Orthographic projection in 3D and Columbus view

[bagnell]

Sandcastle examples for testing: http://cesium-dev.s3-website-us-east-1.amazonaws.com/cesium/ortho-3d/Apps/Sandcastle/index.html

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This isn't ready for a code review. I want to have more people try this and report any problems when moving the camera around or if they have any suggestions for improvement.

There is a new widget to switch between orthographic and perspective projection. It is on by default, but will be disabled when this is ready to be merged.

• Limit terrain/ imagery requests on the horizon.
• Fix morphs
• Add new tests
• Update CHANGES.md
• Fix ground primitives
• Default new widget to hide

After merge:

• Merge to 3d-tiles
• Update 3d-tiles screen space error in for orthographic projections

Fixes #2069.

[pjcozzi]

CC @pmconne

[pjcozzi]

I dig the new widget.

• When switching models, should the icons rotate? The scene mode widget does this to sync with the morph, but, for example, the imagery picker does not.
• Should this widget be shown by default? I would think no since it won't be widely used and uses screen real estate.
• Can we gray this out in 2D and also throw a reasonable exception when someone programmatically switches projection in 2D. Right now it is:

[pjcozzi]

Part of #4678

[pjcozzi]

Do you get these artifacts in the 3D models Sandcastle example?

[pjcozzi]

• Run the 3D models Sandcastle example
• Switch to ortho
• Hit the Home button, and get this exception:

[pjcozzi]

Is this the correct behavior when zooming in ortho when just in front of the balloon model?

[bagnell]

@pjcozzi @lilleyse This is ready for another review.

@pjcozzi This is the change I mentioned offline: e13bc3d#diff-6298b280e4e0977bedd881b65b769863R993 If the camera is above a certain height then we zoom when rotating to avoid artifacts.

[bagnell]

Adjusting the terrain skirts also fixes #3710.

[pjcozzi]

@lilleyse can you please do a final review and testing (and close and notify all the users in #3710)?

I would like to have this in master for a bit before we ship 1.32.

[lilleyse]

There are still some situations where the camera can get stuck (it's possible I'm below the max height that is set). Like in this demo: http://localhost:8080/Apps/Sandcastle/index.html?src=CZML%20Colors.html&label=CZML usually I just rotate backwards completely, and then try to rotate forwards, but it end up getting stuck, though zooming still works.

Otherwise, the new code changes and fixes look good.

Default new widget to hide

Will this one be updated right before merging?

[bagnell]

@lilleyse This is ready for another look. When you get stuck, you can click space to rotate the view to look back at the ground just like if you get stuck looking up at terrain.

Default new widget to hide

Will this one be updated right before merging?

Yes, I updated it. To test, create a viewer with:
var viewer = new Cesium.Viewer('cesiumContainer', { projectionPicker : true });

[lilleyse]

Alright this is ready to go then.

[lilleyse]

Adjusting the terrain skirts also fixes #3710.

For some reason I'm not noticing any of the cracking issues linked in that issue in earlier versions of cesium, I'll check on my laptop tomorrow.

[bagnell]

I could only reproduce using the second link @hpinkos posted and going to 110 45 with the geocoder.