AR HitTest anchor update incompatible with non-HitTest anchors

[hi-liang]

Description: The scene ar-hit-test component keeps a Map anchorToObject3D corresponding to previous hit-test result .

Every ar-hit-test tick, the HitTest.updateAnchorPoses function is called to try to update the pose of aforementioned object3D from the list of XRFrame.trackedAnchors . However, if a tracked anchor is not mapped from a hit-test result, such as an anchor created by the user from some other means, Map lookup will fail and object3DOptions will be undefined.

aframe/src/components/scene/ar-hit-test.js

Lines 197 to 202 in a3f6d12

	if (anchorPose) {
	object3DOptions = HitTest.prototype.anchorToObject3D.get(anchor);
	offset = object3DOptions.offset;
	object3D = object3DOptions.object3D;
	applyPose(anchorPose, object3D, offset);

Could be addressed just by adding a check for object3DOptions before attempting to access its properties and apply the pose

• A-Frame Version: 1.4.2 1.5.0
• Platform / Device: Any device supporting immersive-ar persistent anchors and hit-test
• Reproducible Code Snippet or URL:

[hi-liang]

@dmarcos

Here is an example with a persistent box, roughly based on the new Mixed Reality / Anchored demo:

https://succinct-quaint-mortarboard.glitch.me/

When ar-hit-test component is added to the scene (for instance if you wanted to spawn new boxes by hit-testing the XRMesh/XRplanes) this causes an exception in the above ar-hit-test component once the persistent anchor is restored: