Material Values in Exports
A material is more than its images. Glass is glass because its transmission is 1, and a light glows because its emission is not black — neither needs a texture or a UV map. When you export, Vertexix writes each material's values (the values on Edit Material's Standard PBR tab, apart from Subsurface) alongside its textures, even for a material that has no textures at all. This page explains where those values end up in each format and how they come back when you import the file again.
What each format receives
Each format has its own set of material slots, and most have no slot for many of the values. Vertexix fills the standard slots each format has, so other programs read what they can:
| Format | Standard values written |
|---|---|
| glTF / GLB | Base color, metallic, roughness, emission, alpha mode and cutoff, and double-sided in the core material; specular, sheen, clearcoat, transmission, volume, IOR, emission strength, anisotropy, iridescence and dispersion as their KHR_materials extensions, each only when the material actually uses it. |
| FBX | Base color, metallic and roughness as Maya's Stingray PBS properties, plus a Phong shininess derived from roughness for programs that only read Phong; emissive, diffuse and opacity in the classic slots. |
| OBJ (.mtl) | Diffuse color (Kd), specular color (Ks), emission (Ke), opacity (d) and index of refraction (Ni). |
| Collada (.dae) | The classic diffuse, specular and emission colors, transparency and index of refraction. Collada has no PBR slots. |
| PLY, STL | No material values. |
Exact values for re-import
Because no format holds everything, every glTF/GLB, FBX, OBJ and Collada export also stores the material's complete set of values, exactly, in a place other programs ignore:
| Format | Where the exact values are stored |
|---|---|
| glTF / GLB | The material's extras, as vertexix_factors. This keeps the values glTF has no slot for: the normal-map, height and displacement strengths. |
| FBX | A material property named Vertexix|factors. |
| OBJ | A comment line beginning # vertexix-factors in the .mtl file. |
| Collada | A VERTEXIX technique in the material's <extra> block. |
When Vertexix imports one of these files, it reads the stored values back by material name, and they win over the standard slots: they are exactly what was set, where the slots are only what the format could hold. Values such as IOR, sheen or clearcoat therefore survive a round trip through FBX or OBJ, even though another program opening the same file sees only the standard slots.
The stored set covers the Standard PBR values. The Subsurface rows and the Open PBR tab are not part of it; use Save MTLX... on the Open PBR tab to keep OpenPBR parameters.
Single-value maps as material values
Settings → Export has a checkbox, Write single-value maps as material values, on by default. With it on, a texture that is one value everywhere its material reaches — a flat color, or a node graph that sets Metallic to 1 — is exported as the material's own value instead of an image. It renders the same in every program, with fewer files. Only the texels the material's own polygons cover count, so gutters and other materials' islands in a shared image do not matter.
| Map | When it is one value |
|---|---|
| Base Color, Metallic, Roughness, Emissive, Opacity | Folded into the material's value; the image is not written. |
| Normal, Occlusion, Height | Dropped when neutral (a flat normal map, white occlusion, any uniform height map), since it changes nothing. |
Other maps, and an image shared by several materials, are always written as they are. Exports that use UDIM tiles are never folded, since each tile is its own image over part of the mesh. Turn the checkbox off to write every map as it is.