the material of polygon has a problem that is mirrored of the images

1. A concise explanation of the problem you're experiencing.

the material of polygon has a problem that is mirrored of the images

2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.

var redPolygon = viewer.entities.add({
    name : 'Red polygon on surface',
    polygon : {
        hierarchy : Cesium.Cartesian3.fromDegreesArrayHeights([115.0, 37.0,100000,
                                                               102.0, 35.0,400000,
                                                                102.0, 31.0,6000,
                                                        115.0, 32.0,400000
                                                       
                                                        ]),
         perPositionHeight: true,
        material : '../images/Cesium_Logo_Color.jpg'
    }
});

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

i want to display images normally

4. The Cesium version you're using, your operating system and browser.

cesium 1.50 chrome

Hey, see my response here:

https://groups.google.com/d/msg/cesium-dev/URGHFvXT-uU/ZSw001pbCAAJ