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developer:onloopdirection [2015/09/14] (current)
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 +======Brep Loop and Edge Directions======
 +> **Developer:​** //​[[developer:​opennurbs:​home|openNURBS]]//​
 +> **Summary:​** //Discusses Brep loop end edge directions in the openNURBS toolkit.//
 +
 +=====Question=====
 +Is there a function to query if a loop **ON_BrepLoop** is reversed on the face **ON_BrepFace**?​ In other words, whether the boundary of the face agrees with or opposes that of the corresponding loop?
 +
 +Also, is there a way to query if the edge **ON_BrepEdge** direction is reversed? Or, whether an edge curve agrees with the start and end vertices?
 +
 +
 +=====Answer=====
 +Loops are always oriented so that the active region of the face is to the left of the 2D curve. Thus, outer loops are oriented counter-clockwise and inner loops are oriented clockwise.
 +
 +Also, to determine whether or not an edge is reversed, use **ON_BrepEdge::​ProxyCurveIsReversed()**. See opennurbs_curveproxy.h for details.
 +
 +\\
 +
 +{{tag>​Developer openNURBS}}
  
developer/onloopdirection.txt ยท Last modified: 2015/09/14 (external edit)