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@Derek_Van_Allen_BD Onshape std library is generally written in terms of matrixes. You could certainly write a quat library for your own work, but (imo) the usual reasons for quats (performance, interpolation, and fewer matrix multiplys) don't make much improvement in Onshape. That said: if you write it I will read it!

For avoiding gimbal lock and such: I'd recommend just using the rotation matrix transforms. Onshape has some utilities builtin to make this type of code a little simpler to write but it's still pretty error-prone. In fact: The blog post will mostly be a recitation of the many (many) numerical and programmatic mistakes one person can make when trying to implement euler angle tools!

@eric_pesty Strong agreement. I think @GregBrown identified a core pain point that needs addressing which is why he wanted to write these tools. Onshape dev team has a lot of stuff on their plate so who knows the timing? But they are aware of the need.

Just read through the comments in the documentation. Gimbal lock and Euler angles go together like peanut butter and jelly. That's one of the reasons I was barking up the quaternion tree in my previous coordinate system transformation explorations. Fewer available utils to use there though.

That looks interesting.
A simple option to select a mate connector in the "regular" measure tool is still needed though! Especially in assemblies were there aren't really any decent workarounds.

Announcing: Relative Measure, Euler → MC, and MC → Euler

Written by Joshua Newth (former Part Studios dev, now at Reframe Systems) and Greg Brown (Head of Product at Onshape).

What’s new

Relative Measure — Get X, Y, Z displacements between two points relative to any coordinate system (mate connector), not just the world frame. Ideal for robotics.

Euler → MC — Specify a start frame, an Euler/Tait‑Bryan convention, and a set of angles; the tool creates a mate connector at the resulting orientation. Supports the full set of Euler/Tait‑Bryan conventions.

MC → Euler — Compute Euler angles between two coordinate systems under the chosen Euler/Tait‑Bryan convention (reverse of Euler → MC).

Why it matters

Onshape’s native measurement tools are powerful, but they always report in the world frame. These extensions close that gap for some niche use cases by adding local-frame measurements and reliable Euler conversions.

Care was taken for the conversions to be correct, canonical, and symmetric. The tools also avoid reporting or accepting aliased angle sets, and correctly detect and report gimbal lock and other errors endemic in euler angle workflows.

If you like implementation details: I’ll publish a short blog post covering tricky edge cases and gotchas discovered while building the FeatureScript.

Where to get them

Relative Measure - https://cad.onshape.com/documents/56d995a2ad08f2cdae9d49cf/v/cb21050a585a128c66192b9b/e/29e1313f5a74cb195acb5056

Euler angle tools - https://cad.onshape.com/documents/c5c44c9774eb0052579a2407/v/5b2d4bd4a2b47c132ff86167/e/75b1d59e74c3198627aea7d1

@jnewth @GregBrown