Oh, right. Your shadow is actually at the fore, where the ground tile would sneak through, and the shadow behind is the darker one where tile would probably not be visible. Here I just thought the shadow was at the back full stop. XD
Have you considered dividing the portcullis into beams and crosses as per the photo you linked?
Rivets, I presume, knowing nothing about gates, hold the bars together. As is, looks more like a solid slab of metal with holes punched in it, and the rivets serve no apparent purpose. Throw in those vertical lines, though, and maybe...?
Charlie, I realized what you meant about angles in the shower, and for some strange reason thought I'd already come back here to fix my post and respond - reflected light from the top left, off a smooth surface, will take the same angle on bouncing to enter from the bottom left, like you said. Reflected off a rough surface it might diffuse and with other secondary sources it 'might' make for a central upward push as I did it, but that's not the case here, as you pointed out.