# Artifacts on cube after modulo on coordinates

This happens with the following node configuration:

It is caused by the modulo (or Fract) operation. I stumbled upon this problem while trying to repeat coordinates on a cube. It works fine on a plane.

Any idea why is this happening? The effect is similiar to z-fighting and only happens in perspective view. In orthographic that side is black. Is the modulo operation for some reason unable to determine a value at that side of the cube ?

The Modulo node, when used with vector input repeats the output values at regular intervals, in this case $$1$$ unit.
You are using Generated texture coordinates as input which uses the objects size for coordinates, meaning it that maximum X,Y or Z are always considered at coordinate $$1$$ regardless off absolute dimensions.
Since in this case geometry is a cube, there is a planar face at precisely the coordinate X=$$1$$ which is the boundary point exactly where the Modulo pattern repeats itself and goes from black to white.