This is a screen of a recent OpenGL app I wrote for the OpenGL Challenge.
Nothing that special (a joyriding simulation), but curious is a round noisy
lightmap I added over the scene when I was done with a frame. The noise is
procedurally generated about 20 x a second (I run around 100 fps on a GeForce2),
rides atop a fixed noise value per line, and a cone, providing an effect of an
"old-time" television: noise, discrete horizontal line noise for a slight
banding effect, and corner vignetting.
The effect is better when viewed animated:
The OpenGL Challenge site has it w/ source: http://OGLChallenge.OTri.net/.
The effect can be toggled (key "i"), noise level adjusted (), and size
adjusted (). Or try for a popup menu, and select "Options",
there are plenty of adjustors.
Also of note in the app is a retro 3-2-1 intro, and a closing screen
"splintering" effect, which does 255 variations of "chop the screen into bits
and move them". Toggle key "x" to demo.