Re-worked Part::checkIntersection to give less false positives for pattern features

src/Mod/Part/App/PartFeature.cpp

@@ -27,6 +27,7 @@
 # include <gp_Trsf.hxx>
 # include <gp_Ax1.hxx>
 # include <BRepBuilderAPI_MakeShape.hxx>
+# include <BRepAlgoAPI_Fuse.hxx>
 # include <BRepAlgoAPI_Common.hxx>
 # include <TopTools_ListIteratorOfListOfShape.hxx>
 # include <TopExp.hxx>
@@ -336,33 +337,50 @@ std::vector<Part::cutFaces> Part::findAllFacesCutBy(
     return result;
 }
 
-const bool Part::checkIntersection(const TopoDS_Shape& first, const TopoDS_Shape& second, const bool quick) {
+const bool Part::checkIntersection(const TopoDS_Shape& first, const TopoDS_Shape& second,
+                                   const bool quick, const bool touch_is_intersection) {
     Bnd_Box first_bb, second_bb;
     BRepBndLib::Add(first, first_bb);
     first_bb.SetGap(0);
     BRepBndLib::Add(second, second_bb);
     second_bb.SetGap(0);
 
-    // Note: Both tests fail if the objects are touching one another at zero distance!
+    // Note: This test fails if the objects are touching one another at zero distance
     if (first_bb.IsOut(second_bb))
         return false; // no intersection
-    //if (first_bb.Distance(second_bb) > Precision::Confusion())
-    //    return false;
     if (quick)
         return true; // assumed intersection
 
     // Try harder
-    BRepAlgoAPI_Common mkCommon(first, second);
-    // FIXME: Error in boolean operation, return true by default
-    if (!mkCommon.IsDone())
-        return true;
-    if (mkCommon.Shape().IsNull())
-        return true;
+    if (touch_is_intersection) {
+        // If both shapes fuse to a single solid, then they intersect
+        BRepAlgoAPI_Fuse mkFuse(first, second);
+        if (!mkFuse.IsDone())
+            return false;
+        if (mkFuse.Shape().IsNull())
+            return false;
 
-    TopExp_Explorer xp;
-    xp.Init(mkCommon.Shape(),TopAbs_SOLID);
-    if (xp.More())
-        return true;
+        // Did we get one or two solids?
+        TopExp_Explorer xp;
+        xp.Init(mkFuse.Shape(),TopAbs_SOLID);
+        if (xp.More()) {
+            // At least one solid
+            xp.Next();
+            return (xp.More() == Standard_False);
+        } else {
+            return false;
+        }
+    } else {
+        // If both shapes have common material, then they intersect
+        BRepAlgoAPI_Common mkCommon(first, second);
+        if (!mkCommon.IsDone())
+            return false;
+        if (mkCommon.Shape().IsNull())
+            return false;
 
-    return false;
+        // Did we get a solid?
+        TopExp_Explorer xp;
+        xp.Init(mkCommon.Shape(),TopAbs_SOLID);
+        return (xp.More() == Standard_True);
+    }
 }

src/Mod/Part/App/PartFeature.h

@@ -141,10 +141,18 @@ std::vector<cutFaces> findAllFacesCutBy(const TopoDS_Shape& shape,
   * 1. Bounding box check only - quick but inaccurate
   * 2. Bounding box check plus (if necessary) boolean operation - costly but accurate
   * Return true if the shapes intersect, false if they don't
+  * The flag touch_is_intersection decides whether shapes touching at distance zero are regarded
+  * as intersecting or not
+  * 1. If set to true, a true check result means that a boolean fuse operation between the two shapes
+  *    will return a single solid
+  * 2. If set to false, a true check result means that a boolean common operation will return a
+  *    valid solid
+  * If there is any error in the boolean operations, the check always returns false
   */
 PartExport
-const bool checkIntersection(const TopoDS_Shape& first, const TopoDS_Shape& second, const bool quick = true);
-
+const bool checkIntersection(const TopoDS_Shape& first, const TopoDS_Shape& second,
+                             const bool quick, const bool touch_is_intersection);
+
 } //namespace Part
 
 

src/Mod/PartDesign/App/FeatureTransformed.cpp

@@ -170,7 +170,7 @@ App::DocumentObjectExecReturn *Transformed::execute(void)
                 return new App::DocumentObjectExecReturn("Transformation failed", (*o));
 
             // Check for intersection with support
-            if (!Part::checkIntersection(support, mkTrf.Shape(), false)) {
+            if (!Part::checkIntersection(support, mkTrf.Shape(), false, true)) {
                 Base::Console().Warning("Transformed shape does not intersect support %s: Removed\n", (*o)->getNameInDocument());
                 // Note: The removal happens in getSolid() after the fuse
                 rejected.push_back(*t);
@@ -203,7 +203,7 @@ App::DocumentObjectExecReturn *Transformed::execute(void)
             if (v_transformedShapes.size() == 1)
                 break;
 
-            if (Part::checkIntersection(shape, *s, false))
+            if (Part::checkIntersection(shape, *s, false, false))
                 return new App::DocumentObjectExecReturn("Transformed objects are overlapping, try using a higher length or reducing the number of occurrences", (*o));
                 // Note: This limitation could be overcome by fusing the transformed features instead of
                 // compounding them, probably at the expense of quite a bit of performance and complexity
@@ -218,7 +218,7 @@ App::DocumentObjectExecReturn *Transformed::execute(void)
                 std::vector<TopoDS_Shape>::const_iterator s2 = s;
                 s2++;
                 for (; s2 != v_transformedShapes.end(); s2++)
-                    if (Part::checkIntersection(*s, *s2, false))
+                    if (Part::checkIntersection(*s, *s2, false, false))
                         return new App::DocumentObjectExecReturn("Transformed objects are overlapping, try using a higher length or reducing the number of occurrences", (*o));
             }
         }