OpenSkp 1.0.0

OpenSKP

The open-source SketchUp (.skp) file parser — C# / .NET edition.

Parse .skp files without SketchUp. No SDK. No license. Just code.

🏠 openskp.com · 🌐 Try the Live Web Viewer · 📖 Docs · Changelog

🌟 What is OpenSKP?

OpenSKP is the first and only open-source, cross-platform parser for SketchUp binary files — reverse-engineered from both the modern VFF container (SketchUp 2021+) and the classic MFC CArchive container (SketchUp 2013–2020). It gives .NET developers (desktop, cloud, and mobile) full programmatic access to geometry, materials, components, layers, and metadata, with no SketchUp installation and no proprietary SDK required. The same parser and export API also ship as first-class packages for Python, TypeScript, Dart, and C++ — see the project README for the full cross-language picture.

✨ Features

• Full-fidelity parsing — vertices, edges, faces, normals, UV coordinates, nested component hierarchies, layers/tags, materials, textures, styles, and dynamic-component attributes.
• Both SketchUp file generations — modern VFF (2021+) and legacy MFC (2013–2020) containers, transparently, behind one SkpFile.Open() call.
• Scene baking — an opt-in SkpFile.BuildScene() pass resolves the full placed scene graph to world-space, triangulated, export-ready geometry.
• Native multi-format export — glTF (GLB), Wavefront OBJ/MTL, STL, PLY, AutoCAD DXF (3DFACE and Polyface Mesh), IFC4 (BIM/ISO 10303-21 STEP), and JSON — all written from scratch, no third-party CAD/BIM SDK involved. The DXF writer is verified against real desktop AutoCAD, not just lenient DXF readers.
• No practical file-size ceiling — unlike the CLR's ~2.1 GB array/ MemoryStream cap, OpenSKP's ChunkedBuffer and 64-bit TLV offsets remove that limit entirely: verified against a real 620 MB .skp file (153,586 definitions) with zero special configuration.
• Structured observability — opt-in progress reporting and location-carrying parse errors for debugging malformed or unusual files.

🌐 Try the Live Web Viewer (Drag-and-Drop)

🚀 Installation

Install the package via the .NET CLI:

dotnet add package OpenSkp

Or via the NuGet Package Manager:

Install-Package OpenSkp

💻 Quick Start

1. Parse an SKP File

Open and parse a SketchUp model to inspect its metadata:

using System;
using OpenSkp;

class Program
{
    static void Main()
    {
        // Open and decode an SKP file
        SkpModel model = SkpFile.Open("house.skp");

        Console.WriteLine($"SketchUp File Version: {model.Version}");
        
        // Print Layer Names
        Console.WriteLine("Layers:");
        foreach (var layer in model.Layers)
        {
            Console.WriteLine($"- {layer.Name} (RGB: {layer.ColorR}, {layer.ColorG}, {layer.ColorB})");
        }

        // Print Materials List
        Console.WriteLine("Materials:");
        foreach (var material in model.Materials)
        {
            Console.WriteLine($"- {material.Name} (Transparency: {material.Transparency})");
        }

        // Walk component definitions and their geometry
        foreach (var kvp in model.Definitions)
        {
            Console.WriteLine($"Definition {kvp.Key}: {kvp.Value.Name} - {kvp.Value.Vertices.Count} vertices, {kvp.Value.Faces.Count} faces");
        }

        // model.Root holds whatever is placed directly in the model (not
        // inside any component/group), including root-level instances.
        Console.WriteLine($"Root-level instances: {model.Root.Instances.Count}");

        // Build scene graph into world-space meshes and export to DXF / IFC / GLB / OBJ / STL / PLY
        Scene scene = SkpFile.BuildScene("house.skp");
        DxfExport.ExportDxf(scene, "house.dxf");
        IfcExport.ExportIfc(scene, "house.ifc");
        GlbExport.ExportGlb(scene, "house.glb");
        ObjExport.ExportObj(scene, "house.obj");
        StlExport.ExportStl(scene, "house.stl");
        PlyExport.ExportPly(scene, "house.ply");
    }
}

⚙️ Target Frameworks

OpenSKP targets .NET Standard 2.0, ensuring full compatibility with:

• .NET 5 / 6 / 7 / 8 / 9 (Console, Web APIs, ASP.NET Core)
• .NET Core 2.0+
• .NET Framework 4.6.1+ (WPF, WinForms)
• Mono / Xamarin / .NET MAUI (iOS, Android)

🏭 Used in Production

OpenSKP powers the SketchUp import pipeline for FrameSmart (a 3D collaboration platform with nearly 200 active users) and IngeTrazo (a SketchUp-alternative 3D modeler with a BIM → IFC bridge). Using OpenSKP in your own project? Open an issue or a PR to get added here.

🖥️ Monorepo Package Ecosystem

OpenSKP is designed as a unified cross-platform monorepo:

• Python Package (openskp)
• TypeScript / JS Package (openskp)
• .NET Package (OpenSkp)
• Dart Package (openskp)
• C++ Package (OpenSkp, source releases)

📄 License

This project is licensed under the MIT License — see the LICENSE file for details.