---
title: Curve-Based Primitives
order: 2
---

Three primitives that source their geometry from a Blender curve object. Edit the curve in normal Edit Mode and the SDF re-evaluates live in the viewport.

## Curve

Extrude a 2D curve along the Z axis to create a swept solid. If no curve is selected when you create one, Chisel auto-generates a Bezier circle.

![Curve depth](../assets/curvedeppth.webp)

- **Source curve** — any 2D Blender curve object (assigned via the dropdown)
- **Curve Depth** — extrusion length (default `1.0`, soft max `100.0`)
- **Rounding + Profile** — applies to the top and bottom edges

Use Curve for letterforms, logos, custom flat shapes, or any swept profile that doesn't need rounding along the path.

## Curve Tube

Sweep a circular cross-section along a 3D Bezier path. The result is perfectly smooth all the way down the path — no faceting, no LOD.

![Curve Tube](../assets/curve-tube.webp)

- **Source curve** — any 3D Bezier curve
- **Tube Radius** — global radius (default `0.2`, soft max `5.0`)
- **Per-point radius** — adjust radius per control point with `Alt + S` in curve Edit Mode

No rounding parameter — the swept surface is already smooth all the way along the path.

Curve Tube excels at piping, cables, ropes, hairs, vines, and any flow that benefits from smooth taper.

## Curve Revolve

Revolve a 2D profile around the local Y axis. Perfect for vases, bottles, and turned hardware.

![Curve Revolve](../assets/curve-revolve.webp)

- **Source curve** — a 2D profile curve
- **Revolve Angle** — sweep angle in radians (default `2π` for a full revolution; range `~1°–360°`)
- **Rounding + Profile** — applies along the profile edges

The profile is clamped so it cannot cross the axis (no negative-radius artifacts). Drop the angle below `2π` to get a partial sweep — handy for pie-slice cutouts or one-off architectural details.

## Editing the source curve

Each curve-based primitive references an external curve object. To edit it:

1. Select the curve object (it lives in the same collection as the SDF object).
2. Tab into Edit Mode.
3. Move points, change handle types, or adjust per-point radius (Tube only) with `Alt + S`.
4. The SDF refreshes as you go.

Hide the source curve in the outliner if you don't want it cluttering the viewport — Chisel still finds it.

## See also

- [Standard Shapes](shapes.md) — the eight non-curve primitives
- [Operations: Convert](../operations/convert.md) — convert curve-based SDFs to mesh