Another prominent example of procedural generation is the creation of textures. Similar to terrain generation, the procedural generation of textures uses noise to create variance. This can then be used to create varying textures. Different patterns and equations are also used to create a more controlled noise that forms recognizable patterns.
Generating textures procedurally like this means that you can potentially have an unlimited number of possible textures without any overhead on storage. From a limited pool of initial resources, endless combinations can be generated, an example of which can be seen in the following image:
Perlin noise is just one example of the many algorithms that are commonly used in procedural generation. The study of these algorithms is beyond the scope of this book, but if you want to further explore the use of procedural generation, it would be a good place to start.
Traditionally, game animations are created by animators, and then exported as an animation file that is ready for use in the game. This file will store the various movements that each part of a model will go through during animation. It then gets applied to the game character during runtime. The player's current state will determine which animation should be playing. For example, when you press A to jump, the player will change to a jumping state, and the jumping animation will be triggered. This system works great, but it is very rigid. Each step, jump, and roll is identical.
However, procedural generation can be used to create real-time, dynamic animation. By taking the current position of the character's skeleton and calculating the multiple forces that are being imparted upon it, a new position can be calculated. The most prominent example of procedural animation is ragdoll physics.
Although less common than the previous examples, procedural generation is also used to create game sounds. This will commonly be in the form of manipulating existing sounds. For example, sound can be spatialized, meaning it appears to be coming from a specific position when heard by the user.
At a stretch, short, one-shot sound effects may be synthesized, but due to the little benefit that it brings as compared to the amount of work needed to implement it, it's seldom used. It's simply much easier to load premade sounds.
Note
Sfxr is a small program that generates random sound effects from scratch. Its source is available. So, if sound synthesis interests you, it will serve as a good starting point. You can find the project at https://github.com/grimfang4/sfxr.