axis conventions #40
Description
Thank you for this great project.
I would like to clarify coordinate conventions for the reported state of devices.
The spacemouse devices follow the HID usage specification, where 4.2 specifies axis conventions for HID devices. This follows a regular right-handed coordinate system X pointing right and Z downwards.
These signals are partly inverted in the library for the .state/.read() interfaces though, e.g., here.
This is probably done for a more intuitive interpretation of Z which now points upwards.
Per se that's no big deal, but the reported values for the rotations do not seem to match a regular coordinate system anymore.
For both my SpaceExplorer and a Spacemouse Compact,
rollrotates negatively around the new Y axis (instead of positively around X),pitchrotates positively around X (instead of Y),- and
yawrotates negatively around the new Z axis (instead of positively).
It would be nice if someone could confirm that this is indeed the consistent interpretation in this library and we could document it here. I expect that this convention should not change anymore to retain API, but it seems entirely arbitrary to me. It's not a big problem either because it can always be adjusted in calling code once one knows about it.
Although I looked at this quite a bit now, it might also be that I misuse some component and the whole issue is on my side only. I would be grateful if someone could point this out :-)