An example of rotation about an axis. (You can change the axis using the controls below.) Sometimes your eyes will play tricks on you and the rotation will look wrong. To verify that the model is indeed rotating about the axis, rotate your view so that you are looking straight down the axis of rotation and then vary the rotation angle.

Please use a browser that supports "canvas"
Set the rotation angle about the axis:
-180 180 angle : 0.0

Change the axis of rotation by rotating it in various directions: (The axis of rotation starts from the x axis.)
0.0 360.0 rotation axis x degrees: 0.00
0.0 360.0 rotation axis y degrees: 0.00
0.0 360.0 rotation axis z degrees: 0.00
axis_of_rotation: <1.0, 0.0, 0.0>

Move the model away from the origin:
-1.0 1.0 tx : 0.00
-1.0 1.0 ty : 0.00
-1.0 1.0 tz : 0.00

Notice that when the model is centered at the origin (or anywhere along the axis of rotation) the model changes orientation but does not change location. If you move the model away from the origin, both its orientation and its location change.