三维图形平面单元内外法向量的计算及应用

Calculation and Application of Interior or Exterior Normal-vector of 3-dimension Planer Elements

利用两相邻表面单元的外（或内）法向量关系所遵循的规律，给出了三维图形平面单元外法 向量的算法．并将该算法应用到有限元图形处理中，提高了运算速度，增强了图形表达效果。

This paper presents the algorithm on interior or exterior normal-vector of 3-dimension planar elements by the law between two near elements.Applied to the finite-element post-processing,the algorithm may improve the calculating velocity and expression effect.