Isosurface picking

[philippotto]

URL of deployed dev instance (used for testing):

• https://isohittest.webknossos.xyz

Steps to test:

• open a segmentation in view mode
• shift click on a cell to render an isosurface
• shift click on the isosurface in the 3d viewport
• the position should jump to the clicked position
• also, there should be hovering "effects" when hovering over isosurfaces

Issues:

• fixes Hit-test on isosurface #3704

---

• Updated changelog
• Updated documentation if applicable
• Ready for review

[daniel-wer]

Very impressive! The hover effect is awesome and makes this feature look and feel very futuristic, great job 👍

Out of interest, how did you solve the problem you had during development, where the hit test did not work all the time? With the clippingOffsetFactor?

[daniel-wer]

Could you add a comment explaining why this is needed? :)

[daniel-wer]

Why do we need to intersect recursively? Is this because the segments for one id are in a group or is there another reason?

[philippotto]

Yes, it's because the segments are in a group and the group is only traversed if recursive is true. I'll add a comment!

[daniel-wer]

Did you experiment with throttling this function? To me, during testing, the TD view felt a little sluggish and I was wondering whether this could help to make it feel more performant :) I do understand that the "instantness" of the hover effect contributes to the "coolness" of the future and I do want to keep that, so maybe just throttling it a little is enough.
It's not a blocker though as the performance hit is only noticeable when isosurfaces are loaded.

[philippotto]

You are absolutely right. I definitely needed to add throttling, as it doesn't make sense to compute this on every render. I opted for 150 ms as a throttling delay, which felt like a good trade-off between performance and delay to me.