Collision detection

One of the most basic interactions in games is a collision of two entities. There are several ways to detect collisions. In this chapter, we will cover basic entity collisions. The other popular methods are pixel-perfect collisions and physics engine collisions.

We are going to look at physics engine collisions in Chapter 6, Physics. There is an extension for pixel-perfect collisions as well, but it is unofficial and created for an older version of AndEngine.

The basic collision detection works with the underlying geometry. For example, a sprite is actually a texture drawn on a quad (two triangles). When creating sprites that will be a part of collision detection, we should take extra care about their bounding boxes.

Let's see a bad example of a bounding box. The following figure shows a texture that will be used to create a sprite:

The following figure shows how it will look when detecting collisions. The black bounding box is a boundary of the underlying geometries. The...