Live: instantvoxel.thitichotk.com (desktop first, runs in your browser)

Instant-Voxel turns 3D models and images into voxel art in the browser. A C++ kernel compiled to WebAssembly does the voxelising and three.js reads the model files and draws the result. You can touch the voxels up one by one before exporting them for MagicaVoxel, Minecraft, a game engine or a 3D printer. Your files stay on your computer; only the optional model server receives anything, and you choose where it runs.

Using it

1. Drop a model, an image or a .vox file onto the page, or pick files under Source. For a model in several files, drop them together (.gltf with its .bin and textures, .obj with its .mtl).
2. Set the Size and the other Voxelise options. Models re-voxelise as you change them; the buttons under the viewport turn a model 90° at a time.
3. Touch it up with the Edit tools. With a tool selected, left-drag edits and right-drag orbits. Press ? for the keyboard shortcuts.
4. Choose a format under Export and press Download.

The page opens on a small sample island, so the editor and the exports can be tried straight away.

What it does

• Models in: GLB, glTF, OBJ with MTL, FBX, STL, PLY, 3MF and DAE, with textures, vertex colours, skinning and morphs. Each voxel takes its colour from the nearest surface.
• Images in: pixel art extruded voxel for voxel, or a greyscale heightmap as terrain.
• AI, in the browser: a photo becomes a voxel relief using Depth Anything V2 on your GPU. The background is cut by depth, or by an AI mask where WebGPU is available. The models download once and are then cached.
• AI, on a model server: a photo or a text prompt becomes a full 3D object with Stable Fast 3D, running on your own machine or a hosted GPU (server/).
• Voxelising: up to 512 voxels per side, solid fill, hollow shells, removal of small floating islands, and a ghost of the source model to check the fit.
• Colour: an automatic palette (median cut in Oklab, 2 to 255 colours), Minecraft blocks, a default cube, or any .hex palette, with optional dithering.
• Editing: paint, erase, add, fill a region, pick a colour and box tools, with brush sizes, mirroring across X and Z, undo and redo, and a cut-height slider to work inside the model.

The voxel size in millimetres applies to .glb, .obj and .stl.

Run it locally

Needs Python 3 (or any static file server) and Node 22 for the tests. Rebuilding the kernel also needs Emscripten.

git clone https://github.com/thitichotk/instant-voxel.git
cd instant-voxel
python3 -m http.server -b 127.0.0.1 -d web 3000   # http://127.0.0.1:3000
node tests/run.mjs                                # the kernel and the pure modules
./build.sh                                        # rebuild web/voxelizer.js and .wasm from src/voxelizer.cpp

Python's server lets the browser cache files, so while editing keep DevTools open with Disable cache ticked. The optional model server has its own setup in server/README.md.

Cloudflare Pages deploys web/ from main as it is (there is no build step), and each pull request gets a preview link. The compiled kernel is committed, so rebuild and commit it whenever src/voxelizer.cpp changes.

How it works

1. Reading. three.js loaders read the model files, and loaders.js flattens the scene into one triangle mesh with positions, UVs, vertex colours and materials, in world space.
2. Voxelising. A Web Worker runs the C++ kernel. Every triangle that overlaps a voxel competes for it, and the one closest to the voxel's centre colours it, sampling texture × vertex colour × material colour in linear light. Median cut in Oklab then picks the palette, or each colour maps to the nearest entry of a fixed one. Solid fill floods the air from outside and fills whatever it can't reach.
3. Showing and editing. The grid is one byte per voxel with a 256-colour palette. It is meshed in 32³ chunks with greedy quads, and an edit remeshes only the chunks it touches.
4. Exporting. Each format is written straight from the grid in the browser.

Built with plain HTML, CSS and ES modules, three.js 0.169, Emscripten (C++17 to WebAssembly) and transformers.js 4.3. There are no npm dependencies.

Limits

• 512 voxels per side at most. A grid that size needs about 0.5 GB of memory while it is built.
• .vox files open with their models placed but not rotated; scene rotations are ignored.
• The AI background mask needs WebGPU and downloads about 115 MB once. The depth model is 27 to 50 MB.
• The model server needs a GPU or about 32 GB of unified memory on a Mac.
• The editor is designed for a desktop. On a phone, viewing, converting and exporting work, but editing is awkward.
• When one mesh uses textures with different transforms, every texture takes the first transform.

Credits and licence

• three.js (MIT) and transformers.js (Apache-2.0) load from jsDelivr.
• Depth Anything V2 Small (Apache-2.0) and BiRefNet lite (MIT) load from Hugging Face on first use.
• The model server downloads Stable Fast 3D (Stability AI Community License, "Powered by Stability AI") and SDXL with SDXL-Lightning (CreativeML Open RAIL++-M); see server/README.md.
• Plus Jakarta Sans and JetBrains Mono (SIL Open Font License) and Material Symbols (Apache-2.0) come from Google Fonts.
• The block colours are averages of Minecraft's textures; no textures are included.

MIT © 2026 Thitichot K.

Not affiliated with Mojang, Microsoft, MagicaVoxel or Stability AI.