For some shapes, for instance rectangles, circles, rounded rectangels, it makes a lot of sense to be able to send per instance data into the sdf function so you could change side length/radius without compiling a new shader.

I'm not really sure what the best way to implement this would be... One simple way could be to just have a couple of floats of "user data" that will just always be passed around. It may come with a performance cost, though.

Perhaps some way to toggle it with shader defs would be good, and then have it be an optional component SdfParameters(Vec4) so we don't pay the price for it when not used.