glGetFloatv(GL_MODELVIEW_MATRIX, mat);

Under current matrix.how can I get one point's true location?The init x,y and z of the point have been moved by glTranslatef and some others.

Under current matrix,how can I get one camera's(not real camera!!!) position,direction and up_vector?
I have made a 3d object which like a camera,It's moved by glTranslatef and some others.Now I want make the opengl's camera such as the 3d object.How can i get the position,direction and up_vector?

I'm sorry for my poor English.