Validating Joins Between Shape Faces

To validate the join between two shape faces in a generic way, there are several effective methods you can use:

1. Tolerance-Based Validation

Check if the distance between corresponding points on the two faces is within an acceptable tolerance:

CPPCopied
bool validateJoin(const TopoDS_Face& face1, const TopoDS_Face& face2, double tolerance) {
    // Create a BRepExtrema_DistShapeShape object to compute the minimum distance
    BRepExtrema_DistShapeShape distCalculator(face1, face2);
    if (!distCalculator.IsDone()) {
        return false;
    }
    
    // Check if the minimum distance is within tolerance
    return distCalculator.Value() <= tolerance;
}

2. Shared Edge Analysis

Examine the edges that should be shared between the two faces:

CPPCopied
bool validateEdgeJoin(const TopoDS_Face& face1, const TopoDS_Face& face2) {
    TopExp_Explorer edgeExplorer1(face1, TopAbs_EDGE);
    
    while (edgeExplorer1.More()) {
        TopoDS_Edge edge1 = TopoDS::Edge(edgeExplorer1.Current());
        
        TopExp_Explorer edgeExplorer2(face2, TopAbs_EDGE);
        while (edgeExplorer2.More()) {
            TopoDS_Edge edge2 = TopoDS::Edge(edgeExplorer2.Current());
            
            // Check if edges are the same or equivalent
            if (edge1.IsSame(edge2) || areEdgesEquivalent(edge1, edge2)) {
                return true; // Found a shared edge
            }
            
            edgeExplorer2.Next();
        }
        
        edgeExplorer1.Next();
    }
    
    return false; // No shared edges found
}

3. Boolean Operations

Use boolean operations to check for valid joins:

CPPCopied
bool validateJoinWithBoolean(const TopoDS_Face& face1, const TopoDS_Face& face2) {
    BRepAlgoAPI_Common commonOperation(face1, face2);
    commonOperation.Build();
    
    if (!commonOperation.IsDone()) {
        return false;
    }
    
    // Check if there's a valid intersection
    return !commonOperation.Shape().IsNull();
}

4. Continuity Analysis

For more advanced validation, check the geometric continuity between the faces:

CPPCopied
bool checkContinuity(const TopoDS_Face& face1, const TopoDS_Face& face2, 
                     GeomAbs_Shape continuityType = GeomAbs_C0) {
    BRepLib_CheckCurveOnSurface checker;
    
    // Find shared edges
    TopExp_Explorer edgeExplorer1(face1, TopAbs_EDGE);
    while (edgeExplorer1.More()) {
        TopoDS_Edge edge = TopoDS::Edge(edgeExplorer1.Current());
        
        // Check if this edge belongs to both faces
        if (BRep_Tool::IsClosed(edge, face1, face2)) {
            // Analyze continuity across the edge
            BRepAdaptor_Curve curveAdaptor(edge);
            BRepAdaptor_Surface surfAdaptor1(face1);
            BRepAdaptor_Surface surfAdaptor2(face2);
            
            // Check continuity (implementation depends on specific requirements)
            // This is a simplified example
            return analyzeGeometricContinuity(curveAdaptor, surfAdaptor1, 
                                             surfAdaptor2, continuityType);
        }
        edgeExplorer1.Next();
    }
    
    return false;
}

The most effective approach often combines multiple methods, starting with the simplest checks (like tolerance-based validation) and progressing to more complex analyses if needed. The specific method you choose should depend on your performance requirements and the level of validation precision needed for your application.