Camera dependent coordinate system?

Questions
1

Is there a way to extract or create/update a coordinate system that will rotate along with the camera, like on the pic below, from the current camera position/quaternion etc.?

I can do it using up vector, (X = Up x lookAt, Y = lookAt x X) but it fails if the camera is currently looking down world Y axis.

Thank you!

cam

2

If you’d like to do it just with vectors:

Z → camera.getWorldDirection
Y → camera.up
X → camera.getWorldDirection.applyAxisAngle(camera.up, Math.PI / 2)

You should also be able to transform a Vector3 to local-space by applying Object3D.quaternion (or transform matrix / Euler rotation):

Forward → new Vector3(0.0, 0.0, -1.0).applyQuaternion(camera.quaternion);
Up → new Vector3(0.0, 1.0, 0.0).applyQuaternion(camera.quaternion);
Right → new Vector3(1.0, 0.0, 0.0).applyQuaternion(camera.quaternion);

(It does seem to work nicely when looking directly downwards.)

3

That’s the one, thank you!