Change GameObject material/color animated spreading from hitting point

There was a game as a child a decade ago, and as I remember you had a paint gun and could shoot buildings, when the bullet collided with the building the color spreaded animated from the collision point until it filled the complete object. The the image and link below to see my desired goal. There hundred or thousands of different shapes, so however it can be done, it should be dynamic

I thought it's maybe only possible with shaders, and idk shaders enough yet so is it possible to accomplish almost the same (maybe even without shaders)?

Current progress: http://www.giphy.com/gifs/jaXEvu1QJzYD5eD5GM