texture grow organically in room space?

Hi, I have a room in 3d, in which i want to place a sphere and then outwardly grow a texture change so that it affects the wall. Ive made a picture to explain what i mean below. The ball will 'explode' and a colour will start to expand slowly filling in the entire wall space. I know how to access and change a texture pixel wise but not sure how I will be able to find out which pixels I need to change. Id also like it to possible grow unequally, with some noise at the edges, like shown. Can someone just point me in a direction/ what i could possible look at?

Thanks