Fix periapsis and apoapsis indicator show up even if they are back of camera
Fix periapsis and apoapsis indicator show up even if they are back of camera

Projected position's Z component apparently becomes less than 0 and
sometimes more than 1, in which case it's back of camera.

msakuta/WebGL-Orbiter,msakuta/WebGL-Orbiter,msakuta/WebGL-Orbiter