曲线切向 节点输出曲线在每个控制点指向的方向，这取决于曲线的方向（可以使用 /modeling/geometry_nodes/curve/reverse_curve 控制）。输出值是归一化的向量。
For NURBS and Bézier spline curves, keep in mind that the value retrieved from this node is the value at every control point, which may not correspond to the visible evaluated points. For example, a Bézier spline might have 48 evaluated points, but only four control points, if its resolution is 12. For NURBS splines the difference may be even more pronounced and the result may not be as expected. A 重采样曲线 can be used to create a poly spline, where there is a control point for every evaluated point.