Add crack lines to the object in touch point (by code)

Hi everyone, I have "simple" 3D objects in the game like a cylinder, egg, sphere, etc. I use materials on them. Materials use 2D sprites. When a user clicks on the object, the game should draw cracks on the object from the touchpoint (lines\ starts\combinations). I don't need to change any physical characteristics of the objects. Only image.

What is the simplest way for it? Thank you!