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PostPosted: Thu May 11, 2017 11:02 am 
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Saturn also had a DSP in a bus management chip for doing stream calculations.

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PostPosted: Fri May 12, 2017 12:56 am 
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adam_smasher wrote:
Oziphantom wrote:
And if you ever look at developing for a PS1,2 or 3 and wonder why it is soo bat shit crazy, remember they were designed by the guy who made the SPC700 ;)

The PS2 and PS3 are legendary for their insane hardware, but I'd always been under the (possibly misinformed) impression that the PS1 was a fairly pleasant platform to work on, and that's one of the reasons why developers flocked to it instead of the comparatively nasty N64 or Saturn. What's so batshit crazy about it?

Well the PS1 is probably not "batshit" unlike the other 2, just annoying.
So no FPU, zero floating point support, on a 3D system ( sure the DS does it too but that is a handheld )
No perspective texture correction

So that is why a lot of PS1 games have the "jitters"

If you look at some meshes from PS1 games you will see where the artists had to make a bunch of "scaffolding" to move the polygons back around under and through things. Also there can be no gaps or holes in the mesh, and they needed to be single, that might have been an engine limit rather than the hardware though. I worked on a PS1 port, not an actual PS1, just when I had to ask why does the code do this, why is this like that, I usually got some hand-waving with "because it didn't have logical thing X but had Y, Kutaragi" But I did learn the "PS1 lean", to make the disc load.

Sony gave a library and wouldn't allow people to hit the hardware directly, they eventually relented. Then the graphics programmers could see why they made a lib ;)

Compared to the Saturn the PS1 is a dream. Jaguar, 3D0 heaven ;)

The reason to go PS1 over N64 is more to do with policy than hardware. Programmable pipeline with display lists, fpu, perspective texture correction in hardware and 4MBs with fast transfer from Cart makes the N64 at lot easier to balance, just trying to pack movie and audio and games into 64MB is pain ;)

But to make an N64 game you had to pay for 1 million carts before Nintendo would publish it, this acted as a quality barrier, as the company had to be confident of selling said 1 million carts. Sony wooed devs with we can do runs of 50,000 if you want. So things like Vib Ribbon could be done on PS1 but not N64, this is why the PS1 becomes a glut for shovelware, Sony would do low runs, CDs were cheap, Sony wanted devs all the devs, while Nintendo were ivory tower elitists who would tell you to get stuffed ( still are I guess )
Having the cheap CD format for the SNES at the end of its life with such mentality would have been interesting, but I guess it is no different from the Flash Cart system they had in Japan for the SNES but by then most had moved on.

the PSP was mostly sane baring one strange omissions from its fixed pipeline, dest colour blend? dest stencil? and the square button ;) Oh and the 90 degrees LCDs on the 2000,3000 models that gave red and blue lines on everything... or the PSP Go with no UMD drive...... hmmm


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PostPosted: Fri May 12, 2017 8:40 pm 
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Oziphantom wrote:
If you look at some meshes from PS1 games you will see where the artists had to make a bunch of "scaffolding" to move the polygons back around under and through things. Also there can be no gaps or holes in the mesh, and they needed to be single, that might have been an engine limit rather than the hardware though.

I've always been curious about the PS1's depth sorting and mesh formats. Do you have any links on the topic?


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PostPosted: Sat May 13, 2017 12:10 am 
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No sorry, back in the day I just read the official "book". The emulator programmers have probably made docs on it though.


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PostPosted: Sat May 13, 2017 12:13 am 
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Rahsennor wrote:
I've always been curious about the PS1's depth sorting and mesh formats. Do you have any links on the topic?

Depth sorting is a software matter on the PS1, as there is no depth buffer. It's a "painter's algorithm" situation; a BSP tree was a common way to do it.


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PostPosted: Sat May 13, 2017 2:51 am 
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I wonder how the later games worked around the int precision problems, causing the jitters. Compare ff7 to ff9, they're like different consoles.


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PostPosted: Sat May 13, 2017 4:52 am 
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It could have been something simple like switching from integer to fixed-point vertex calculations, but I've never dug into the graphical parts of any PlayStation games' code.


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PostPosted: Sat May 13, 2017 7:03 pm 
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rainwarrior wrote:
Depth sorting is a software matter on the PS1, as there is no depth buffer. It's a "painter's algorithm" situation; a BSP tree was a common way to do it.

I know that, that's why I asked. BSP should produce perfect sorting of world geometry and fail completely on anything that moves, which is the opposite of what I've actually observed - moving objects look fine, and world geometry is glitchy. So I'm wondering of the depth sorting was part of Sony's SDK or if every developer had to solve it independantly, and what kinds of algorithms were used to handle moving objects, especially the plethora of bendy stuff.


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PostPosted: Sat May 13, 2017 7:26 pm 
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Google playstation polygon sorting pulls up an article about games using a bucket sort, which divides polygons into lists covering various distance ranges from the camera. Then each list is sorted and passed to the GPU.

American flag sort:
1. Count polygons in each distance range
2. Classify polygons into distance ranges
3. Sort polygons within each distance range


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