee named above and may be legally privileged. If you are not the intended recipient of this message, you are hereby notified that any use, dissemination, distribution or reproduction of this message is prohibited. Any views expressed in this message are those of the individual sender and may not necessarily reflect the views of NTICS or Sheffield City Council.
