Aside from which direction is positive with respect to the x, y, and z axis, there is also the matter of which direction an object will rotate about an axis with positive numbers. I think in the lesson, Ben only talked about rotating about the z axis in the video. But, what about rotating about the x and y axis? I found that the same rule applies when rotating about the x and y axis as well.
To visualize in which direction an object will rotate about the x or y axis in a left-handed coordinate system, do the same as what Ben did for the z axis. That is, take your left thumb and point it in the positive direction of the axis you want to rotate. Now, curl your fingers. The direction in which the fingers curl is positive rotation.
Below is an image that shows positive rotation about x, y, and z axis’.
To validate this, I used the Unity editor and my rocket ship. Below I rotate my rocket ship about the y axis.
Below is with Rotation y = 0:
Below is with Rotation y = 10:
You’ll notice that the ship rotates in the direction your left hand fingers curl when your left thumb points up in the direction of the green arrow, the y axis.
You’ll notice the same when changing the Rotation X value in Inspector => Transform.
Hope you guys find this helpful.