I have used the official case of Three.js for implementing rain, but it cannot be controlled by a transformation controller, such as using a transformation controller to translate, scale, or rotate the rain. Is there a better implementation for rain.
If there is a better implementation, then some person has already spent efforts and time to make it. But in most cases, it will not be exactly what you want.
If there is no such implementation, would you be willing to be that person? It might not be easy, but at the end you will have what you want and … as a side effect … you will improve your Three.js skills. The latter is much more important, though.
I only have one idea, to modify the scaling, rotation, and translation API of the rain model