Rendering imposters (billboards)
Many mobile survival games render thousands of zombies, and real-time strategy games render lots of armies smoothly by not using full 3D models for each one. Instead, they rely on billboards—flat, camera-facing quads with textures. A billboard’s surface normally always aligns with the camera, creating a 3D illusion while keeping geometry simple and performance high.
Billboards are commonly used in the following scenarios:
- Particles: Each particle (smoke, fire, explosions, dust) is a small, camera-facing quad, providing a volumetric look without heavy geometry.
- Foliage/trees: Distant plants are rendered as quads to reduce rendering costs; from afar, the difference is barely noticeable.
- Light flares/glows: Sun glare or headlight glow can be a simple billboard with an additive texture, delivering realistic effects inexpensively.
- Crowds: Large, distant groups are easily represented by billboards when great...