I specified the diffuse and specular PBR maps in a .mtl file. I followed Sketchfab's recommended naming conventions, and as expected, Sketchfab was able to automatically assign the two maps to the correct slots. This is great.
Now I want to add two more maps -- glossiness and normal maps. AFAIK, the canonical .mtl standards do not support these two maps (although some newer standards support glossiness maps with tag
map_Pr and normal maps with tag
I tried referencing the glossiness and normal maps in my .mtl file anyways, followed Sketchfab's naming conventions, and hoped for the best.
... newmtl Material.001 Ns 96.078431 Ka 1.000000 1.000000 1.000000 Kd 0.640000 0.640000 0.640000 Ks 0.500000 0.500000 0.500000 Ke 0.000000 0.000000 0.000000 Ni 1.000000 d 1.000000 illum 2 map_Kd WoodPlanksWorn19_diffuse.jpg map_Pr WoodPlanksWorn19_glossiness.jpg norm WoodPlanksWorn19_normal.jpg map_Ns WoodPlanksWorn19_specular.jpg ...
No miracle happened -- the glossiness and normal maps didn't load automatically into their slots.
Is there a way for Sketchfab to automatically allocate the glossiness and normal maps to their slots, just like how it automatically loads the diffuse and specular maps?