Can the bumpmap texture be combined into a single channel?

[Mugen87]

There is only a single combination of different textures which is officially supported, see PBR from one image - #2 by Mugen87

@EFun

Could I create a custom shader to handle a bump map that just uses a single channel?

That is not necessary. If you declare the format of a texture as THREE.LuminanceFormat (or THREE.RedFormat with WebGL 2), the texture will only allocate the memory for a single color channel. I recommend you use this approach and don’t combine bump maps into different textures.