DE_Wrapper Sample - CAD File Format Converter

Overview

DE_Wrapper Sample is a demonstration application showcasing the Data Exchange Wrapper (DE_Wrapper) functionality in OpenCASCADE Technology (OCCT). This project provides a flexible, configurable CAD file format converter with dynamic library loading capabilities, supporting conversion between various CAD formats including STEP, IGES, STL, glTF, OBJ, PLY, VRML, BREP, and XBF.

Key Features

• Multiple CAD Format Support: Convert between STEP, IGES, STL, glTF, OBJ, PLY, VRML, BREP, and XBF formats
• Dynamic Library Loading: Load only necessary Data Exchange libraries at runtime
• Cross-Platform Support: Works on Windows, Linux, and macOS
• Configurable Transfer Process: Fine-tune conversion parameters via resource files
• Optional Tessellation: Generate meshes from CAD models before export
• Thread-Safe Operations: Safe multi-threaded library loading

Table of Contents

• Requirements
• Build Instructions
• Installation
• Usage
• Configuration
• Supported Formats
• API Documentation
• Architecture
• Troubleshooting

Requirements

Prerequisites

• OCCT 7.8.0 or newer
• CMake 3.15 or newer
• C++17 compatible compiler:
  • Visual Studio 2019+ (Windows)
  • GCC 7+ (Linux)
  • Clang 9+ (macOS)
• Optional Dependencies (for full format support):
  • draco (for mesh compression support in glTF)
  • RapidJSON (for glTF format)

Supported Platforms

• Windows 10/11 (x64)
• Ubuntu 20.04+ / Debian 10+
• macOS 11.0+ (Big Sur or newer)
• RHEL/CentOS 8+

Build Instructions

1. Clone the Repository

git clone https://github.com/yourusername/DE_Wrapper-Sample.git
cd DE_Wrapper-Sample

2. Create Build Directory

mkdir build
cd build

3. Configure with CMake

Windows (Visual Studio)

cmake -G "Visual Studio 17 2022" -A x64 \
  -DBUILD_CONSOLE_CPP=ON \
  -DOpenCASCADE_DIR="C:/path/to/occt" \
  -DCMAKE_INSTALL_PREFIX="C:/path/to/install" ..

Linux/macOS (Unix Makefiles or Ninja)

cmake -G Ninja \
  -DCMAKE_BUILD_TYPE=Release \
  -DBUILD_CONSOLE_CPP=ON \
  -DOpenCASCADE_DIR="/path/to/occt" \
  -DCMAKE_INSTALL_PREFIX="/path/to/install" ..

4. Build the Project

Windows

cmake --build . --config Release --target install -j 8

Linux/macOS

cmake --build . --target install -j 8
# or with make:
make -j8 install

Installation

After successful build and installation:

1. Library Dependencies: The installation process automatically copies required OCCT libraries to the installation directory.

2. Directory Structure:

install_dir/
├── bin/           # Release executables and libraries
├── bind/          # Debug executables and libraries  
├── bini/          # RelWithDebInfo executables and libraries
├── CONF           # Default configuration file
└── LIBS           # Default library list

3. Environment Setup (Optional):

# Linux/macOS
export LD_LIBRARY_PATH=/path/to/install/bin:$LD_LIBRARY_PATH
export PATH=/path/to/install/bin:$PATH

# Windows
set PATH=C:\path\to\install\bin;%PATH%

Usage

Command Line Interface

The console application provides a simple interface for CAD file conversion:

./ConsoleCPP [options]

Options

Option	Description	Required	Example
-from <path>	Input CAD file path	Yes	-from model.step
-to <path>	Output CAD file path	Yes	-to model.stl
-lib <path>	Path to library list file	No	-lib custom_libs.txt
-config <path>	Path to configuration file	No	-config myconfig.conf
--tess	Enable tessellation before export	No	--tess
-dump <path>	Generate configuration template	No	-dump newconfig.conf

Basic Examples

1. Simple Format Conversion

# Convert STEP to STL
./ConsoleCPP -from input.step -to output.stl

# Convert IGES to glTF with tessellation
./ConsoleCPP -from model.iges -to model.gltf --tess

2. Using Custom Configuration

# Use custom configuration for fine-tuned conversion
./ConsoleCPP -from input.stp -to output.obj -config custom.conf

3. Generate Configuration Template

# Create a new configuration file for specified libraries
./ConsoleCPP -lib my_libs.txt -dump my_config.conf

Advanced Examples

Batch Processing (Shell Script)

#!/bin/bash
for file in *.step; do
    ./ConsoleCPP -from "$file" -to "${file%.step}.stl" --tess
done

Using Custom Library Set

Create a file minimal_libs.txt:

TKDESTEP
TKDESTL

Then use it:

./ConsoleCPP -from model.stp -to model.stl -lib minimal_libs.txt

Configuration

Library List File (LIBS)

The LIBS file specifies which Data Exchange libraries to load. Default content:

TKDESTEP        # STEP format support
TKDEIGES        # IGES format support  
TKDEGLTF        # glTF format support
TKDEOBJ         # OBJ format support
TKDEPLY         # PLY format support
TKDEVRML        # VRML format support
TKDESTL         # STL format support
TKDECascade     # Native OCCT BREP and XBF format

Configuration File (CONF)

The CONF file contains detailed parameters for each format. Key sections include:

Global Settings

global.priority.vendor : TKDESTEP TKDEIGES TKDESTL
global.length.unit : 1
global.angular.unit : 1

Format-Specific Settings (Example: STEP)

provider.STEP.OCC.read.precision.mode : 0
provider.STEP.OCC.read.precision.val : 0.0001
provider.STEP.OCC.read.step.product.name : 1
provider.STEP.OCC.read.step.product.context : 1
provider.STEP.OCC.read.step.shape.repr : 1
provider.STEP.OCC.read.step.assembly.level : 1
provider.STEP.OCC.read.step.shape.relationship : 1
provider.STEP.OCC.read.step.shape.aspect : 1
provider.STEP.OCC.read.step.constructivegeom.representation : 0
provider.STEP.OCC.read.step.stepcaf.subshapes.name : 0
provider.STEP.OCC.read.step.encoding : 0
provider.STEP.OCC.read.step.nonmanifold : 0
provider.STEP.OCC.read.step.ideas : 0
provider.STEP.OCC.read.step.all.shapes : 0
provider.STEP.OCC.read.step.root.transformation : 1
provider.STEP.OCC.read.color : 1
provider.STEP.OCC.read.name : 1
provider.STEP.OCC.read.layer : 1
provider.STEP.OCC.read.props : 1
provider.STEP.OCC.read.metadata : 1

provider.STEP.OCC.write.precision.mode : 0
provider.STEP.OCC.write.precision.val : 0.0001
provider.STEP.OCC.write.step.assembly : 2
provider.STEP.OCC.write.step.schema : 1
provider.STEP.OCC.write.step.product.name : 
provider.STEP.OCC.write.step.tessellated : 2
provider.STEP.OCC.write.step.vertex.mode : 0
provider.STEP.OCC.write.color : 1
provider.STEP.OCC.write.name : 1
provider.STEP.OCC.write.layer : 1
provider.STEP.OCC.write.props : 1
provider.STEP.OCC.write.model.type : 0

Supported Formats

Format	Extension	Read	Write	Tessellation	Colors	Assembly
STEP	.step, .stp	✅	✅	Optional	✅	✅
IGES	.iges, .igs	✅	✅	Optional	✅	❌
STL	.stl	✅	✅	Required	❌	❌
glTF	.gltf, .glb	✅	✅	Required	✅	✅
OBJ	.obj	✅	✅	Required	✅	❌
PLY	.ply	✅	✅	Required	✅	❌
VRML	.vrml, .wrl	✅	✅	Required	✅	❌
BREP	.brep	✅	✅	Optional	❌	❌
XBF	.xbf	✅	✅	Optional	✅	✅

API Documentation

CoreDE Library API

The CoreDE library provides the main conversion functionality:

// Main conversion function
bool Convert(const std::string& theInputPath, 
             const std::string& theOutputPath,
             bool theTessellate = false);

// Configuration management
bool LoadConfiguration(const std::string& theConfigPath);
bool SaveConfiguration(const std::string& theConfigPath);

// Dynamic library management
bool LoadComponent(std::string theComp);
const std::map<std::string, bool>& Components();

Usage in Your Application

#include "Converter.hxx"

int main() {
    // Load configuration
    if (!LoadConfiguration("config.conf")) {
        std::cerr << "Failed to load configuration" << std::endl;
        return 1;
    }
    
    // Perform conversion with tessellation
    bool success = Convert("input.step", "output.stl", true);
    
    if (success) {
        std::cout << "Conversion successful!" << std::endl;
    }
    
    return success ? 0 : 1;
}

Architecture

Component Overview

DE_Wrapper-Sample/
├── src/
│   ├── CoreDE/          # Core library with conversion logic
│   │   ├── Converter.hxx
│   │   └── Converter.cxx
│   └── ConsoleCPP/      # Command-line interface
│       └── Console.cxx
├── data/
│   ├── CONF             # Default configuration
│   └── LIBS             # Default library list
└── adm/
    └── cmake/           # CMake modules
        └── FindOCCT.cmake

Design Patterns

• Singleton Pattern: Global DE_Wrapper instance management
• Factory Pattern: Dynamic component loading
• Mutex Protection: Thread-safe library loading
• Resource Management: External configuration files

Troubleshooting

Common Issues

1. Library Not Found

Error: Could not open: [libTKDESTEP.so] or [TKDESTEP.so]

Solution:

• Ensure OCCT libraries are in the library path
• Check file permissions
• Verify library naming convention

2. Conversion Failure

Error: Cannot read file: unsupported format

Solution:

• Verify the input file format
• Check if required library is listed in LIBS file
• Ensure file is not corrupted

3. Tessellation Issues

Error: Tessellation failed for shape

Solution:

• Adjust mesh parameters in configuration
• Check model validity using OCCT tools
• Try different precision values

Performance Tips

1. Library Loading: Load only necessary libraries for your formats
2. Tessellation: Adjust mesh deflection for quality vs. speed
3. Parallel Processing: Use thread pools for batch conversions
4. Memory Management: Clear document between conversions for large batches

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

License

This sample is provided under the same license as OCCT. Please refer to OCCT documentation for licensing details.

References

• OCCT Documentation
• DE_Wrapper User Guide
• OCCT Data Exchange

Support

For issues, questions, or suggestions:

• Open an issue on GitHub
• Consult OCCT forums
• Review OCCT documentation

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Version: 1.0.0
Last Updated: 2025-08-07
Compatibility: OCCT 7.8.0+