Cesium: Transparent objects flicker when using scene.pick

[lilleyse]

When moving the mouse around in an app that uses scene.pick, translucent objects flicker. The gif capture is not best, the flickering is much faster.

Sample code:

http://cesium-dev.s3-website-us-east-1.amazonaws.com/cesium/master/Apps/Sandcastle/?src=Hello%20World.html&label=Showcases&gist=eaae1407cd39601a2c3ba62b30f00a1f

[emackey]

This brings back bad memories of #2790. That bug was caused by a stray scissor test preventing the frame from being cleared at the start, causing OIT to blend with the previous animation frame. It was fixed, and I don't know if this new problem is some way related, but the symptom looks suspiciously similar.

[pjcozzi]

Could someone track down what version/commit this was added? It could be a fix we want soon. I'm surprised it hasn't come up on the forum and in other issues.

[mramato]

This does not happen in 1.32, so it was introduces recently. It's really annoying so I marked this for next release, someone needs to at least triage this.

[mramato]

I'm also running into cases where picking randomly stops working until the canvas is resized, but that could be an unrelated issue. Unfortunately it's hard to reproduce.

[pjcozzi]

@emackey do you want to help @klingerj track this down?

[klingerj]

Git bisect says that the first bad commit is: a9a275f8e6286ae509633d00cc622d195ad4e29b

[bagnell]

Thanks for finding the commit @klingerj. I have a fix for this. I'll open a PR soon.