Now we know what procedural generation is, and that it's the element of randomness we add that lets us create dynamic systems, let's take a look at some examples of how it is used in games. There are countless ways in which it can be utilized; the following are just a few major implementations.
Necessity, as the saying goes, is the mother of invention. As developers of today we're spoiled with the hardware that we have at our disposal. Even the most baseline machines that you'll get today will have a hard drive of 500 GB in size and up as standard. This is quite a luxury considering that just a couple of decades ago that would be MB and not GB.
Game distribution was also a very different game back then. Today, we either buy games on a physical disk, with Blu-ray disks offering a whopping 25 GB per layer, or download them off the Internet, where there are no size restrictions at all. Keeping this in mind, now consider the fact that the size of most Nintendo Entertainment System (NES) games was a mere 128 to 384 KB! These storage restrictions meant that game developers had to fit lots of content into a small space, and procedural generation was a great way to do this.
Since building large levels and storing them wasn't possible in the past, games were designed to build their levels and resources algorithmically. You'd put all the resources needed on your storage media, and have the software assemble the level at the player's end.
Hopefully now, the earlier desk analogy makes more sense. It's just like how flat-packed furniture is easier to transport, and it can then be built at home. As hardware has developed, this has become less of a problem, but it was a great solution for early developers who had storage concerns.
One of the most prominent uses of procedural generation in modern video games is the generation of game maps and terrain. The extent to which this can be used is vast, and ranges from generating simple 2D maps to full 3D worlds and terrain.
When procedurally generating 3D terrain, noise maps, such as the ones generated by Perlin noise, are used to represent random distribution by producing an image with areas of both high and low concentration. This data, the variance in concentration and intensity, can then be used in many ways. When generating a terrain, it's commonly used to determine the height at any given position.
The procedural generation of complex 3D terrain is beyond the scope of this book. However, we will generate 2D dungeons later in this book.