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Re: Playstation WIP thread [Re: crazyc] #85069 01/30/13 06:00 PM
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AFAIK the joystick does respond like the pad (the joystick appears as the left stick) but I think the IDs are different.

Re: Playstation WIP thread [Re: crazyc] #85070 01/30/13 06:41 PM
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Originally Posted By crazyc
Originally Posted By zillion
Descent NTSC-U

Works perfectly! Controls surprisingly well! FMVs look great!

This game also supports the Playstation Analog Joystick, so hopefully someday we'll have that as a slot device!

Any docs anywhere about the joystick? If it responded like the analog pad it would just work (probably).


Is this of any use? Search for "SCPH-1110"

http://www.zen35383.zen.co.uk/stnield/psxpads.txt

Re: Playstation WIP thread [Re: crazyc] #85071 01/30/13 06:54 PM
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That's perfect. And I forgot about the "alternate" analog mode of the dual-analog where it emulated the analog joystick smile

Re: Playstation WIP thread [Re: R. Belmont] #85073 01/30/13 07:08 PM
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Originally Posted By R. Belmont
That's perfect. And I forgot about the "alternate" analog mode of the dual-analog where it emulated the analog joystick smile


Is that the controller that has the red AND green analog LEDs? That's pretty fancy!

Re: Playstation WIP thread [Re: crazyc] #85074 01/30/13 07:32 PM
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Looks like it should be straightforward unless it expects different replies for config mode commands.

Re: Playstation WIP thread [Re: crazyc] #85076 01/30/13 08:03 PM
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I apologize for having two off-topic questions about the playstation hardware, but here goes...

pSX seems to be the only playstation emulator that attempts the dithering effect that I remember seeing on Metal Gear Solid. Is that a feature of the hardware? I'm guessing it is and will be emulated in MESS someday.

The other question is something that I've always wondered about the playstation hardware... In most 3D playstation games (Metal Gear Solid and Descent are ones I've seen recently), the geometry (or maybe textures) of walls sometimes seems to jump around (like they aren't translating smoothly). Is that an artifact of an imprecise floating point unit or something else?


(edit: Thank you for the answers! It's really interesting!)

Last edited by zillion; 01/30/13 08:52 PM.
Re: Playstation WIP thread [Re: crazyc] #85077 01/30/13 08:08 PM
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I'm far from a graphics expert but my understanding is the lack of perspective correct texturing causes the warping.

Re: Playstation WIP thread [Re: crazyc] #85078 01/30/13 08:39 PM
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Textures "warp" as they go off-axis because of the lack of perspective correction. Geometry jitters because the PlayStation uses fixed-point calculations. It sounds primitive now, but it had hardware T&L in 1994 and something had to give smile

Regarding the dithering, that's a hardware feature to smooth out Gouraud shaded polygons. Early hardware (including US launch units) shaded and dithered in 4 steps, later ones did 16.

Re: Playstation WIP thread [Re: R. Belmont] #85079 01/30/13 09:13 PM
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Originally Posted By R. Belmont
Textures "warp" as they go off-axis because of the lack of perspective correction. Geometry jitters because the PlayStation uses fixed-point calculations. It sounds primitive now, but it had hardware T&L in 1994 and something had to give smile


PSX had as much hardware T&L as a PC with a Pentium MMX and a Voodoo 1, which is to say none, unless I've been in the dark all these years and GTE opcodes are executed asynchronously alongside the scalar opcodes...

ETA: At the risk of over-explaining, my point is that "hardware T&L" has always referred to being able to offload the geometry transforms piecemeal to the GPU to be executed asynchronously. MMX (and later, SSE) could be used to accelerate transforms just like the GTE (modulo some lighting-specific opcodes in the GTE), but nobody would have called that "hardware T&L" at the time.

Re: Playstation WIP thread [Re: crazyc] #85080 01/30/13 09:21 PM
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GTE opcodes do execute asynch, or at least Icer spent a lot of time interleaving MIPS instructions with them and counting the cycles ;-)

Also, MMX was, as I understand it, completely useless for T&L. Whereas all the GTE ops are very specific and very useful for graphics.

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