private void defineBox(UWB_PrimitiveList list, Vector3 min, Vector3 max)
        {
            UWB_PrimitiveLine l = new UWB_PrimitiveLine();
            l.setStartPoint(min.X, min.Y, min.Z);
            l.setEndPoint(max.X, min.Y, min.Z);
            list.append(l);
            l = new UWB_PrimitiveLine();
            l.setStartPoint(min.X, min.Y, min.Z);
            l.setEndPoint(min.X, max.Y, min.Z);
            list.append(l);
            l = new UWB_PrimitiveLine();
            l.setStartPoint(min.X, min.Y, min.Z);
            l.setEndPoint(min.X, min.Y, max.Z);
            list.append(l);

            l = new UWB_PrimitiveLine();
            l.setStartPoint(max.X, max.Y, max.Z);
            l.setEndPoint(min.X, max.Y, max.Z);
            list.append(l);
            l = new UWB_PrimitiveLine();
            l.setStartPoint(max.X, max.Y, max.Z);
            l.setEndPoint(max.X, min.Y, max.Z);
            list.append(l);
            l = new UWB_PrimitiveLine();
            l.setStartPoint(max.X, max.Y, max.Z);
            l.setEndPoint(max.X, max.Y, min.Z);
            list.append(l);

            l = new UWB_PrimitiveLine();
            l.setStartPoint(min.X, max.Y, min.Z);
            l.setEndPoint(max.X, max.Y, min.Z);
            list.append(l);
            l = new UWB_PrimitiveLine();
            l.setStartPoint(min.X, max.Y, min.Z);
            l.setEndPoint(min.X, max.Y, max.Z);
            list.append(l);

            l = new UWB_PrimitiveLine();
            l.setStartPoint(min.X, min.Y, max.Z);
            l.setEndPoint(max.X, min.Y, max.Z);
            list.append(l);
            l = new UWB_PrimitiveLine();
            l.setStartPoint(min.X, min.Y, max.Z);
            l.setEndPoint(min.X, max.Y, max.Z);
            list.append(l);

            l = new UWB_PrimitiveLine();
            l.setStartPoint(max.X, min.Y, min.Z);
            l.setEndPoint(max.X, max.Y, min.Z);
            list.append(l);
        }
        internal void AddDebugRays(RayTracer_552.RTCore rtCore)
        {
            if (null == rtCore)
                return;

            while ((mShownRayY < rtCore.CurrentY) ||
                    (((mShownRayY == rtCore.CurrentY) && (mShownRayX < rtCore.CurrentX))))
            {
                lock (rtCore)
                {
                    Vector3 p = new Vector3();
                    System.Drawing.Color c = new System.Drawing.Color();
                    float dist;
                    rtCore.GetPixelValues(mShownRayX, mShownRayY, out p, out c, out dist);

                    if (rtCore.DisplayDebugRays())
                    {
                        UWB_PrimitiveLine line = new UWB_PrimitiveLine();
                        Vector3 v = p - mCameraPosition;
                        float len = v.Length();
                        v /= len;
                        if (dist > (float.MaxValue / 2f))
                            dist = len;
                        p = mCameraPosition + dist * v;
                        line.setStartPoint(mCameraPosition.X, mCameraPosition.Y, mCameraPosition.Z);
                        line.setEndPoint(p.X, p.Y, p.Z);
                        line.Material.Diffuse = Vector4.Zero;
                        line.Material.Specular = Vector4.Zero;
                        line.Material.Ambient = Vector4.Zero;
                        line.Material.Emissive = Vector4.One;
                        mRaysToShow.append(line);
                    }

                    mShownRayX++;
                    if (mShownRayX >= rtCore.ImageWidth)
                    {
                        mShownRayX = 0;
                        mShownRayY++;
                    }
                }
            }
        }
        private void AddCamera(RayTracer_552.RTCamera c)
        {
            // Look at position
            UWB_SceneNode atN = new UWB_SceneNode();
            UWB_XNAPrimitiveMesh at = new UWB_XNAPrimitiveMesh("sphere");
            at.Material.Diffuse = new Vector4(0.8f, 0.1f, 0.1f, 1.0f);
            atN.setPrimitive(at);
            UWB_XFormInfo atxf = atN.getXFormInfo();
            atxf.SetTranslation(c.AtPosition);
            atxf.SetScale(new Vector3(0.3f, 0.3f, 0.3f));
            atN.setXFormInfo(atxf);

            // Eye position
            UWB_SceneNode eyeN = new UWB_SceneNode();
            UWB_XNAPrimitiveMesh eye = new UWB_XNAPrimitiveMesh("cone");
            eyeN.setPrimitive(eye);
            UWB_XFormInfo eyexf = eyeN.getXFormInfo();
            eyexf.SetTranslation(c.EyePosition);
            mCameraPosition = c.EyePosition;
            Vector3 init = new Vector3(0, 0, 1); // initial cone orientation
            Vector3 final = c.AtPosition - c.EyePosition;
            final = Vector3.Normalize(final);
            float dot = Vector3.Dot(init, final);
            if (Math.Abs(dot) < 0.9999)
            {
                float angle = (float)Math.Acos(dot);
                Vector3 axis = Vector3.Cross(init, final);
                axis = Vector3.Normalize(axis);
                Quaternion q = Quaternion.CreateFromAxisAngle(axis, angle);
                eyexf.SetRotationQuat(q);
            }
            eyeN.setXFormInfo(eyexf);

            // Lines ...
            UWB_SceneNode lineN = new UWB_SceneNode();
            mCameraPrimitives = new UWB_PrimitiveList();
            lineN.setPrimitive(mCameraPrimitives);
            UWB_PrimitiveLine l = new UWB_PrimitiveLine();
            l.setStartPoint(c.EyePosition.X, c.EyePosition.Y, c.EyePosition.Z);
            l.setEndPoint(c.AtPosition.X, c.AtPosition.Y, c.AtPosition.Z);
            mCameraPrimitives.append(l);

            mCamera.insertChildNode(lineN);
            mCamera.insertChildNode(atN);
            mCamera.insertChildNode(eyeN);
        }
        internal void AddImageFrame(RayTracer_552.RTCore rtCore)
        {
            if (null == rtCore)
                return;

            // construct the image frame
            Vector3 tl = rtCore.GetTopLeftPixelPosition();
            Vector3 tr = rtCore.GetTopRightPixelPosition();
            Vector3 bl = rtCore.GetBottomLeftPixelPosition();
            Vector3 br = rtCore.GetBottomRightPixelPosition();
            UWB_PrimitiveLine t, b, l, r;
            t = new UWB_PrimitiveLine();
            b = new UWB_PrimitiveLine();
            l = new UWB_PrimitiveLine();
            r = new UWB_PrimitiveLine();

            t.setStartPoint(tr.X, tr.Y, tr.Z);
            t.setEndPoint(tl.X, tl.Y, tl.Z);
            t.Material.Emissive = Vector4.UnitX;

            l.setStartPoint(tl.X, tl.Y, tl.Z);
            l.setEndPoint(bl.X, bl.Y, bl.Z);
            l.Material.Emissive = Vector4.UnitX;

            b.setStartPoint(br.X, br.Y, br.Z);
            b.setEndPoint(bl.X, bl.Y, bl.Z);
            b.Material.Emissive = Vector4.UnitX;

            r.setStartPoint(tr.X, tr.Y, tr.Z);
            r.setEndPoint(br.X, br.Y, br.Z);
            r.Material.Emissive = Vector4.UnitX;

            mCameraPrimitives.append(t);
            mCameraPrimitives.append(b);
            mCameraPrimitives.append(l);
            mCameraPrimitives.append(r);
        }