EmissionTextureUnit() 设置自发光纹理单元 Members staticconstantSuperMap3D.EmissionTextureUnit.First : Number 设置第一重纹理自发光 staticconstantSuperMap3D.EmissionTextureUnit.None : Number 设置默认状态 staticconstantSuperMap3D.EmissionTextureUnit.Second : Number 设置第二重纹理自发光