Fix Corridor Geometry for sharp corners

[mramato]

As reported on the forum. The below code was generating an incorrect shape. I traced the problem down to a bad epsilon value in CorridorGeometryLibrary. I'm not at all confident in this area of the code, so @bagnell please double check my work. I also wasn't sure how to test it, so I just mimicked the other tests.

Should we have a single constant defined somewhere for all geometry epsilon checking?

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

var blueCorridor = viewer.entities.add({
    name : 'Blue corridor',
    corridor : {
        positions : Cesium.Cartesian3.fromDegreesArray([
            2.00571672577652,52.7781459942399,
            1.99188457974115,52.7764958852886,
            2.01325961458495,52.7674170680511,
            1.98708058340534,52.7733979856253,
            2.00634853946644,52.7650460748473
        ]),
        height : 1000.0,
        extrudedHeight : 50.0,
        width : 100.0,
        cornerType: Cesium.CornerType.MITERED,
        material : Cesium.Color.BLUE.withAlpha(0.5),
        outline : true,
        outlineColor : Cesium.Color.BLUE
    }
});


var polyline = viewer.entities.add({
    name : 'Polyline',
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArray([
            2.00571672577652,52.7781459942399,
            1.99188457974115,52.7764958852886,
            2.01325961458495,52.7674170680511,
            1.98708058340534,52.7733979856253,
            2.00634853946644,52.7650460748473
        ]),
        height : 1000.0,
        width : 10.0,
        material : Cesium.Color.RED.withAlpha(0.5)
    }
});

viewer.zoomTo(viewer.entities);

[bagnell]

This looks good to me. I introduced the bad epsilon for a fix where corridors should have been straight but had sharp corners instead. You should also add the same fix to the PolylineVolumeGeometry here

[mramato]

Yep, I managed to reproduce a similar problem in polyline volume with this code, which is now fixed.

var polylineVolume = viewer.entities.add({
    name : 'Polyline',
    polylineVolume : {
        shape : [new Cesium.Cartesian2(-100,-100), new Cesium.Cartesian2(-100,100),
                 new Cesium.Cartesian2(100,100), new Cesium.Cartesian2(100,-100)],
        positions : Cesium.Cartesian3.fromDegreesArrayHeights([
            2.00571672577652,52.7781459942399,500,
            1.99188457974115,52.7764958852886,500,
            2.01325961458495,52.7674170680511,500,
            1.98708058340534,52.7733979856253,500,
            2.00634853946644,52.7650460748473,500
        ]),
        material : Cesium.Color.RED,
        outline : true
    }
});

This is ready.

[bagnell]

Looks good.