3D to 2D Space coordinates

How do you convert 3D to 2D Space coordinate system when you want some 2d effect like OCLRays or Optical Flares to be connected to a 3D Point Light?

Using a Locator3D - you can then connect any parameter to its 2D coordinates (as seen through a Camera 3D) using right click -> connect to.

But be sure to feed the camera into the locator 3D or it doesn't work. Just putting it in the 3D scene isn't enough.

Thanks you!