Overview
OpenGeometry can export B-Reps to binary STL. You can export a single B-Rep payload or export a
whole scene through OGSceneManager.
STL export is experimental. Output, config fields, and file-writing helpers may change. If you hit
an exporter limitation or confusing output, reach out on
Discord. The WebAssembly build returns STL as bytes (Uint8Array). You are responsible for downloading or
persisting those bytes. Some file-writing convenience methods exist only in native builds.
Initialization
Initialize the WASM module once before using OGSceneManager:
import { OpenGeometry } from "opengeometry";
await OpenGeometry.create({ wasmURL: "/opengeometry_bg.wasm" });
Export APIs
exportBrepToStl
Export a single serialized B-Rep JSON string to STL bytes.
import { OGSceneManager } from "opengeometry";
const manager = new OGSceneManager();
const result = manager.exportBrepToStl(brepSerialized);
exportSceneToStl / exportCurrentSceneToStl
Export a stored scene (or the current scene) to STL bytes.
import { OGSceneManager } from "opengeometry";
const manager = new OGSceneManager();
const sceneId = manager.createScene("stl export");
// Add entities to the scene, then:
const result = manager.exportSceneToStl(sceneId);
// or:
const result2 = manager.exportCurrentSceneToStl();
Result type
export*ToStl(...) returns an OGStlExportResult:
A JSON string containing export statistics (triangle counts, skipped faces, topology errors).
Config JSON
All STL exports accept an optional config_json string. If it is null, undefined, or an empty
string, OpenGeometry uses defaults. If you provide config_json, it must deserialize into the full
StlExportConfig shape.
Default configuration (Rust):
StlExportConfig {
header: Some("OpenGeometry STL Export".to_string()),
scale: 1.0,
error_policy: StlErrorPolicy::BestEffort,
validate_topology: true,
}
{
"header": "My STL export",
"scale": 1.0,
"error_policy": "BestEffort",
"validate_topology": true
}
Examples
Export a wrapper shape to STL
OGSceneManager expects a serialized B-Rep string. Wrapper shapes expose one of getBrep(),
getBrepData(), or getBrepSerialized() depending on the type.
import { Cuboid, OGSceneManager, Vector3 } from "opengeometry";
function toBrepSerialized(source: unknown) {
const value =
source && typeof (source as any).getBrepSerialized === "function"
? (source as any).getBrepSerialized()
: source && typeof (source as any).getBrepData === "function"
? (source as any).getBrepData()
: source && typeof (source as any).getBrep === "function"
? (source as any).getBrep()
: source;
return typeof value === "string" ? value : JSON.stringify(value);
}
const manager = new OGSceneManager();
const sceneId = manager.createScene("export");
const cuboid = new Cuboid({
center: new Vector3(0, 0.5, 0),
width: 2,
height: 1,
depth: 1,
color: 0x10b981,
});
manager.addBrepEntityToScene(
sceneId,
"box-1",
"Cuboid",
toBrepSerialized(cuboid)
);
const result = manager.exportSceneToStl(sceneId);
console.log(JSON.parse(result.reportJson));
Download STL in the browser
const blob = new Blob([result.bytes], { type: "application/octet-stream" });
const url = URL.createObjectURL(blob);
const link = document.createElement("a");
link.href = url;
link.download = "model.stl";
link.click();
URL.revokeObjectURL(url);
Write STL in Node.js
import { writeFileSync } from "node:fs";
writeFileSync("model.stl", Buffer.from(result.bytes));
Native-only file export
Native-only builds also expose exportSceneToStlFile(...) (not available in browser/WASM builds).
