transforms.py 文件源码

def get(self,
            frame_to,
            frame_from = None):
        '''
        Get the transform from one frame to another, assuming they are connected
        in the transform tree. 

        If the frames are not connected a NetworkXNoPath error will be raised.

        Arguments
        ---------
        frame_from: hashable object, usually a string (eg 'world').
                    If left as None it will be set to self.base_frame
        frame_to:   hashable object, usually a string (eg 'mesh_0')

        Returns
        ---------
        transform:  (4,4) homogenous transformation matrix
        '''

        if frame_from is None:
            frame_from = self.base_frame
        transform = np.eye(4)
        path = self._get_path(frame_from, frame_to)

        for i in range(len(path) - 1):
            data, direction = self.transforms.get_edge_data_direction(path[i],
                                                                      path[i+1])
            matrix = data['matrix']
            if direction < 0: 
                matrix = np.linalg.inv(matrix)
            transform = np.dot(transform, matrix)
        return transform