Update MeshDataTool tutorial

Adds C# code examples, links to the class reference and minor changes to the GDScript examples

Author: TelePete

tutorials/3d/procedural_geometry/meshdatatool.rst

@@ -6,15 +6,15 @@ Using the MeshDataTool
 The :ref:`MeshDataTool <class_meshdatatool>` is not used to generate geometry. But it is helpful for dynamically altering geometry, for example
 if you want to write a script to tessellate, simplify, or deform meshes.
 
-The MeshDataTool is not as fast as altering arrays directly using ArrayMesh. However, it provides more information
+The MeshDataTool is not as fast as altering arrays directly using :ref:`ArrayMesh <class_arraymesh>`. However, it provides more information
 and tools to work with meshes than the ArrayMesh does. When the MeshDataTool
 is used, it calculates mesh data that is not available in ArrayMeshes such as faces and edges, which are necessary
 for certain mesh algorithms. If you do not need this extra information then it may be better to use an ArrayMesh.
 
 .. note:: MeshDataTool can only be used on Meshes that use the PrimitiveType ``Mesh.PRIMITIVE_TRIANGLES``.
 
-We initialize the MeshDataTool from an ArrayMesh by calling ``create_from_surface()``. If there is already data initialized in the MeshDataTool,
-calling ``create_from_surface()`` will clear it for you. Alternatively, you can call ``clear()`` yourself before re-using the MeshDataTool.
+We initialize the MeshDataTool from an ArrayMesh by calling :ref:`create_from_surface() <class_meshdatatool_method_create_from_surface>`. If there is already data initialized in the MeshDataTool,
+calling ``create_from_surface()`` will clear it for you. Alternatively, you can call :ref:`clear() <class_meshdatatool_method_clear>` yourself before re-using the MeshDataTool.
 
 In the examples below, assume an ArrayMesh called ``mesh`` has already been created. See :ref:`ArrayMesh tutorial <doc_arraymesh>` for an example of mesh generation.
 
@@ -24,6 +24,11 @@ In the examples below, assume an ArrayMesh called ``mesh`` has already been crea
     var mdt = MeshDataTool.new()
     mdt.create_from_surface(mesh, 0)
 
+ .. code-tab:: csharp C#
+
+    var mdt = new MeshDataTool();
+    mdt.CreateFromSurface(mesh, 0);
+
 ``create_from_surface()`` uses the vertex arrays from the ArrayMesh to calculate two additional arrays,
 one for edges and one for faces, for a total of three arrays.
 
@@ -41,22 +46,38 @@ To access information from these arrays you use a function of the form ``get_***
 .. tabs::
  .. code-tab:: gdscript GDScript
 
-    mdt.get_vertex_count() # Returns number of vertices in vertex array.
-    mdt.get_vertex_faces(0) # Returns array of faces that contain vertex[0].
-    mdt.get_face_normal(1) # Calculates and returns face normal of the second face.
+    mdt.get_vertex_count() # Returns the number of vertices in the vertex array.
+    mdt.get_vertex_faces(0) # Returns an array of faces that contain vertex[0].
+    mdt.get_face_normal(1) # Calculates and returns the face normal of the second face.
     mdt.get_edge_vertex(10, 1) # Returns the second vertex comprising the edge at index 10.
 
+ .. code-tab:: csharp C#
+
+    mdt.GetVertexCount(); // Returns the number of vertices in the vertex array.
+    mdt.GetVertexFaces(0); // Returns an array of faces that contain vertex[0].
+    mdt.GetFaceNormal(1); // Calculates and returns the face normal of the second face.
+    mdt.GetEdgeVertex(10, 1); // Returns the second vertex comprising the edge at index 10.
+
 What you choose to do with these functions is up to you. A common use case is to iterate over all vertices
 and transform them in some way:
 
 .. tabs::
  .. code-tab:: gdscript GDScript
 
-    for i in range(get_vertex_count):
+    for i in range(mdt.get_vertex_count()):
         var vert = mdt.get_vertex(i)
-        vert *= 2.0 # Scales the vertex by doubling size.
+        vert *= 2.0 # Scales the vertex by doubling its size.
         mdt.set_vertex(i, vert)
 
+ .. code-tab:: csharp C#
+
+    for (var i = 0; i < mdt.GetVertexCount(); i++)
+    {
+        Vector3 vert = mdt.GetVertex(i);
+        vert *= 2.0f; // Scales the vertex by doubling its size.
+        mdt.SetVertex(i, vert);
+    }
+
 These modifications are not done in place on the ArrayMesh. If you are dynamically updating an existing ArrayMesh,
 first delete the existing surface before adding a new one using :ref:`commit_to_surface() <class_meshdatatool_method_commit_to_surface>`:
 
@@ -66,6 +87,11 @@ first delete the existing surface before adding a new one using :ref:`commit_to_
     mesh.clear_surfaces() # Deletes all of the mesh's surfaces.
     mdt.commit_to_surface(mesh)
 
+ .. code-tab:: csharp C#
+
+    mesh.ClearSurfaces(); // Deletes all of the mesh's surfaces.
+    mdt.CommitToSurface(mesh);
+
 Below is a complete example that turns a spherical mesh called ``mesh`` into a randomly deformed blob complete with updated normals and vertex colors.
 See :ref:`ArrayMesh tutorial <doc_arraymesh>` for how to generate the base mesh.
 
@@ -84,34 +110,92 @@ See :ref:`ArrayMesh tutorial <doc_arraymesh>` for how to generate the base mesh.
 
         for i in range(mdt.get_vertex_count()):
             var vertex = mdt.get_vertex(i).normalized()
-            # Push out vertex by noise.
+            # Scale the vertices using noise.
             vertex = vertex * (fnl.get_noise_3dv(vertex) * 0.5 + 0.75)
             mdt.set_vertex(i, vertex)
 
-        # Calculate vertex normals, face-by-face.
+        # Calculate the vertex normals, face-by-face.
         for i in range(mdt.get_face_count()):
             # Get the index in the vertex array.
             var a = mdt.get_face_vertex(i, 0)
             var b = mdt.get_face_vertex(i, 1)
             var c = mdt.get_face_vertex(i, 2)
-            # Get vertex position using vertex index.
+            # Get the vertex position using the vertex index.
             var ap = mdt.get_vertex(a)
             var bp = mdt.get_vertex(b)
             var cp = mdt.get_vertex(c)
-            # Calculate face normal.
+            # Calculate the normal of the face.
             var n = (bp - cp).cross(ap - bp).normalized()
-            # Add face normal to current vertex normal.
+            # Add this face normal to the current vertex normals.
             # This will not result in perfect normals, but it will be close.
             mdt.set_vertex_normal(a, n + mdt.get_vertex_normal(a))
             mdt.set_vertex_normal(b, n + mdt.get_vertex_normal(b))
             mdt.set_vertex_normal(c, n + mdt.get_vertex_normal(c))
 
-        # Run through vertices one last time to normalize normals and
-        # set color to normal.
+        # Run through the vertices one last time to normalize their normals and
+        # set the vertex colors to these new normals.
         for i in range(mdt.get_vertex_count()):
             var v = mdt.get_vertex_normal(i).normalized()
             mdt.set_vertex_normal(i, v)
             mdt.set_vertex_color(i, Color(v.x, v.y, v.z))
 
         mesh.clear_surfaces()
         mdt.commit_to_surface(mesh)
+
+ .. code-tab:: csharp C#
+
+    using Godot;
+
+    public partial class MyMeshInstance3D : MeshInstance3D
+    {
+        MeshDataTool mdt = new MeshDataTool();
+        FastNoiseLite fnl = new FastNoiseLite();
+
+        public override void _Ready()
+        {
+            fnl.Frequency = 0.7f;
+
+            ArrayMesh mesh = Mesh as ArrayMesh; // The mesh assigned the MeshInstance3D needs to be an ArrayMesh.
+            mdt.CreateFromSurface(mesh, 0);
+
+            for (var i = 0; i < mdt.GetVertexCount(); i++)
+            {
+                Vector3 vertex = mdt.GetVertex(i).Normalized();
+                // Scale the vertices using noise.
+                vertex = vertex * (fnl.GetNoise3Dv(vertex) * 0.5f + 0.75f);
+                mdt.SetVertex(i, vertex);
+            }
+
+            // Calculate the vertex normals, face-by-face.
+            for (var i = 0; i < mdt.GetFaceCount(); i++)
+            {
+                // Get the index in the vertex array.
+                var a = mdt.GetFaceVertex(i, 0);
+                var b = mdt.GetFaceVertex(i, 1);
+                var c = mdt.GetFaceVertex(i, 2);
+                // Get the vertex position using the vertex index.
+                var ap = mdt.GetVertex(a);
+                var bp = mdt.GetVertex(b);
+                var cp = mdt.GetVertex(c);
+                // Calculate the normal of the face.
+                var n = (bp - cp).Cross(ap - bp).Normalized();
+                // Add this face normal to the current vertex normals.
+                // This will not result in perfect normals, but it will be close.
+                mdt.SetVertexNormal(a, n + mdt.GetVertexNormal(a));
+                mdt.SetVertexNormal(b, n + mdt.GetVertexNormal(b));
+                mdt.SetVertexNormal(c, n + mdt.GetVertexNormal(c));
+            }
+
+            // Run through the vertices one last time to normalize their normals and
+            // set the vertex colors to these new normals.
+            for (var i = 0; i < mdt.GetVertexCount(); i++)
+            {
+                var v = mdt.GetVertexNormal(i).Normalized();
+                mdt.SetVertexNormal(i, v);
+                mdt.SetVertexColor(i, new Color(v.X, v.Y, v.Z));
+            }
+
+            mesh.ClearSurfaces();
+            mdt.CommitToSurface(mesh);
+        }
+    }