How to customize render terrain 3dtiles?

CesiumJS
1

Hello. Recently I meet a problem, I can not coustomize 3dtiles shader in runtime.

In Building 3dtiles model I can use

    buildingTileSet.tileLoad.addEventListener(tile => {
      let content = tile.content;
      let featuresLength = content.featuresLength;

      for (var i = 0; i < featuresLength; i += 2) {
        let feature = content.getFeature(i);
        let model = feature.content._model;

        Object.keys(model._sourcePrograms).forEach(key => {
          let program = model._sourcePrograms[key];
          model._rendererResources.sourceShaders[
            program.vertexShader
          ] = VS;
          model._rendererResources.sourceShaders[
            program.fragmentShader
          ] = FS;
        });
        model._shouldRegenerateShaders = true;
      }
    });

to get sourceprograme but in model we use drones product it can not use this function get shader.

is there any way i can to customize 3dtiles model render in your runtime property?