/// <summary>
        /// Constructor
        /// </summary>
        public SkinnedGame()
        {
            // XNA startup
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";

            // Some basic setup for the display window
            this.IsMouseVisible = true;
            this.Window.AllowUserResizing = true;
            this.graphics.PreferredBackBufferWidth = 1024;
            this.graphics.PreferredBackBufferHeight = 768;

            // Create a simple mouse-based camera
            camera = new Camera(graphics);
            camera.Eye = new Vector3(190, 247, 387);
            camera.Center = new Vector3(-20, 86, 159);
        }
        /// <summary>
        /// Draw the model
        /// </summary>
        /// <param name="graphics">The graphics device to draw on</param>
        /// <param name="camera">A camera to determine the view</param>
        /// <param name="world">A world matrix to place the model</param>
        public void Draw(GraphicsDevice graphics, Camera camera, Matrix world)
        {
            if (model == null)
                return;

            //
            // Compute all of the bone absolute transforms
            //

            Matrix[] boneTransforms = new Matrix[bones.Count];

            for (int i = 0; i < bones.Count; i++)
            {
                Bone bone = bones[i];
                bone.ComputeAbsoluteTransform();

                boneTransforms[i] = bone.AbsoluteTransform;
            }

            //
            // Determine the skin transforms from the skeleton
            //

            Matrix[] skeleton = new Matrix[modelExtra.Skeleton.Count];
            for (int s = 0; s < modelExtra.Skeleton.Count; s++)
            {
                Bone bone = bones[modelExtra.Skeleton[s]];
                skeleton[s] = bone.SkinTransform * bone.AbsoluteTransform;
            }

            // Draw the model.
            foreach (ModelMesh modelMesh in model.Meshes)
            {
                foreach (Effect effect in modelMesh.Effects)
                {
                    if (effect is BasicEffect)
                    {
                        BasicEffect beffect = effect as BasicEffect;
                        beffect.World = boneTransforms[modelMesh.ParentBone.Index] * world;
                        beffect.View = camera.View;
                        beffect.Projection = camera.Projection;
                        beffect.EnableDefaultLighting();
                        beffect.PreferPerPixelLighting = true;
                    }

                    if (effect is SkinnedEffect)
                    {
                        SkinnedEffect seffect = effect as SkinnedEffect;
                        seffect.World = boneTransforms[modelMesh.ParentBone.Index] * world;
                        seffect.View = camera.View;
                        seffect.Projection = camera.Projection;
                        seffect.EnableDefaultLighting();
                        seffect.PreferPerPixelLighting = true;
                        seffect.SetBoneTransforms(skeleton);
                    }
                }

                modelMesh.Draw();
            }
        }