How to Display Character View Frustum?


I’m a newbie to jme (not a newbie to render engines in general, though). I want to implement a game where I have to display an enemy’s view frustum like this:

It also has to be obstructed by objects:

How can I do this using jme? It looks like a job for shadow maps with distance falloff, but as far as I can see, jme only implements shadow volumes.

Any help would be greatly appreciated.