Volumetric Clouds Write-up(翻译)
原文地址
The basis of this effect is drawing a vertical stack of quads, each one showing a slice of the cloud. The cloud texture itself is just a world-mapped, top-down animated noise that is piped into opacity.
这种效果的基础是绘制一组垂直堆叠的四边形(简称为:四边形堆栈,vertical stack of quads),每个四边形都显示一片云。 云纹理本身只是一个世界映射的(world-mapped)、自上而下的(top-down)的动画噪声,它通过渲染,管道传输到不透明度中。
To animate the noise, I use the same trick that I use in countless other shaders to create a natural looking motion that appears free of obvious repetition, which is to blend the noise with either a copy of itself with a different UV scale, or a different noise texture, and pan these two noise textures against each other in opposite directions, and then blend them together through multiplication or some other desired blend mode.