Flip Screen (not rotate but flip)

[patoperales]

Hi guys.
May be is a simple question for you.
I need to flip my screen to use my Raspberry with a dedicated arcade cab that uses a mirror to display the image (Atari Race Drivin).
I found that adding the line "display_rotate 0x10000" to my config.txt do what I need but....only works if I remove the line "dtoverlay=vc4-kms-v3c" ...and then, MAME stops working.
So my question is, Do we have any alternative to this problem?

[mitu]

@patoperales said in Flip Screen (not rotate but flip):

I found that adding the line "display_rotate 0x10000" to my config.txt do what I need but....only works if I remove the line "dtoverlay=vc4-kms-v3c" ...and then, MAME stops working.

I assume you have a Pi4 ? If so, then yes, removing the dtoverlay=vc4-kms-v3d like would break the GPU drivers used by the Pi and render emulators unusable.
The old/previous display_rotate parameters are not applied when the KMS overlay is loaded. Starting the RaspiOS 11 (Bullseye), this is the default and the display_rotate (as well as other similar parameters interpreted by the firmware) are no longer supported.

So my question is, Do we have any alternative to this problem?

You can run either use a Pi3 and - with the current RetroPie image - the display_rotate configuration will work, but you have to keep the installed system as is and not update it. Another option is to install the full RaspiOS image (with the default) and run emulators from the desktop environment (i.e. no RetroPIe). The desktop has a screen configuration utility where you can set the resolution and rotation paramters.

[patoperales]

@mitu Thanks for your response, Your assumption is correct, im running PI4. Do you happend to know if shaders in retroarch may help? I was surfing on retroarch config wit no luck....

[mitu]

@patoperales a 'flip' shader could help, but it's active only during gameplay. There's a 'flip horizontal' shader, does it sound like it would work ?

[patoperales]

@mitu Yes..it could help for me, but I dont have any flip shader available from emulationstation under retropie setup menu. Any way to make it ready? Thank you!!

[mitu]

@patoperales said in Flip Screen (not rotate but flip):

Any way to make it ready? Thank you!!

Shaders are only applied in RetroArch, there's no similar function available outside of the emulator.

[patoperales]

@mitu I google and found "flip-horizontal.glslp", Dowloaded and copied to /opt/retropie/emulators/retroarch/shader. Is that the correct way to add a new shader? Because despite I chosse this new flip-horizontal.glslp shader from RetroPie Setup menu ..nothign happend. It does work with other shaders already available in the same directory...but doesnt work with flip-horizontal.glslp

[mitu]

@patoperales You need both the .glslp (preset) file and the actual shader referenced in the file - the .glsl file.

[patoperales]

@mitu ooohhhhhh!! That was the key, I only had the reference and was missing the actual -code- . Problem solved. Noy I get the video flipped. Thank you so much for your help.