I wanted to plug a bump map into the normal inputs of a Diffuse and a Glossy shader. But if that is done, for some unknown reason it renders only on part of the mesh.
A line across the image will appear. On the left side of the image below it looks fine, but on the right side it isn't. It looks as if it has rendered image without the Bump map plugged into the Normal input of the Glossy shader.
Bump node group:
I used spec map as factor of Mix shader:
I discovered that the problem is caused by Bump map plugged into Normal input of Glossy shader.
It seems that the artifact is caused by the last "Add" node in the Bump map group connection which is combining all free bumps together.
if the Blend type is changed to e.g. "multiply", the line across the image (the artifact) will disappear. However, the resulting image is much to dark. Which is obvious (wrong blend type).
So why does the blend type "Add" on the last node of Bump group cause this issue?
Bump maps are classic *.png images with greyish background color (#b3b3b3), content in a image has dark color (#0a0a0a)
I'm using Blender v2.69.