Skip to main content
STEP export is experimental and may change. If you hit an exporter limitation or confusing output, reach out on Discord.

​
Overview

OpenGeometry can export B-Reps to STEP Part 21 text. You can export a single B-Rep payload or export a whole scene through OGSceneManager.

​
Initialization

Initialize the WASM module once before using OGSceneManager: 
import { OpenGeometry } from "opengeometry";

await OpenGeometry.create({ wasmURL: "/opengeometry_bg.wasm" });

​
Export APIs

​
exportBrepToStep

import { OGSceneManager } from "opengeometry";

const manager = new OGSceneManager();
const result = manager.exportBrepToStep(brepSerialized);

​
exportSceneToStep / exportCurrentSceneToStep

import { OGSceneManager } from "opengeometry";

const manager = new OGSceneManager();
const sceneId = manager.createScene("step export");

const result = manager.exportSceneToStep(sceneId);
// or:
const result2 = manager.exportCurrentSceneToStep();

​
Result type

export*ToStep(...) returns an OGStepExportResult:
​
text
string
STEP Part 21 text output.
​
reportJson
string
A JSON string containing export statistics (skipped entities, triangle counts, topology errors).

​
Config JSON

All STEP 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 StepExportConfig shape (required fields must be present). Default configuration (Rust): 
StepExportConfig {
  schema: StepSchema::AutomotiveDesign,
  product_name: Some("OpenGeometry STEP Export".to_string()),
  scale: 1.0,
  error_policy: StepErrorPolicy::BestEffort,
  validate_topology: true,
  require_closed_shell: true,
}
Example JSON payload: 
{
  "schema": "AutomotiveDesign",
  "product_name": "OpenGeometry STEP Export",
  "scale": 1.0,
  "error_policy": "BestEffort",
  "validate_topology": true,
  "require_closed_shell": true
}

​
Key constraints

  • When require_closed_shell is true, non-solid inputs are skipped in best-effort mode.
  • When validate_topology is true, invalid B-Reps are skipped (or fail in strict mode).

​
Examples

​
Export and download STEP in the browser

const result = manager.exportCurrentSceneToStep();

const blob = new Blob([result.text], { type: "text/plain" });
const url = URL.createObjectURL(blob);

const link = document.createElement("a");
link.href = url;
link.download = "model.step";
link.click();

URL.revokeObjectURL(url);

​
Native-only file export

Native-only builds also expose exportSceneToStepFile(...) (not available in browser/WASM builds).
Last modified on March 14, 2026