三个js - 纹理控制

Question

我有这个材料

"materials": [{
    "colorAmbient": [0.64,0.64,0.64],
    "shading": "phong",
    "mapDiffuseAnisotropy": 1,
    "mapDiffuseWrap": ["RepeatWrapping","RepeatWrapping"],
    "colorDiffuse": [0.64,0.64,0.64],
    "DbgName": "Material",
    "blending": "NormalBlending",
    "colorSpecular": [0.5,0.5,0.5],
    "DbgIndex": 0,
    "depthTest": true,
    "visible": true,
    "colorEmissive": [0,0,0],
    "wireframe": false,
    "mapDiffuseRepeat": [1,1],
    "depthWrite": true,
    "opacity": 1,
    "specularCoef": 50,
    "DbgColor": 15658734,
    "mapDiffuse": "w.jpg",
    "transparent": false
}]

我的对象中的纹理是平行四边形。我希望纹理只在平行四边形的一侧，并且上面的值不会发生。如何才能使图像只在我对象的一侧？

谢谢！