Learn Three.js - Third Edition

Alpha map

The alpha map is a way to control the opacity of the surface. If the value of the map is black, that part of the model will be fully transparent, and if it is white, it will be fully opaque. Before we look at the texture and how to apply it, we'll first look at the example (14-alpha-map.html): 

In this example, we've rendered a sphere and set the alphaMap property of the material. If you open this example, you'll notice that you can only see the front-facing part of the sphere, unlike the preceding example, where you can look through the sphere and see the other side. The reason is that by default, the side property of the used material ...