WebXR: Add support for hand tracking

[dsnopek]

This adds support for hand tracking in WebXR!

It only gives direct access to the raw hand-tracking data, in a way that's similar to OpenXRInterface. It doesn't add a node similar to OpenXRHand to make animating a skeleton from hand tracking data easier - I'll address that in a follow up PR.

UPDATE: This is now rebuilt on top of PR #88639, and so will be marked as a draft until that PR is merged first.

It works in my testing on the Meta Quest 3!

Closes https://github.com/godotengine/internal-team-priorities/issues/38

[BastiaanOlij]

Cool! But I'm going to take my reaction into the XR contributors channel because I think we need to change tack here :)

[dsnopek]

This is now rebuilt on top of PR #88639, and so will be marked as a draft until that PR is merged first.

(BTW, XRHandModifier3D seems to be working in WebXR with these changes :-))

[BastiaanOlij]

Not really an expert on webXR, code looks great and I trust you when you say it works :)

[dsnopek]

PR #88639 was just merged! 🚀 So, rebasing this one and taking out of draft again

[akien-mga]

Thanks!

[akien-mga]

For some reason, this PR didn't fail the CI checks, but once merged we got a JS linter failure: https://github.com/godotengine/godot/actions/runs/8025645968/job/21926705818

/home/runner/work/godot/godot/modules/webxr/native/library_godot_webxr.js
  322:104  error  Strings must use singlequote         quotes
  570:42   error  Expected '!==' and instead saw '!='  eqeqeq
  570:63   error  Expected '!==' and instead saw '!='  eqeqeq

Edit: Oh, our logic doesn't expect any JS outside platform/web...

if grep -q "platform/web" changed.txt || [ -z "$(cat changed.txt)" ]; then
    cd platform/web
    npm ci
    npm run lint
    npm run docs -- -d dry-run
  else
    echo "Skipping JavaScript formatting as no Web/JS files were changed."
  fi

Should probably grep for .js extension instead.

[dsnopek]

Eep! I'll make a PR to fix the linting issues in a moment.

[akien-mga]

If you can include this, I think it should fix running the linter on PRs:

diff --git a/.github/workflows/static_checks.yml b/.github/workflows/static_checks.yml
index e7ebd2fb64..cf8b0f4132 100644
--- a/.github/workflows/static_checks.yml
+++ b/.github/workflows/static_checks.yml
@@ -76,7 +76,7 @@ jobs:
 
       - name: JavaScript style and documentation checks via ESLint and JSDoc
         run: |
-          if grep -q "platform/web" changed.txt || [ -z "$(cat changed.txt)" ]; then
+          if grep -q "\.js" changed.txt || [ -z "$(cat changed.txt)" ]; then
             cd platform/web
             npm ci
             npm run lint

[dsnopek]

Sure! Here's the new PR: #88740

And it does appear to be running eslint on CI :-)