A visible atmosphere

Abstract

In previous chapters, we have attached shaders to the instances of geometric objects and to the camera. As a ray proceeds from our eye (the camera), we intersect geometric surfaces. Shaders associated with that surface can specify its color and the modification of its geometric properties. However, for natural phenomena like fog and smoke, no similar geometric surfaces exist. Or at least, no geometric surfaces that we could effectively model exist—we hardly want to create individual geometric objects for the enormous number of microscopic water particles that a cloud contains.