I´m developing a VR project in Unity Engine and I need to implement a Rain Effect. I have considered the following:

  • A VR game must run at least 90 frames per second.
  • The Rain must be detailed.
  • The Rain Drops interact with other objects.

These are the approaches I have considered:

  • Particles Systems: I think it is expensive since there are two cameras rendering the scene and checking collision per particle could be expensive.
  • Image Effect on the canvas: I think the result would be unreal, and there would not be interaction with other objects.

I have seen examples of rain effect like in Resident Evil 4, Halo Reach, Crysis, FarCry, Project Cars 2 VR and Batman Arkham Knight.

A last approach I haven´t considered yet is by shading, maybe shading would work for the rain drops in the cameras´ lens.

I would like to know optimal approaches to emulate rain effects without making too much computations.

Thanks for your attention.


1 Answer 1


Particle collisions are super fast

That was one of the requirements Unity had when they added them in 4.0.0

From the blog

With Unity 4.0 we are adding support for world particle collsion detection. It’s quite awesome and very fast.

We spent a lot of time optimizing world particle collisions and also did more than a few optimizations to Shuriken in general. Especially on mobile devices Shuriken got a very big performance boost.


Shuriken is multithreaded and so is collision detection.

So this should be fine, even for VR.


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