From 87ae516e1ecc15d3b5db2d44caa8d0db43013d61 Mon Sep 17 00:00:00 2001
From: balrobs <73989799+balrobs@users.noreply.github.com>
Date: Thu, 10 Jun 2021 19:26:30 +0200
Subject: [PATCH] Fixing connection error for structural surface members

This changes improve connections between structural surface members with coincident edges
See forum: https://forum.freecadweb.org/viewtopic.php?f=39&t=54286&p=509311#p509311
---
 src/Mod/Arch/exportIFCStructuralTools.py | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/Mod/Arch/exportIFCStructuralTools.py b/src/Mod/Arch/exportIFCStructuralTools.py
index a154aa05d8..aa879cc198 100644
--- a/src/Mod/Arch/exportIFCStructuralTools.py
+++ b/src/Mod/Arch/exportIFCStructuralTools.py
@@ -139,7 +139,7 @@ def createStructuralMember(ifcfile, ifcbin, obj):
 
     """Creates a structural member if possible. Returns the member"""
 
-    global structural_nodes
+    global structural_nodes, structural_curves
     structuralMember = None
     import Draft
     import Part
@@ -277,19 +277,29 @@ def createStructuralMember(ifcfile, ifcbin, obj):
                 
     # check for existing connection curves
     for edge in edges:
-        if edge in structural_curves:
-            if structural_curves[edge]:
+        verts12 = tuple([edge.Vertexes[ 0].Point.x, edge.Vertexes[ 0].Point.y, edge.Vertexes[ 0].Point.z,
+                         edge.Vertexes[-1].Point.x, edge.Vertexes[-1].Point.y, edge.Vertexes[-1].Point.z])
+        verts21 = tuple([edge.Vertexes[-1].Point.x, edge.Vertexes[-1].Point.y, edge.Vertexes[-1].Point.z,
+                         edge.Vertexes[ 0].Point.x, edge.Vertexes[ 0].Point.y, edge.Vertexes[ 0].Point.z])                
+        verts12_in_curves = verts12 in structural_curves
+        verts21_in_curves = verts21 in structural_curves
+        if verts21_in_curves:
+            verts = verts21
+        else:
+            verts = verts12
+        if (verts12_in_curves or verts21_in_curves):
+            if structural_curves[verts]:
                 # there is already another member using this curve
-                strucCrvConn = structural_curves[edge]
+                strucCrvConn = structural_curves[verts]
             else:
                 # there is another member with same edge, create a new curve connection
                 strucCrvConn = createStructuralCurve(ifcfile, ifcbin, edge)
-                structural_curves[edge] = strucCrvConn
+                structural_curves[verts] = strucCrvConn
             ifcfile.createIfcRelConnectsStructuralMember(
                 uid(), None, None, None, structuralMember, strucCrvConn, None, None, None, None)
         else:
             # just add the curve, no other member using it yet
-            structural_curves[edge] = None
+            structural_curves[verts] = None
     return structuralMember