Exporting materials which only store colors

[Gildor]

Because of this materials storing all needed data (colors, spec, metal, rough etc.) as parameters are not exported, is this the intended behavior?

I've added "props.txt" much later, compared to .mat file export, so it is rather a side effect, not intended behavior.

PS: glTF skel/staticmesh export seems to not have the properties text file (props.txt) dump code while psk does, is there any reason for this?

Seems the same as with .mat files - just a side effect. Probably explicitly added props.txt for skeletal mesh in psk format, but forgot to add for glTF.

[Gildor]

when ue build ,shader  will finall  to be hlsl or  dxbc  ? 

For PC/DirectX platform, it will store compiled bytecode.

anything  progress  about  material or shader export？

This is even not planned, not worth asking about any "progress" here at all.