Swap face bound orientation of Cube Advanced Brep

[thbeu]

I failed to obtain a positive volume of the Cube Advanced Brep.

One solution is to swap the face bound orientation of five faces.

Can you please cross-check and verify. Thanks a lot.

[aothms]

Thanks for looking into this. This is quite a puzzle. I know there are some issues wrt to orientation in this model. The thing I'm most interested in is making sure that every edge is visited twice in opposite direction so that we have a manifold structure. I don't think your fix completely resolves this:

If we print the tree structure and underneath evaluated edge start and end points, in my interpretation we obtain the following (partially printed below). The evaluated begin->end points with an x in front are visited twice in the same direction.

• When the Face Bound is reversed it means all edges are reversed and the order within the bound is reversed.

• When an individual Oriented Edge is reversed it only means its respective underlying edge begin and end are reversed.

• Face and Edge sense itself I think only affect the parametrization of the curve / normal of the surface, it doesn't affect topology (but I'm not 100% sure of this).

#104=IfcAdvancedFace((#99),#100,.T.)
 #99=IfcFaceOuterBound(#98,.F.)
  #98=IfcEdgeLoop((#94,#95,#96,#97))
    #94=IfcOrientedEdge(*,*,#49,.T.)
      #49=IfcEdgeCurve(#30,#36,#48,.T.)
       #30=IfcVertexPoint(#31)
        #31=IfcCartesianPoint((-0.5,-0.5,0.0))
       #36=IfcVertexPoint(#37)
        #37=IfcCartesianPoint((-0.5,0.5,0.0))
x (-0.5, -0.5, 0.0)->(0.5, -0.5, 0.0)
x (0.5, -0.5, 0.0)->(0.5, 0.5, 0.0)
x (0.5, 0.5, 0.0)->(-0.5, 0.5, 0.0)
x (-0.5, 0.5, 0.0)->(-0.5, -0.5, 0.0)
#115=IfcAdvancedFace((#110),#111,.T.)
#110=IfcFaceOuterBound(#109,.T.)
  (-0.683012701892219, -0.183012701892219, 1.0)->(0.183012701892219, -0.683012701892219, 1.0)
  (0.183012701892219, -0.683012701892219, 1.0)->(0.683012701892219, 0.183012701892219, 1.0)
  (0.683012701892219, 0.183012701892219, 1.0)->(-0.183012701892219, 0.683012701892219, 1.0)
  (-0.183012701892219, 0.683012701892219, 1.0)->(-0.683012701892219, -0.183012701892219, 1.0)
#131=IfcAdvancedFace((#121),#122,.F.)
 #121=IfcFaceOuterBound(#120,.F.)
  #120=IfcEdgeLoop((#116,#117,#118,#119))
   #116=IfcOrientedEdge(*,*,#93,.T.)
    #93=IfcEdgeCurve(#36,#38,#92,.T.)
     #36=IfcVertexPoint(#37)
      #37=IfcCartesianPoint((-0.5,0.5,0.0))
     #38=IfcVertexPoint(#39)
      #39=IfcCartesianPoint((-0.683012701892219,-0.183012701892219,1.0))
   #117=IfcOrientedEdge(*,*,#65,.T.)
    #65=IfcEdgeCurve(#38,#44,#64,.T.)
     #38=IfcVertexPoint(#39)
      #39=IfcCartesianPoint((-0.683012701892219,-0.183012701892219,1.0))
     #44=IfcVertexPoint(#45)
      #45=IfcCartesianPoint((0.183012701892219,-0.683012701892219,1.0))
   #118=IfcOrientedEdge(*,*,#81,.F.)
    #81=IfcEdgeCurve(#30,#44,#80,.T.)
     #30=IfcVertexPoint(#31)
      #31=IfcCartesianPoint((-0.5,-0.5,0.0))
     #44=IfcVertexPoint(#45)
      #45=IfcCartesianPoint((0.183012701892219,-0.683012701892219,1.0))
   #119=IfcOrientedEdge(*,*,#49,.T.)
    #49=IfcEdgeCurve(#30,#36,#48,.T.)
     #30=IfcVertexPoint(#31)
      #31=IfcCartesianPoint((-0.5,-0.5,0.0))
     #36=IfcVertexPoint(#37)
      #37=IfcCartesianPoint((-0.5,0.5,0.0))
x (-0.5, 0.5, 0.0)->(-0.5, -0.5, 0.0)
  (-0.5, -0.5, 0.0)->(0.183012701892219, -0.683012701892219, 1.0)
  (0.183012701892219, -0.683012701892219, 1.0)->(-0.683012701892219, -0.183012701892219, 1.0)
  (-0.683012701892219, -0.183012701892219, 1.0)->(-0.5, 0.5, 0.0)
#147=IfcAdvancedFace((#137),#138,.F.)
#137=IfcFaceOuterBound(#136,.F.)
  (0.5, -0.5, 0.0)->(0.683012701892219, 0.183012701892219, 1.0)
  (0.683012701892219, 0.183012701892219, 1.0)->(0.183012701892219, -0.683012701892219, 1.0)
  (0.183012701892219, -0.683012701892219, 1.0)->(-0.5, -0.5, 0.0)
x (-0.5, -0.5, 0.0)->(0.5, -0.5, 0.0)
#163=IfcAdvancedFace((#153),#154,.F.)
#153=IfcFaceOuterBound(#152,.F.)
  (0.5, 0.5, 0.0)->(-0.183012701892219, 0.683012701892219, 1.0)
  (-0.183012701892219, 0.683012701892219, 1.0)->(0.683012701892219, 0.183012701892219, 1.0)
  (0.683012701892219, 0.183012701892219, 1.0)->(0.5, -0.5, 0.0)
x (0.5, -0.5, 0.0)->(0.5, 0.5, 0.0)
#179=IfcAdvancedFace((#169),#170,.F.)
#169=IfcFaceOuterBound(#168,.F.)
  (-0.5, 0.5, 0.0)->(-0.683012701892219, -0.183012701892219, 1.0)
  (-0.683012701892219, -0.183012701892219, 1.0)->(-0.183012701892219, 0.683012701892219, 1.0)
  (-0.183012701892219, 0.683012701892219, 1.0)->(0.5, 0.5, 0.0)
x (0.5, 0.5, 0.0)->(-0.5, 0.5, 0.0)

[thbeu]

Thanks for the feedback. I did exactly the same with print-debugging on point level. I also tried to reverse edges individually and still failed. That's why I came up with the proposed changes. There are other fixes likely.

Before:

After: