I've just my old SNES framework source, so if I get a chance I'll clean it up and release it. Not sure who its of use to but its always fun to look at others code so... It does have a nice squareroot function in it, so you could always steal that. Its also (of course) 65816 based, so C64 SuperCPU users could steal more from it. If its of immediate interest let me know and I'll try and do it sooner....
Speaking of SNES.... I found this video on youtube ( YouTubes great! ) of the end sequence to Lemmings II. I had pretty good fun doing this. Theres actually a single pixel on the front end screen that if you click it, you get to the end sequence without playing the whole game - see if you can find it. ;-)
Showing posts with label 65816. Show all posts
Showing posts with label 65816. Show all posts
Friday, October 24, 2008
Thursday, July 17, 2008
Super CPU ideas....
Theres been several comments on the last post so let me go through them here...
First parallax scrollers. Games that have done these in the past have been limited to character blocks to do it's parallax effects and these have worked pretty well for the most part, but perhaps if you actually MASKED a full bitmap onto another you could produce something pretty special looking. Of course doing this would negate the use of the full attibutes as you would get colour clash... still dual playfields is always nice. You COULD stick to doing character based parallax and do a full bitmap scroller which would look pretty good, but not THAT much different from a stock C64 game using characters i suspect. This is what MetalDust does (I think) and its...okay... but we've come to expect games doing that kind of parallax.
Sprites. Now its true that anything I do I'll immediately load it up with as many software sprites as I can, and that I expect the screen to be crawling with baddies+effects. C64 games do this usually with lots of cheats, but if you can draw large sprites, you can push the boat out a little. However these will obviously suffer from colour clash again, which is never good. I suspect that if I arrange the bitmap better (straight rows rather than the funny character mode way) I can seriously increase the number of sprites I can actually draw. I'd then convert the screen on the fly as its copied down the VIC memory. Since the SuperCPU has a 1 byte write cache that gives me 20 cycles to get the next byte, and thats more than enough to convert the straight row format into the silly Commodore one. Of course on top of that, I now have 16bit registers allowing me to load and mask things on better, and upto 4Mb RAM (although mine has 16Mb, I think 4Mb is a good limit - anyone have less?) allowing me to pre-rotate everything at the start.
Now its also been suggested that you could do a full PROPER Lemmings game, and this is also true. You wouldn't be able to get the lemmings as the blue/white/green we all now and love, but a full white would be possible. In fact the best way (and to avoid colour clash) would be to use the full bitmap mode for the backgrounds and multiplex Hires-expanded sprites (on X at least) for the lemmings. That would have MCM resolution but it hires. Thats doable and gives a full dual playfield for drawing sprites + explsions easily. Not only that but because the SuperCPU can quickly multiplex sprites, you're only going to lose a few scanlines making this new playfield. On top of that... It only takes 7 sprites to do the playfield, leaving 1 hardware sprite for the cursor! Using the Commodore mouse you could finally replicate the proper lemmings game on the C64 - complete with the full 100 lemmings!
Lastly.... I suspect this will become a pet project and would be the ULTIMATE game for a SuperCPU, as theres no WAY a stock machine could even hope to do it.... GTA. Yup, I've been giving it some thought, and I think I could replicate the graphics engine I did on GTA1 on the SuperCPU. Im not sure I'd zoom in and out in the same way, but I think I can certainly do the perspective buildings... They may or may not be textured though... that Might be asking too much, but you would certainly get the effect GTA had of zooming around a 3D city... now that WOULD be cool....
First parallax scrollers. Games that have done these in the past have been limited to character blocks to do it's parallax effects and these have worked pretty well for the most part, but perhaps if you actually MASKED a full bitmap onto another you could produce something pretty special looking. Of course doing this would negate the use of the full attibutes as you would get colour clash... still dual playfields is always nice. You COULD stick to doing character based parallax and do a full bitmap scroller which would look pretty good, but not THAT much different from a stock C64 game using characters i suspect. This is what MetalDust does (I think) and its...okay... but we've come to expect games doing that kind of parallax.
Sprites. Now its true that anything I do I'll immediately load it up with as many software sprites as I can, and that I expect the screen to be crawling with baddies+effects. C64 games do this usually with lots of cheats, but if you can draw large sprites, you can push the boat out a little. However these will obviously suffer from colour clash again, which is never good. I suspect that if I arrange the bitmap better (straight rows rather than the funny character mode way) I can seriously increase the number of sprites I can actually draw. I'd then convert the screen on the fly as its copied down the VIC memory. Since the SuperCPU has a 1 byte write cache that gives me 20 cycles to get the next byte, and thats more than enough to convert the straight row format into the silly Commodore one. Of course on top of that, I now have 16bit registers allowing me to load and mask things on better, and upto 4Mb RAM (although mine has 16Mb, I think 4Mb is a good limit - anyone have less?) allowing me to pre-rotate everything at the start.
Now its also been suggested that you could do a full PROPER Lemmings game, and this is also true. You wouldn't be able to get the lemmings as the blue/white/green we all now and love, but a full white would be possible. In fact the best way (and to avoid colour clash) would be to use the full bitmap mode for the backgrounds and multiplex Hires-expanded sprites (on X at least) for the lemmings. That would have MCM resolution but it hires. Thats doable and gives a full dual playfield for drawing sprites + explsions easily. Not only that but because the SuperCPU can quickly multiplex sprites, you're only going to lose a few scanlines making this new playfield. On top of that... It only takes 7 sprites to do the playfield, leaving 1 hardware sprite for the cursor! Using the Commodore mouse you could finally replicate the proper lemmings game on the C64 - complete with the full 100 lemmings!
Lastly.... I suspect this will become a pet project and would be the ULTIMATE game for a SuperCPU, as theres no WAY a stock machine could even hope to do it.... GTA. Yup, I've been giving it some thought, and I think I could replicate the graphics engine I did on GTA1 on the SuperCPU. Im not sure I'd zoom in and out in the same way, but I think I can certainly do the perspective buildings... They may or may not be textured though... that Might be asking too much, but you would certainly get the effect GTA had of zooming around a 3D city... now that WOULD be cool....
Friday, November 30, 2007
65816: Aaaaaaaannnnnnnddddd we're done..........
Well, I appear to have now finished 65816 support. I had some nasty little bugglets that were messing with my REP/SEP commands which is exactly the reason I couldn't swap in/out of it easily! Basically, even in 16bit mode, Rep/Sep are 8bit commands, but it was saving 16bit immediate values, which meant it would then hit a $00 (brk) as the next instuction.
So, this is pretty cool, as I'm now done with the core supprt for 65816 and 65c02. It still needs heavy testing, but looks like its mostly there.
While I was at it, I also fixed a couple of other instructions in normal 6502 mode that were broken ( jmp($1234), and lax $00,y). So that helps me anyway for XeO3.
So all I need to do now is release this version and then back onto paths for xeo3!
(have I mentioned just how much I HATE doing paths???)
So, this is pretty cool, as I'm now done with the core supprt for 65816 and 65c02. It still needs heavy testing, but looks like its mostly there.
While I was at it, I also fixed a couple of other instructions in normal 6502 mode that were broken ( jmp($1234), and lax $00,y). So that helps me anyway for XeO3.
So all I need to do now is release this version and then back onto paths for xeo3!
(have I mentioned just how much I HATE doing paths???)
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