A very simple, yet very effective GLSL bloom shader. Creative Commons license; https://creativecommons.org/licenses/by-sa/2.0/
Perfect for 2D fullscreen blooming.
Blur size (recommended to keep small - make it high if you want some intense weird drunk effect) Bloom intensity (0 = none, 1 = quite a bit, 80 = wow)
Example uses the application surface and a background to apply bloom to.
Image courtesy of "anotverycreativemind" on flickr.
Based on this shader: https://www.shadertoy.com/view/lsXGWn