镜面卷积（也称为预过滤环境贴图）。
Each pixel of this Cubemap texture is replaced with the integral of incident illumination towards corresponding direction weighted with the Phong lobe. Each mipmap is convolved with varying Phong exponent - high resolution mipmaps represent glossy reflection while low resolution mips are very blurry and useful for very rough specular reflection.
可用于在光泽对象和粗糙对象上反射光线（通过使用反射矢量进行采样）。
另请参阅：TextureImporterSettings.cubemapConvolution。