Mine

        my $width = (32 * 2 ) / 640 ;
        my $height = (32 * 2)  /  480 ;

        my $x = -1;
        my $y = 1;
        my $xmax = $x + $width;
        my $ymax = $y - $height;
       
        glBegin(GL_QUADS);                                   
        glVertex($x, $y, 0.0);         # Top Left
        glVertex( $xmax, $y, 0.0);     # Top Right
        glVertex( $xmax,$ymax, 0.0); # Bottom Right
        glVertex($x,$ymax, 0.0);       # Bottom Left   
        glEnd();                       # done with the polygon