Irrlicht Engine

Is there a way built in to irrlicht to determine if a billboard object is visible to the player? (I.e on screne/in scene), or does it require some custom functionality?

I think you will have to code a little to get that.

You can find out what is visible in the scene by checking the view frustum. You get that from your active camera with SViewFrustum * frustum = camera->getViewFrustum ();

For a first check you might compare the boundingboxes of frustum and scenenode - if you only need a fast test to ignore nodes that might be already good enough. Otherwise I think you will have to work your way through the math.

Hmm, that shouldn't be much of a problem. I just didn't want to start doing something only to find I had reinvented the wheel

Maybe it would be wise to give access to the culling method. That way one could check for visibility just as the scene manager does. Another alternative would be a visibility map which can be queried after the render loop.. That's much more expensive, though.