Flipbook (Sprite Sheet)
Animated texture made of a grid of frames
Also known as: Flipbook texture · Sprite sheet · SubUV · Texture sheet animation · Flipbook animation · VFX flipbook
Definition
A flipbook is a texture made of a grid of animation frames, played one after another on a particle or a surface, like the pages of a flip book. It is the main way to give realistic, hand-crafted motion to smoke, fire, explosions and magic without simulating them in real time. Flipbooks are rendered from a simulation in Houdini or similar tools, or painted by hand, and packed into a sheet such as 8 by 8 frames. Unreal Engine calls it SubUV and Unity calls it a Texture Sheet Animation.
In production
Render simulations with a clean, evenly lit look and bake the lighting information, such as a lighting direction map, if the engine supports it. Keep the sheet size reasonable, as a large sheet of many frames uses a lot of memory, and use frame blending to hide a low frame count. Make flipbooks loop when the effect needs it, and encode the alpha carefully, since overdraw and the edge look matter.
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Tools that use Flipbook (Sprite Sheet)
See also
Particle System
Spawns and animates many small elements
Flipbook Animation Looks Choppy
Smoke and fire jump between frames
Texture Atlas
Multiple assets, one texture
Alpha Channel
Fourth channel that stores transparency or a mask
Texture Memory Budget
How much memory textures use
Additive vs Alpha Blending
Two ways particles combine with the scene