ofxgrabcam + rotate

how would i rotate the camera around just one axis at a time.

i know i can grab the scene and shift / rotate it.

but i would like to adjust what is seen through the viewport in such a way that it appears the world is on an angle.
(like looking out a window with the floor not horizontal but tilted)

seems like pan tilt roll should do it, but how would i define the rotation’s origin?

thanks for any advice.

s.

using

ofQuaternion q(c_rotX,ofVec3f(1,0,0),c_rotY,ofVec3f(0,1,0),c_rotZ,ofVec3f(0,0,1));
camera.setGlobalOrientation(q);

seems to do some sort of look around with the center of the viewport being the center of rotation, always.