Paper has used rotated cubic arc for fiffing a curve and has showed the method of curve-fitting with fitting flexuose direction of curve.

文用单拐曲线弧作曲线填充，给出一个能符合指定弯曲方向的填充方法。

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And when I am on the curve I am on the boundary of the surface, so there is a direction along the surface that is the curve and the other one is pointing into the surface.

当我在曲线上时，我是在曲面的边上的，所以一个是沿着曲面的边指，那个就是曲线的定向，另外一个就要指向曲面里面的那个方向。

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And we looked at the component of a vector field in the direction that was normal to the curve.

我们研究的是，向量场在曲线法向量方向的情况。

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