snake.py 文件源码

def reshape(self, vertices):
        """Make snake smoother."""

        arc_length = 0
        # calculate the total arc-length
        for i in range(1, self.length):
            arc_length += norm(vertices[i] - vertices[i - 1])
        # average length for each segment
        seg_length = arc_length / (self.length - 1)
        if self._bc == 'PBC':
            arc_length += norm(vertices[0] - vertices[-1])
            seg_length = arc_length / self.length
        for i in range(1, self.length - 1 if self._bc == 'OBC' else self.length):
            # normalized tangent direction at node i-1
            tan_direction = vertices[i] - vertices[i - 1]
            tan_direction /= norm(tan_direction)
            # move node i
            vertices[i] = vertices[i - 1] + tan_direction * seg_length
        return vertices