API Reference > geometry-core > Curve > LineString3d > quickUnitNormal quickUnitNormal Method compute and normalize cross product among 3 points on the linestring. "any" 3 points are acceptable -- no test for positive overall sense. This is appropriate for polygon known to be convex. use points spread at index step n/3, hopefully avoiding colinear points. If that fails, try points 012 quickUnitNormal(result?: Vector3d): undefined | Vector3d Parameter Type Description result Vector3d computed normal. Returns - undefined | Vector3d Defined in curve/LineString3d.ts Line 775 Last Updated: 12 June, 2024