RPi Rotary Encoder DIY #Spinner - whats missing

[hopwon]

Hi
I have successfully built my own #spinner using an optical rotary encoder connected directly to the GPIO and tested this out on a PiZero after much experimentation using "pigpio" daemon.
Now I want to connect it up to my RPi3 RetroPie setup via the GPIO.
What is the next step in getting ES to recognise it.
In other words, this is NOT a USB device but connected directly to the #RPi.

Has anyone else successfully done this?
What should I be looking at in terms of translating what is coming from the pins to a device ES can recognise?
I have looked in the docs but it seems that it assumes Spinners are always USB devices.
Any pointers and help much appreciated.

[mitu]

You'll need to translate the encoder GPIO signals into an input device - something similar to https://blog.ploetzli.ch/2018/ky-040-rotary-encoder-linux-raspberry-pi/.
How do you want to use the encoder ?

[hopwon]

@mitu It will be a Spinner to control old classics like Arkanoid and Asteroid. No buttons or "press" functionality needed. Just one axis with decent response, i.e. better than a keyboard press.

The link you shared - thank you very much - looks like it could be what I am looking for. I will try later tonight and then see how I pull that new device into RetroPie/ES.

Thanks a million