I would like to find out if it is possible to add shaders for glTF building models? Any recommended library/plugins?
An example is this : https://github.com/AnalyticalGraphicsInc/cesium/wiki/Geometry-and-Appearances (but it is not for building models).
Do you have an example of the kind of effect you’re trying to achieve? The easiest way might be using CesiumJS’s post processing framework. This example shows you how to apply a custom shader just to a specific model:
https://sandcastle.cesium.com/index.html?src=Custom%20Per-Feature%20Post%20Process.html
This gives it a red highlight when you hover over it with the mouse.
Are you referring to the shadows cast by the buildings? If so, you can turn on shadows in the viewer constructor like in this example:
https://sandcastle.cesium.com/index.html?src=3D%20Tiles%20Adjust%20Height.html
The shadows will be cast from the direction of the sun, based on the time of day set by the timeline at the bottom.
There’s a few things you can tweak about shadows in CesiumJS to get better visual quality at the cost of performance or vice versa. For example, you can get a reference to the shadow map from the viewer (https://cesium.com/docs/cesiumjs-ref-doc/Viewer.html?classFilter=viewe#shadowMap) which has a number of properties you can tweak.
The two that have the biggest impact in my experience are turning on soft shadows (https://cesium.com/docs/cesiumjs-ref-doc/ShadowMap.html#softShadows) and increasing the shadow map size (https://cesium.com/docs/cesiumjs-ref-doc/ShadowMap.html#size).
