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New 3D FPS released for 1979 Atari 800

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Re: New 3D FPS released for 1979 Atari 800

#51

Post by legoxx »

brianpaul wrote: post #22
mywittyname wrote: post #16

Earlier quoted context omitted.

So I was curious about how the Atari 800 handled floating point calculations. As it turns out, Steve Wozniak helped develop the FP routines for the 6502. http://archive.6502.org/publications/dr_dobbs_journal_select...

IIRC, the Atari ROM routines used a different 6-byte BCD floating point format.

I can assure you that no BCD routines (nor Woz's nor Atari's) were hurt during production of this game. They are really slow. You need to use all kind of tricks and cheats when creating 3d game on 8bit machine and all needed calculations are precalculated in lookup tables.

Re: New 3D FPS released for 1979 Atari 800

#53

Post by bluGill »

michaelcampbell wrote: post #44
buescher wrote: post #18

Earlier quoted context omitted.

Yeah, you had ROM space (and potentially cartridge ROM space) eating into your 64K on all the models and had to bank-switch for anything more than 48K IIRC. With a BASIC cartridge in place you'd lose another 8K. Also I don't recall any of the 400/800 3rd party upgrades being compatible - they used a different bank-switching mechanism - with the later XL/XE models.

"bank switching" sounds familiar, so I'm pretty sure my memory of 64k is correct then. I can't say I understand what it means, but I remember something of that term at the time.

You group your memory into groups of 16k (could be other sizes, 16k is what I recall but it has been years). Then you have a switch that you can program the switches between groups (also called banks). You can only access one at a time, but you can switch between them very fast. It was possible to get up to 5 MB of memory that way, even though you could only use 64K at a time.

Re: New 3D FPS released for 1979 Atari 800

#54

Post by legoxx »

jhbadger wrote: post #12
chaganated wrote: post #5

i'm not surprised. atari 800 was an exceptional machine. great work on the game though.

Yes, it had a lot of custom chips, and some of the same people (like Jay Miner) who worked on the Atari 800 design later were involved in designing the Amiga which likewise was based on custom chips.

there were 3 custom chips (ANTIC, GTIA and POKEY) 1 semi-custom (SALLY was a VERY MINOR modification of 6502) and 1 common industry chip (PIA). I would not say exactlly "lot of" ;-)

Re: New 3D FPS released for 1979 Atari 800

#55

Post by [deleted] »

pixelpoet wrote: post #21

Having written realtime ray tracers in the classic demoscene style on e.g. 300 MHz Pentium 2 Celeron (the original one with no cache, that overclocked to 450-550 MHz), I sometimes wonder about how cool it would be to open source a modern rendering engine around the time of the first Pentium 3 with SSE, in 1999. You could completely revolutionise computer graphics on that era of hardware, with the view to increasing v…

[deleted]

Re: New 3D FPS released for 1979 Atari 800

#56

Post by dahart »

romwell wrote: post #42
pixelpoet wrote: post #21

Having written realtime ray tracers in the classic demoscene style on e.g. 300 MHz Pentium 2 Celeron (the original one with no cache, that overclocked to 450-550 MHz), I sometimes wonder about how cool it would be to open source a modern rendering engine around the time of the first Pentium 3 with SSE, in 1999. You could completely revolutionise computer graphics on that era of hardware, with the view to increasing v…

First time reading about BVH. Sounds like Kirkpatrick's hierarchy, but in arbitrary dimension. What's the advantage over BSP/kD-trees/octrees? And what do you mean by rasterization - we still have to deal with pixels in the end, so it has to happen somewhere? (..I'd love to play with a color vector monitor though!).

> And what do you mean by rasterization - we still have to deal with pixels in the end, so it has to happen somewhere?

At a high level, you could think about it as where in your nested loops you put the loop over geometry (say, triangles). A basic rasterizer loops over triangles first, and the inner loop is over pixels. A basic ray tracer loops over pixels, and the inner loop is over triangles (with the BVH acting as a loop accelerator). Just swapping the order of the two loops has significant implications.

Re: New 3D FPS released for 1979 Atari 800

#57

Post by Thoreandan »

GekkePrutser wrote: post #37
flatiron wrote: post #7

Earlier quoted context omitted.

Comment a bit of a limitation of the ray casting: https://atariage.com/forums/topic/326709-final-assault-new-g... simply amazing what they did. could you imagine if this came out in the 80s?!?!

Yes this would have been mind-blowing. Ps there was a game that had a similar FPS view in those days. It was a maze game with polygon graphics but no textures. I forget the name. No shooting though!

* Mercenary: Escape from Targ (Novagen) http://mercenarysite.free.fr/mercframes_graphic.htm "open world" vector FPS/RPG, fully RAM-resident, in 48k & 64k editions.

* Alternate Reality: The City (Datasoft/Paradise Programming) FRPG with 90-degree turns, rendered walls/doors as scaled textures between the animated backdrop and foreground NPC sprites.

I wrote an FAQ as a kid for Mercenary for local BBS' - I think I discovered at least 3 victory conditions. :^)

Re: New 3D FPS released for 1979 Atari 800

#58

Post by codedokode »

pixelpoet wrote: post #21

Having written realtime ray tracers in the classic demoscene style on e.g. 300 MHz Pentium 2 Celeron (the original one with no cache, that overclocked to 450-550 MHz), I sometimes wonder about how cool it would be to open source a modern rendering engine around the time of the first Pentium 3 with SSE, in 1999. You could completely revolutionise computer graphics on that era of hardware, with the view to increasing v…

The game uses ray casting, not ray tracing. Ray casting is when you send a ray once for every column of pixels to get a distance to a wall. Also, if the walls are only horizontal or vertical the calculations get simpler.

Also I wonder how you can achieve clock frequency like 300 MHz without a cache. Shouldn't CPU stumble on fetching every command?

Re: New 3D FPS released for 1979 Atari 800

#59

Post by fistynuts »

q_andrew wrote: post #47
pixelpoet wrote: post #21

Having written realtime ray tracers in the classic demoscene style on e.g. 300 MHz Pentium 2 Celeron (the original one with no cache, that overclocked to 450-550 MHz), I sometimes wonder about how cool it would be to open source a modern rendering engine around the time of the first Pentium 3 with SSE, in 1999. You could completely revolutionise computer graphics on that era of hardware, with the view to increasing v…

I was under the impression that the theory was there but the hardware was not. Like, rasterization was a necessary evil because it gave better results more quickly (and artists needed that feedback).

Yes, absolutely right, and for games it was the only option with no fast floating point and very limited memory.

Re: New 3D FPS released for 1979 Atari 800

#60

Post by dahart »

codedokode wrote: post #58
pixelpoet wrote: post #21

Having written realtime ray tracers in the classic demoscene style on e.g. 300 MHz Pentium 2 Celeron (the original one with no cache, that overclocked to 450-550 MHz), I sometimes wonder about how cool it would be to open source a modern rendering engine around the time of the first Pentium 3 with SSE, in 1999. You could completely revolutionise computer graphics on that era of hardware, with the view to increasing v…

The game uses ray casting, not ray tracing. Ray casting is when you send a ray once for every column of pixels to get a distance to a wall. Also, if the walls are only horizontal or vertical the calculations get simpler. Also I wonder how you can achieve clock frequency like 300 MHz without a cache. Shouldn't CPU stumble on fetching every command?

> The game uses ray casting, not ray tracing. Ray casting is when you send a ray once for every column of pixels

Both ‘ray casting’ and ‘ray tracing’ are overloaded terms, the distinction isn’t as clear as you suggest. You’re talking about 2d ray casting, but 3d ray casting is common, and means to many people the same thing as ‘ray tracing’. Ray casting “is essentially the same as ray tracing for computer graphics”. https://en.wikipedia.org/wiki/Ray_casting

There’s also Whitted-style recursive ray tracing, and path tracing style ray tracing, but ray tracing in it’s most basic form means to test visibility between two points, which is what ray casting also means from time to time.

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