Why does a quad only recieve lighting on one of its two triangles?

Unity Engine
1

I’m attempting to light a quad and for some reason only half of it will light. It’s as though the edge that runs diagonally through its center is blocking light. I’ve tried multiple types of light sources, tried moving the quad and the light sources around, and tested the light sources on other objects. Only quads seem to have this issue. Could anyone enlighten me as to why this happens?

Also, aside from this I can’t find any reason to use a plane instead of a quad. Wouldn’t it be better to use a quad since a plane has a pretty large amount of faces? For that matter, in most instances wouldn’t it be better to use a cube instead of a plane since you’re then only using 6 faces instead of the planes 200?

Attached is a picture of what the lighting issue looks like. The floor is a cube and is receiving full lighting from a point light that’s spaced halfway between it and the quad ceiling. I turned intensity and range on the light to full to exaggerate the effect.

1493273--83506--$Quad Lighting.jpg
1493273--83506--$Quad Lighting.jpg1360×725 131 KB

2

Is this something you created in a modeling package and imported? Most likely the normals are incorrect for the other face and pointing upward, making it not render.

3

No the quad is one of Unity’s standard quads. I figured out what the problem was though. It was because the quad didn’t have any scale on the Z axis. Not sure how I missed that one, must’ve been from being awake for more hours than the human body is meant to be awake lol.

The question about quads vs planes vs cubes still stands though.