Amiga 1200 with 2mb RAM vs SuperFX chip and Starfox/Starwing?

[Amiga_Nut]

So I was wondering if anybody with experience in polygon filled 3D programming could compare level 1 of Starfox/Starwing on Super Nintendo with what is possible on an unexpanded A1200 (which is effectively a 7mhz 68020 thanks to no FAST Ram as we know).

I've looked at Guardian (what little footage there is on youtube) and I think it's the CD32 version which may or may not be faster than the Akiko chip devoid Amiga 1200 AGA machines.

It's doesn't look like there is much going on at all, the intro sequence is definitely do-able with sound too IMO.

[Matt_H]

Guardian is probably a good benchmark - I don't think it actually uses the Akiko chip.

[Coolhand]

Maybe Starglider - Starfox is a direct descendent of Starglider for the Amiga / ST, both were made by Argonaut.

[Amiga_Nut]

Starglider II runs quite fast on an A1200, about 200% speed or similar IIRC.

Actually how far off is AMOS 3D compared to the maximum polygon performance of an Amiga with machine code? I might try doing the intro when the ships are flying through the wireframe tunnel at the start (WinUAE 14mhz 020 A500 as it doesn't work on Amiga 1200s).

Zeewolf is also fast but it does use small sized polygons mostly.

[bloodline]

AMOS 3D is actually surprisingly good, but when the polygon count gets high, it really bogs down :-/

[Amiga_Nut]

Apparently Amos 3D doesn't work on the A1200 I read all over various boards Might have to try it with relokick to 1.3 etc

The Amiga bogs down on large polygons which is why Zeewolf is so swift and why on Elite they used the blitter's fill operation I think it is. Also seem to remember Amiga Format or CUA in their review saying something about using textures. Could make the ships wings a single polygon (pentagon probably) and just use 1 simple area texture on one side to make it look like 3 or more of the SNES polygon design.

[fishy_fiz]

Lack of fastram doesnt make it effectively a 7mhz '020, it simply shares mem bandwidth (which is slower than "fast" ram) between cpu and chipset, meaning it'll be saturated in most situations, leading to sub-optimal results.
SuperFX is probably weaker than a stock a1200, but not a lot. Starfox looks ok, but isnt fullscreen, and polygons are removed at the slightest whim to keep up framerates.

p.s. AMOS3d does indeed work on an a1200,... I just now checked.

[commodorejohn]

Not to mention that the 020 has cache - not a lot, but enough that it's not completely bound to external memory the way the 68000 is.

No question that a stock 1200 is a good deal slower than one with fast RAM, but let's not get crazy here.

[matthey]

Not to mention that the 020 has cache - not a lot, but enough that it's not completely bound to external memory the way the 68000 is.

No question that a stock 1200 is a good deal slower than one with fast RAM, but let's not get crazy here.

I agree. The 68020 has a 256 byte instruction cache but no data cache. It also has 16 general purpose registers. The chipset doesn't need all the bus cycles unless running high resolutions with lot of sprites and lots of sound/music.  With efficient code, the line drawing part isn't a problem. The filling or texturing is more difficult. I would expect the 3D computation and collision detection to be the most difficult. These would still be table lookups on the 68020 and that is where fast memory and a data cache would be beneficial. Many 3D environments for low end machines are pseudo 3D that still look good. It may be possible to pre-calculate some 3D data if there are limitations on movement/path in the 3D environment. Some demos use tricks like this.

[Britelite]

Starfox looks ok, but isnt fullscreen, and polygons are removed at the slightest whim to keep up framerates.

Yeah, it's also good to remember that the horizontal resolution of the SNES is 256 pixels vs the 320 pixels usually used on the Amiga.

[psxphill]

The Amiga bogs down on large polygons which is why Zeewolf is so swift and why on Elite they used the blitter's fill operation I think it is.

The blitter fill on the A1200 is pretty much the same speed as on the A500. It just has more bandwidth, so it can blit and display more colours and run from chip ram at the same time.
 
Ideally you'd be able to plug in different rendering engines, AMOS3D is probably not the way to go though.

[Amiga_Nut]

I read the general figure is about 20,000 polygons per second (so divide by 60) you get around 333 or so. I'm not sure there is that many polygons on screen being actively updated each frame in the game, looks DOS 286 era but I couldn't find a similar game on PC AT era DOS gaming to compare.

I did however have a good look at the intro 'launch tunnel' sound effects and music and they should be possible using just 4 channels of Portia/Paula which is nice but will lose stereo effect. Sampled the instruments for the alert sequence anyway so one day.....

[psxphill]

I read the general figure is about 20,000 polygons per second (so divide by 60) you get around 333 or so.

Those polygon counts are as dodgy as the diesel car tests.

The super fx is a 10mhz cpu and everything is software rendered. So you can easily write a test program that pushes 20,0000 polygons that wouldn't be practical for a game.

Unless they specify what they are doing with the polygon and how big it is then you can't tell if they timed drawing 20,000 polygons so far away that they were only 1 pixel.

The later superfx games clocked the chip at 20mhz & I online there is a suggestion that the 20,000 polygon figure is for that.

Certainly Star Fox doesn't look like it's got 20,000 polygon, I think the game runs at 15fps, which means you should see over a thousand polygons on screen. From memory Guardian looked pretty much as good, but neither of them really had the game play. Robocop 3 had a similar issue.

It would be great to see a 3d game written for un-accelerated a500/a1200 using sub pixel techniques etc https://www.youtube.com/watch?v=f4a7rxGL7b0 I've always wondered if you could use HAM for it's original intended function of fast line fills. It would limit colour selection as you'd need one of the r/g/b channels to be constant, as there isn't a NOP pixel. What you save on fill rate, you may end up losing in managing where all the polygons intersect. But with all the work going on in c64 demos, I always find the amiga scene a bit lacking.

[BozzerBigD]

@psxphill

Certainly Star Fox doesn't look like it's got 20,000 polygon, I think  the game runs at 15fps, which means you should see over a thousand  polygons on screen. From memory Guardian looked pretty much as good, but  neither of them really had the game play.

Guardian was a  3-D version of a Defender type game. It has awesome 'arcade' gameplay and  smooth controls on a stock A1200/CD32. Give it some fast ram and a 030  and it's rock solid. Yes, it doesn't have talking frogs, rabbits and  foxes and yes it doesn't have a pretentious plot but the gameplay is  awesome in a 'let's save the planet from invasion' kind of way (a bit  like the Resogun of its day). You have to avoid blowing up friendly  structures and there is good variation of enemy ships including boss  battles! A CD32 pad is a must for A1200 owners though.

Guardian  is under rated and Star Fox is definitely over rated IMHO. Same with  Bltiz Bombers vs BomberMan, The Great Giana Sisters vs Super Mario Bros.  and the same as Xtreme Racing vs SNES Mario Kart. There simply is very  little reason to idolise Nintendo if your an Amiga fan. Heck, Turrican 2  beats the hell out of Super Metroid too IMHO.

[Amiga_Nut]

Unfortunately I couldn't find exact figures from a verified source but did learn there are differences with SuperFX and FX2 and I think Star Fox is running on the first version, which is quoted as 10,000 polygons per second also more specifically. If the N64 is anything to go by then as soon as you do anything to the polygons the figure will drop drastically. Had the Amiga 1200 been configured with 1mb chip and 1mb fast I think you could have got something similar. Remember what the apparent polygon count on screen is could be achieved with further design shortcuts, coding competence can also make a huge difference.

If it was a game that was also converted to an unassisted Megadrive you could get a better idea of the CPU grunt. Talking of which I don't think anything less than a 28mhz 020 with some fast RAM could do Virtua Racing in true polygon based 3D as per the SVP chip of said game, not a stock as sold in shops 2mb only config. Some have stated the raw polygon processing power of the SVP was higher than the FX chip but that was on a site that did not differentiate the different clock speeds/performance of various SuperFX game cartridges sold.

For those who liked Guardian you might like the Windows game called G'tok.