There isn't anything to learn.
optionally glBlendEquation() but I still have yet to use that for anything other than default.
It comes down to what you want to do with glBlendFunc(), If you want a cloud that has alpha, the GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA. If you want a glowing effect, GL_ONE, GL_ONE works. Thats pretty much it.
If your cloud is glColor4f(1,1,1,.7), then
will make the pixel drawn .7*incoming pixel + (1.0-.7) = .3*current pixel. = mostly cloud.
if the cloud is not very dense, then
If your cloud is glColor4f(1,1,1,.2), then
will make the pixel drawn .2*incoming pixel + (1.0-.2) = .8*current pixel. = not much cloud showing.
Edited by dpadam450, 19 July 2012 - 02:00 PM.