> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/cadd/curve-cadd.md).

# Curve

A **Curve** is a smooth interpolating curve that passes through every control point — unlike a Bezier, which is shaped by intermediate points without passing through them. In bridge drawings it's used for splines through known stations, profile traces sampled from a survey, and any path that should hit a specific set of points exactly while flowing smoothly between them.

To draw: pick each interpolation point in turn. Press Enter or double-click to finish.

## Geometry

**Name:** Identifier within the parent CAD document. Must be unique.

**Level:** The layer controlling color, line weight, and dash style.

The curve's shape is controlled by its child Point objects, which are the points the curve passes through (in order).

## Editing

**Move a point:** drag the handle to relocate one of the points the curve passes through. The curve reshapes to remain smooth and continue passing through every point.

**Add a point:** insert a new point at the desired location and the curve will route through it.

**Remove a point:** the curve simplifies between the two adjacent points.

## Notes

For straight-segment polylines (where corners are sharp, not smoothed), use a Line.

For smooth curves where you want intermediate control without the curve passing through specific points, use a Bezier.

Curves are useful for tracing irregular surveyed profiles or for drafting a soft curve through a known set of locations on a drawing — for example, a finish-grade trace that has to hit specific elevations at specific stations.


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