> Hey MooglyGuy, it was me on Reddit and I pinged you back on Twitter but not sure if
> you noticed. I'll repeat what I said there:
> Hey, not a problem.
> Arch Linux 64bit. Kernel 4.10.13. Nvidia GTX 1060 GPU. 381.22 Nvidia drivers.
> Command line I'm using is simply "sdlmame (gamename)" and I'm setting the shader in
> mame.ini via "bgfx_screen_chains hq4x".
> Here's what the shaders look like in MAME - http://imgur.com/a/Xu1w1 - you probably
> don't need the RetroArch ones for comparison as this isn't a case of them looks "just
> slightly off" haha.
Sorry about that, I've been completely busy with personal stuff for the past couple of days, so I haven't had the chance to go through my Twitter backlog yet.
I confirm that your issue also exists on Windows: With the DirectX 11 BGFX backend with the HQ4x chain, btime looks fine (for sufficiently loose definitions of 'fine', since it's HQ4x we're talking about). With the OpenGL BGFX backend, same chain and game, I get the same sort of corruption you're seeing. With the DirectX 9 BGFX backend, same settings, I get no image at all.
Having dug into it, I don't see anything that leaps out at me as being overtly wrong when it comes to any sort of half-texel offset, so I'm going to have to dig into it a bit more deeply with either RenderDoc or NVidia NSight and figure out exactly where things are going wrong.
On a personal note, thank you for actually taking the time to put together such a well-written bug report. There are a lot of users who have probably tried it, found it non-functional, and in turn simply told other people that it doesn't work, and not to use it. Now that I have a bit clearer a picture of the issue, I can actually start to look into it. So, again, thanks!