Emulator

Does this happen in OpenGL?

Yes, this also happens in OpenGL. Found a more obvious case - The save select screen. At higher internal resolutions, the fog fades and the background clouds move further away.

Screenshots showing OpenGL in various internal resolutions, 8x is essentially just blue sky behind the foreground clouds: http://imgur.com/a/eVZix

This is one of those things where the game uses resolution for calculations; turn off scaled EFB if you want to fix it. If you can confirm that fixes it, I'll be closing this issue.

Hello JMC4789. Toggling the 'Scaled EFB Copy' option seems to have no effect on the issue, and still renders differently compared to native internal resolution.

8x Native, Scaled EFB Copy ON: http://i.imgur.com/q1KePL0.jpg
8x Native, Scaled EFB Copy OFF: http://i.imgur.com/dtTWCFX.jpg
Native: http://i.imgur.com/FL00OZ0.jpg

If it's not Scaled EFB I don't know. I remember it being related to Depth Matrix Shaders, but, honestly, I'm guessing if you want it to render more accurately, you're going to need to play at 1x IR in most cases.

It is worth noting that this also happens with various types of anisotropic filtering turned on. Because of this, I think it is similar to Issue #9620

I tried to investigate this today but am still a novice at debugging Dolphin so haven't really found much. I was using Renderdoc and tried to compare textures/vertex-fragment shaders but didn't see anything odd.

JMC4789 wrote:

Reproduced in a simple homebrew test. Something is weird.

Would this be something you should add to https://github.com/dolphin-emu/hwtests ?

After talking to @degasus and @hthh, we believe the issue is related to mip levels. We didn't come to a good conclusive answer on whether there was a workaround but the proposed issue makes sense, here's there comments for preservation:

dagasus

Higher resolutions triggers higher LOD levels
could calculate the mipmap level based on native resolutions, but this would bur almost every texture effect
we use the automatic mip level, just as the hardware itself. But when we scale the framebuffer, we choose a wrong mipmap. This is usually a good enhancement through

hthh

I think I understand it a bit differently: you always have five mipmap levels (32, 16, 8, 4, 2, 1)
the highest resolution level (32) is completely transparent, so the fog clears when you are close
but lower resolutions have opaque fog

Thank you guys for your information, I didn't even think of mip levels when thinking about this problem!

iwubcode wrote:

After talking to @degasus and @hthh, we believe the issue is related to mip levels. We didn't come to a good conclusive answer on whether there was a workaround but the proposed issue makes sense, here's there comments for preservation:

dagasus

Higher resolutions triggers higher LOD levels
could calculate the mipmap level based on native resolutions, but this would bur almost every texture effect
we use the automatic mip level, just as the hardware itself. But when we scale the framebuffer, we choose a wrong mipmap. This is usually a good enhancement through

hthh

I think I understand it a bit differently: you always have five mipmap levels (32, 16, 8, 4, 2, 1)
the highest resolution level (32) is completely transparent, so the fog clears when you are close
but lower resolutions have opaque fog

Thank you guys for your information, I didn't even think of mip levels when thinking about this problem!

I was fiddling with Dolphin Ishiiruka's graphics settings and found out something strange.

As you may know, Ishiiruka has some extra graphical options that don't exist in the master branch.

What I found out is that if you enable texture scaling, the fog's size will change. For example, if you set the internal resolution to 4x and the texture scaling also to 4x (any scaling mode will do, I used XBRZ), the white fog will be rendered correctly. It will work as long as the internal resolution multiplier is the same as the texture scaling multiplier.

Curiously enough, if you set the internal resolution to native and enable texture scaling (setting any multiplier), the fog will be too big.

Also, by selecting "Disable Texture Filtering", the fog disappears entirely.

I know Ishiiruka is not the official emulator, but perhaps this behaviour gives a hint to what is going on?

crudelios wrote:

I was fiddling with Dolphin Ishiiruka's graphics settings and found out something strange.

As you may know, Ishiiruka has some extra graphical options that don't exist in the master branch.

What I found out is that if you enable texture scaling, the fog's size will change. For example, if you set the internal resolution to 4x and the texture scaling also to 4x (any scaling mode will do, I used XBRZ), the white fog will be rendered correctly. It will work as long as the internal resolution multiplier is the same as the texture scaling multiplier.

Curiously enough, if you set the internal resolution to native and enable texture scaling (setting any multiplier), the fog will be too big.

Also, by selecting "Disable Texture Filtering", the fog disappears entirely.

I know Ishiiruka is not the official emulator, but perhaps this behaviour gives a hint to what is going on?

I think that mostly helps confirm suspicion but is a good workaround for now.

Also worth noting that Zelda Twilight Princess's "sunrays" is also due to this issue (see https://wiki.dolphin-emu.org/index.php?title=The_Legend_of_Zelda:_Twilight_Princess_(GC) )