Godot uses JPL style quaternions instead of Hamilton

[fire]

Your Godot version:
godotengine/godot@0c23a2c

Issue description:

Software	Quaternion convention
Godot Engine	JPL
Blender	?
ISO 8855:2011	?
Unreal Engine	?
Unity	?
Three.js	?
Eigen	?

Godot uses JPL style quaternions instead of Hamilton. We should add a note somewhere so people don't get frustrated why their math doesn't work.

https://fzheng.me/2017/11/12/quaternion_conventions_en/

https://arxiv.org/abs/1801.07478

This is a report so it doesn't get lost.

The math for conversion from JPL or Hamilton is take x,y,z,w where x,y,z is the axis and multiply the axis by -1. W is the scalar like 1.

URL to the documentation page:
Not that familiar.

[YuriSizov]

Where should we add such a note?

[fire]

When I last asked GDQuest our residential uiux person, he said that most people don't read the docs, and that putting it in the tooltips of Quaternion is probably the most usable place. If that doesn't work at least in the help browser xml.

[fire]

aaronfranke — Today at 09:44
iFire I just checked in Blender using its Python scripting https://docs.blender.org/api/current/mathutils.html
The Quaternion type follows the rule ij = k and ijk = -1 so it's Hamilton.