TL Clothoid

TL Clothoid

Win64, English

Todor Latev
A set of dynamic tools to work with Clothoid transition curves in Autodesk® AutoCAD®.

General Usage Instructions

Utilize the curve creation command TLClothoidNew to compute and draw stand-alone Clothoid spirals in AutoCAD. Switch between all six modes using the Tab key. Use Ctrl+Tab to flip left/right direction.
The second column in the CUI contains various curve-fitting commands - those require a set of arcs/circles or lines/tangents from user and compute/draw geometry which smoothly transitions between them with one or more clothoid curves.
Finally the third column of commands in the CUI contains misc commands, which operate on already computed/drawn clothoid polylines.

Use the Points setting to control the number of vertices of the generated polyline as well as how the distance between those points is computed:
 * positive number of +n  means a point will be computed every n units along the curve
 * negative number -n will be rounded to the nearest integer and will be interpreted by the app as the total number of points along the entire curve. The distance between individual points will be auto-computed. Note that total points is limited to 1000.

You can use the UCS command in AutoCAD to align the coordinate system to your alignment segment. The Clothoid app respects the active UCS and the polylines generated will have the proper orientation

Refer to the individual command descriptions and animated gifs for more information/demo on each available command


Ribbon/Toolbar Icon Command Command Description


Activates the TL Clothoid App with the Autodesk App Store. An active internet connection is required. Once activated the app can be used offline. This command is not available in the ribbon and needs to be manually typed in at the AutoCAD command prompt


Draw a new clothoid curve


Fit a Spiral-Curve-Spiral combo between two tangents


Fit a Spiral-Line-Spiral combo between two curves


Fit a Spiral-Spiral combo between two curves


Fit a Spiral-Spiral combo between two tangents


Fit a single segmental clothoid between two curves


Locate elements - station, radius, tangent/theta along the last computed clothoid curve


Print clothoid information on the command line


Redraw last computed clothoid to its original location


Draw a from-to station range of the last computed clothoid curve


The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin. You may need to restart the Autodesk product to activate the app/plug-in. To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, click Control Panel > Programs > Programs and Features (Windows 7/8.1/10/11) and uninstall as you would any other application from your system.

Additional Information

Known Issues

The info and hint text lines visible while clothoid commands are active may not display properly in certain drawings. This is due to a bug in the Autocad Editor -> GetCurrentView -> CenterPoint API call, which appears to return incorrect coordinates of the center point for the current view


Author/Company Information

Todor Latev

Support Information

For questions/comments/suggestions/bug reports etc please email to:

Version History

Version Number Version Description


Major app update with new/revised functionality and interface


Initial release
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