While it’s possible to make games with art assets that only use vertex colors, like our triangle in the last chapter, it would take millions of vertices to render an image as detailed as the parrot photo in Figure 3-1. This would not only mean that games needed very complicated meshes to display an image, it would also make it very difficult to swap images out if they needed to change later. For these reasons, most games don’t use vertex colors, which can only vary on a per-vertex basis, to render detailed surfaces. Instead, they use image files to provide information that can vary on a per-fragment basis. In computer graphics these image files are referred to as textures, and this chapter is going to introduce the basics of working with them.