A suggest for a api of Cesium.Cartesian3

1. A concise explanation of the problem you’re experiencing.

I am using the api below

Cesium.Cartesian3.subtract(left, right, result)

just like other api,

the third parameters is “result”

but it is not optinal

the other api in cesium,the third parameters “result” mostly is optinal

why is this api not?

2. A minimal code example. If you’ve found a bug, this helps us reproduce and repair it.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

I want all the cesium api keep the same style

4. The Cesium version you’re using, your operating system and browser.


Requiring the result parameter here is actually intentional, see the discussion on this GitHub issue https://github.com/AnalyticalGraphicsInc/cesium/issues/7444#issue-394816893