RayHit trace(inout Ray ray)
{
    RayHit hit = createRayHit();

    // floor
    intersectPlane(ray, hit, vec3(0.0,-1.5,0.0),vec3(0.0,1.0,0.0));

    // spheres
    for (int i = 0; i < _activeSpheres; i++)
    {
        intersectSphere(ray, hit, _spheres[i]);
    }

    Sphere s;
    s.cr = vec4(0.0,0.0,0.0,INF*2.0);
    s.material = MAT_GLOW;
    s.albedo = vec3(1.0,1.0,1.0);
    intersectInsideOutSphere(ray, hit, s);

    //ray.distance += hit.material == MAT_CHROME
    //    ? hit.distance * length(ray.energy) * float(hit.distance < INF)
    //    : hit.distance * float(hit.distance < INF);
    //ray.distance += hit.distance * float(hit.distance < INF);
    ray.distance += hit.distance;
    //ray.distance = clamp(ray.distance, 0, INF);
    //ray.distance += hit.distance * length(ray.energy);

    return hit;
}