Point the camera in the direction of the given vector

def view_vector(self, vector, viewup=None):
        """Point the camera in the direction of the given vector"""
        focal_pt = self.center
        if viewup is None:
            viewup = rcParams['camera']['viewup']
        cpos = [vector + np.array(focal_pt),
                focal_pt, viewup]
        self.camera_position = cpos
        return self.reset_camera()