Feedback Avoid FindObjectWithTag in Camera.main

What have several Unite talks, the Unity documentation and Unity learning materials in common?

Spoiler

They tell us "Accessing Camera.main is expensive".

For example, I'm currently reading this document and came across the same statement again:

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My feedback is: Just fix it! Make it fast! Return a cached reference when accessing Camera.main instead, like you describe yourself in the "Solution".

Bonus points for adding a "mainCameraChange(oldCamera, newCamera)" event that allows to receive a notification when the main camera was changed.

 

The purpose of Camera.main is to return something that "just works". A cached solution would introduce edge cases. If you're doing something where you care about the performance of Camera.main and/or you're doing something complicated enough to where Camera.main is not the best solution, then you won't be using Camera.main anyway. A more complicated or comprehensive system in my opinion would necessarily create too many assumptions about the use-case of the user. For example, there's a reason that Cinemachine is a plugin and not the required built-in way to manage cameras.

There's no incentive to make Camera.main faster since anyone who cares is not using it.

 

If you look at Unity's source code, such as the UI, you'll find Camera.main is used in their code / hot-paths.

 

fyi: This has been fixed in Unity 2020.2.0a16. Not sure if the fix gets backported to LTS.
@richardkettlewell