any idea how? for processing, openframeworks, unity3d...

is there a general way to get the output of such? is it possible at all? or maybe via a virtual display?

looking forward to get this working, but i do not have a clue how...

Edit: There is an older openframeworks addon here: https://github.com/arturoc/ofxGstV4L2Sink, but it doesn't work with the current release of OF (0.9 as of writing this). I'm attempting to get it working, but any help would be very appreciated.

Edit 2: Streaming from Processing can be done using ffmpeg, through the VideoExport library. An example script can be found in this gist, which relies on creating three v4l2loopback devices beforehand.