why do shapes vanish when on a box

[coder787]

when I place a shape on a box it vanishes completely now and then when rotating

I know there is z-fighting which can be seen when a rectangle is on a rectangle but wouldn't expect it to vanish completely. Tried to do grouping to fix it but doesn't seem to make a difference.

see simple demo I created here, thanks.

https://codepen.io/coder787/pen/MWJbJQo

[snissn]

hi - i think i have a similar issue here https://jsbin.com/kukabohixe/edit?html,css,console,output

[different55]

I know this is old but just to add an answer here, mostly for my own reference tbh, this is a Z-fighting issue. Specifically, it's the last example of it in the docs here. When the center of the big object becomes closer to the camera than the center of the small object, it'll vanish entirely behind it even if you know, physically, that it wouldn't be occluded at all.

This is something that can be worked around by adding a balancing invisible object to a group, a good choice is often reflecting the visible object around to the opposite side of the surface it's clinging to.

This is coder787's example, with the top rect being given a counterbalance and the bottom left with the issue for comparison. Wiggling the camera up and down from the preset position demonstrates the issue and fix pretty well.

https://codepen.io/different55/pen/MYgXdzj