theoretically this should prob work

backend/CMakeLists.txt

@@ -8,6 +8,8 @@ include_directories(${OCE_INCLUDE_DIRS})
 
 add_executable(cad_to_gcode src/cad_to_gcode.cpp)
 add_executable(iges_to_topo src/iges_to_topo.cpp)
+add_executable(shape_to_bspline src/shape_to_bspline.cpp)
 target_link_libraries(cad_to_gcode ${OpenCASCADE_LIBRARIES})
 target_link_libraries(iges_to_topo ${OpenCASCADE_LIBRARIES})
+target_link_libraries(shape_to_bspline ${OpenCASCADE_LIBRARIES})
 

backend/src/shape_to_bspline.cpp

@@ -0,0 +1,104 @@
+#include <TopoDS_Shape.hxx>
+#include <TopExp_Explorer.hxx>
+#include <TopoDS_Edge.hxx>
+#include <BRep_Tool.hxx>
+#include <Geom_Curve.hxx>
+#include <GeomAPI_Interpolate.hxx>
+#include <TColgp_HArray1OfPnt.hxx>
+#include <GCPnts_AbscissaPoint.hxx>
+#include <GeomAdaptor_Curve.hxx>
+#include <vector>
+#include <GeomAPI_PointsToBSpline.hxx>
+#include <TopoDS_Vertex.hxx>
+#include <TopExp.hxx>
+#include <TopoDS.hxx>
+#include <gp_Pnt.hxx>
+
+bool VerticesMatch(const TopoDS_Vertex& v1, const TopoDS_Vertex& v2) {
+    gp_Pnt p1 = BRep_Tool::Pnt(v1);
+    gp_Pnt p2 = BRep_Tool::Pnt(v2);
+    return p1.IsEqual(p2, Precision::Confusion());
+}
+
+std::vector<TopoDS_Edge> OrderEdges(const TopoDS_Shape& shape) {
+    std::vector<TopoDS_Edge> unorderedEdges, orderedEdges;
+
+    // Fill unorderedEdges with all edges in the shape
+    for (TopExp_Explorer exp(shape, TopAbs_EDGE); exp.More(); exp.Next()) {
+        unorderedEdges.push_back(TopoDS::Edge(exp.Current()));
+    }
+
+    if (unorderedEdges.empty()) return orderedEdges;
+
+    // Start with a random edge
+    orderedEdges.push_back(unorderedEdges.front());
+    unorderedEdges.erase(unorderedEdges.begin());
+
+    while (!unorderedEdges.empty()) {
+        bool matchFound = false;
+
+        TopoDS_Vertex startV, endV;
+        TopExp::Vertices(orderedEdges.front(), startV, endV); // Get start/end vertices of the current path
+
+        for (auto it = unorderedEdges.begin(); it != unorderedEdges.end(); ++it) {
+            TopoDS_Vertex startVNext, endVNext;
+            TopExp::Vertices(*it, startVNext, endVNext); // Get vertices of the next candidate edge
+
+            if (VerticesMatch(endV, startVNext)) { // Match end to start
+                orderedEdges.push_back(*it); // Place it at the end
+                endV = endVNext; // Update end vertex of the path
+                unorderedEdges.erase(it);
+                matchFound = true;
+                break;
+            } else if (VerticesMatch(startV, endVNext)) { // Match start to end
+                orderedEdges.insert(orderedEdges.begin(), *it); // Place it at the beginning
+                startV = startVNext; // Update start vertex of the path
+                unorderedEdges.erase(it);
+                matchFound = true;
+                break;
+            }
+        }
+
+        if (!matchFound) {
+            break;
+        }
+    }
+
+    return orderedEdges;
+}
+
+// Function to sample points from an edge
+std::vector<gp_Pnt> SamplePointsFromEdge(const TopoDS_Edge& edge, int numPoints) {
+    std::vector<gp_Pnt> points;
+    double first, last;
+    Handle(Geom_Curve) curve = BRep_Tool::Curve(edge, first, last);
+    if (!curve.IsNull()) {
+        double step = (last - first) / (numPoints - 1);
+        for (int i = 0; i < numPoints; ++i) {
+            gp_Pnt pnt = curve->Value(first + i * step);
+            points.push_back(pnt);
+        }
+    }
+    return points;
+}
+
+Handle(Geom_BSplineCurve) CreateBSplineFromShape(const TopoDS_Shape& shape) {
+    std::vector<TopoDS_Edge> orderedEdges = OrderEdges(shape);
+    std::vector<gp_Pnt> allPoints;
+    const int SAMPLE_NUM = 10;
+
+    for (const auto& edge : orderedEdges) {
+        std::vector<gp_Pnt> edgePoints = SamplePointsFromEdge(edge, SAMPLE_NUM);
+        allPoints.insert(allPoints.end(), edgePoints.begin(), edgePoints.end());
+    }
+
+    // Convert std::vector<gp_Pnt> to TColgp_Array1OfPnt
+    TColgp_Array1OfPnt arrayPoints(1, allPoints.size());
+    for (Standard_Integer i = 0; i < allPoints.size(); ++i) {
+        arrayPoints.SetValue(i + 1, allPoints[i]);
+    }
+
+    GeomAPI_PointsToBSpline splineBuilder(arrayPoints);
+    return splineBuilder.Curve();
+}
+