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Some problems I found playing on Zenfone 5 Lite
04-28-2015, 03:15 PM (This post was last modified: 04-28-2015 03:16 PM by fivefeet8.)
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RE: Some problems I found playing on Zenfone 5 Lite
(04-28-2015 02:02 AM)DarkZX00 Wrote:  
(04-20-2015 09:25 PM)fivefeet8 Wrote:  Probably because your phone uses an Imagine PowerVR GPU. They are known to have rendering bugs with PPSSPP.

Are there plans on fixing these issues on later releases?

Here is a quote from a PPSSPP dev:

"Anyway, the problem is that the GPU just wants to DRAW. It doesn't want someone constantly grabbing it's arm and saying "hey wait, not that one. You have to skip that pixel." This makes PowerVR especially very slow, because it's not built to stop-and-go like that (and, as I mentioned, it's somewhat of an antiquated practice to make the gpu do that.)

If someone were to redo the way the game draws things, and make it use more modern techniques, the problem would go away. That wouldn't be emulation though, that would be a port or a remake.

Aside from that though, the PowerVR SGX540 and 544 have not terribly good precision in shaders. One thing was fixed recently by replacing a modulus (remainder of division) math operator with a function that did _exactly_ what the spec _requires_ the modulus operator to be equivalent to. So some of the mathematics on the gpu (or its drivers, hard to tell) don't actually have correct results. That's kinda scary, and makes it hard to make things come out right, especially when a lot of PSP games do really neat tricks to get 150% out of the PSP hardware, and we have to translate these neat tricks into things that work on OpenGL.

We may be able to find ways to workaround the bad math and precision in that GPU, but ultimately it's just going to make things slower, not faster, because we will have to do more complicated things or do them in more steps or in multiple ways to get the precision necessary for things to actually work and show up.
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RE: Some problems I found playing on Zenfone 5 Lite - fivefeet8 - 04-28-2015 03:15 PM

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