Hello

I am doing something in Open GL and here is my problem:

I've got polygon rotating around z-axis and I want it to stop rotating at 60 degrees and then return it back to stating point.
How could i do this:
here is the code:

float angle= 1.0;

.......

glPushMatrix();
glTranslatef(-50,0.0,0.0);
glRotatef(-angle,0.0,0.0,0.1);

glBegin(GL_QUADS);

glColor3f(0,0,0); glVertex3f(0.0f, 10.0f, -10.0f);
glColor3f(0,0,0); glVertex3f(0.0f, 10.0f, 10.0f);
glColor3f(0,0,0); glVertex3f( 50.0f, 10.0f, 10.0f);
glColor3f(0,0,0); glVertex3f( 50.0f, 10.0f, -10.0f); glEnd();

glPopMatrix();