Fuse cylindrical faces

Thank you Evgeny Nicolaich,

I'll try to implement this method into an algorithm for my programme.

Cheers,

Dennis

Dear Evgeny Nicolaich,

Your example is very precious to me, but still I can't solve the problem inside my programme. I can construct a wire and the BRepBuilderAPI_MakeFace class creates a face (with an incredibly huge area).

Here's what I do when fusing of two faces (f1, f2) on the same surface fails...

[code ****************************************************]
if(f1.ShapeType() == TopAbs_Cylinder)
{
// prepare faces
///////////////////////////////////
BRepAdaptor_Surface baS(f1);
gp_Cylinder aCyl = baS.Cylinder();
TopoDS_Face cylFc = BRepBuilderAPI_MakeFace(aCyl).Face();

BRepAlgoAPI_Common cmn1(cylFc, f1);
TopoDS_Shape cmnShp1;
if(cmn1.IsDone())
cmnShp1 = cmn1.Shape();

BRepAlgoAPI_Common cmn2(cylFc, f2);
TopoDS_Shape cmnShp2;
if(cmn2.IsDone())
cmnShp2 = cmn2.Shape();

if(cmnShp1.IsNull() || cmnShp2.IsNull())
break;

// extract faces
///////////////////////////////////
...
// check if common faces are OK
// final common faces are fc1 and fc2
...
// extract edges
///////////////////////////////////
Handle(TopTools_HSequenceOfShape) edges = new TopTools_HSequenceOfShape;

for(TopExp_Explorer ee(fc1, TopAbs_EDGE); ee.More(); ee.Next())
edges->Append(ee.Current());
for(TopExp_Explorer ee(fc2, TopAbs_EDGE); ee.More(); ee.Next())
edges->Append(ee.Current());

// remove redundant edges and sort
////////////////////////////////////////
...
// I assume that only two of the four linear edges can be considered as redundant
// therefore I check for the curve type and delete two linear curves with the same length and location but
// opposite orientation
// this leaves 6 edges (of formerly 8)
...
// This is what I pass to the BRepBuilderAPI_MakeWire below:
//
// Edge : 1 Length : 32.8768 is circle ... REVERSED
// Edge : 2 Length : 32.8768 is circle ... REVERSED
// Edge : 3 Length : 67.0167 is line ... REVERSED
// Edge : 4 Length : 39.9784 is ellipse ... FORWARD
// Edge : 5 Length : 39.9784 is ellipse ... FORWARD
// Edge : 6 Length : 67.0167 is line ... FORWARD
//
...
// make wire
///////////////////////////////
BRepBuilderAPI_MakeWire wrMkr;
for(int i=1; i<=sortedEdges->Length(); i++)
{
TopoDS_Edge E = TopoDS::Edge(sortedEdges->Value(i));
wrMkr.Add(E);
if(!wrMkr.IsDone())
cout << "WireMaker.Add() failed for edge : " << i << endl;
}
wrMkr.Build();

TopoDS_Wire w = wrMkr.Wire();

// the wire construction seems to be OK, but the wire still contains 6 edges, as TopExp_Explorer reveals
// while the wire in your DRAWEXE example consists of only four edges (nbshapes ...)
//
// Number of shapes in w
// VERTEX : 4
// EDGE : 4
// WIRE : 1 ...
//
// This is why I assume the error within the wire construction.
// I tried different arangements of the edges but with no success.

TopoDS_Face theFace = BRepBuilderAPI_MakeFace(aCyl, w).Face();

if(theFace.IsNull())
cout << "NULL face!!!\n";

// Face Area : 2.63014e+102 || Ooops, that's huge!!!

// output final face into step file
////////////////////////////////////
STEPControl_Writer wrt;
wrt.Transfer(theFace, STEPControl_AsIs);
wrt.Write("theFace.stp");

// ***** Segmentation fault ******
}
[/code ***************************************************]

What could be the problem?

Thanks,

Dennis