What is a sprite sheet and how does it work?

A sprite sheet is a single bitmap image that contains a collection of smaller graphics—called sprites. Game engines use sprite sheets to improve performance by loading only one file instead of many individual images, reducing loading times and memory usage.

When a game engine needs to render a sprite, it copies its pixel data from the sprite sheet into the scene. To do this, the engine must know where each sprite is located on the sheet.

In simple sprite sheets with equal-sized sprites, the sprite index may be enough to find its position. However, in optimized sheets with differently sized sprites, a data file is required. This file contains each sprite's position, size, and possibly more information like:

• Borders for 9-slice scaling
• Anchor points
• Rotation flags
• Trimmed bounds

Optimized sprite sheets allow tighter packing and flexibility, making them ideal for complex or performance-critical games.