OSM buildings lightning

Hi Cesium-Team,

we are trying to color the OSM-Buildings in Cesium in white. As we’ve understood we need to synchronize the camera and the sun light so that it always shines on the buildings from the camera perspective. This is the code we’ve found to achieve that:

    this.viewer.scene.light = new DirectionalLight({
      direction: this.viewer.scene.camera.directionWC
    this.viewer.scene.preRender.addEventListener((scene) => {
      scene.light.direction = Cesium.Cartesian3.clone(scene.camera.directionWC, scene.light.direction);

We are configuring the builings color as follows:

    const osmBuildingsTileset = await Cesium.createOsmBuildingsAsync();
    osmBuildingsTileset.maximumScreenSpaceError = 3; 
    osmBuildingsTileset.style = new Cesium.Cesium3DTileStyle({
      defines: {
        material: "${feature['building:material']}",
      color: {
        conditions: [
          ["true", "color('white', 1.0)"]

Unfortunatelly the buildings still appear only white from the top or from 90 degree and are grey when looking from the side. Any ideas how to solve this problem?