How to draw waves in X and Y position like this oscilloscope example? I would like to know how to "draw sound" so i could achieve shapes like the ones in this video:
http://www.modularsynth.ru/en/2014/01/24/ed120_chaotica/
I have programming background ( as in: i can't read complex equations ) so please, is possible i would like to see explanation by "code" even if just pseudo-code, i don't mind seeing the "hardcore" equations, but at this stage i can't read them so they wouldn't be very helpful, although i would love to see the equation side by side with code ( and hopefully learn something from it ).
Thank you very much
( i'm new on stackexchange, so sorry if i'm on the wrong "department" )
 A: [this is not physics at all, but I'll answer it anyway here and you can migrate it to stackoverflow if desired]
You connect the left and right stereo audio outputs from the sound port on the PC to the X and Y inputs on the oscilloscope, and set the scope to XY mode. In this mode the electron beam is steered on the screen by the voltage on the X and Y inputs, which in turn are the digital->analog conversions of the sound data you play on the PC's soundcard.
So you need code on the PC that sends a stereo digital audio buffer to the soundcard and set it to repeat (or send the same block of audio continuously), and then put the X positions for the beam in the Left channel and the Y positions in the Right channel (or vice versa).
To draw a circle, you therefore calculate for example (for an 8-bit sound file) 127*cos(k*t) in the left channel buffer, and 127*sin(k*t) in the right channel buffer. t is the buffer index, say from 0 to 255, and k should map the buffer to a whole number of circles, so for a buffersize of 256 in total, k = 2*pi/256.
You play the buffer differently depending on the OS but for testing, just output the data to a raw file, and open it in a sound editing program, there you can see that the sin/cos waves look OK and you can play it on repeat while you test with the scope.
