Painting on a waterproofing membrane
I've been trying to work out how to use an object (in this case a roller or a paintbrush) to paint colour over some text. I want the colour to appear over the text gradually, just as if it were being painted with the roller. I can move the roller along a motion path, but how do I paint the text?
I'd like to incorporate this into a quiz about waterproofing, where the learner paints their chosen answer and then hits submit.
Do I need a graphics package to do this?