Spline Tool

spline_dat/Tool_bline_icon.png ALT-B


Spline are the most used objects in any normal animation done with Synfig, and the Spline Tool allows you to create them.


Select the Spline Tool in the or use keyboard the shortcut Alt+b to enable it. To leave that mode just select another from the Toolbox.

It is easy to use this tool

  • Each single click creates a new Vertex. Its Tangent values are set to (0,0) and the Vertex becomes a sharp corner.

  • Click and drag creates a new Vertex and allows the modification of the Tangent value at that Vertex. Extending the Tangent smooths the corners.

  • Each new Vertex is attached to the previous by a Bézier Spline defined by the vertices’ position and tangents.

  • The Spline is created sequentially, one Vertex follows the previous one.

  • The end point of the previous Spline arc guides the next arc created until you close it. The next created Spline will be independent of the previously created one.

  • You can tweak the newly created Vertices by clicking on their Handle and dragging them.

  • You can also right click on a Vertex handle or a Tangent handle and it will provide a context menu:

    • For Tangent handles: Split Tangent's Angle and Split Tangent's Radius will split the Tangent so that you can independently modify the arch of an end point of a Bézier curve. On the opposite, Merge Tangent's Angle and Merge Tangent's Radius will merge the independent Tangents so that you can align the arches of the end points of two connecting Bézier curves.

    • For Vertex handles: Loop Spline or Unloop Spline (depending if already looped or not) allows you to close or open the Spline. Delete Vertex allows you to delete the Vertex.

  • You can also right click in the middle of a Bézier curve. Insert Vertex allows the insertion of a Vertex (and sets its Tangents intelligently according to the neighboring Vertices) where you clicked.

To finish the Spline

  1. Select another tool in the .

  2. Or click on the gear button Gear_icon.png of the Tool Options Panel.

To clear out the working Spline, press the Esc button.




This tool has the following options:

Other sources of information

TODO: Add sources