A Houdini SOP idea, in Cinema 4D since 2005.
SplineTools
A parametric Object Generator that merges multiple splines into a single output curve, with carve and shift controls for animated reveals and procedural growth.
What it does
Drop two or more splines underneath a SplineTools object and they merge into a single continuous curve. You choose how they connect, the output spline type, and you can carve out a portion of the result that slides along the curve, with optional cyclic looping. Originally written in 2005, still maintained today.
Parameters
Drop SplineTools in your scene and place any number of splines under it. Open the Object tab to access these controls.
A flat list of splines
SplineTools sits in the hierarchy like any other generator. Place any number of splines as direct children. The plugin reads them in order and merges them into a single output curve, ready to feed into Extrude, Sweep, MoSpline or any other spline driven generator.
All controls in one panel
Two compact groups of parameters: the merge controls at the top, and the carve controls below.
Merge
- Closed, when enabled, closes the merged spline into a loop by connecting the last point back to the first. When disabled, the result is an open curve.
- Join Mode, with Normal, joins the child splines in the order they appear in the Object Manager. Closest Ends automatically chains them by finding the nearest endpoints, regardless of hierarchy order.
- Tangent Mult. is active only when output type is Bezier. It controls how strongly the merged segments blend into each other at the connection points. Lower values give sharper transitions, higher values produce smoother flowing curves.
- Spline Type, sets the interpolation type of the resulting spline. Available options are Linear, Cubic, Akima, B-Spline and Bezier. Choose Bezier when you want full control over tangent blending.
Carve
- Carve On, enables the Carve section. When active, only a portion of the merged spline is rendered, defined by the parameters below. When off, the full merged spline is produced.
- Subdivision, sets the number of points used to sample the carved portion of the spline. Higher values give smoother curves but cost more to compute. Range is 2 to 1000.
- Carve Amount defines how much of the merged spline is kept, expressed as a percentage from 0 to 100. At 100 the entire spline is rendered, at 50 only half. Useful for animated reveals, growth effects, or trimming a long path.
- Cycle Spline, when enabled, the carved portion can wrap around the spline endpoints. As Shift moves past the start or end of the curve, the section continues from the opposite side instead of being clipped. Ideal for looping animations on closed splines.
- Shift slides the carved portion along the merged spline, from 0 to 100 percent. Animate this parameter to make a segment travel along the curve over time.
Installation
Get the ZIP from the Download button above and extract it.
Move the Py-SplineTools folder into your Cinema 4D plugins directory.
SplineTools appears under the Generators menu, ready to use.
Plugins directory:
Windows: %APPDATA%\Maxon\<version>\plugins\
macOS: ~/Library/Preferences/Maxon/<version>/plugins/
FAQ
Is SplineTools really free?
Yes. It has been free since 2005 and it stays free. If you find it useful, a small donation on Ko-fi helps keep these tools alive.
Does it work on macOS?
Yes. SplineTools is pure Python with no native dependencies. The same plugin file works on Windows and macOS.
Will it work in newer Cinema 4D versions?
The plugin uses the standard Cinema 4D Python API. It runs from R20 onwards on every version it has been tested on.
Does it work with Cloners or Arrays?
Yes. If you place a Cloner or Array as the only child of SplineTools, the splines generated inside the Cloner are read from cache and merged exactly as if they were placed manually.
Can I animate the Carve parameters?
Yes. Carve Amount and Shift are designed to be animated. Combine them with Cycle Spline on a closed input to get smooth looping growth and reveal effects.
Where do I report bugs or ask for features?
Send an email to renato [dot] tarabella [at] gmail [dot] com and I will get back to you. Include your Cinema 4D version and a short description of the issue.
Add SplineTools to your Cinema 4D toolkit.
Free download, no license, works on all platforms.