Fix polyline clipping against the near plane.

[bagnell]

Fixes the issue from this comment: #6741 (comment)

[cesium-concierge]

Thanks for the pull request @bagnell!

• ✔️ Signed CLA found.
• ❔ CHANGES.md was not updated.
  • If this change updates the public API in any way, please add a bullet point to CHANGES.md.

Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.
• Works (or fails gracefully) in IE11.

---

I am a bot who helps you make Cesium awesome! Contributions to my configuration are welcome.

🌍 🌎 🌏

[hpinkos]

@bagnell This seems to fix the camera angle posted in that issue, but I'm still seeing some weirdness from different angles.

[bagnell]

Thanks @hpinkos. It's fixed. This seems like it should have been a bug for a while, but I couldn't find any issue for it.

[hpinkos]

@bagnell looks fine in chrome now. It's doing something weird in IE though.

That doesn't happen in master. It happens in this branch with logarithmicDepthBuffer set to true or false.

var viewer = new Cesium.Viewer('cesiumContainer');
var scene = viewer.scene;
scene.logarithmicDepthBuffer = false;

var blueCartographic = new Cesium.Cartographic(-1.3196863177294136, 0.6988508714746624, 30.0);
var redCartographic = new Cesium.Cartographic(-1.319681841889412, 0.6989153500784591, 30.0);

var arrowPositions = [
    Cesium.Cartographic.toCartesian(blueCartographic),
    Cesium.Cartographic.toCartesian(redCartographic)
];

var line = viewer.entities.add({
    polyline : {
        positions : arrowPositions,
        width : 50,
        followSurface : false,
        material : new Cesium.PolylineArrowMaterialProperty(Cesium.Color.CYAN)
    }
});

viewer.zoomTo(viewer.entities);

[bagnell]

@hpinkos this is ready for another look.

[hpinkos]

Looks great, thanks @bagnell!