private void AddLights(RayTracer_552.SceneDatabase rtScene)
        {
            UWB_XNAGraphicsDevice.m_TheAPI.LightManager.ResetAllLights();
            for (int l = 0; l < rtScene.GetNumLights(); l++)
            {
                RTLight lgt = rtScene.GetLight(l);
                Vector4 useColor = new Vector4(lgt.GetColor(new Vector3(0,0,0)),1f);
                UWB_XNALight theLight = null;

                if (lgt.GetLightSourceType() == RTLightType.RTLightSourceType.RTLightSourceTypeDirection)
                {
                    theLight = UWB_XNAGraphicsDevice.m_TheAPI.LightManager.CreateDirectionalLight();
                }
                else if (lgt.GetLightSourceType() == RTLightType.RTLightSourceType.RTLightSourceTypeSpot)
                {
                    theLight = UWB_XNAGraphicsDevice.m_TheAPI.LightManager.CreateSpotLight();
                }
                else
                {
                    theLight = UWB_XNAGraphicsDevice.m_TheAPI.LightManager.CreatePointLight();
                }

                theLight.Ambient = Vector4.Zero;
                theLight.Diffuse = useColor;
                theLight.Specular = useColor;
                theLight.Position = lgt.GetLightPosition();
                theLight.Direction = -lgt.GetNormalizedDirection(Vector3.Zero);
                theLight.Color = useColor;
                theLight.Attenuation = new Vector3(1f, 0.0f, 0.0f);
                theLight.Range = 10000f;
                theLight.SwitchOnLight();

                UWB_Primitive prim = CreateSphereMesh();
                SetMeshMaterial(prim, rtScene.GetMaterial(0));
                float scale = 0.25f;
                CreateNode(lgt.GetLightPosition(), scale, scale, scale, prim);
            }
        }
        internal void AddRTScene(RayTracer_552.RTCamera c, RayTracer_552.SceneDatabase rtScene)
        {
            UWB_Primitive prim;

            NewSceneDatabase();
            SceneResource<RTGeometry> allGeom = rtScene.GetAllGeom();
            for (int i = 0; i < allGeom.Count; i++)
            {
                RTGeometry g = (RTGeometry)allGeom.ResourceLookup(i);
                switch (g.GeomType()) {
                    case RTGeometry.RTGeometryType.Sphere:
                        RTSphere s = (RTSphere)g;
                        prim = CreateSphereMesh();
                        SetMeshMaterial(prim, rtScene.GetMaterial(s.GetMaterialIndex()));
                        float scale =s.Radius/2f;
                        CreateNode(s.Center, scale, scale, scale, prim);
                        break;
                    case RTGeometry.RTGeometryType.Rectangle:
                        RTRectangle r = (RTRectangle) g;
                        prim = CreateRectangle(r);
                        SetMeshMaterial(prim, rtScene.GetMaterial(r.GetMaterialIndex()));
                        UWB_SceneNode node = CreateNode(r.GetCenter(), r.GetUSize()/2f, 1f, r.GetVSize()/2f, prim);
                        // now rotate the y-vector of node to point towards r.Normal;
                        float dot = (float)Math.Abs(Vector3.Dot(Vector3.UnitY, r.GetNormal()));
                        if (dot < 0.9999f)
                        {
                            float angle = (float)Math.Acos(dot);
                            Vector3 axis = Vector3.Cross(Vector3.UnitY, r.GetNormal());
                            axis.Normalize();
                            Quaternion q = Quaternion.CreateFromAxisAngle(axis, angle);
                            UWB_XFormInfo xf = node.getXFormInfo();
                            xf.SetRotationQuat(q);
                            node.setXFormInfo(xf);
                        }
                        break;
                    case RTGeometry.RTGeometryType.Triangle:
                        RTTriangle t = (RTTriangle)g;
                        Vector3[] v = t.GetVertices();
                        prim = new UWB_PrimitiveTriangle(v[0], v[1], v[2]);
                        prim.EnableLighting(true);
                        prim.EnableTexturing(false);
                        SetMeshMaterial(prim, rtScene.GetMaterial(t.GetMaterialIndex()));
                        CreateNode(Vector3.Zero, 1f, 1f, 1f, prim);
                        break;
                    }
            }
            AddCamera(c);
            AddLights(rtScene);

            // to show ray list
            mShownRayX = mShownRayY = 0;
            mRaysToShow = new UWB_PrimitiveList();

            mDebugInfo = new UWB_SceneNode();
            mDebugInfo.setPrimitive(mRaysToShow);
            mDebugInfo.insertChildNode(mPixelsToShow.GetAllPixels());
            mDebugInfo.insertChildNode(mPixelInWorld.GetAllPixels());
        }