Rotation and shaders

I’m rather confused by the rotation results I’m seeing here.

What is the supposed correct way of rotating so that there is no mismatch between gui and video direction with MAME and FBNeo and shaders are correctly displayed?

FBNeo does rotation wrong and I made an issue on GitHub like 2 years ago, lol. The programmer couldn’t understand why you would want vertical games to remain un-rotated and he eventually just insulted me :laughing:.

We have too many ways to rotate things and we need just one way, which is already in the video options in RA. Automatically rotating stuff causes all kinds of headaches. The core should not be altering the image in any way, that should all be done in the frontend and not under the hood. Just my opinion. :man_shrugging:

MAME gets it right, it displays vertical games unrotated and the user rotates the image by using the rotate option in RA.

I’ve seen a lot of people mentioning this over the past year or so, but good luck getting FBNeo fixed. Maybe if enough people post the same issue on GitHub the programmer will reconsider his position.

In MAME, first image is rotated by internal MAME menu, (screen was rotated by me Irfanview afterwards), the second one is rotated by RA screen rotation.

Isn’t the first one correct ?

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first one is correct

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Yes, it looks there is some consistency in the sense that you can get a correct emulation image if using the core options and rotating the display, but RA rotation options mess things up and it’s not possible to make the gui behave accordingly.

btw, what shader is that? Looking for something that works for vertical games, guest-dr-venom is good but the scanlines get wonky when you alter the vertical scale, for some reason.

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I always use crt-hyllian for TATE, but crt-geom’s TATE mode is pretty good these, too, IIRC

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That’s TV-Out Interlacing, it makes things very obvious by default when something is wrong with scaling, that and the parameters are useful for some quick testing. Part of why I was just looking into vertical content again now was also that I’m planning to use a 480p EDTV (easily rotable), but as you can probably imagine, not a lot of shaders are usable with that :neutral_face:

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The FBNeo approach has a nice benefit, that allows many crt shaders to display vertical scanlines by default. The drawback is a loss of mask accuracy with HW rotation after the shaders are applied. But’s it’s not this of a great deal.

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FB Neo’s rotation also doesn’t work in the d3d10-12 drivers, since it relies on set_viewport, which hasn’t been implemented in them yet: https://github.com/libretro/RetroArch/issues/7660

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