Normal Map Nodes on Mesh with Multiple UV Tiles

sampei

New member
so i've been trying to set up some normal maps on a single mesh with two UV tiles (UV_u1_v1 and UV_u2_v1) but unlike the regular image nodes the normal map node has no bg / fg color inputs so the following setup that I've been using for standard image nodes is useless:



I have tried using things like math > vector > add and tools > mixer but nothing seems to work, get lots of shading errors especially with the mixer node. Any workaround or maybe something I am overlooking?
I'm looking for a node editor solution, without having to edit the current UV map or assign new surfaces.
By the way here's the UV tiles, color maps and mesh for the sake of clarity.





thanks in advance for any :help:
 

sampei

New member
alright, think I might have found a decent workaround, this sort of works if you have only two uv tiles for a single mesh:



basically I used a pure black square image to mask the opacity of one of two tiles (in this case u2_v1) since the normalMap plugged into the bg input in the mixer basically overrides every other tile despite being set to default u1_v1 and having both tiling options set to reset. For some reason the image node in question needs "invert" to be active in its Texture editor (this is also true if it's pure white, not sure why).
I also tried using a weight map but this won't work well because of the bleeding, you'd need extra edge loops to minimize it and it's not ideal at all.
The result is decent even if some small artifacts are present, but on close inspection this might be due to the normal maps not being consistent with one another...probably need to tweak some parameters in the mudbox map exporter. Also it gets less noticeable once all the other maps are plugged in.



If more than 2 UV tiles are present, it gets more complicated. For example with a single mesh with 4 UV tiles, you need to combine two mixer nodes (each like the one in the flow above) into a third mixer node which opacity will be controlled by a fourth mixer node fed with the necessary masking image maps. Took a while to get it right while testing in VPR as Layout tended to crash every time some inputs were swapped.

edit_got the idea here, thanks to vfxwizard http://forums.newtek.com/showthread.php?85596-Mixing-Normals&highlight=normal+map
 
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