I'm having a bit of trouble understanding what glLoadIdentity(); does in OpenGL . This is a quote from the Redbook.
"Recall that the viewing transformation is analogous to positioning and aiming a camera. In this code example, before the viewing transformation can be specified, the current matrix is set to the identity matrix with glLoadIdentity(). This step is necessary since most of the transformation commands multiply the current matrix by the specified matrix and then set the result to be the current matrix. If you don't clear the current matrix by loading it with the identity matrix, you continue to combine previous transformation matrices with the new one you supply"

I'm not sure what he means by the "new one you supply". Any help would be appreciated?

When you perform any kind of transformations on the scene or on any object, its transformation matrix (the way with which it is displayed) is modified. When any transformations are performed, they are performed on the current matrix which is then modified depending on the operation to be performed.

Since for that particular code snippet, a clean matrix was required, it was necessary to reset the transformation to identity matrix. Hope it made sense, haven't been in touch with graphics for a long time.

Thanks.

My mostly incorrect but simpler answer: "It clears the screen." Again that is probably not a good answer but a person new to 3D may find it useful...