Bug in zoom with disableDepthTestDistance on billboards !

[benjaminmur]

Hi everyone !

first, the sandcastle : link

It's a bug when you zoom, while a billboard is perfectly centered, with depht test against terrain activated, AND disableDepthTestDistance Number.POSITIVE_INFINITY set on this billboard.
Pretty easy to reproduce if you wait the scene to finish loading, then use the mouse wheel, or any other way to zoom in / out.

Just wait for the scene to load, if you zoom while the scene is loading, it won't happen.

You can't zoom in or out anymore.

It happens on startup because our view is centered to a billboard, but also randomly when we move the camera, zooming in and out, and a billboard come accross the center of the view.
The more billboards on screen, the more frequently it happens.

If you need more info, let me know.
It may seem related to another issue: disableDepthTestDistance causes weird mouse interaction #6840 what do you think ? Related ?

Just so you know...this bug is really impactfull on our work.

"Help me Obi Wan Kenobi you're my only hope".

[raycrummey]

Thanks for identifying this!

I also have this exact issue! I call it "zoom lock". Because I cannot zoom in/out until I pan the camera.

I could never reproduce the issue consistently enough to make a sandcastle (although I have observed it in a sandcastle).

I ended up manually implementing a zoom function to bypass the Cesium default zoom behavior to make progress.

[hpinkos]

@benjaminmur yes, this is a duplicate of #6840
When the billboard is at the exact center of the screen, disableDepthTestDistance makes the billboard act as if the camera is right on top of it, and the camera can't zoom in because it thinks there is a collision. We had this come up with another user recently, so it's possible we might be able to look at it before too long. I'm not sure when though. In the meantime, keep an eye on #6840. Or if you would like to investigate a fix and open a pull request, we would be happy to review it! Thanks