Billboard (3D)

In 3D games, we often make use of flat planes that draw a texture. This is useful for all sorts of things that don't necessarily need thickness, like trees in the distance, grass, fire, or even clouds.

When a flat plane is seen from the side, it becomes nearly invisible since it has no thickness. To remedy this, modern game engines often use a technique called "billboarding." This technique consists of making the plane always face the camera, no matter the angle.

This imitates early 3D games like Wolfenstein 3D or Doom, where all sprites were rendered separately from the walls. Back then, this was the only way to render complicated shapes like organic bodies.