Sketchfab Forum

Mesh receive light on the wrong side


(Solu9) #1

Hey there.

I've got an odd lightning problem.
I have this model with several planes. I use environment lightning and 1 directional light. In the pictures I have linked the directional light is aimed directly at the front of the model. However the planes on the top part of the model receives inverse light.

I have tried flipping the normals and in the pictures the model uses double mesh on the planes with normals in each direction. The issue still there.
I have turned double sided material on/off. Same story.

If I shift from normal to bump map the lighting is fine, but I would of course like to use my normal map as a normal map.


Hmm weird. Did you use a mirror modifier or something similar that would cause those meshes to have a non-uniform scale (e.g. [1, -1, 1]) ?

Have you tried using the 3ds Max plugin?

(Solu9) #4

Hey james.

No not mirror but I did use the Symmetry modifier. And I did think that that might be the cause, but. The feathers up top. The middle one and those of the left side (looking at the model's front) are just copied out. The ones on the right side are the symmetrized. But the error occurs on all of the feathers, even the middle one which did not get a Symmetry modifier.

Oh and no I didn't know about that plugin. I'll have a look at it. Does this make up for mirror errors?

Got any other ideas to what could cause this?


I'm not sure if the plugin will help this specific issue, but it might be useful for your workflow.

Could you check the Scale on those objects to see if they have non-uniform signs?

(Solu9) #6

I have attached all elements of the mask together in the version seen in the pictures.
I've just checked an older version where the individual feathers still have the Symmetry modifier (not collapsed) and their scale are 100/100/100.

Perhaps I should note that all the feathers on the left side are not copies of the middle one, they are instances. Which then have the symmetry modifier. But since they are all collapsed into one mesh and I have reset xforms... I dunno.


Hmm ok. @waleguene might be able to help

(Solu9) #8

tl;dr: It works!

Okay this is the weirdest thing ever. You need a short background story.

Originally I baked the normal map for the model without the feather. So only the mask. Later on I got around and did the feather as well. I baked a normal map for that and cut and pasted it into the mask's normal map.

I saved this as .tga.

After having reimported god knows how many versions of the whole mask into Sketchfab I just now tried to apply the normal map before the diffuse map.
To my big surprise the feather part of the normal map was not there! I double checked in Photoshop and the filename. And I had done nothing wrong.

I noticed that my maps, once imported to Sketchfab, where called XXXXX.tga.png <- .png (so Sketchfab converts whatever filetype to .png?)
I then opened my .tga normal map in Photoshop, saved it as .png. Imported it to Sketchfab, and abracadabra the feathers receive light correctly!!


So glad you got it working!

That sounds very strange. I'm afraid I'm not familiar enough with 3ds Max to suggest what was going wrong :confused:

Regarding texture processing, yes. Details here: