Polygon lighting issue

[GatorScott]

[
    {
        "id": "document",
        "name": "TopicID=33",
        "version": "1.0"
    },
    {
        "id": "aPolygon",
        "polygon": {
            "positions": {
                "cartographicDegrees": [
                     0.0,  0.0, 100000.0,
                     0.0, 10.0, 500000.0,
                    10.0, 10.0, 100000.0,
                    10.0,  0.0, 500000.0 ]
            },
            "perPositionHeight": true
        }
    },
   {
        "id": "LowerLeft",
        "position": {
            "cartographicDegrees": [ 0.0, 0.0, 100000.0 ]
        },
        "point": {
            "color": {
                "rgba": [ 30, 144, 255, 255 ]
            },
            "pixelSize": 10
        }
    },
    {
        "id": "UpperLeft",
        "position": {
            "cartographicDegrees": [ 0.0, 10.0, 500000.0 ]
        },
        "point": {
            "color": {
                "rgba": [ 30, 144, 255, 255 ]
            },
            "pixelSize": 10
        }
    },
    {
        "id": "UpperRight",
        "position": {
            "cartographicDegrees": [ 10.0, 10.0, 100000.0 ]
        },
        "point": {
            "color": {
                "rgba": [ 30, 144, 255, 255 ]
            },
            "pixelSize": 10
        }
    },
    {
        "id": "LowerRight",
        "position": {
            "cartographicDegrees": [ 10.0, 0.0, 500000.0 ]
        },
        "point": {
            "color": {
                "rgba": [ 30, 144, 255, 255 ]
            },
            "pixelSize": 10
        }
    }
]```

[mramato]

This is most likely the same thing as #1825, but we'll keep this open until we can confirm both are fixed.

[pjcozzi]

I suspect this is different than #1825 and is due to the normal computation.

[YouLu]

Hello all,

Is there a time frame when this bug is going to be fixed?
Thanks,

Steven

[pjcozzi]

Hi Steven - we're heads down on KML support at the moment so I can't say that any of us are going to be available to look at it before the Cesium 1.7 release on March 2.

[hpinkos]

@pjcozzi I can't reproduce this. I was using this example:

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

viewer.entities.add({
    polygon : {
        hierarchy : Cesium.Cartesian3.fromDegreesArrayHeights([0.0,  0.0, 100000.0,
                     0.0, 10.0, 500000.0,
                    10.0, 10.0, 100000.0,
                    10.0,  0.0, 500000.0]),
        extrudedHeight: 0,
        perPositionHeight : true,
        material : Cesium.Color.WHITE
    }
});

viewer.zoomTo(viewer.entities);

Regardless, if you're using perPositionHeights and your polygon is not planar, there is no guarantee that it will triangulate the way you would expect it to, and that may lead to some weird issues.

[pjcozzi]

@hpinkos your example looks good, but if you drag and drop the CZML in the first comment, there is still an issue:

[mramato]

We recently found and fixed an issue with perPositionHeight normals, but it does not appear to fix this issue. (See above link).