PBR material definition

mitm · November 15, 2018, 6:51am

I am wondering what is going wrong when using the PBR material definition and using a texture where the RGB channels are packed with the AO-Roughness-Metallic maps.

The Khronos group says to do this,

The Ambient Occlusion, Roughness, and Metallic textures are saved in a single channel-packed texture to reduce the number of texture loads. The textures need to be packed into the channels of your texture as follows:
•Red: Ambient Occlusion
•Green: Roughness
•Blue: Metallic

the Khronos group Blender node setup is as follows,

https://imgur.com/a/F56Zhq2

it sets Linear space for the non-color texture metallic-roughness and the AO sockets.

I see in the PBR definition this,

github.com

jMonkeyEngine/jmonkeyengine/blob/d57c362ec3b510c1ba6356f719efa3b1576b95c6/jme3-core/src/main/resources/Common/MatDefs/Light/PBRLighting.j3md#L31


      
          // BaseColor map
          Texture2D BaseColorMap
          
          // Metallic map
          Texture2D MetallicMap -LINEAR
          
          // Roughness Map
          Texture2D RoughnessMap -LINEAR
          
          //Metallic and Roughness are packed respectively in the b and g channel of a single map
          // r: unspecified
          // g: Roughness
          // b: Metallic
          Texture2D MetallicRoughnessMap -LINEAR
          
          // Texture of the emissive parts of the material
          Texture2D EmissiveMap
          
          // Normal map
          Texture2D NormalMap -LINEAR

I get this warning about the setting the LightMap when doing this.

The texture xxx.png has linear color space, but the material parameter LightMap specifies no color space requirement, this may lead to unexpected behavior.
Check if the image was not set to another material parameter with a linear color space, or that you did not set the ColorSpace to Linear using texture.getImage.setColorSpace().

How can I fix this or is this a bug in the PBR material?