It's not that different from drawing with SVG, except that SVG is meant for it. Check out this example halfway down
http://en.wikipedia.org/wiki/Scalable_Vector_Graphics The text is the actual file, and the little sign on the right is how it should actually look (if your browser can show svg.) Those using IE probably need a plugin or something to view it. Also, if you ever used POV-Ray in ancient times, you had to hand code the position of objects and light sources, then drop that into POV-Ray and it would render a 3D scene based on your code. I'm so glad we have tools for that stuff now! :-)