How to colorize a model with gradient colors?

[Bill-XU]

Hello,

I found the manual here https://dev.opencascade.org/doc/overview/html/index.html#intro_overview_modalgo,
on which there is a picture of a hexagon nut, which is colorized with linearly gradient colors from red to blue.

Is this picture generated by OCCViewer?
I wonder how to implement the same effect using OCC.
Could anybody help give some hints?

Best regards,
Bill

[Bill-XU]

Got an answer from another repo.
This is simply done by shaders.