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Curviloft    v2.0a

  • Overview
  • Quick Start
  • Documentation
  • Release Notes

Overview of Curviloft

  • Sketchup version: SU2017 and above
  • Platform: Windows and Mac OSX
  • LibFredo6: v14.3b or above
  • Sketchucation ExtensionStore: v4.4.0 or above
  • Usage: Paid, Licensed under Sketchucation SCFLicense
    • Free Trial period (full features): 30 days from first usage
    • Perpetual license (3 seats): $12
    • Fredo6Bundle2022 license (8 plugins): $40
    • Information on licensing extensions at Sketchucation: this post

To purchase a license of Curviloft or the Bundle of 8 plugins, go to this page

Curviloft is a script dedicated to Loft and Skinning, that is, generation of surfaces from contours.

  • Loft by Spline joins separate contours, open or closed, by smooth splines
  • Loft along Path joins contours, along a given rail curve.
  • Skinning creates surfaces bounded by 4 or 3 contiguous contours

Because there are many solutions to calculate Loft and Skinning geometries, the script offers various options to adjust parameters depending on the configuration of contours.

Discussion forum

Links to Sketchucation Forum: Main Post Latest Release

Installation of Curviloft

IMPORTANT: Make sure that you have first installed LibFredo6 v8.1 or above.

Curviloft is released as a regular RBZ extension file on the Sketchucation Site.

To download the RBZ file, use the red button on the right side of this page:

  • Download If your are already logged in.
  • Log in to get it! otherwise, in order to log in or to register to Sketchucation as a new user (this is FREE). Then you will be able to download the RBZ file.

Then, you can install the RBZ file from within Sketchup, via the Sketchup Extension Manager

If you are not familiar with the installation of Sketchup extensions and Sketchucation, it is advised to watch the video LibFredo6 installation.

IMPORTANT: Whatever way you choose, you MUST quit and restart Sketchup to get Curviloft (and LibFredo6) properly loaded.

After the installation, you should have the following footprint in the Sketchup Plugins directory:

  • Sketchup versions: SU2017 and above
  • Platform: Windows and Mac OSX
  • Language: English, German, Spanish
  • Menus: by default, it is installed in Tools > Fredo6 Collection > Curviloft...
  • Icon toolbar: Curviloft

Permission to use this software for any purpose and without fee is hereby granted

Distribution of this software for any purpose is subject to:

- the expressed, written consent of the author

- the inclusion of the present copyright notice in all copies.

There are many options in Curviloft, each having a purpose. So it's good to explore and try in Preview mode and see changes reflected in the model preview. Each generated surface can also be edited and adjusted individually. Just click on it and a Floating palette will be shown, allowing you to set individual parameters.


  • Pre-Selection mode (automatic ordering): Select one or several contours (faces, edges) and Click on the icon
  • Manual Selection (user-specified ordering): Click on the icon and then pick contours in order. Click in empty space to separate contours when contiguous. Then click again in the empty space when done with the selection
  • In preview mode, you can adjust parameters via the main button palette (global setting) or the floating palette (individually by section). You can also modify vertex matching by selecting a vertex and dragging it to a new position.
  • Click in the empty space to validate and generate the shape geometry.
  • You can go back to Preview mode via the roll-back button
  • It is a good idea to check the tooltips and contextual menu to see available options


  • Select the Rail path and click in the empty space (it should be highlighted in thick red). In Pre-selection mode, Curviloft will try to identify the Rail path automatically if there is no ambiguity.
  • Select the other contour(s) that should follow the path (currently it works with 1 or 2 contours)
  • Click in the empty space (or Return) to move to the Preview mode
  • You have three methods for generating the shape: Stretch (default), Offset and Sweep. You may have to try each one to get the desired shape, since there are several ways to generate the surface along a rail. See video for illustration. Offset and Sweep ensure a correct thickness of the shape and therefore are more adapted to models with closed contours and winding path. Stretch is based on deformation of the path curve by moving extremities.


  • Interactive selection:Select the contours one by one (click in the empty space between two contours). Then click again in the empty space to generate the preview shape. All cells should have 3 or 4 bordering contours.
  • Pre-selection mode works as well, but may not be able to handle ambiguous cases. Also, it is always a good idea to draw small open segments at the vertex which you want to use to separate contours.
  • you can play with the Interpolation and rail over-sampling to add / remove divisions in the mesh


Curviloft is still released in BETA and has NO documentation yet. Please be aware of potential crashes and therefore always save your work before launching it.


Tutorial on Loft by Spline

Loft Along Path

Tutorial on all 3 Curviloft tools by Tutorials Up

There is also an impressive tutorial made by Charly2008, showing how to draw golden rings, crowns and all sort of twisted objects.

Custom Ruby commands to launch Curviloft

If you have a custom toolbar (or a plugin for that), you can safely launch the Curviloft tools with the following Ruby code:


where action_code is a Symbol, with value:

  • :loft_by_spline
  • :loft_along_path
  • :skinning

If you need the icons, they are in the subfolder Fredo6_Curviloft/IMAGES_Standard.

Links to Sketchucation Forum: Main Post   Latest Release

New features in Curviloft v1.6a

Release History

Curviloft 2.0a – 31 Mar 24: Future compatibility

Curviloft 1.9b – 21 Apr 23: Bug fixing and error catching

Curviloft 1.9a – 13 Feb 22: Compatibility with 3D mouse devices

Curviloft 1.8a – 31 Oct 18: Maintenance release for bug fixing

Curviloft 1.7d – 31 May 18: Maintenance release to fix a bug in the ordering process of the contours (spline)

Curviloft 1.7c – 27 Feb 18: Maintenance release to fix bugs in the Selection process

Curviloft 1.7a – 23 Feb 18: Maintenance release and preservation of parameters across Sketchup sessions

Curviloft 1.6a – 13 Aug 17: Maintenance release (compatibility with hi-resolution screens) Here is the start post for this release

Curviloft 1.5b – 12 Aug 17: Maintenance release (bug fixing for non-ascii usernames) Here is the start post for this release

Curviloft 1.5a – 13 Nov 15: Maintenance release Here is the start post for this release

Curviloft 1.4a – 19 Oct 14: Release for support of username containing non-ascii characters Here is the start post for this release

Curviloft 1.3a – 27 Nov 13: Release for future Sketchup Compatibility

Curviloft 1.2d – 13 Apr 12: Small update about diagonals to better guide the mesh construction in Thomthom's QuadFaceTools and [url=http:http://forums.sketchucation.com/viewtopic.php?f=323&t=44552#p397448]ThruPaint[/url]. In all generation modes, diagonals in the mesh are now generated with property Casts Shadow = false, which is the convention for diagonals (invented by Thomthom). In version 1.2c, this was the case only if the Pseudo-quad option was selected.

Curviloft 1.2c – 15 Nov 11: Slight change for the generation of Quads, to align with new definitions used by Thomthom's QuadFaceTools - Border: Soft + Smooth (+ Cast Shadows) - Diagonal: Soft + Smooth + NO Cast Shadows

Curviloft 1.2b – 26 Sep 11: Include more options in the Default Parameters Dialog box for generating pseudo-quads. By default, pseudo-quads are now generated with: - Border: Soft + Smooth - Diagonal: Soft + Smooth + Hidden See Release Notes for detail

Curviloft 1.2a – 21 Sep 11: Include the generation of Pseudo-quads allowing the usage of the new QuafFaceTools by Thomthom. Also, it avoids generation of empty group if there is a problem. See Release Notes for details on pseudo-quads generation.

Curviloft 1.1c – 29 Jun 11: Fix to a bug concerning mean internmediate curves when the contour are closed loops. Thanks to Defisto for signaling this issue

Curviloft 1.1b – 27 Jun 11: small upgrade to help generating mean curves between contours. This is done by an additional options for geometry, so that you can just draw Junction lines, intermediate lines or both (i.e. mesh) without the faces. See this post for discussion about the feature.

Curviloft 1.1a – 12 Jan 11: Fourth beta version, dedicated to Loft Along Path. Main evolutions are: *Some fixes in Loft by Spline and Skinning. *Loft Along Path should be functional and handle 1, 2 or more contours with 3 methods: Stretch, Offset and Sweep *Two-phase loading of the script[/list] On top of potential bugs and geometry issues (including bugsplats), there are still some limitations and unfinished work: *VCB is not active *No interactive edition in the floating palette *B-Spline and F-Spline do not close nicely in loop mode *No later reedition of shape generated (this will come)

Curviloft 1.0c – LibFredo6 3.5c – 20 Aug 10: Third beta version, dedicated to fix bugs in Loft by Spline and Skinning. Loft Along Path is still not fully functional.

Curviloft 1.0b – LibFredo6 3.5b – 11 Jul 10: Second beta version.

Curviloft 1.0a – LibFredo6 3.5a – 13 Jun 10: First beta version.