Question How to use ShaderWarmup.WarmupShaderFromCollection

I am trying hard to use this:

https://docs.unity3d.com/ScriptRefe....ShaderWarmup.WarmupShaderFromCollection.html

I don't know why it's asking for a ShaderVariantCollection and then asking for a shader? The shaders are in the collection.

I also am confused about the

Unity needs more information to correctly build GPU representations of the shader variants ('pipeline state objects' or PSOs) if your application runs on one of the following graphics APIs:

• DirectX 12
• Metal
• Vulkan

How do I know what graphics API and then how to get the vertex data for each shader?

Help please anyone!

 

Thank you sir!