Help me with scent

[juankax]

Hi!

I want to implement a scent-like system in my program. It would work in a way, that if there is color on the canvas, then it would spread to the pixels nearby (kinda like a blur) and disappear over time. I imagine it would look like the colors diffuse, which is what I want.
Do I need some sort of shader to do this? If so, how? I don't really understand how they work, so any help would be really appreciated!

Thanks!

[Nikki]

maybe this is useful:
http://www.roguebasin.com/index.php/Tra ... _and_Sound