Next, we'll terraform our sphere into a globe of the Earth by rendering a texture onto the surface of the sphere.
Shaders can get quite complex, implementing all kinds of specular highlights, reflections, shadows, and so on. A simpler algorithm that still makes use of a color texture and lighting is a diffuse material. This is what we'll use here. The word diffuse refers to the fact that light diffuses across the surface, as opposed to being reflective or shiny (specular lighting).
A texture is just an image file (for example,
.jpg) that can be mapped (projected) onto a geometric surface. Since a sphere isn't easily flattened or unpeeled into a two-dimensional map (as centuries of cartographers can attest), the ...