fix：

Views/UserControl/Viewport3D.xaml.cs

@@ -413,21 +413,7 @@ public partial class Viewport3D
                 ViewportManager.ResetChooseAddModels();
                 break;
             case "ViewportRightMenuShowMeshLines":
-                var center = ViewportManager.ModelBounds.Center;
+                ViewportManager.ShowMeshLines(checkResult, ViewportHelperPro.IsCrown());
-                var maxDimension = ViewportManager.ModelBounds.Size.Length();
-                var distance = maxDimension * 1.2; // 调整相机到模型的距离，保证视野范围内
-                // 获取当前相机
-                var camera = Viewport3Dx.Camera as HelixToolkit.Wpf.SharpDX.OrthographicCamera;
-                var Position = camera.Position;
-                var LookDirection = camera.LookDirection;
-                bool isCrown = false;
-                if(camera.LookDirection.Y >= 0 && camera.UpDirection.Y<=0)
-                {
-                    isCrown = true;
-                }
-                ViewportManager.ShowMeshLines(checkResult, isCrown);
-                //camera.LookDirection = new Vector3D(center.X - camera.Position.X, center.Y - camera.Position.Y, center.Z - camera.Position.Z);
-
                 break;
         }
     }

Views/UserControl/ViewportData/Helper/ViewportHelperPro.cs

@@ -1283,7 +1283,10 @@ public class ViewportHelperPro
     /// <returns></returns>
     public static List<LineGeometryModel3D> ShowMeshLines(List<Viewport3DTriangleEntity> entities, bool isCrown = true, double thickness = 1.0)
     {
-        moveLines = new();
+        if (isCrown)
+        {
+            moveLines = new();
+        }
         List<LineGeometryModel3D> lines = new();
         var Y = -0.01F;
         if (!isCrown)
@@ -1552,6 +1555,10 @@ public class ViewportHelperPro
                 // 现在鼠标对于3d模型的位置
                 var mousePosition = ev.Position;
                 var Y = -0.01F;
+                if (!IsCrown())
+                {
+                    Y = ViewportManager.ModelBounds.Maximum.Y + 0.01F;
+                }
                 var center = ViewportManager.CenterVector;
                 center.Y = Y;
 
@@ -1619,6 +1626,10 @@ public class ViewportHelperPro
             dragStartPoint = ev.Position;
             Point3D mouseWorldPosition = Get3DPointFromMouse(dragStartPoint);
             var Y = -0.01F;
+            if(!IsCrown())
+            {
+                Y = ViewportManager.ModelBounds.Maximum.Y + 0.01F;
+            }
             var center = ViewportManager.CenterVector;
             center.Y = Y;
             initDistance = CalculateDistance(mouseWorldPosition, center.ToPoint3D());
@@ -1627,6 +1638,16 @@ public class ViewportHelperPro
             Viewport.CaptureMouse();
         }
     }
+    public static bool IsCrown()
+    {
+        bool isCrown = false;
+        var camera = ViewportManager.GetViewport3D().Camera;
+        if (camera.LookDirection.Y >= 0 && camera.UpDirection.Y <= 0)
+        {
+            isCrown = true;
+        }
+        return isCrown;
+    }
     #region 私有方法
 
     /// <summary>