Inaccurate primitive placement?

[reaperman]

I've seen this error not only in this emulator but in the graphics plugins in ePSXe as well

it seems as though that some primitives are placed a pixel or two off from where they should be and I'm guessing that faulty documentation is to blame for this and not faulty coding. I'll use Breath of Fire 4 (US) as an example. I attached a screenshot and a save state so that you can see what I'm talking about and so that you can do some debugging as well

version used: 1.10
BIOS used: spch1001.bin
game SLUS #: SLUS_013.24
Windows 2000, Athlon XP 1800, 768MB RAM, Radeon 8500 SE.

here's the screenshot:

notice the dark, glitchy primitives near the camp fire

also I think the glitch is also related to this as well... notice the black dots in the logo:

in the yellow, right to the left of the bottom of the "P"

and this is the link to the save state (right click to save)

[kinghanco]

Yea I notice the dots on the bio screen.

Breath of Fire 3 and 4 have some minor graphics issue. I can show you here. I can't believe nobody have report this at all on their list. They ether didn't see the graphics issues or they didn't want to report this issue. psxemulator.proboards54.com/index.cgi?board=gamecompatibility&action=display&thread=1167336679

Edit: I will put the images back up later on. So don't worry about those right now.

[pSX Author]

I know about this issue. It is caused by not knowing the exact rasterization rules for the GPU. To figure it out exactly will be quite hard and will require me to write a lot of tests to run on a real PS1. I am not bothering with this for now because the bugs it causes are relatively minor.

[reaperman]

admin said:

I know about this issue. It is caused by not knowing the exact rasterization rules for the GPU.

Ah, so that's what it is, interesting

To figure it out exactly will be quite hard and will require me to write a lot of tests to run on a real PS1.

you should probably talk to byuu since he has written test programs for he SNES and that doing it for the PSX should be rather similar in execution. I'm not asking for you to work with him per se, but talking to him, he might be able to give you a few pointers to get you going in the right direction

I am not bothering with this for now because the bugs it causes are relatively minor.

this is an obvious accuracy related issue, so shouldn't this be one of your first priorities? You may find the bugs to be relatively minor, but for other people those bugs are quite undesirable and every PSX emu has it (as far as I know)

just think man, having the first PSX emulator with 100% accurate rasterization.

[reaperman]

sooo, has any work been done on this?

[Heihachi_73]

With that screenshot; the missing thext at the bottom. Doesn't that only happen with ripped games? I made a ripped version of Tekken 2 (minus MDEC/XA/CDA) and a similar glitch shows two single lowercase d's instead of the text. The original CD does't have a problem.

I'd have to put something in - When you run a game with the SCPH-7502 BIOS the screen stays at 512 pixels instead of going back to 480 after. Edit: Happens on all PAL BIOSes.

The PSX logo screen also has a glitch (all known BIOSes tested): Shouldn't the SCEA text at the bottom change along with the region of the game? Tested pSX with a lot of PAL games and it never changes to SCEE like the real PlayStation (my 7502) does. The Japanese version of Tekken 1 doesn't change the text either.

I had an SCPH-5502 "A" model originally (as stated on the box), with a chip, and the well known problem making half of the games only work upside-down. I "swapped" the console with a brand new SCPH-7502 model after and have had no problems since, apart from not being able to play the two non-PAL Tekkens I have (proper versions with instructions and all, I refuse to buy pirated CDs, or even real CDs if they don't have everything with them).

[f1reb4ll]

hei73 said:

The PSX logo screen also has a glitch (all known BIOSes tested): Shouldn't the SCEA text at the bottom change along with the region of the game? Tested pSX with a lot of PAL games and it never changes to SCEE like the real PlayStation (my 7502) does. The Japanese version of Tekken 1 doesn't change the text either.

Those 4 symbols are present only on the original CDs and encoded in the 22 khz wobble (a part of the copy protection), it won't be possible to emulate this correctly. But it's possible to simulate this, setting the correct text depending on the region, like it was made in Xebra.