for example if you set attenuation distance to 10m for a 1cm object (meaning a very light material, very little density), but leave transmittance value at rgb 0, the material will still be opaque.
例如你设定一个1厘米厚的物体的衰减距离是10厘米(只有很少光被吸收)但设定能见度为rgb0(纯黑),那么这个物体还是不透明的。