Snaptrude models more than straight walls and boxes. You can work with curved surfaces and solids such as spheres, domes, vaults, B-spline surfaces, and round columns and beams, and shape them with operations like twist, taper, fillet, chamfer, shell, offset, sweep and loft. Use this article when a design needs a barrel-vaulted roof, a domed atrium, rounded corners or a free-form canopy.

Before you start

The Snaptrude Agent can build and edit all of these curved forms from a prompt. Agent requests use AI credits; see the Snaptrude Agent article for plan and credit details.
Simple curves, such as arc-shaped spaces and roofs, can also be drawn by hand with the Arc (A) and Circle tools in the top toolbar.

What you can create

Type	Examples
Curved solids	Spheres, domes, vaults
Free-form surfaces	B-spline surfaces and surface patches, such as canopies
Round structural elements	Round columns and beams
Curved plan elements	Arc walls, curved spaces, curved floor slab boundaries

What you can do to geometry

Fillet and chamfer: round or bevel edges and corners.
Twist and taper: rotate a form along its height, or narrow it toward one end.
Shell: hollow out a solid, leaving a thickness.
Offset: grow or shrink a profile or surface by a distance.
Sweep: run a profile along a curve, for example for a handrail or a curved beam.
Loft: build a form that transitions between profiles.

Create curved geometry with the Snaptrude Agent

Click the Agent button at the top of the far-left rail to open the AI chat panel on the left of the screen.
In the Ask anything box, describe the form in plain language, with the dimensions and placement you want. For example: "Add a 12 m diameter dome over the central atrium on the top story" or "Create a barrel vault roof spanning the east wing, 8 m wide."
To point at a specific location or object, click Redline this view, mark up the canvas and send it with your prompt.
Click Send and review the result on the canvas.
Refine it with follow-up prompts, such as "Make the vault 1.5 m taller" or "Fillet the canopy edges with a 300 mm radius."

Tip: Be specific about size, story and which object you mean, so the agent edits the right element.

Edit existing curved geometry

Click the Agent button on the far-left rail to open the AI chat panel.
Describe the change and identify the object by name or location, or mark it with Redline this view. For example: "Twist the north tower 45 degrees over its height", "Taper the lobby columns toward the top" or "Shell the atrium dome to 200 mm thick."
Check the result. If it isn't what you wanted, use Undo (Ctrl + Z, or Cmd + Z on Mac) and rephrase the prompt.

Draw simple curves by hand

For arcs and circles you don't need the agent.

Pick the Arc (A) or Circle tool from the top toolbar.
Choose the object type in the Object Type Panel. Spaces are drawn in Design Mode; building elements such as Roof are drawn in BIM Mode.
Draw the shape on the canvas, then adjust it in the Properties tab of the right panel or with Push-pull.

You can also split curved faces: Split Face accepts a polyline drawn on arc faces, and a 3D arc face can be split with a single perpendicular line.

Use curves in parametric components

Parametric Components (Families) can carry curved geometry. You can ask the Snaptrude Agent to build a component with curves, such as a curved bench, a rounded reception desk or a domed skylight. In team projects, components the agent creates are added to the team library automatically (Team Library is available on the Organization and Enterprise plans); you can make them public from Libraries.

Curved geometry in imports and exports

Revit export: arc walls and curved parametric floor boundaries export to Revit. Direct Revit export needs Snaptrude Manager.
Revit import: simple circular arc walls import as editable parametric walls (start, end, radius, height, thickness and layers). Arc walls with doors or windows, non-circular arcs, curtain walls and stacked walls import as non-parametric geometry. Revit rooms with curved boundaries import as editable Spaces.
Rhino import (via the Snaptrude Plugin): complex curved forms import as direct shapes, without the split-story option that simple shapes get.
CAD import (.dwg): arcs, circles and curved polylines import as curves rather than being straightened.

Troubleshooting

The agent changed the wrong object: undo, describe the intended object more precisely or mark it with Redline this view, and prompt again.
A curved shape from Rhino can't be split by story: this is expected for complex curves, which import as direct shapes.
An arc wall from Revit isn't editable: only simple circular arc walls without doors or windows import as parametric walls.

Snaptrude Agent
Parametric Components and Families
Walls
Columns
Beams
Floor Slabs and Roofs
Keyboard Shortcuts

Curved Geometry and Surfaces