cesium定义线面

面：

var polygon = viewer.entities.add({
            polygon : {
                hierarchy : {
                    positions : null,
                    holes : [{
                        positions : null
                    }]
                },
                material: Cesium.Color.GREEN.withAlpha(1),
                height: 5000
            }

        });

线：

var polyline = viewer.entities.add({
            show:true,
            polyline: {
                positions: [],
                width: 8,
                material: Cesium.Color.WHITE
            }
        });