cylinder in opengl

Have a nice day to all

i have a problem in rotation, i have made the cylindrical shape glasses in opengl when i rotate the glass so it become large in size. so please if any body know about this problem please guide me.

Numan Ali
Pakistan

i rotate the glass so it become large in size

to rotate an object you can apply a rotation matrix to the viewmodel matrix with glRotatef
to change the size of an object you can apply a scale matrix to the viewmodel matrix with glScalef

do these prior to drawing the object