Minimal program to generate ORM (ambient occlusion, roughness, metallicity) textures as specified in the Khronos documentation: https://www.khronos.org/blog/art-pipeline-for-gltf

The channels are:

• Red: AO
• Blue: Roughness
• Green: Metallicity

Usage:

make
./ormGenerate /mnt/c/ambientcg/materials/DiamondPlate007D_2K-JPG/DiamondPlate007D_2K-JPG_Color.jpg jpg

The last parameter is the file format which can be either jpg or png.

An included example can be built with:

make example

The program assumes the folder contains files with the convention:

• DiamondPlate007D_2K-JPG_Color.jpg - diffuse, not used by this program but assumed as a base path
• DiamondPlate007D_2K-JPG_AmbientOcclusion.jpg
• DiamondPlate007D_2K-JPG_Roughness.jpg
• DiamondPlate007D_2K-JPG_Metalness.jpg

Note that:

• If one or several files are missing, they are written as zero in the output ORM.
• If any file has mismatching size or channel count, the program exits with error.
• If any of the input files has over 1 channel, only the red channel is read. Generally speaking, these files should be single channel grayscale images.