lightmapper-wasm

A browser-ready JavaScript/WebAssembly wrapper around ands/lightmapper, a single-header C library for baking lightmaps using your existing WebGL2 renderer.

The original C library is included as a submodule under thirdparty/lightmapper.

Prerequisites

| Requirement | Version | |---|---| | Browser with WebGL2 | Chrome 56+, Firefox 51+, Safari 15+, Edge 79+ | | Emscripten (build only) | 3.x recommended | | CMake (build only) | 3.13+ | | Node.js (dev server) | 18+ |

See WASM_SETUP.md for detailed Emscripten installation and build instructions.

Installation

npm install lightmapper-wasm

Then import in your project:

import { createLightmapperModule } from "lightmapper-wasm";

Build from source

# 1. Ensure Emscripten is on your PATH (see WASM_SETUP.md)
# 2. Configure & compile
npm run configure:wasm
npm run build:wasm
# 3. Serve the demo
npm run serve:demo

Quick Start

import { createLightmapperModule } from "lightmapper-wasm";

// 1. Initialize with an existing WebGL2 canvas
const canvas = document.getElementById("viewport");
const gl = canvas.getContext("webgl2");
const lm = await createLightmapperModule({ canvas, webglContext: gl, autoRegisterEmscriptenContext: true });

// 2. Allocate a lightmap buffer on the WASM heap
const W = 256, H = 256, C = 4;
const floatCount = W * H * C;
const lightmapPtr = lm.allocF32(floatCount);
lm.viewF32(lightmapPtr, floatCount).fill(0);           // clear to black

// 3. Create a lightmapper context
lm.makeBoundContextCurrent();
const ctx = lm.lmCreate(64, 0.001, 100.0, 0, 0, 0, 2, 0.01, 0.0);

// 4. Bind lightmap + geometry
lm.lmSetTargetLightmap(ctx, lightmapPtr, W, H, C);
lm.lmSetGeometry(ctx, 0,
  lm.LM_FLOAT, verticesPtr, strideBytes,
  lm.LM_NONE, 0, 0,
  lm.LM_FLOAT, verticesPtr + 12, strideBytes,          // UV offset = 3 floats × 4 bytes
  indexCount, lm.LM_UNSIGNED_SHORT, indicesPtr);

// 5. Render loop — keep calling lmBegin until it returns false
const bufs = lm.makeBeginFrameBuffers();
while (lm.lmBegin(ctx, bufs.viewportPtr, bufs.viewPtr, bufs.projectionPtr)) {
  const vp   = bufs.readViewport();
  const view = bufs.readViewMatrix();
  const proj = bufs.readProjectionMatrix();

  gl.viewport(vp[0], vp[1], vp[2], vp[3]);
  drawScene(gl, view, proj);                            // your scene draw call
  lm.lmEnd(ctx);
}
bufs.dispose();

// 6. Post-process and read back
const tmpPtr = lm.allocF32(floatCount);
lm.lmImageDilate(lightmapPtr, tmpPtr, W, H, C);
lm.lmImageDilate(tmpPtr, lightmapPtr, W, H, C);
lm.lmImagePower(lightmapPtr, W, H, C, 1.0 / 2.2, 0x7); // gamma correct RGB

const result = lm.copyFromHeap(lightmapPtr, new Float32Array(floatCount));

// 7. Clean up
lm.lmDestroy(ctx);
lm.free(tmpPtr);
lm.free(lightmapPtr);

Documentation

• LIGHTMAPPER.md — full API reference
• WASM_SETUP.md — Emscripten installation & build guide

License

See the original lightmapper repository for license details.