Add Image Rotation Support

[wallw-teal]

This adds image rotation support and then uses it in KML GroundOverlays to address some of our issues with displaying those.

Additionally, if the GroundOverlay contains an unsupported LatLonQuad value, then a warning is issued. I can write a ticket for further support of that. It requires non-affine transforms which are not supported in CanvasRenderingContext2D but could be done by us since the image would only need to be redrawn once.

I have not decided what warnings to show or not show regarding the lack of projection information for the raster image. Right now it is simply assumed to be in the application projection (probably a bad assumption).

Test Files (test in 2D/3D and in multiple projections):
GroundOverlays_etna_rotation_compare.txt
GroundOverlay_unsupported_quad.txt
GroundOverlay_rotation_test.txt

• Extent reduction from the KML tree is not working as expected, so I'm going to see if I can clean that up here since it is affecting the ease of viewing GroundOverlay items.
• 3D Image Layer Sync

[schmidtk]

I have one code comment, and in testing found the following:

• When animating ground overlays with a timestamp in 3D, the overlay flickers on each timeline change.
• When switching projections in 3D, the ground overlay image clips the globe.

[wallw-teal]

When animating ground overlays with a timestamp in 3D, the overlay flickers on each timeline change.

This is an unrelated issue with KMLSource's override of updateAnimationOverlay().

When switching projections in 3D, the ground overlay image clips the globe.

Ignoring all the other projection assumptions we have already made for this (... ew), I am not getting that artifact. Your screenshot that you sent me (which you should post) looks like raster reprojection from OpenLayers, which we should have off by default. Is that enabled in your environment?

I also updated with a projection bug fix in 3f552c3.

[schmidtk]

I'm seeing the artifacts in both Chrome and Firefox on macOS, in both debug and compiled builds. It doesn't seem to matter which projection I start in (only trying 3857 and 4326), I get the same result. I do not have raster reprojection enabled.

Here's the screenshot:

And the KML: Overlays.txt

This happens in 3D mode if I load the file and switch to a different projection.

[schmidtk]

One more issue in 3D mode:

If a ground overlay isn't within the view extent when loaded, it will not be visible on the globe when the view extent does contain the overlay.

[wallw-teal]

The latest commit adds a synchronizer specific to static image sources. This essentially just loads and adds the primitive once and controls visibility only with primitive.show, which makes it much slicker when animating and also means that it is no longer concerned with the view extent.

I still have concerns about the original raster projection for GroundOverlay images.