HeightReference.CLAMP_TO_GROUND Can't clame to ground

[gitgitczl]

When I draw a polygon and set Cesium.Heightreference.CLAMP_ TO_ Group, but some polygons will not be displayed. The terrain used here is ArcGISTiledElevationTerrainProvider.
like this,The lower right corner is not shown.

this is my code:

[ggetz]

Hi @gitgitczl. I'm having trouble reproducing the issue with this sandcastle example which uses an ArcGISTiledElevationTerrainProvider. Can you provide the positions which you're seeing the issue with?

[gitgitczl]

ok.Thank you for your help.this is my positions.
`const kmlData =
[{ "x": 37.98687453755564, "y": -122.45322404219581, "z": 0.0 }, { "x": 37.985523140145915, "y": -122.45322402653679, "z": 0.0 }, { "x": 37.983834554207704, "y": -122.45007250299474, "z": 0.0 }, { "x": 37.984085361076765, "y": -122.4493854604648, "z": 0.0 }, { "x": 37.98475797590966, "y": -122.44834404879718, "z": 0.0 }, { "x": 37.9869980801418, "y": -122.44794628816878, "z": 0.0 }, { "x": 37.98687453755564, "y": -122.45151654965713, "z": 0.0 }, { "x": 37.98687453755564, "y": -122.45322404219581, "z": 0.0 }];

let positions = [];
for (let i = 0; i < kmlData.length; i++) {
    let item = kmlData[i];
    positions.push(Cesium.Cartesian3.fromDegrees(item.y, item.x));
}

`
@ggetz

[ggetz]

Thanks @gitgitczl, I'm able to reproduce your issue with those positions. This does appear to be a bug. We'll update this ticket when we're able to take a look.

[ggetz]

I believe this is actually a duplicate of #8480. I'll mention this report in that issue to keep everything in one place.