How to create a sphere programmatically in XNA

I "discovered" an easy but silly way to create a sphere programmatically in XNA, it is very simple. The idea came to me when I wanted to create huge planets in XNA to make an endless map. Any way the method is very simple, I don't know If someone knows it or it was used before, but till now it is working and efficient. You can control the resolution or how "round" the sphere is.

The code is written in C# with microsoft's XNA 4.0.

Here is a high resolution sphere in wire frame:

The sphere contains 8100 vertices and 48600 indices.

Code:

    public class Sphere
    {
        VertexPositionColor[] vertices; //later, I will provide another example with VertexPositionNormalTexture
        VertexBuffer vbuffer;
        short[] indices; //my laptop can only afford Reach, no HiDef :(
        IndexBuffer ibuffer;
        float radius;
        int nvertices, nindices;
        BasicEffect effect;
        GraphicsDevice graphicd;
        public Sphere(float Radius, GraphicsDevice graphics)
        {
            radius = Radius;
            graphicd = graphics;
            effect = new BasicEffect(graphicd);
            nvertices = 90 * 90; // 90 vertices in a circle, 90 circles in a sphere
            nindices = 90 * 90 * 6;
            vbuffer = new VertexBuffer(graphics, typeof(VertexPositionNormalTexture), nvertices, BufferUsage.WriteOnly);
            ibuffer = new IndexBuffer(graphics, IndexElementSize.SixteenBits, nindices, BufferUsage.WriteOnly);
            createspherevertices();
            createindices();
            vbuffer.SetData<VertexPositionColor>(vertices);
            ibuffer.SetData<short>(indices);
            effect.VertexColorEnabled = true;
        }
        void createspherevertices()
        {
            vertices = new VertexPositionColor[nvertices];
            Vector3 center = new Vector3(0, 0, 0);
            Vector3 rad = new Vector3((float)Math.Abs(radius), 0, 0);
            for (int x = 0; x < 90; x++) //90 circles, difference between each is 4 degrees
            {
                float difx = 360.0f / 90.0f;
                for (int y = 0; y < 90; y++) //90 veritces, difference between each is 4 degrees 
                {
                    float dify = 360.0f / 90.0f;
                    Matrix zrot = Matrix.CreateRotationZ(MathHelper.ToRadians(y * dify)); rotate vertex around z
                    Matrix yrot = Matrix.CreateRotationY(MathHelper.ToRadians(x * difx)); rotate circle around y
                    Vector3 point = Vector3.Transform(Vector3.Transform(rad, zrot), yrot);//transformation

                    vertices[x + y * 90] = new VertexPositionColor(point, Color.Black);
                }
            }
        }
        void createindices()
        {
            indices = new short[nindices];
            int i = 0;
            for (int x = 0; x < 90; x++)
            {
                for (int y = 0; y < 90; y++)
                {
                    int s1 = x == 89 ? 0 : x + 1;
                    int s2 = y == 89 ? 0 : y + 1;
                    short upperLeft = (short)(x * 90 + y);
                    short upperRight = (short)(s1 * 90 + y);
                    short lowerLeft = (short)(x * 90 + s2);
                    short lowerRight = (short)(s1 * 90 + s2);
                    indices[i++] = upperLeft;
                    indices[i++] = upperRight;
                    indices[i++] = lowerLeft;
                    indices[i++] = lowerLeft;
                    indices[i++] = upperRight;
                    indices[i++] = lowerRight;
                }
            }
        }
        public void Draw(Camera cam) // the camera class contains the View and Projection Matrices
        {
            effect.View = cam.View;
            effect.Projection =  cam.Projection;
            graphicd.RasterizerState = new RasterizerState() { FillMode = FillMode.WireFrame }; // Wireframe as in the picture
            foreach (EffectPass pass in effect.CurrentTechnique.Passes)
            {
                pass.Apply();
                graphicd.DrawUserIndexedPrimitives<VertexPositionColor>(PrimitiveType.TriangleList, vertices, 0, nvertices, indices, 0, indices.Length / 3);
            }
        }
    }