The world-space radius to draw a ring edge at, given the radius the body
itself is being drawn at. Scaling off the body's rendered radius rather
than converting the ring's km directly keeps the ring in proportion to
the body even when the pixel floor (pixelFloor.ts) has inflated a small
body well past its true size — otherwise a floored planet would swallow
its own rings.
The world-space radius to draw a ring edge at, given the radius the body itself is being drawn at. Scaling off the body's rendered radius rather than converting the ring's km directly keeps the ring in proportion to the body even when the pixel floor (pixelFloor.ts) has inflated a small body well past its true size — otherwise a floored planet would swallow its own rings.