From 3e9b578e6dfe587417b150463a663ce8fa48b52a Mon Sep 17 00:00:00 2001
From: chuongmep <31106432+chuongmep@users.noreply.github.com>
Date: Wed, 26 Jun 2024 20:55:43 +0800
Subject: [PATCH] Create FaceIntersectCommand.cs

---
 Test/FaceIntersectCommand.cs | 155 +++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)
 create mode 100644 Test/FaceIntersectCommand.cs

diff --git a/Test/FaceIntersectCommand.cs b/Test/FaceIntersectCommand.cs
new file mode 100644
index 0000000..30e2d35
--- /dev/null
+++ b/Test/FaceIntersectCommand.cs
@@ -0,0 +1,155 @@
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using Autodesk.Revit.Attributes;
+using Autodesk.Revit.DB;
+using Autodesk.Revit.UI;
+using Autodesk.Revit.UI.Selection;
+
+namespace Test;
+
+[Transaction(TransactionMode.Manual)]
+public class FaceIntersectCommand : IExternalCommand
+{
+    public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
+    {
+        // select a extrusion element
+        Reference reference =
+            commandData.Application.ActiveUIDocument.Selection.PickObject(ObjectType.Element,
+                new ExtrusionFaceSelectionFilter(),
+                "Select a extrusion element");
+        var doc = commandData.Application.ActiveUIDocument.Document;
+        var e1 = doc.GetElement(reference);
+        var r2 = commandData.Application.ActiveUIDocument.Selection.PickObject(ObjectType.Element,
+            new ExtrusionFaceSelectionFilter(), "Select another extrusion element");
+        var e2 = doc.GetElement(r2);
+        // try see intersect
+        var face1 = GetTopFace(e1 as Extrusion);
+        var face2 = GetTopFace(e2 as Extrusion);
+        if (face1 != null && face2 != null)
+        {
+            Trace.WriteLine("CheckIntersect:");
+            CheckIntersect(face1, face2);
+        }
+        // try with another method
+        var poly1 = face1.Triangulate().Vertices.ToList();
+        var poly2 = face2.Triangulate().Vertices.ToList();
+        List<XYZ> intersection = GetIntersection(poly1, poly2);
+        Trace.WriteLine("Intersection:");
+        foreach (var xyz in intersection)
+        {
+            Trace.WriteLine(xyz.ToString());
+        }
+        return Result.Succeeded;
+    }
+    public PlanarFace? GetTopFace(Extrusion? extrusion)
+    {
+        Options options = new Options();
+        options.ComputeReferences = true;
+        options.DetailLevel = ViewDetailLevel.Fine;
+        options.IncludeNonVisibleObjects = false;
+        GeometryElement geomElem = extrusion.get_Geometry(options);
+        foreach (GeometryObject geomObj in geomElem)
+        {
+            Solid? solid = geomObj as Solid;
+            if (solid != null)
+            {
+                foreach (Face face in solid.Faces)
+                {
+                    PlanarFace? planarFace = face as PlanarFace;
+                    if (planarFace != null)
+                    {
+                        // make sure it is top face
+                        if (planarFace.FaceNormal.Z > 0)
+                        {
+                            return planarFace;
+                        }
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
+    public void CheckIntersect(PlanarFace face1, PlanarFace face2)
+    {
+        FaceIntersectionFaceResult result = face1.Intersect(face2, out Curve curve);
+        Trace.WriteLine(result.ToString());
+        // fu...k, why ?????????? ^🫡🫡^
+
+    }
+    public static List<XYZ> GetIntersection(List<XYZ> poly1, List<XYZ> poly2)
+    {
+        List<XYZ> outputList = poly1;
+
+        // Each segment of the clipping polygon
+        for (int i = 0; i < poly2.Count; i++)
+        {
+            List<XYZ> inputList = new List<XYZ>(outputList);
+            outputList.Clear();
+
+            XYZ A = poly2[(i + poly2.Count - 1) % poly2.Count];
+            XYZ B = poly2[i];
+
+            for (int j = 0; j < inputList.Count; j++)
+            {
+                XYZ P = inputList[(j + inputList.Count - 1) % inputList.Count];
+                XYZ Q = inputList[j];
+
+                if (IsInside(A, B, Q))
+                {
+                    if (!IsInside(A, B, P))
+                        outputList.Add(Intersection(A, B, P, Q));
+                    outputList.Add(Q);
+                }
+                else if (IsInside(A, B, P))
+                {
+                    outputList.Add(Intersection(A, B, P, Q));
+                }
+            }
+        }
+
+        return outputList;
+    }
+
+    private static bool IsInside(XYZ A, XYZ B, XYZ C)
+    {
+        return (B.X - A.X) * (C.Y - A.Y) > (B.Y - A.Y) * (C.X - A.X);
+    }
+
+    private static XYZ Intersection(XYZ A, XYZ B, XYZ P, XYZ Q)
+    {
+        double A1 = B.Y - A.Y;
+        double B1 = A.X - B.X;
+        double C1 = A1 * A.X + B1 * A.Y;
+
+        double A2 = Q.Y - P.Y;
+        double B2 = P.X - Q.X;
+        double C2 = A2 * P.X + B2 * P.Y;
+
+        double determinant = A1 * B2 - A2 * B1;
+        if (determinant == 0)
+            return new XYZ();  // Lines are parallel
+        else
+        {
+            double x = (B2 * C1 - B1 * C2) / determinant;
+            double y = (A1 * C2 - A2 * C1) / determinant;
+            return new XYZ(x, y,A.Z);
+        }
+    }
+
+
+}
+
+public class ExtrusionFaceSelectionFilter : ISelectionFilter
+{
+    public bool AllowElement(Element elem)
+    {
+        return elem is Autodesk.Revit.DB.Extrusion;
+    }
+
+    public bool AllowReference(Reference reference, XYZ position)
+    {
+        return false;
+    }
+}
\ No newline at end of file