"Warped" lighting on a sphere


I have a strange lighting on my sphere in a scene.
The scene is very simple: One sphere and one directional light. With that setting the light warps around the poles, which looks weired.
In the image you see the sphere from top and a duplicate from bottom.

The sphere has been imported from blender with UV maps in cylindrical projection, but the built-in sphere is the same. I found, that the lighting is correct without UV-mapping, but than, of course, the texture is not placed correctly.


Okay,finally I got it.

The strumpy has a function called “unpack normals”, which has to be in the pipeline for the normals.
Now it works as expected.

Thanks for reading