Fix Label position height may not be correctly updated when its HeightReference is relative.

[plainheart]

Description

Hi,

I noticed Label position height doesn't work anymore when its HeightReference is relative since the commit 8e271f1 (diff).

This bug might be caused by a premature assignment to owner._clampedPosition [1]. As the _clampedPosition setter of Label clones the inputted value, the following modification for the owner_clampedPosition won't be applied to the Label glyph billboard [2], which causes the user-specified height not to work as expected. So I moved the assignment to the last line to fix this issue.

[1] https://github.com/CesiumGS/cesium/blob/1.116/packages/engine/Source/Scene/Billboard.js#L1141-L1145
[2] https://github.com/CesiumGS/cesium/tree/1.116/packages/engine/Source/Scene/Label.js#L1155-L1172

Stage	Initial	After Update
Before
After

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have update the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

Code snippet for reproduction (Sandcastle)

const labels = new Cesium.LabelCollection({ scene: viewer.scene })
const label = labels.add({
    show: true,
    position: Cesium.Cartesian3.fromDegrees(113.563889, 34.646389, 50),
    text: 'LABEL HEIGHT: 50',
    font: '32px Arial',
    horizontalOrigin: Cesium.HorizontalOrigin.CENTER,
    heightReference: Cesium.HeightReference.RELATIVE_TO_GROUND,
    disableDepthTestDistance: Number.POSITIVE_INFINITY
})
viewer.scene.primitives.add(labels)

setTimeout(() => {
   label.text = 'LABEL HEIGHT: 200'
   label.position = Cesium.Cartesian3.fromDegrees(113.563889, 34.646389, 200)
}, 2000)

[github-actions]

Thank you for the pull request, @plainheart!

✅ We can confirm we have a CLA on file for you.

[ggetz]

Thanks for the fix @plainheart! We'll take a look at this shortly.

[ggetz]

Thanks @plainheart for the fix, and for the testing Sandcastle example making this PR easy to review! I can confirm this addresses the behavior.