} // ModelRendererFrustumCulling

        /// <summary>
        /// This is task that's is performed over the threads.
        /// </summary>
        private static void ModelRendererFrustumCullingTask(FrustumCullingParameters parameters)
        {
            BoundingFrustum      boundingFrustum = parameters.boundingFrustum;
            List <ModelRenderer> modelsToRender  = parameters.modelsToRender;
            int startPosition = parameters.startPosition;
            int count         = parameters.count;

            FastBoundingFrustum fastBoundingFrustum = new FastBoundingFrustum(boundingFrustum);

            // I improved memory locality with FrustumCullingDataPool.
            // However, in order to do that I had to make the code a little more complicated and error prone.
            // There is a performance gain, but it is small.
            // I recommend to perform this kind of optimizations is the game/application has a CPU bottleneck.
            // Besides, the old code was half data oriented.
            for (int i = startPosition; i < (count + startPosition); i++)
            {
                ModelRenderer.FrustumCullingData frustumCullingData = ModelRenderer.FrustumCullingDataPool.Elements[i];
                if (frustumCullingData.model != null && // Not need to waste cycles in this, how many ModelRenderer components will not have a model?
                    // Is Visible?
                    Layer.IsVisible(frustumCullingData.layerMask) && frustumCullingData.ownerActive && frustumCullingData.enabled)
                {
                    if (fastBoundingFrustum.Intersects(ref frustumCullingData.boundingSphere))
                    {
                        modelsToRender.Add(frustumCullingData.component);
                    }
                }
            }
        } // ModelRendererFrustumCullingTask
        } // PointLightFrustumCulling

        /// <summary>
        /// Frustum Culling.
        /// </summary>
        /// <param name="boundingFrustum">Bounding Frustum.</param>
        /// <param name="spotLightsToRender">The result.</param>
        public static void SpotLightFrustumCulling(BoundingFrustum boundingFrustum, List <SpotLight> spotLightsToRender)
        {
            FastBoundingFrustum fastBoundingFrustum = new FastBoundingFrustum(boundingFrustum);

            for (int i = 0; i < SpotLight.ComponentPool.Count; i++)
            {
                SpotLight component = SpotLight.ComponentPool.Elements[i];
                if (component.Intensity > 0 && component.IsVisible)
                {
                    BoundingSphere boundingSphere = new BoundingSphere(component.cachedPosition, component.Range);
                    if (fastBoundingFrustum.Intersects(ref boundingSphere))
                    {
                        //if (boundingFrustum.Intersects(frustumCullingData.boundingSphere)) // It is not thread safe and is slow as hell.
                        spotLightsToRender.Add(component);
                    }
                }
            }
        } // FrustumCulling