Two Pass Gaussian Blur for Bloom Effect

 

This is a demo of Bloom effect I made in OpenGL using a two pass Gaussian Blur, I will explain the process to blur the image below:

If we look at the next video, in RenderDoc we can watch the brightness texture I blurred:

I used Ping Pong Buffers for this technique, which is basically to use two framebuffers that blur the input brightness image, one horizontallly and the other vertically. (That is the reason of the name two pass Gaussian Blur). 

This blurring happens for multiple passes, if we iterate sufficiently we can get a pretty good blur effect, in this case I iterated 10 times in total, which is 5 blur passes (1 horizontal and 1 vertical).

This blurred image is added on top of the original HDR color buffer to get the Bloom effect.