How to Draw Splines in BricsCAD

Quick answer: A spline is an open or closed smooth curve defined by a set of points, used for curved lines a polyline simply can’t produce. After placing your points, you also get to control the curve’s tangent direction at both the start and end.

Finding the Spline Tool

The Draw menu, the Draw toolbar, the Draw ribbon panel, or the Draw tab of the No Selection Quad.

Drawing a Spline: General Procedure

1. Launch SPLINE. You’re prompted for the first point of the spline.
2. Specify a point. You’re prompted for a second point.
3. Specify a point. You’re prompted for the next one, or to choose Close, Fit tolerance, or Undo.
4. Repeat step 3 to add as many additional points as you need.
5. Right-click to stop adding points. You’re then prompted to select a starting tangent point, and a line tangent to the spline displays dynamically from its start point.
6. Click to define the spline’s starting curve. You’re prompted to select an ending tangent point, with a tangent line now displaying dynamically from the spline’s end point.
7. Click to finalize the ending tangent and create the spline.

Frequently Asked Questions

What can a spline do that a polyline can’t? Draw genuinely smooth curved lines. A polyline is limited to straight segments and circular arcs; a spline isn’t.

What are the tangent point steps at the end of the SPLINE command for? They let you control the exact curve shape at the spline’s start and end points, rather than leaving that shape entirely determined by your placed points.

Can I create a closed spline? Yes, choose the Close option when prompted for the next point.

What does Fit tolerance control while drawing a spline? It’s one of the options available while specifying points, alongside Close and Undo. The source documentation doesn’t spell out its exact effect beyond the name, so if precise control over this matters for your work, it’s worth testing directly in BricsCAD.