The back model rendered in front when 3d tiles are loading

1. A concise explanation of the problem you’re experiencing.

When I render a 3d tiles model. There is a problem of depth when loading the tile model.

It seems the model in back is rendered before the model in front. so it looks weird when loading;

when loading

loading finished

You can see the pipeline inside the wall is rendered in front of the wall when the tiles are loading.

After the loading is finished, the render order is correct.

I can also see this in the BIM example of Cesium Sandcastle. But the tiles load so fast, so the distorted effect only appear in a wink.

2. A minimal code example. If you’ve found a bug, this helps us reproduce and repair it.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

My 3d tiles is generated from a complicated BIM project. Sometimes the tiles in view is so many. That makes the loading time longer than other 3d tiles.

So this problem appear frequently. It really affect the user exprience;

4. The Cesium version you’re using, your operating system and browser.

Cesium 1.54/1.63

Windows 10

Chrome 77.0.3865.90 (64bit)

Hi everyone,

It turns out it’s the problem of bivariateVisibilityTest. The comment in the code says it render the backface of parent tile first, then render child tile and the frontface.

So I asume the child tile inside the parent tile appear in front of the parent tile when the frontface of parent tile is not rendered.

That’s my guess. It that right?


在 2019年11月26日星期二 UTC+8下午4:41:49,Chris Wang写道: