Revit.Extensions 2026.0.1

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Revit.Extensions

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A collection of extension methods for the Autodesk Revit API, designed to reduce boilerplate and make Revit add-in development more expressive. Supports Revit 2020 – 2026.

Installation

dotnet add package Revit.Extensions

Or search for Revit.Extensions in the NuGet Package Manager inside Visual Studio.

Revit version support

The package automatically targets the correct framework — no manual configuration needed.

API reference

DrawSession — transient geometry (no transaction required)

DrawSession renders geometry directly into Revit's 3D views via the DirectContext3D API. No model elements are created and no Transaction is needed. All geometry disappears when the session is disposed or Clear() is called.

All distances are in Revit internal units (feet). Use UnitUtils.ConvertToInternalUnits to convert from meters or millimeters.

Setup in App.cs

Registration must happen in IExternalApplication.OnStartup via RegisterDrawSession():

using Revit.Extensions;

public class App : IExternalApplication
{
    public static DrawSession? DrawSession { get; private set; }

    public Result OnStartup(UIControlledApplication application)
    {
        // Registers the session with Revit's DirectContext3D service.
        DrawSession = application.RegisterDrawSession();
        return Result.Succeeded;
    }

    public Result OnShutdown(UIControlledApplication application)
    {
        DrawSession?.Dispose();   // unregisters the server and releases GPU buffers
        DrawSession = null;
        return Result.Succeeded;
    }
}

Supply UIApplication from your command

DrawSession needs UIApplication to call RefreshActiveView() after drawing. Pass it once from the first command that uses the session:

public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
{
    var session = App.DrawSession;
    if (session is null) return Result.Failed;

    // Supply once — idempotent, safe to call every time.
    session.SetUIApplication(commandData.Application);

    // ... drawing calls ...
    return Result.Succeeded;
}

Important: Do not wrap DrawSession in a using statement inside a command. Revit renders the 3D view after Execute() returns, so the session must stay alive. Store it at application scope and call Dispose() only in OnShutdown.

Lines and wireframes

var session = App.DrawSession;
session.SetUIApplication(commandData.Application);

// Line between two points
session.DrawLine(new XYZ(0, 0, 0), new XYZ(10, 0, 0), DrawExtensions.Blue);

// Revit Line object
session.DrawLine(line, DrawExtensions.Red);

// 3-axis cross marker (radius in feet; default ≈ 0.1 m)
session.DrawCross(new XYZ(5, 5, 0), radius: 0.328, DrawExtensions.Red);

// Point marker (alias for DrawCross)
session.DrawPoint(new XYZ(5, 5, 0), radius: 0.328, DrawExtensions.Green);

// Point marker with a text label
session.DrawPoint(new XYZ(5, 5, 0), label: "P0", radius: 0.328, DrawExtensions.Orange);

// Closed polygon (edges only)
session.DrawPolygon(new[] { new XYZ(0,0,0), new XYZ(10,0,0), new XYZ(5,10,0) }, DrawExtensions.Orange);

// Wireframe bounding box (12 edges)
session.DrawBoundingBox(element.get_BoundingBox(null), DrawExtensions.Cyan);

// Calls are fluent — chain them
session
    .DrawLine(p0, p1, DrawExtensions.Blue)
    .DrawCross(p0, color: DrawExtensions.Red)
    .DrawBoundingBox(bbox, DrawExtensions.Cyan);

Solids and meshes

DrawSolid and DrawMesh render shaded geometry with optional transparency. Face triangulation is performed on the main thread (Revit geometry API requirement); GPU buffers are built lazily on the render thread.

// Revit Solid — shaded faces + tessellated edges
session.DrawSolid(solid,
    faceColor:    DrawExtensions.Blue,
    edgeColor:    DrawExtensions.DarkBlue,
    transparency: 0.5);   // 0.0 = opaque, 1.0 = invisible

// Revit Mesh — flat-shaded triangles
session.DrawMesh(mesh, DrawExtensions.Green);

// Extract geometry from an element and draw it
var opts = new Options { ComputeReferences = false };
foreach (GeometryObject obj in element.get_Geometry(opts))
{
    if (obj is Solid solid && solid.Volume > 0)
        session.DrawSolid(solid, DrawExtensions.Blue, transparency: 0.3);
}

Box and sphere primitives

Filled, shaded primitives that do not require a Solid — useful for debug markers:

// Filled box from corner points
session.DrawBox(
    min: new XYZ(0, 0, 0),
    max: new XYZ(3.28, 3.28, 3.28),   // 1 m × 1 m × 1 m
    faceColor:    DrawExtensions.Blue,
    edgeColor:    DrawExtensions.DarkBlue,
    transparency: 0.4);

// Filled box from a BoundingBoxXYZ
session.DrawBox(element.get_BoundingBox(null), DrawExtensions.Blue, transparency: 0.3);

// Filled box from an Outline
session.DrawBox(outline, DrawExtensions.Cyan);

// UV sphere
session.DrawSphere(
    center:       new XYZ(5, 5, 3),
    radius:       1.64,                // 0.5 m
    faceColor:    DrawExtensions.Red,
    edgeColor:    DrawExtensions.DarkBlue,   // null = no equator lines
    transparency: 0.0);

Text labels

Text is tessellated from a real system font via System.Drawing.GraphicsPath + LibTessDotNet. Results are cached per (text, fontFamily), so repeated calls are cheap. Inner glyph holes (letters like O A B D) are handled correctly via EvenOdd winding.

// Basic label at a position (height in feet; default 0.5 ft ≈ 15 cm)
session.DrawText("Hello, Revit!", origin: new XYZ(0, 0, 0));

// Custom height, color and font
session.DrawText(
    text:       "Column C1",
    origin:     new XYZ(10, 5, 0),
    height:     1.0,                        // ~30 cm
    color:      DrawExtensions.Red,
    fontFamily: "Consolas");

// Text on a vertical face (supply the face normal)
session.DrawText(
    text:   "Front",
    origin: new XYZ(0, 0, 5),
    height: 0.5,
    normal: XYZ.BasisY);                    // text lies in the XZ plane

// Semi-transparent label
session.DrawText("Ghost", origin, transparency: 0.5);

Clearing geometry

// Remove all drawn primitives; the session stays registered and alive.
session.Clear();

Available colors

DrawExtensions provides ten predefined Autodesk.Revit.DB.Color values:

Pass null to any color parameter to use the default (DarkBlue for lines, Blue for faces). You can also pass any new Color(r, g, b) directly.

DrawSession method reference

DrawExtensions — persistent geometry (requires transaction)

Creates DirectShape elements and text notes permanently in the model. All methods must be called inside an active Transaction.

using var t = new Transaction(doc, "Debug draw");
t.Start();

doc.DrawLine(pt1, pt2, DrawExtensions.Red);
doc.DrawCross(center, radius: 0.5, DrawExtensions.Blue);
doc.DrawPoint(center, label: "P0", radius: 0.3, DrawExtensions.Green);
doc.DrawText("Hello", position, DrawExtensions.Purple);
doc.DrawPolygon(new[] { p0, p1, p2 }, DrawExtensions.Orange);
bbox.Draw(doc, DrawExtensions.Cyan, drawPoints: true);

t.Commit();

GeometryExtensions

Helpers for working with Revit geometry types (XYZ, Outline, BoundingBoxXYZ).

using Revit.Extensions;

// Convert XYZ ↔ value tuple
XYZ point = new XYZ(1.0, 2.0, 3.0);
(double X, double Y, double Z) vec = point.ToVector();   // (1.0, 2.0, 3.0)
XYZ restored = vec.ToXYZ();                              // XYZ(1.0, 2.0, 3.0)

// Expand an Outline uniformly
Outline outline = new Outline(new XYZ(0, 0, 0), new XYZ(5, 5, 5));
Outline expanded = outline.Extend(size: 2);   // min −2, max +2 on every axis

// Transform a BoundingBoxXYZ from local to world space
BoundingBoxXYZ bbox = element.get_BoundingBox(view);
BoundingBoxXYZ? worldBbox = bbox.TransformBoundingBox();

PointExtensions

Unit conversion for XYZ coordinates using Revit's UnitUtils.

using Autodesk.Revit.DB;
using Revit.Extensions;

// Revit stores coordinates internally in feet.
// Convert a point from feet to meters (Revit 2021+):
XYZ pointInFeet = new XYZ(3.28084, 0, 0);
XYZ pointInMeters = pointInFeet.Recalculate(UnitTypeId.Meters);
// → XYZ(1.0, 0, 0)

Revit 2020 uses the legacy DisplayUnitType enum — the overload is selected automatically via conditional compilation.

ElementExtensions

Helpers for collecting elements and grids from the active document.

using Revit.Extensions;

// Collect selected elements, or fall back to all FamilyInstances + HostObjects in the active view
IList<Element> elements = ElementExtensions.GetAllElementOrSelected(uiDocument);

// Get all grids from the level closest to elevation 0
IList<Grid> grids = ElementExtensions.GetAllGridFromFirstLevel(document, out string? levelName);
if (levelName is not null)
    TaskDialog.Show("Grids", $"Found {grids.Count} grids on level '{levelName}'.");

AsyncTasksExecutor

Run async code synchronously inside the Revit event loop, where async/await on the main thread is unsupported.

using Revit.Extensions;

// Execute a Task<T> synchronously
string result = AsyncTasksExecutor.Execute(async () =>
{
    await Task.Delay(100);
    return "done";
});

// Execute a ValueTask<T> synchronously
int value = AsyncTasksExecutor.Execute(async () =>
{
    await Task.Yield();
    return 42;
});

Contributing

Contributions are welcome! Please open an issue or submit a pull request.

1. Fork the repository
2. Create a feature branch: git checkout -b feature/my-extension
3. Add your extension in Revit.Extensions/Extensions/ with a corresponding test in tests/Extensions/
4. Open a pull request against main

License

MIT © Apibim SpA