From cb391962ca6503bbb46d75b449e3b781bf1b6fa8 Mon Sep 17 00:00:00 2001
From: Taylor Howell <taylorhowell@google.com>
Date: Mon, 24 Nov 2025 02:02:38 -0800
Subject: [PATCH] MuJoCo Warp documentation: Orientation representation.

PiperOrigin-RevId: 836127570
Change-Id: I0f381e57cfb53e1cb623f9c4178d258dfc1f75b6
---
 doc/mjwarp/index.rst | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/doc/mjwarp/index.rst b/doc/mjwarp/index.rst
index 94f08aec..e6d1bf6a 100644
--- a/doc/mjwarp/index.rst
+++ b/doc/mjwarp/index.rst
@@ -341,3 +341,25 @@ It is possible to override the field shape and set the field values after graph
    :class: note
 
    Heterogeneous worlds, for example: per-world meshes or number of degrees of freedom, are not currently available.
+
+.. _mjwFAQ:
+
+Frequently Asked Questions
+==========================
+
+Orientation representation
+--------------------------
+
+**How are orientations represented?**
+
+Orientations are represented as unit quaternions and follow :ref:`MuJoCo's convention <floating-objects>`:
+``w, x, y, z`` or ``scalar, vector``.
+
+.. admonition:: ``wp.quaternion``
+  :class: note
+
+  MJWarp utilizes Warp's `built-in type <https://nvidia.github.io/warp/modules/functions.html#warp.quaternion>`__
+  ``wp.quaternion``. Importantly however, MJWarp does not utilize Warp's ``x, y, z, w`` quaternion convention or
+  operations and instead implements quaternion routines that follow MuJoCo's conventions. Please see
+  `math.py <https://github.com/google-deepmind/mujoco_warp/blob/main/mujoco_warp/_src/math.py>`__ for the
+  implementations.