GeometryHelper.IfcConvert 3.2.0

GeometryHelper.IfcConvert

Converts geometry between IFC models (via xBIM) and GeometryHelper (GeometryHelper.CommonGeometry and GeometryHelper.SolidGeometry): points, vectors, transformation matrices, planar faces, curved surfaces, and 3D solids.

What It Does

GeometryHelper.IfcConvert bridges building information models in IFC (IFC2x3, IFC4, IFC4x3) to pure computational geometry structures in GeometryHelper:

• Converts 3D points (XbimPoint3D), vectors (XbimVector3D), and homogeneous transformation matrices (XbimMatrix3D / GeoTransform3).
• Converts IFC boundary representations and swept solids (IXbimSolid, IIfcGeometricRepresentationItem, IIfcProduct, IIfcMappedItem) into GeoSolid3 bodies.
• Handles planar faces with both outer boundaries and inner cutout loops/holes (InnerBounds).
• Automatically tessellates curved and non-planar faces into planar triangles, maintaining strict coplanarity compliance for SolidGeometry.
• Preserves hierarchical coordinate placements across nested mapped items and product placements.
• Provides thread-safe IFC store caching (IfcStoreCache) with GlobalId indexing.

Installation

dotnet add package GeometryHelper.IfcConvert

The package is self-contained: it bundles all required customized xBIM managed assemblies and the 64-bit native geometry engine (Xbim.Geometry.Engine64.dll). Targets Windows x64.

How Winding and Orientations are Handled

SolidGeometry measures volumes and point containment assuming outward-pointing face normals. Like TeklaConvert, IfcConvert verifies the signed volume of every converted solid body: if body.GetSignedVolume() < 0.0, all faces are automatically flipped via face.Flip() so that normals consistently point outwards.

Planar vs Curved Faces

GeometryHelper.SolidGeometry.Geometry.GeoPolygon3 enforces strict coplanarity at construction. When an xBIM face is planar (face.IsPlanar), its outer boundary loop and any inner hole loops are read directly as polygons. When a face is curved (such as a cylindrical pipe or rounded fillet), FaceConvert automatically tessellates the surface into planar triangles (GeoTriangle3 / GeoFace3), preventing ArgumentException and accurately capturing curved geometry.

Quick Start

using GeometryHelper.IfcConvert.Core;
using GeometryHelper.IfcConvert.Converters;
using GeometryHelper.SolidGeometry.Geometry;
using Xbim.Ifc4.Interfaces;

// 1. Open or retrieve an IFC model from cache
using (var storeCache = IfcStoreCache.GetOrCreate("sample.ifc"))
{
    // 2. Retrieve a specific product by GlobalId
    IIfcProduct product = storeCache.GetProduct("0123456789ABCDEF012345");

    if (product != null)
    {
        // 3. Convert product geometry to GeoSolid3 bodies in global coordinates
        List<GeoSolid3> solids = product.ToGeoSolids();

        foreach (GeoSolid3 solid in solids)
        {
            Console.WriteLine($"Solid volume: {solid.Volume}");
        }
    }

    // 4. Or retrieve complete geometry information with ToProductGeometry
    IfcProductGeometry geom = product.ToProductGeometry();

    Console.WriteLine($"Product Name: {geom.Name}, GUID: {geom.GlobalId}");
    Console.WriteLine($"Total Volume: {geom.TotalVolume:F2}");
    Console.WriteLine($"Bounding Box: Min={geom.BoundingBox.Min}, Max={geom.BoundingBox.Max}");
    Console.WriteLine($"Placement Origin: {geom.Placement.Transform(GeoPoint3.Origin)}");

    // Closed manifold solid bodies
    foreach (GeoSolid3 solid in geom.Solids)
    {
        Console.WriteLine($"  Solid Faces: {solid.Faces.Count}, Volume: {solid.Volume:F2}");
    }

    // Open surface models or thin sheets (if any)
    foreach (GeoFace3 surface in geom.OpenSurfaces)
    {
        Console.WriteLine($"  Surface Area: {surface.Area:F2}");
    }

    // 5. Subtracting openings/voids (doors, windows) automatically
    var optionsWithVoids = new IfcConvertOptions { ApplyVoids = true };
    var allWalls = storeCache.GetProducts<IIfcWall>();
    foreach (var wall in allWalls)
    {
        // Solids will have window and door cutouts subtracted
        var wallSolids = wall.ToGeoSolids(optionsWithVoids);
    }
}

Matrix Transformations

xBIM uses row-vector convention ($v \cdot M$) with translations located in the fourth row (OffsetX, OffsetY, OffsetZ). GeoTransform3 uses column-vector convention ($M \cdot v$) with translations located in the fourth column. MatrixConvert.ToGeoTransform3 and MatrixConvert.ToXbimMatrix3D transpose the linear 3x3 block and swap offset rows/columns accordingly, ensuring mathematically identical coordinate transformations between the two systems.