# alit
> Paint with light. AI-generated PBR maps you relight in real time in your browser.

alit takes a text prompt, asks OpenAI's gpt-image-2 to paint a 3×3 grid of PBR texture maps for the scene (albedo, tangent-space normal, depth, roughness, reflectiveness, ambient occlusion, emissive, specular intensity, clearcoat), slices the grid client-side, and feeds the nine textures into a custom GLSL shader. The user moves their cursor to position a virtual light source and "paint" the flat scene into a lit, parallax-shifted, atmospheric render — like running a director-of-photography lighting session against an AI-generated still.

## What it is
- A web app at https://alit.dev
- Free to use under a BYOK (bring-your-own-OpenAI-key) model
- Source-available PBR experimentation playground

## How it works
1. User pastes their OpenAI API key once (stored in browser localStorage, never logged server-side)
2. User types a scene prompt in the gallery panel
3. The Cloudflare Worker forwards the request to gpt-image-2 with a strict 3×3 grid prompt that demands one specific PBR map per cell
4. gpt-image-2 returns a 2048×2048 composite, the worker stores it in R2
5. Browser slices the grid into nine cells, repacks AO/Roughness/Metalness into a single ORM texture, optionally aligns cells via Sobel-edge SSD shift correlation
6. A custom Three.js ShaderMaterial renders a 192×192 vertex-displaced plane through GGX BRDF, parallax occlusion mapping, depth-shadow raymarch, env reflection (faked from albedo), bloom, ACES tone-mapping, film grain, and SMAA — at 60fps in the browser

## Stack
- Vite + React 18 + TypeScript
- Zustand for state
- Three.js + custom GLSL fragment shader (GGX/Smith/Disney remap)
- pmndrs/postprocessing (BloomEffect, ToneMappingEffect, NoiseEffect, SMAAEffect)
- Cloudflare Workers + Pages + R2 (storage + delivery)
- OpenAI gpt-image-2 (textures), Replicate google/upscaler (optional)

## Pricing
- Free. Users provide their own OpenAI API key for generation.
- Each generation costs ~$0.20 on the user's OpenAI account.

## Features
- AI-generated 3×3 PBR map grid from a single prompt
- Auto-place virtual point lights at bright emissive blobs
- Auto-tune exposure, ambient, bloom threshold, and cursor light intensity from albedo brightness
- Cursor-driven cinematic relighting with smooth lerp on movement
- Mobile gyroscope controls camera tilt
- Public gallery — share scenes via slug, browse community submissions
- Drag-and-drop upload of pre-existing 3×3 PBR grids
- Per-map debug isolation (toggle each map on/off, fullscreen-preview any map)
- Random shader-parameter scramble for visual exploration

## Use cases
- Game artists prototyping lighting on AI-generated environments
- Photographers / cinematographers exploring chiaroscuro composition
- Educators teaching PBR concepts (each map's contribution is toggleable)
- Generative-art creators sharing relit scenes

## Links
- App: https://alit.dev
- Public gallery: https://alit.dev (default tab)
- OpenAI key signup: https://platform.openai.com/api-keys