FalSprite

Game-ready sprite sheet animations from a single text prompt. Built on fal.ai + Google Gemini.

What it does

Type a character description, pick a grid size, choose animation actions — FalSprite generates a full sprite sheet with transparent background and animated preview.

Pipeline:

• Google Gemini 2.5 Flash-Lite — intelligent prompt rewriting with character design + choreography
• Google Gemini 2.5 Flash Image — sprite sheet image generation (with optional reference image)
• fal.ai BRIA — automatic background removal

Features

• Configurable grid: 2x2, 3x3, 4x4, 5x5, 6x6
• Multi-action selection: pick multiple animation actions per grid row (idle, walk, run, attack, cast, jump, dance, death, dodge, or custom)
• LLM prompt rewrite: your simple prompt becomes a detailed character + choreography direction
• Auto background removal: BRIA removes the background automatically
• Live preview: real-time frame-by-frame animation with FPS control
• Downloads: sprite sheet PNG, transparent PNG, animated GIF
• Reference image: upload a reference to guide the generation
• Showcase examples: curated animated GIF examples

Quick start

git clone https://github.com/lovisdotio/falsprite.git
cd falsprite
npm install
cp .env.example .env.local
npm run dev

Open http://localhost:8787

Set these env vars in .env.local:

• GOOGLE_API_KEY (for prompt enhancement + sprite generation via Gemini)
• FAL_KEY (for BRIA background removal on fal.ai)

Deploy to Vercel

npm i -g vercel
vercel

The project includes Vercel-ready serverless functions in api/ and static assets in public/.

Project structure

├── public/           Static frontend
│   ├── index.html    Main app
│   ├── app.js        Frontend logic
│   ├── styles.css    Styles
│   ├── showcase/     Example GIFs
│   └── select.html   Showcase curation tool
├── api/              Vercel serverless functions
│   ├── generate.mjs  Sprite generation endpoint
│   ├── upload.mjs    Image upload endpoint
│   └── fal/media.mjs Media proxy endpoint
├── lib/fal.mjs       Shared FAL API helpers
├── server.mjs        Local dev server
├── batch-generate.mjs  Batch generation tool (dev)
└── process-showcase.mjs Showcase processor (dev)

Tech stack

• Frontend: Vanilla JS, no framework, no build step
• Backend: Node.js (native HTTP server for dev, Vercel serverless for prod)
• AI: Google Gemini (rewrite + sprite generation) + fal.ai BRIA (background removal)
• GIF: gif.js (browser) + gifenc (server-side batch)

License

MIT