static void AddSphere(Camera camera, Sphere sphere)
        {
            Vec3[] positions;
            int[]  indices;
            GeometryGenerator.GenerateSphere(sphere.Radius, 4, 4, false, out positions, out indices);

            Mat4 transform = new Mat4(Mat3.Identity, sphere.Origin);

            camera.DebugGeometry.AddVertexIndexBuffer(positions, indices, transform, false, true);
        }
        static void AddSphere(Camera camera, Sphere sphere)
        {
            if (addSpherePositions == null)
            {
                GeometryGenerator.GenerateSphere(sphere.Radius, 8, 8, false, out addSpherePositions, out addSphereIndices);
            }

            Mat4 transform = new Mat4(Mat3.Identity, sphere.Origin);

            camera.DebugGeometry.AddVertexIndexBuffer(addSpherePositions, addSphereIndices, transform, false, true);
        }