I want to be able to achieve spell effects that cause a fragmenting/discoloring effect on the sprite. The first couple seconds of this video http://www.youtube.com/watch?v=HNCFh7mkvuc shows what I mean. When the enemy gets hit by an electric attack, the effect I'd like to achieve activates (in yellow).
I'll have to use shaders to do this (if I don't, other, practical ways to do it would be extremely helpful). I have no idea where to start with a shader like this (beyond the obvious - using time and base color as parameters), and was curious if someone had something similar I could use as a base, or had a good idea where to start. I know the basic of glsl, but was hoping to spare myself some pain if someone has something like this already or could provide a starting point.
Any help would be appreciated,
Just to clarify, I'm looking to apply this against a 2D texture in OpenGL using glsl shaders