Change camera zoom to not pick positions in the middle of a zoom.

[emackey]

This fixes an issue where if you start zooming in from some point off the globe, when you're close enough that the limb of the globe touches your starting point, the globe suddenly twists.

This should also fix #4177 and #4440, but I could use some help testing.

Can someone test if this fixes the illusive zoom-crash? @amc723 @smills2929 @willemvdg @lucasvw

/cc @bagnell

[jbo023]

We checked this branch against the bug, we filed some time ago: #4407.
We could not reproduce the old Bug.

So it looks nice 👍

[jbo023]

During testing i also noted another Bug with touch pinch gestures.

If you start with a pinch gesture the origin of the zoom/rotate gesture is in the upperleft corner of the screen. (Only if this is the first touch/mouse event)

If you then do a short one finger movement the next pinch gesture will use the that movement position as a new origin.

Maybe you can also check this out.

[pjcozzi]

@emackey is it possible to write a reasonable unit test for this?

Also update CHANGES.md.

[pjcozzi]

CC @pmconne

[mramato]

@emackey I can confirm that this fixes the "upper left pixel zoom" crash you mentioned previously as well as the "pinch first" bug. Awesome! I agree it would be nice to add a test for this if we can, if perhaps indirectly test it at least if it was an initialization issue. Even a simple test without any expects that crashed in master but now doesn't crash now would be good.

If tests can't be done cleanly, I'm okay with merging this as-is.

[emackey]

Thanks everyone for helping to test!

Added a unit test for this.

[emackey]

@jbo023 I think I addressed your additional bug in 52e1a90. A start position was not being computed for the pinch, now it is. Thanks!

[mramato]

I can confirm the new test fails in master and passes in this branch and everything looks good to me.

@bagnell or someone with more camera knowledge should probably merge this.

[mmccartn]

Tested and can confirm this fixes #4177. Thanks

[jbo023]

Tested again, origin on pinch gestures is now correct. Thanks

[bagnell]

I updated CHANGES.md in master 39169f7

[pjcozzi]

@lilleyse can you please merge master to 3d-tiles so @pmconne has this fix?

[lilleyse]

Done.