Fix imagery request render

[ggetz]

Fixes #6193

invalidateAllTiles was not being called reliably at the correct time.

[cesium-concierge]

@ggetz, thanks for the pull request! Maintainers, we have a signed CLA from @ggetz, so you can review this at any time.

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[hpinkos]

@ggetz I'm seeing a crash if I alternate between Enable terrain and Disable terrain in the example I pasted in #6193

DeveloperError: requestTileGeometry must not be called before the terrain provider is ready.
Error
    at new DeveloperError (http://localhost:8080/Source/Core/DeveloperError.js:43:19)
    at CesiumTerrainProvider.requestTileGeometry (http://localhost:8080/Source/Core/CesiumTerrainProvider.js:569:19)
    at doRequest (http://localhost:8080/Source/Scene/TileTerrain.js:149:48)
    at requestTileGeometry (http://localhost:8080/Source/Scene/TileTerrain.js:163:9)
    at TileTerrain.processLoadStateMachine (http://localhost:8080/Source/Scene/TileTerrain.js:97:13)
    at processTerrainStateMachine (http://localhost:8080/Source/Scene/GlobeSurfaceTile.js:384:20)
    at Function.GlobeSurfaceTile.processStateMachine (http://localhost:8080/Source/Scene/GlobeSurfaceTile.js:281:13)
    at GlobeSurfaceTileProvider.loadTile (http://localhost:8080/Source/Scene/GlobeSurfaceTileProvider.js:505:26)
    at processSinglePriorityLoadQueue (http://localhost:8080/Source/Scene/QuadtreePrimitive.js:768:26)
    at processTileLoadQueue (http://localhost:8080/Source/Scene/QuadtreePrimitive.js:759:9)

[hpinkos]

I'm also still seeing a problem where sometimes the tiles don't load in if I zoom in and double click the Disable terrain button.
Sometimes they start to load in when I move the camera, but not always

[mramato]

Just a reminder not to forget about this for next release, I've hit it several times today.

[ggetz]

@hpinkos I believe this is resolved. I moved the invalidate logic to right before we process the tile load queue. I am no longer seeing any errors when switching back and forth, and repeatedly clicking disable terrain always reload the globe.

[mramato]

@ggetz, not sure if this is the same bug but I still see this in this branch:

1. Start Cesium Viewer: http://cesium-dev.s3-website-us-east-1.amazonaws.com/cesium/fix-imagery-requestRender/Build/Apps/CesiumViewer/index.html
2. Switch to Ellipsoid via Base Layer Picker (nothing will update until you move the mouse)

[ggetz]

@mramato That's a regression because of the changes here. Fixed and added a new spec. @hpinkos in your sample code, you should no longer need to request a render after setting the terrain provider.

[hpinkos]

@ggetz I'm still seeing issues here. If I double click the Disable terrain button, I can still get a globe with no tiles. It doesn't happen as consistently, but I can still reproduce it within a few tries.

[ggetz]

@hpinkos I don't think I can reproduce.

The first time I hit disable terrain, it takes a second or two for the new terrain provider to load in, but will re-render without mouse input. That's the same behavior as when we are not in requestRender mode.

If you comment out
viewer.terrainProvider = cesiumTerrainProviderMeshes; in your example, disbaleTerrain doesn't cause that initial delay since it was initially loaded with the EllipsoidTerrainProvider

[hpinkos]

@ggetz I can show you when you're in the office

[hpinkos]

@ggetz I just merged master and pushed it to your branch

[hpinkos]

Looks like this fixed the issue! Thanks @ggetz

@bagnell can you please review the Globe and QuadtreePrimitive changes?

[bagnell]

@hpinkos @ggetz This looks good to me.

[ggetz]

Thanks @bagnell! @hpinkos tests are cleaned up as well now.

[hpinkos]

Thanks @ggetz!