Hi, I've been looking at some 2D fluid simulation code in Processing ( http://memo.tv/msafluid_for_processing - relevant code for demo setup near bottom of page) and was wondering how Processing, by default, implements the image scaling and particularly the smoothing that takes place in this code. 

I guess the line of particular interest is:

Can anyone suggest what the equivalent of this is in gl-----()  calls in C? I'm trying to do something similar in OpenGL (scale up an image of a fluid which is being updated every frame and smooth it) and I can't achieve as smooth an effect as Processing seems to. Also curious if anyone knows whether behind the scenes Processing is rendering to a GL texture and scaling it, or drawing a bunch of GL_QUADS like pixels, or something else?

Thanks!