Let's say what I have is a planet like so:
What I want to do is to add a scorch mark like this:
Now, if this was a one time thing, it wouldn't be a problem. I'd make a sprite for this specific occasion and move on. The problem is however, I want the scorch marks to look different and to not use all that much memory (because there might be too many of them on screen and this is for mobile).
The scorch marks will almost always be the same size but the planets will be different sizes, so one sprite that is scaled is not what I want (it would look too big on bigger planets and too small on smaller ones). Also, I want to be able to rotate the sprite to make it look different.
I've thought about adding another sprite on top of the planet (a border-like hack) to hide this but there can be other planets that are really close by to this one and they would be hidden too.
I've looked at a lot of stuff but nothing like this exists.
I've managed to create some stuff with a stencil shader and the use of a sphere with zero Z scale. This does create the problem of showing the sprite on other planets and I haven't been able to push forward on this.
This is what I can currently make:
This is what I need to make: