垂直的多边形材质,两个面显示的不一致

您好,我定义了一个垂直的面,材质设置是一个图片,当旋转视图的时候,背面的材质显示不正常
代码:
let entities = viewer.entities.add({
name: “Cyan vertical polygon with per-position heights and outline”,
polygon: {
hierarchy: Cesium.Cartesian3.fromDegreesArrayHeights([
-90.0, 41.0, 20000.0, -89.0, 41.0, 20000.0, -89.0, 41.0, 0.0, -90.0, 41.0, 0.0
]),
perPositionHeight: true,
material: new Cesium.ImageMaterialProperty({ image: “/images/Cesium_Logo_overlay.png”, color: Cesium.Color.WHITE }),
outline: true,
outlineColor: Cesium.Color.WHITE,
outlineWidth: 5,
perPositionHeight: true,
stRotation: Cesium.Math.toRadians(-180)
},
});
image
image