Avoid importing Cesium3DTileset in Picking.js

[puckey]

Since updating to the latest version of Cesium, I noticed my project's bundle size had grown 85% by over 850kb minified.

I tracked down a large chunk of it to a single instanceof Cesium3DTileset use here: https://github.com/AnalyticalGraphicsInc/cesium/blob/d26ccfea38dcf4623cf5da3faca141913c64cfe1/Source/Scene/Picking.js#L549 causing the bundle size to grow by 549 kB, while I do not use Cesium3DTileset in my project.

Perhaps instead of using instanceof we could have a static type enum property to check against? For example if (primitive.type === Type.Cesium3DTileset)

[hpinkos]

@lilleyse please make this a priority before the October release

[lilleyse]

@puckey All the code in Picking.js used to exist in Scene.js. Was Scene.js previously included in your project's bundle?

Perhaps instead of using instanceof we could have a static type enum property to check against?

Yes, something like that might work.

[hpinkos]

Ahhh, I do see that Cesium3DTileset has been required by Scene for a few releases. It probably shouldn't be though for apps not using combined Cesium. I downgraded this to priority - high.

@puckey were you using the latest version of cesium before you upgraded to the 1.62 release?

[puckey]

I wasn't using the very latest version before – I must have been a few releases behind.

[hpinkos]

Gotcha, no problem @puckey
I'm going to keep this open because this is absolutely something we should fix. There's no need to pull in the entire 3D tiles source into this