White outlines when performing 2d lighting

Question

I have a very simple shader that just sets the normal to:

NORMAL = normalize(vec3(-1, 0, 1)); 

when I enable lighting, it has white artefacts at the edges (1 pixel, no matter how far I zoom in):

https://i.imgur.com/PyYXFa2.mp4

when I set the render mode to unshaded, the lines don't show up.
Any ideas how to prevent the white lines ?

this also happens when I run the scene (and enable more normals etc...):

https://i.imgur.com/e8o1W3I.mp4

Any ideas how to prevent this?
Thanks.

Answer 1

Answer my own question:

Disable anti-alias on the polygons!