OcctSharp.Native.win-x64 8.0.1-preview.24

OcctSharp

OcctSharp is a .NET 10 SDK for Open CASCADE Technology (OCCT) 8.0.1. It combines a versioned native C ABI, generated low-level bindings, and friendly managed CAD APIs for modeling, STEP/IGES/STL exchange, XDE assemblies and metadata, meshing, inspection, and Windows visualization.

Current local preview target: 8.0.1-preview.24 for Windows x64 (validation status in STATUS). The NuGet graph contains 12 managed modules, the OcctSharp compatibility/facade package, and one shared OcctSharp.Native.win-x64 runtime package. The native package places the complete 62-DLL runtime in the application's occt/ directory; no machine-wide OCCT installation or PATH change is required.

Preview.23 expands generated numeric and copied-reference bindings across existing modules, including image sizes, document bytes, mesh flags and retained runtime types. See Batch X changes for scope and limitations.

Install

dotnet add package OcctSharp --version 8.0.1-preview.24 --source ./OcctSharp/artifacts/packages

A narrow consumer can reference a module directly, for example:

dotnet add package OcctSharp.Modeling --version 8.0.1-preview.24 --source ./OcctSharp/artifacts/packages

The supported runtime baseline is .NET 10, Windows x64, and OCCT 8.0.1. Preview.23 is local-only; it is not published on NuGet.org. Create the local package feed with OcctSharp/eng/pack.ps1 using the contributor toolchain, or run the repository samples directly with the committed runtime.

Configure review lighting and capture copied frames

With an existing live OcctViewer viewer on its creating UI thread:

using var box = ShapeFactory.CreateBox(40, 30, 20);
using var presentation = viewer.Display(box);
presentation.SetDisplayMode(ViewerDisplayMode.Shaded);
viewer.FitAll();
var rendering = viewer.Rendering;
rendering.ReplaceLightRig([
    new(ViewerLightKind.Ambient, new(.2, .2, .2)),
    new(ViewerLightKind.Directional, new(1, 1, 1))
    { Direction = new(0, 0, -1), Headlight = true }
]);
rendering.SetAppearance(presentation, new()
{ Front = new(new(.15, .45, .8)), Shading = ViewerShading.Phong });
ViewerColorFrame frame = rendering.CaptureColor(new(1024, 768, TileSize: 256));
byte[] rgba = frame.CopyPixels(); // Independent top-down RGBA8, even after disposal.
ViewerDepthFrame depth = rendering.CaptureDepth(new(1024, 768));
if (depth.TryReconstruct(512, 384, out var hit)) Console.WriteLine(hit);
rendering.ResetAppearance(presentation); // Restores original effective XDE/default style.

See W review/capture contracts and the WPF viewer snapshot example. Captures still require a live HWND/OpenGL context. PBR/IBL and advanced quality modes are capability-checked; copied frames do not provide live D3DImage compositing.

Create a solid

using OcctSharp;

using Shape box = ShapeFactory.CreateBox(40, 30, 20);
using Shape cylinder = ShapeFactory.CreateCylinder(6, 20);

Console.WriteLine($"Box faces: {box.FaceCount}");
Console.WriteLine($"Cylinder faces: {cylinder.FaceCount}");

Partition exact material regions

using var left = ShapeFactory.CreateBox(10, 10, 10);
using var right = left.Transformed(ShapeTransform.CreateTranslation(5, 0, 0));
using var plan = PartitionPlan.Create([left, right]);
using var result = plan.Build([
    new RegionProgram("overlap", [new(RegionExpression.Input(0).Intersect(RegionExpression.Input(1)), 7)])
]);
using var overlap = result.CopyOutput("overlap"); // Independent owning topology.
Console.WriteLine($"Full partition: {result.Cells.Count} cells; selected: {overlap.FaceCount} faces");

Cell and interface IDs belong to one result revision. See the Batch V matrix for bounded volumes, point selection, atomic parametric outputs, XDE products and STEP/IGES format limits.

Apply a source-bound variable-radius fillet

using OcctSharp;

using var box = ShapeFactory.CreateBox(10, 12, 15);
using var source = RepairSnapshot.Create(box);
var seed = source.Topology.First(t => t.Kind == ShapeKind.Edge).Selection;
var law = ScalarLawDefinition.Linear(new LawDomain(0, 1), .5, 1.5);
var recipe = ContourFilletRecipe.Create(source, [FilletContourProgram.FromLaw(seed, law)]);
using var sections = recipe.Simulate(source); // Copied circle sections, no native builder.
using var result = recipe.Build(source);
using var acceptance = LocalFeatureAcceptance.Inspect(source, result);
using var accepted = acceptance.Accept(); // Independent topology after Q budget checks.
Console.WriteLine($"Sections: {sections.SimulatedSections.Count}; faces: {accepted.FaceCount}");

Recipes also support contour chamfers, per-face draft and explicit local-feature limits. Partial fillets are diagnostics, never accepted fallback geometry. Radius-law interpolation and pinned SDK limiter limitations are disclosed in Preview.20 notes.

Recompute a persisted parametric feature

using OcctSharp;

static ParametricParameter Mm(double value) =>
    ParametricParameter.FromValue(ParametricValue.FromReal(value, ParametricUnit.Millimeter));

using var graph = ParametricDocument.Create();
var box = new ParametricFeatureDefinition(Guid.NewGuid(), "Parametric box", ParametricFeatureKind.Box,
    new Dictionary<string, ParametricParameter> { ["x"] = Mm(40), ["y"] = Mm(30), ["z"] = Mm(20) }, []);
graph.Add(box);
var report = graph.Recompute();
if (!report.Succeeded) throw new InvalidOperationException(string.Join("; ", report.Issues.Select(x => x.Message)));
using var result = graph.GetResult(box.Id); // Independent owning shape, no stale result by default.
string file = graph.Save("parametric.cbf", DocumentStorageFormat.BinOcaf);
using var reopened = ParametricDocument.Open(file, graph.RootEntry);
var changed = reopened.EditAndRecompute(box.WithParameter("x", Mm(60)));
Console.WriteLine($"Recomputed: {changed.Succeeded}");

Incremental/full/targeted recompute supports typed primitives, profile features, Boolean, repair, guided sweep/fill and mesh recipes. Failed runs retain explicitly stale last-good results; persistent selections can report unsupported or ambiguous topology changes. See Preview.19 notes for ownership and format limits.

Build a 2D sketch with a hole and extrude it

using OcctSharp;

SketchCurveChain2d outer = SketchCurveChain2d.Create([
    SketchCurve2d.Segment(new(0, 0), new(40, 0)),
    SketchCurve2d.Segment(new(40, 0), new(40, 30)),
    SketchCurve2d.Segment(new(40, 30), new(0, 30)),
    SketchCurve2d.Segment(new(0, 30), new(0, 0))], requireClosed: true);
SketchCurveChain2d hole = SketchCurveChain2d.Create([
    SketchCurve2d.Circle(new(20, 15), 5)], requireClosed: true);
SketchProfile2d profile = SketchProfile2d.Classify([hole, outer]);

using Shape solid = profile.Extrude(SketchPlane.XY, 8);
SketchProfile2d.WriteStep(solid, "sketch.step",
    new XdePartMetadata("Sketch plate", new XdeColor(0.2, 0.7, 0.35), ["Sketch"]));

Sketch definitions own copied data. Curves support evaluation, projection, intersection, trim/split/reverse, translation, rotation, uniform scale, and mirror. Bezier and B-spline definitions support rational weights; Interpolate creates a degree-one, piecewise-linear B-spline. Wire/face/feature results are independent IDisposable shapes. The API does not include a parametric constraint solver.

Work on a curved surface in UV space

using OcctSharp;

using Shape cylinder = SurfaceModeling.CreateAnalyticFace(
    AnalyticSurfaceKind.Cylinder, SketchPlane.XY,
    new SurfaceParameterBounds(0, Math.Tau, 0, 20), radius: 8);
SurfaceEvaluationPoint sample = SurfaceModeling.Evaluate(cylinder, new(1, 5));
SurfaceCurveDefinition uv = SurfaceModeling.InterpolateUv(
    [new(0.3, 2), new(1.5, 8), new(3.2, 17)]);
using Shape edge = SurfaceModeling.LiftCurve(cylinder, uv.Curve);
IReadOnlyList<SurfaceCurveSample> samples = SurfaceModeling.SampleCurve(cylinder, edge, 50);
using Shape section = SurfaceModeling.IntersectPlane(cylinder,
    new SketchPlane(new(0, 0, 10), new(1, 0, 0), new(0, 1, 0)),
    new SurfaceParameterBounds(-10, 10, -10, 10));

SurfaceModeling also supports hole-aware UV classification, full/batch projections, seam branches and tracing, UV offsets, boundary measurements, trimmed faces, copied topology repair, and face splitting with diagnostics. Points and derivatives are in world coordinates; UV values are surface-local. UV offset distance is not world-space distance. Definitions and reports are copied; returned shapes and repair/split result containers must be disposed. See the 32-capability Batch P scope and Preview.15 notes.

Inspect and preview a bounded repair

using OcctSharp;

using Shape original = ShapeExchange.ReadStep("part.step");
using RepairSnapshot source = RepairSnapshot.Create(original, unit: "mm");
RepairPlan plan = new(source, [
    new("Normalize shells", new ShellNormalizationRepair()),
    new("Normalize solid orientation", new SolidNormalizationRepair())],
    tolerance: new(Minimum: 1e-7, Maximum: 1e-3),
    budget: new(MaximumTolerance: 1e-3, MaximumRelativeVolumeChange: 0.001));
using RepairPreview preview = ShapeRepair.Preview(source, plan);

if (preview.CanAccept)
{
    using Shape repaired = preview.Accept();
    ShapeExchange.WriteStep(repaired, "repaired.step");
}
else
{
    foreach (RepairBudgetCheck check in preview.BudgetChecks)
        Console.WriteLine($"{check.Name}: {check.State}");
}

Snapshots and previews own independent copies. Selections bind to a snapshot/revision; history reports modified/generated/deleted/unknown mappings, never native addresses. An unavailable required budget (for example closed volume for an open shell) blocks acceptance. Hole/small-feature removal is opt-in. RepairDocumentSession publishes a shared XDE definition transactionally only when metadata mapping is unambiguous; RepairViewerReview selects copied defects and rejects stale review selections. See Batch Q's 40 capabilities and Preview.16 notes.

Author, edit and deliver a mesh

using OcctSharp;

AuthoredMesh mesh = new(
    [new(0, 0, 0), new(20, 0, 0), new(20, 20, 0), new(0, 20, 0)],
    [new(0, 1, 2), new(0, 2, 3)]);
MeshEditResult edited = MeshEditing.SetPositions(
    mesh, mesh.SelectVertices([2]), [new(20, 20, 5)]);
AuthoredMesh withNormals = MeshEditing.RebuildNormals(edited.Mesh).Mesh;
AuthoredMeshStatistics statistics = MeshEditing.Inspect(withNormals);

using DiscreteMeshModel model = MeshTopology.Create(withNormals);
using Shape independentShape = model.CopyShape();
AuthoredMeshExportResult output = AuthoredMeshExchange.Write(withNormals, "edited.glb");
Console.WriteLine($"Triangles: {statistics.TriangleCount}, area: {statistics.SurfaceArea}");
foreach (string disclosure in output.Disclosures) Console.WriteLine(disclosure);

Mesh inputs and edits are immutable copies. Selections and exact one-to-many/deletion maps belong to specific revisions. Editing includes connected selections, welding, crease splitting, orientation, normal/UV channels, affine transforms and unit conversion. STL/OBJ can be loaded directly for editing; STL/OBJ/glTF/GLB/PLY export uses existing triangulations without remeshing. Missing channels are disclosed, not filled with zeros. MeshAssembly publishes grouped materials/repeated rigid occurrences; MeshViewerReview supports styled display and revision replacement on the existing HWND viewer. Discrete shapes are not exact CAD solids and cannot be exported as exact STEP/IGES. See Batch R's 40 capabilities and Preview.17 notes.

Preview and build a law-scaled guided sweep

using OcctSharp;

using Shape spine = ShapeFactory.CreatePolygonWire([new(0, 0, 0), new(0, 0, 10)]);
using Shape profile = ShapeFactory.CreatePolygonWire(
    [new(0, 0, 0), new(2, 0, 0), new(2, 2, 0), new(0, 2, 0)], true);
ScalarLawDefinition scale = ScalarLawDefinition.Linear(new(0, 1), 1, 2);
using GuidedSweepPlan plan = GuidedSweepPlan.Create(spine, [new(profile)],
    new() { SolidPolicy = SweepSolidPolicy.RequireSolid }, scaleLaw: scale);
using AuthoringResult preview = plan.Simulate(5);
using AuthoringResult result = plan.Build();
Console.WriteLine(result.Diagnostics.Message);
ShapeExchange.WriteStep(result.RequireShape(), "guided.step");

Plans own a copied input dependency graph; results and history survive input disposal. Laws expose copied definitions, explicit domains and nullable derivatives. Guided frames, auxiliary contact, section simulation and compatible loft provenance are available alongside per-edge G0/G1/G2 filling, seed/support/UV constraints and copied Bezier/B-spline conversion. ConstrainedFillResult.Accepted checks validity and every required residual; successful kernel execution alone is insufficient. Residuals are bounded samples, not global error proofs. Auxiliary guides cannot combine with scale laws; keep-contact has a C0 limit. Recipes persist in BinXCAF, not generic STEP/IGES. See Batch S's 40 capabilities and Preview.18 notes.

Read ordinary STEP geometry

Use the geometry-only API when product structure and presentation metadata are not needed:

using OcctSharp;

using Shape shape = ShapeExchange.ReadStep("part.step");
Console.WriteLine($"Imported faces: {shape.FaceCount}");

Read STEP/XDE colors and subshape styles

Use XdeDocument for assemblies, names, layers, colors, materials, visibility, and location-aware face/subshape presentation styles:

using OcctSharp;

using XdeDocument document = XdeDocument.ReadStep("assembly.step");

foreach (XdeLabel root in document.GetFreeShapes())
{
    IReadOnlyList<XdePresentationStyle> styles = root.GetPresentationStyles();
    try
    {
        foreach (XdePresentationStyle style in styles)
        {
            XdeColor? color = style.EffectiveColor;
            Console.WriteLine(
                $"faces={style.Shape.FaceCount}, visible={style.IsVisible}, " +
                $"rgba={color?.Red:F3},{color?.Green:F3},{color?.Blue:F3},{color?.Alpha:F3}");
        }
    }
    finally
    {
        foreach (XdePresentationStyle style in styles) style.Dispose();
    }
}

OcctViewer.Display(XdeLabel) applies the same inherited occurrence, part, face, edge, material, alpha, and visibility styles to one AIS_ColoredShape presentation. Viewer objects are UI-thread-affine and require a native child-window handle.

Read or write metadata-aware IGES

Use the XDE-centered exchange API for IGES names, colors, layers, visibility, diagnostics, and Unicode Windows paths. The format-neutral methods route STEP or IGES by extension:

using OcctSharp;

using XdeDocument document = XdeDocument.ReadIges(
    @"C:\CAD\彩色装配.iges",
    new XdeIgesReadOptions(ReadNames: true, ReadColors: true, ReadLayers: true),
    out XdeIgesReadReport report);

Console.WriteLine($"Transferred {report.TransferredRootCount} IGES roots");
document.WriteExchange(@"C:\CAD\导出副本.igs");

using XdeDocument routed = XdeDocument.ReadExchange("assembly.step");

Imported labels remain bound to their owning XdeDocument; copied diagnostics and independently owned topology do not retain the native IGES transfer session.

Samples

The repository contains two runnable .NET 10 sample projects. Both use the committed, manifest-verified Windows x64 runtime, so a normal clone does not need a separate OCCT SDK or native build toolchain.

Run the console sample from the inner workspace:

cd OcctSharp
dotnet run --project .\samples\OcctSharp.Samples --configuration Release

Run the WPF/MVVM viewer:

dotnet run --project .\samples\OcctSharpViewer.Wpf --configuration Release

The WPF viewer hosts OCCT's OpenGL output with HwndHost. WPF controls can be placed around the viewport, but WPF airspace rules prevent reliable overlays above it; a D3DImage bridge is not included. See the project README for architecture, mouse controls, STEP color behavior, and troubleshooting.

Clone and run without an OCCT SDK

On Windows x64 with .NET SDK 10.0.400:

git clone https://github.com/yoi102/OcctSharp.git
cd OcctSharp\OcctSharp
dotnet run --project .\samples\OcctSharp.Samples -- --smoke

The committed, SHA256-pinned Release runtime is copied automatically. Building the native bridge or regenerating bindings still requires the documented MSVC/OCCT contributor toolchain.

License and third-party runtime terms

The OcctSharp project code, generated bindings, and repository-built OcctSharp.Native.dll are licensed under the MIT License. The NuGet packages therefore declare MIT for the OcctSharp-owned package content.

That MIT declaration does not relicense OCCT or the other native libraries bundled in OcctSharp.Native.win-x64. In particular, the Open CASCADE Technology 8.0.1 DLLs are distributed under LGPL-2.1-only with the Open CASCADE exception. oneTBB, FreeImage, FreeType, OpenVR, FFmpeg, and jemalloc retain their respective upstream terms.

Before redistributing the native package or an application that ships its occt/ directory, review the complete third-party runtime notice and the accompanying license texts. Those files are included in OcctSharp.Native.win-x64 under its licenses/ directory.

Project structure and status

• docs/ contains architecture, decisions, compatibility, packaging, samples, and status.
• OcctSharp/ contains the solution, source, tests, generator, runtime, samples, and release tooling.
• Project code is MIT licensed; bundled native components remain governed by the terms summarized above.

See documentation, current status, samples, NuGet packaging, and build/release instructions.