Ho:
I am having a bit of trouble with my tumble camera. It is supposed to allow a user to use his mouse to tumble a camera around a particular focal point. mouseX spins the camera left and right while mouseY tumbles the camera vertically. The camera itself always rests in a spherical shell looking at a central focal point.

The tumbling itself works just fine, the problem is when the camera is looking directly down (in the –z direction) at the focal point. As it passes over the point, the camera flips itself PI radians and continues down. This causes a complete discontinuity in the motion. My guess is P3D (or Joggle, I guess) is forcing the z axis to always point “up”. Here my call to the camera function to set the camera position.
Code:

camera(camLoc.x, camLoc.y, camLoc.z, currentFocalPoint.x, currentFocalPoint.y, currentFocalPoint.z, 0, 0, -1);

//‘camLoc’ is the location the camera is placed at
//‘currentFocalPoint’ is the point the camera is looking at
 

Any suggestions on how I can solve this? I'd like a smooth orbiting camera to allow users to tumble objects in all direction.