add docfx samples.

Geom/DemoBuildGeom.cs

@@ -5,8 +5,7 @@ using Hi.Mech.Topo;
 namespace Sample.Geom
 {
     /// <remarks>
-    /// ## Source Code
-    /// 
+    /// ### Source Code
     /// [!code-csharp[SampleCode](~/../Hi.Sample/Geom/DemoBuildGeom.cs)]
     /// </remarks>
     public static class DemoBuildGeom

Geom/DemoIExpandToBox3d.cs

@@ -0,0 +1,24 @@
+using Hi.Geom;
+using System;
+
+namespace Sample.Geom
+{
+    /// <remarks>
+    /// ### Source Code
+    /// [!code-csharp[SampleCode](~/../Hi.Sample/Geom/DemoIExpandToBox3d.cs)]
+    /// </remarks>
+    public static class DemoIExpandToBox3d
+	{
+		static void Main()
+		{
+			#region DocSite.CountBoundingBox
+			Box3d objA = new Box3d(0, 0, 0, 1, 1, 1);
+			Box3d objB = new Box3d(-1, -2, -3, 3, 2, 1);
+			Vec3d objC = new Vec3d(-2, 3, -5);
+
+			Box3d boundingbox = new Box3d(objA, objB, objC);
+			Console.WriteLine("boundingbox: " + boundingbox);
+			#endregion
+		}
+	}
+}