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Merge pull request #122 from AnalyticalGraphicsInc/update-readme 

Update readme with more info about mtl slots
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Shehzan Mohammed 2017-12-29 07:42:35 -08:00 committed by GitHub
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@ -62,13 +62,31 @@ In general, if a model is authored with traditional diffuse, specular, and shini
The glTF will be saved with the `KHR_materials_common` extension and the Blinn-Phong shading model will be used.
However if the model is created with PBR textures, either the `metallicRoughness` or `specularGlossiness` flag should be passed in.
See the command line flags below for more information about how to specify PBR values inside the .mtl file.
See the table below for more information about how to specify PBR values inside the .mtl file.
If none of these flags are provided, the .mtl is assumed to contain traditional Blinn-Phong materials which will be converted to metallic-roughness PBR.
There may be some quality loss as traditional materials do not map perfectly to PBR materials.
Commonly in PBR workflows the the .mtl file may not exist or its values may be outdated or incorrect.
As a convenience the PBR textures may be supplied directly to the command line. See the options below.
As a convenience the PBR textures may be supplied directly to the command line.
**Mapping of mtl slots to shading models**
Slot | Metallic roughness | Specular glossiness | Materials common
--- | --- | --- | ---
Ka | occlusion value | occlusion value | ambient color
Ke | emissive color | emissive color | emissive color
Kd | base color | diffuse color | diffuse color
Ks | metallic value | specular color | specular color
Ns | roughness value | glossiness value | specular shininess value
d | alpha | alpha | alpha
Tr | 1.0 - alpha | 1.0 - alpha | 1.0 - alpha
map_Ka | occlusion texture | occlusion texture | ambient texture
map_Ke | emissive texture | emissive texture | emissive texture
map_Kd | base color texture | diffuse texture | diffuse texture
map_Ks | metallic texture | specular texture | specular texture
map_Ns | roughness texture | glossiness texture | specular shininess texture
map_Bump | normal texture | normal texture | normal texture
## Usage