How can I draw (not bake) normal map over my model, like a texture in texture paint mode? Render cycles.
Thank you in advance!
It is easier and more intuitive to paint a height-map, then convert it into a normal map:
There is GIMP normalmap plugin, Photoshop plugins like xNormal, apps like CrazyBump and a lot of others. These all can do the conversion. Also, it can be done through Blender Baking.
If you already have a normal map, and you need to add to it, you can combine normal maps with overlay blending operation - generally it is ok enough but note that it is not the correct operation - more on combining normal maps is here: Blending in detail.
You can also paint directly into normal maps:
you can paint with a special texture brush:
There is no accurate tutorial from the creator of this method but I've managed to get it to work in a way presented below:
You'll need to create Paint Slot, assign it to Height Map Image in Texture Group and connect Normals to shaders.
Don't forget to set Texture X and Texture Y size in Bump_to_normal group accordingly to created Paint Slot.
That's really all you'll need to do.
I don't know what sorcery is behind this but it is converting Height Map to Normal Map pretty good.