fixed scaling in opengl -

Someone can help me in scaling the OpenLL; I am using the glScalef () function to scale the polygon , But what do I need to do is scaling it at a certain point, but it has not been achieved with the following function. Can some put some light on it?

normally occurs around the scaling roots, therefore, a point (X, Y, Z) To scale around, someone should translate the Genesis, and return.

Specifically: Translation by (- x, -)

scale

by translating (x, y) , Z)

Note: This is the same thing as rotation around a point.