Some IXbimSolid elements don't exist when performing boolean operations about xbimgeometry

[andyward]

Can't really advise without seeing an example. Can you supply some example code and this test model?

[ar98nau]

Hi @andyward, thank you for giving this issue a try.
Here you have the IFC file of the screenshots above, hope it helps.
EN-04.zip.

To put into context I may explain the scope of the project. The initial IFC model has all solids spread in the space in a random position from the origin, I need to move those solids to a desired position and make some other transformations in their axis, all while maintaining the relative position between solids. Once I have this, I need the collisions between all solids with the name CAVITAT and those with the name XPS since I want those parts that are in touch with XPS solids. To do so without altering the original model I generate several new IfcStores along the way and put inside the modifications and transformations done to the elements. It's here when, after some translations and although being visible and identical to the original solid (only transformed) in the new IfcStore model, the Boolean operations start to fail for some random solids.

Here is an example of how I transform my solids:

var solidSet = geomEngine.CreateSolidSet();
solidSet.Add(solid);
var newTransform = new XbimMatrix3D();
newTransform.RotateAroundYAxis((180.0 * Math.PI) / 180.0);
var transformFlip = (IXbimSolidSet)solidSet.Transform(newTransform);

Here is how I create an object into a new IfcStore from the solid obtained after doing some transformations:

private static void CreateIfcGeometriesFromSolids(IfcStore model, IfcSpatialStructureElement parent, IXbimSolid shapeGeometry, IfcBuildingElement element, CustomXYZ position, string materialName, bool toMillimetres)
{
    double milli = toMillimetres ? 1000 : 1;

    var ifcFacetedBrep = model.Instances.New<IfcFacetedBrep>();
    var shell = model.Instances.New<IfcClosedShell>();

    foreach (var face in shapeGeometry.Faces)
    {
        var ifcFace = model.Instances.New<IfcFace>();
        var outerbound = model.Instances.New<IfcFaceOuterBound>();
        var polyloop = model.Instances.New<IfcPolyLoop>();

        List<IXbimVertex> vertices = face.OuterBound.Edges.SelectMany(e =>
        {
            List<IXbimVertex> verticesE = new List<IXbimVertex>
                    {
                        e.EdgeStart,
                        e.EdgeEnd
                    };
            return verticesE;
        }).ToList();
        vertices = vertices.Distinct().ToList();

        foreach (IXbimVertex vertice in vertices)
        {

            double x = vertice.VertexGeometry.X * milli;
            double y = vertice.VertexGeometry.Y * milli;
            double z = vertice.VertexGeometry.Z * milli;

            var cartesianPoint = model.Instances.New<IfcCartesianPoint>();
            cartesianPoint.SetXYZ(x, y, z);
            polyloop.Polygon.Add(cartesianPoint);
        }

        outerbound.Bound = polyloop;
        ifcFace.Bounds.Add(outerbound);
        shell.CfsFaces.Add(ifcFace);
    }

    CreateStructure(model, element, ifcFacetedBrep, shell);

    AddMaterial(model, element, materialName);

    SetPosition(position * milli, model, parent, element);
}

private static void CreateStructure(IfcStore model, IfcBuildingElement element, IfcFacetedBrep ifcFacetedBrep, IfcClosedShell shell)
{
	ifcFacetedBrep.Outer = shell;
	var shapeRepresentation = model.Instances.New<IfcShapeRepresentation>();
	var modelContext = model.Instances.OfType<IfcGeometricRepresentationContext>().FirstOrDefault();
	shapeRepresentation.ContextOfItems = modelContext;
	shapeRepresentation.RepresentationType = "Brep";
	shapeRepresentation.RepresentationIdentifier = "Body";
	shapeRepresentation.Items.Add(ifcFacetedBrep);
	var productDefinitionShape = model.Instances.New<IfcProductDefinitionShape>();
	productDefinitionShape.Representations.Add(shapeRepresentation);
	element.Representation = productDefinitionShape;
}

private static void AddMaterial(IfcStore model, IfcBuildingElement element, string materialName)
{
	var material = model.Instances.New<IfcMaterial>();
	material.Name = materialName;
	var ifcRelAssociatesMaterial = model.Instances.New<IfcRelAssociatesMaterial>();
	ifcRelAssociatesMaterial.RelatingMaterial = material;
	ifcRelAssociatesMaterial.RelatedObjects.Add(element);
}

private static void SetPosition(CustomXYZ position, IfcStore model, IfcSpatialStructureElement parent, IfcBuildingElement element)
{
	var origin = model.Instances.New<IfcCartesianPoint>();
	origin.SetXYZ(position.x, position.y, position.z);
	var lp = model.Instances.New<IfcLocalPlacement>();
	var ax3D = model.Instances.New<IfcAxis2Placement3D>();
	ax3D.Location = origin;
	lp.RelativePlacement = ax3D;
	lp.PlacementRelTo = parent.ObjectPlacement;
	element.ObjectPlacement = lp;
}

This is the fragment of my code where I have issues after performing the Intersect boolean operation:

List<IfcBuildingElementProxy> XPSs = ifcModel.Instances.OfType<IfcBuildingElementProxy>().Where(i => ((IfcMaterial)i.Material).Name.Value.ToString().Contains(XPS_OBJECT_ID) && i.Representation != null).ToList();
List<IfcBuildingElementProxy> fresades = ifcModel.Instances.OfType<IfcBuildingElementProxy>().Where(i => ((IfcMaterial)i.Material).Name.Value.ToString().Contains(CAVITAT_OBJECT_ID) && i.Representation != null).ToList();

IXbimSolidSet xpsSolids = null;
foreach (IfcBuildingElementProxy xps in XPSs)
{
    var xpsBrep = xps.Representation.Representations.SelectMany(r => r.Items.OfType<IfcFacetedBrep>()).FirstOrDefault();
    var xpsGeom = geomEngine.CreateSolidSet(xpsBrep, _logger);
    XbimMatrix3D matrixXPS = geomEngine.ToMatrix3D(xps.ObjectPlacement, _logger);
    var xpsGeomTransform = (IXbimSolidSet)xpsGeom.Transform(matrixXPS);

    if (xpsSolids == null) xpsSolids = xpsGeomTransform;
    else xpsSolids.Add(xpsGeomTransform);
}

IXbimSolidSet resultsIntersect = null;
foreach (IfcBuildingElementProxy fresada in fresades)
{
    var fresadaBrep = fresada.Representation.Representations.SelectMany(r => r.Items.OfType<IfcFacetedBrep>()).FirstOrDefault();
    var fresadaGeom = geomEngine.CreateSolidSet(fresadaBrep, _logger);
    XbimMatrix3D matrixF = geomEngine.ToMatrix3D(fresada.ObjectPlacement, _logger);
    var fresadaGeomTransform = (IXbimSolidSet)fresadaGeom.Transform(matrixF);

    var fresadaIntersect = xpsSolids.Intersection(fresadaGeomTransform, 0, _logger);

    if (fresadaIntersect.Count > 0)
    {
        if (resultsIntersect == null)
            resultsIntersect = fresadaIntersect;
        else
            resultsIntersect.Add(fresadaIntersect);
    }
}

Also I've recently tried performing the intersect boolean operation between CAVITAT solids and XPS solids directly to the initial IFC model (without any transformation) and the result is slightly different, in this case, I only lose the two cylinders. So the behaviour is driving me mad since it seems totally random to me.

[ar98nau]

Hi @andyward ,
I was hoping to have some news about this issue. If there's something I can do or the information provided isn't enough just tell me.

Thanks in advance.

[andyward]

Sorry, this is too hard to diagnose from the above. It needs a solution someone can debug. I'd create a minimal working project demonstrating the issue. I.e. in this case select two elements that you expect to intersect but maybe don't. Perhaps build up some unit tests to check your assumptions?