MIKKTSPACE tangents in sketchfab

stkopp

Ok, so how to get MIKKTSPACE to work correctly with sketchfab?

model
As you might see, all sides of cube is completely broken

Or maybe there is some sort of softwere (like handplane) which converts MIKKT to Sketchfab normal map type?

cromadbomber

Not sure about your other maps but it looks like that normal map is heavily dithered on that sketchfab link you posted.

stkopp

cromadbomber said:

Not sure about your other maps but it looks like that normal map is heavily dithered on that sketchfab link you posted.

It is not an issue. Main issue - distortion of tangents. 
NM can be anyhow compressed/dithered, but it should always be correct in terms of shading.

ActionDawg

I replicate this too, and even tried every tspace in Handplane as well as Xnormal and Substance bakes and they all come out wrong. Unfortunately I don't think this will get a clearer answer without contacting them.

This quote from a staff member is the closest I got:

Note that if the format you use support tangent space export, we will keep your tangent spaces. Otherwise, provided that you exported some UVs, we will generate the tangents.

Same quote is also here:
https://help.sketchfab.com/hc/en-us/articles/211714583-Tangent-Space-and-Normal-Maps

stkopp

somedoggy said:

I replicate this too, and even tried every tspace in Handplane as well as Xnormal and Substance bakes and they all come out wrong. Unfortunately I don't think this will get a clearer answer without contacting them.

This quote from a staff member is the closest I got:

Note that if the format you use support tangent space export, we will keep your tangent spaces. Otherwise, provided that you exported some UVs, we will generate the tangents.

Same quote is also here:
https://help.sketchfab.com/hc/en-us/articles/211714583-Tangent-Space-and-Normal-Maps

Sad

Some time ago we tryed to bring MIKKTSPACE in JME:
https://hub.jmonkeyengine.org/t/normal-map-shading-problems/34947

I dont think that this is hard to make open source code to be WebGL. Maybe if many of us will write to support and give them some handy links (like mine) they solve problem faster.