seq.mutate(width);
PathInfo pi = new PathInfo(scene, sample.getWavelengthPacket());
Lens lens = scene.getLens();
PathNode eyeTail = strategy.traceEyePath(lens, p,
pi, seq);
seq.mark();
seq.mutate(width);
Light light = scene.getLight();
PathNode lightTail = strategy.traceLightPath(
light, pi, seq);