The simulation of snow has always been a challenge in games. The vast majority of games simply includes snow directly in the model's textures so that their tops look white. However, what if one of these objects starts rotating? Snow is not just a lick of paint on a surface; it is a proper accumulation of material and should be treated as such. This recipe shows you how to give a snowy look to your models using just a shader.
This effect is achieved in two steps. First, a white color is used for all the triangles facing the sky. Second, their vertices are extruded to simulate the effect of snow accumulation. You can see the result in the following picture:
Keep in mind that this recipe does not aim to create a photorealistic snow effect. It provides a good starting point, but it is up to an artist to create the right textures and find the right parameters to make it fit your game.