I have a sphere in the scene with position P_world and radius R_world. I want to be able to create a circle with position P_screen and radius R_screen. This is for a gameplay purpose like creating a 2D circle collider that matches the sphere. What I did so far: I know that I can convert P_world to screen space via Camera.WorldToScreenPoint. I don't know the math to convert a "World Space Length" into a "Screen Space Length". My best guess here is to do something where I find how far the sphere is away from the camera, use it as some ratio to scale down the radius?