How to make an object semi transparent?

If the objects are all opaque, Cesium will set the opaque material to the primary . What can I do if I want to make some objects semi transparent?

The material is selected per glTF primitive. So you can have some opaque primitives and some translucent ones.

Thank you. If material of glTF primitive is opaque, that means need change to translucent material first? how to apply the material parameter that setted in Cesium Internal?

There’s currently no way to make some (but not all) of the opaque primitives in a glTF translucent.