/// <summary>
/// Fills in a set of spherically mapped texture coordinates to the passed in mesh
/// </summary>
private static void SetSphericalTextureCoordinates(Mesh mesh)
{
BoundingSphere boundingSphere = BufferHelper.ComputeBoundingSphere(mesh);
var vertexes = BufferHelper.ReadVertexBuffer <PositionNormalTextured>(mesh);
for (int i = 0; i < vertexes.Length; i++)
{
Vector3 vertexRay = Vector3.Normalize(vertexes[i].Position - boundingSphere.Center);
double phi = Math.Acos(vertexRay.Z);
vertexes[i].Tu = CalculateTu(vertexRay, phi);
vertexes[i].Tv = (float)(phi / Math.PI);
}
BufferHelper.WriteVertexBuffer(mesh, vertexes);
}