I have a block model that renders an overlay onto the block beside it. The overlay functions perfectly when both block blocks are in the same chunk, but when one of the blocks is in another chunk as the first one then the overlay and the block start to z-fight. Here's an image of what I'm talking about:

The black block renders the overlay onto the cobblestone block to the left of it. As you can see when both blocks are in the same chunk they're fine, but when they're in different chunks the cobblestone z-fights the overlay. I think the reason this happens is because each chunk is drawn separately, and two quads in the same draw won't z-fight. But when a quad from one draw is in the same position as a quad from another draw then they z-fight. Is this theory correct? And if it is, is there a way to solve this?

Edited February 19, 20178 yr by Silly511

That's because each chunk is baked down to a single 3D object and rendered.  The z-fighting doesn't occur because the overlay and the cobblestone are in the same mesh and it gets simplified to remove unneeded faces.  But when you render across a chunk boundary, both faces exist in the same space and OpenGL has to render both of them, but can't z-sort them.

47 minutes ago, Draco18s said:

That's because each chunk is baked down to a single 3D object and rendered.  The z-fighting doesn't occur because the overlay and the cobblestone are in the same mesh and it gets simplified to remove unneeded faces.  But when you render across a chunk boundary, both faces exist in the same space and OpenGL has to render both of them, but can't z-sort them.

Ok that makes sense. So there really isn't a good way to solve this?

offset the overlay from the block position by a tiny amount. 0.001 is sufficient.

Thank you that worked. I was trying to avoid offsetting it a bit because I thought if you looked at the model top-down you could see a tiny gap, but you really can't see anything at all.

Edited February 19, 20178 yr by Silly511

Nope, the distance is too tiny.