More effective rendering with regions and atlases

Creating Texture objects from different image files and rendering them with SpriteBatch is the most straightforward way of building scenes with Libgdx. However, it is far from being the most efficient one. Games are real-time, performance-critical applications, and writing efficient systems becomes even more important when dealing with resource-limited platforms such as tablets, phones, or browsers.

Surely drawing a handful of individual images is not going to make a massive impact when running the game on a high-end phone with a dedicated GPU. However, the landscape can rapidly change the second we add different backgrounds, dozens of different characters on screen, particle effects, and so on.

Luckily enough, it is fairly simple to set up our assets and rendering process so that it does the job amazingly fast. The key concept here is drawing thousands of little chunks from a massive texture is preferable than a few individual images. We will...