
The Coons Mesh generator provides the user with a simple yet effective tool to enable free-form mesh development by defining the four side-curves enclosing a region in space.
Usually found in CAD software, Coons Mesh is based on the Coons surface definition (Wikipedia) which requires four curves to meet at their reciprocal end points and defining the mesh vertex positions by bi-linearly interpolating the discrete positions across the curves.
Workflow
To adapt to user’s individual workflow the Coons Mesh generator can operate using the standard approach pinning input curves as generator’s children or to populate the proper curve’s link in the Attribute Manager.
GUI

General parameters
- S-steps: Number of mesh subdivisions in the “S” direction.
- T-steps: Number of mesh subdivisions in the “T”direction.
- Junction Type: Type of junction check to operate on the curves’ start/end points [Tight/Loose]. “Tight” mode forces the ending points of the curves to meet with the tolerance specified by the “Junction Tolerance” (see below). “Loose” mode permits the mesh to be created even if the four curves don’t match at ending points (“Junction Tolerance” is ignored).
- Junction Tol.: Junction check tolerance value (used also to auto-flip curves’ direction).
- Flip Normals: Invert mesh normals for coherent mesh connections.
N-th curve parameters:
- Link: Link to the n-th input curve (disabled if children pinned under the generator).
- Sampling: Sampling mode used to sample curve to define point positions [Natural/Uniform]. “Natural” mode samples the curve based on its slope variation. “Uniform” mode samples the curve applying a constant step.
- Cleanup: Enables curve clean-up to remove redundant points found within the specified tolerance.
- Tol.: Curve clean-up tolerance.
Best practice
- Keep the curves as simple as possible to avoid awkward point distribution in the final mesh.
- Avoid using splines with multiple segments. Please favour single segment splines with more points rather than splines featuring multiple segments with less points.
- When possible explode multi-segment splines to obtain single-segment splines.
- Start using low values for S/T steps in order to refine the model later on with other operators (Subdivision Surface, Connect object, Symmetry, etc.).
- Use open curves/splines. Closed splines may (and will) lead to unexpected results.
- All of Cinema 4D’s open procedural splines are supported (Arc, Cycloid, …).
- Prefer “Tight” junction connection type over “Loose”. Although “Loose” might be helpful in certain situations (i.e. when using splines obtained by deformers or other generators which could hardly be controlled to meet at a specific point), “Tight” provides you with the most coherent results creating a mesh whose shape and final appearance properly matches the expected result.
- Using the link-fields instead of child splines to define the generative curves, enables mutual updates when a curve is used on two or more Coons Mesh generators. Very useful to create connected patches of Coons Meshes (use Connect object as parent to get smooth seams).
Curves setup

The four curves enclosing the region can be specified following a CW or CCW order. Preferring the first to the second mode has no influence except for the orientation of the polygons’ normals.
The following orders for the input curves are allowed (1st ->2nd -> 3rd ->4th):
- Red -> Yellow -> Blue -> Green
- Yellow -> Blue -> Green -> Red
- Blue -> Green -> Red -> Yellow
- Green -> Red -> Yellow -> Blue
- Green -> Blue -> Yellow -> Red
- Blue -> Yellow -> Red -> Green
- Yellow -> Red -> Green -> Blue
- Red -> Green -> Blue -> Yellow
Curve cleanup
It might happen that during curve sketching multiple control points get positioned very close to each other, resulting in a very dense or degenerated curve. By activating “Cleanup” for a specific curve, the curve will be checked and if multiple points are found in a range specified by tolerance parameter only one is considered during the mesh creation time, leading to a cleaner and more evenly distributed mesh.

Junction Type
Although the Coons Mesh has been designed to work with a set of curves forming a closed loop, it might be useful, when input splines are generated procedurally by other tools, to let the Coons Mesh compute a result even if the splines’ end points are not matching. It’s relevant to note that final mesh extension depends on the position of curves 2 and 4 endpoints and is not influenced by the moving endpoints of curves 1 and 3.

Requirements
Cinema 4D R17 and higher.
Download
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Terms of Use
Acceptance of Terms of Use of this site (“Site”) constitutes a legal agreement between you and MAXON Computer GmbH. By accessing, browsing and/or using this Site you acknowledge that you have read, understood, and agree to be bound by its Terms of Use. Please review the Terms of Use. If you do not agree to these terms, do not use this Site and the materials provided on this Site.
Copyright Information
The copyright on all material provided on this Site is held by MAXON Computer GmbH and its subsidiaries (MAXON Computer Inc. and MAXON Computer Ltd.) or by the original creator of the material. Except as stated herein, none of the material may be copied, reproduced, distributed, republished, downloaded, displayed, posted or transmitted in any form or by any means, including, but not limited to, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of MAXON Computer or the copyright owner. Permission is granted to display, copy, distribute and download the materials on this Site for personal, non-commercial use only provided you do not modify the materials and that you retain all copyright and other proprietary notices contained in the materials. You also may not, without MAXON Computer’s permission, use the materials for the development, production or marketing of other materials, works or media of any kind and/or “mirror” any material contained on this Site on any other server. This permission terminates automatically if you breach any of these terms. Upon termination, you will immediately destroy any downloaded and printed materials. Any unauthorized use of any material contained on this Site may violate copyright laws, trademark laws, the laws of privacy and publicity, and communications regulations and statutes.
Privacy Policy
The protection of personal information submitted to us is very important. We strictly adhere to prevailing German Data Protection Act (BDSG), the German Telemedia Act (TMG) and other privacy protection provisions of the Federal Republic of Germany. For privacy protection issues outside of Germany we will, of course, adhere to respective privacy protection provisions.
Your personal information is transmitted via SSL (a network protocol for the secure transmission of data) in encrypted form. The Site is protected against damage, destruction or unauthorized access.
Object of Privacy Policy
Object of the Privacy Policy are details regarding personal information or personal or factual circumstances about a specific determinable person according to § 3 Abs. 1. BDSG. Included is information such as name, postal address, e-mail address or telephone number.
Scope of Data Gathering, Storage and Use
We gather and store your personal information for the purposes of rendering services or as necessary for contractual fulfillment. Your information is used by MAXON to make using the Site and the materials as pleasant and comfortable as possible.
Your personal information will not be given to third parties without your expressed consent unless it is required for providing services or contractual fulfillment. It may, however, be necessary to supply your personal information to certified MAXON partner companies that MAXON implements to provide certain services. We will require that the recipient of the personal information agrees to process such information in compliance with our Privacy Policy and applicable data protection laws.
Transmission of personal information to authorized government institutions or authorities will only be done according to the statutory obligation to provide such information or if obliged to do so in accordance with a court order.
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By accessing, browsing and/or using this Site, you agree to comply with all applicable laws and regulations, including the export and re-export control laws and regulations of Germany, the United States of America and the United Kingdom. This Site is controlled and operated by MAXON Computer from its offices and servers within Germany, the United States, and the United Kingdom. MAXON Computer makes no representation that materials on the Site are appropriate or available for use in other locations. Access to the materials on this Site from territories where their contents are illegal is prohibited. Those who choose to access this Site from other locations do so on their own initiative and are responsible for compliance with applicable local laws.
Trademarks
The trademarks, service marks and logos (the “Trademarks”) used and displayed on this Site are registered and unregistered trademarks of MAXON Computer and others. Nothing on this Site should be construed as granting, by implication, estoppel, or otherwise, any license or right to use any Trademark displayed on the Site without the written permission of the Trademark owner. MAXON Computer aggressively enforces its intellectual property rights to the fullest extent of the law. The name of MAXON Computer or the MAXON Computer logo may not be used in any form, including advertising or public display pertaining to distribution of materials on this Site without prior written permission. MAXON Computer prohibits use of the MAXON Computer logo as a “hot” link to any MAXON Computer site unless written approval to establish such a link is granted in advance by MAXON Computer. Any questions concerning the use of Trademarks owned by MAXON Computer should be referred to MAXON Computer Inc., 2640 Lavery court suite a, Newbury Park, CA 91320, USA, tel: 805-376-3333 or MAXON Computer GmbH, Max-Planck-str. 20, D-61381 Friedrichsdorf, Germany, or MAXON Computer Ltd., The old school Greenfield, Bedford, MK45 5DE, England.
Disclaimer of Warranty
This Site and the materials on this Site are provided “as is” without warranties of any kind either express or implied. The Site and the materials may be incorrect, incomplete and may have defects that could cause program malfunctions, program crashes, system failures and loss of data. The Site and the materials may not be merchantable, fit for a particular purpose, or non-infringing. MAXON Computer does not warrant or make any representations regarding the use, validity, accuracy, or reliability of, or the results of the use of the Site and the materials on this Site or any sites linked to this Site. MAXON Computer is under no obligation to provide technical maintenance and support, to rectify defects and to restore failed systems and lost data.
Limitation of Liability
MAXON Computer shall be liable without limitations (1) in case of intent and gross negligence; (2) in case of injuries to life, body or health; (3) pursuant to the terms of the German Product Liability Act; and (4) under a guarantee granted by MAXON Computer. MAXON Computer’s liability for slightly negligent breaches of cardinal duties shall be limited to such damage which was foreseeable and typical for the intended use of the Site and the materials. Cardinal duties are duties of MAXON Computer which enable the use of the Site and the materials and which you may therefore rely on. Any other liability of MAXON Computer is excluded. If your use of materials from this Site results in the need for servicing, repair or correction of equipment or data, you assume any costs thereof.
Transmissions
Any material, information or idea you transmit to or post on this Site by any means will be treated as non-confidential and may be used by MAXON Computer or its affiliates to operate the Site and to provide the materials. You are prohibited from posting or transmitting to or from this Site any unlawful, threatening, libelous, defamatory, obscene, inflammatory, pornographic, profane or any other material that could give rise to any civil or criminal liability under the law.
Term of Use Revisions
MAXON Computer may at any time revise these Terms of Use. You may access and review the revised terms on this Site, and your continued use of this Site means that you accept those revised terms.
Liability notice
Despite thorough examination of contents, MAXON Computer assumes no liability for the content of external links. The operators of the linked sites are exclusively responsible for their content.
Applicable Law and Jurisdiction
The Terms of Use are governed by the laws of Germany, but excluding the principles of conflict of laws and the United Nation Convention on the International Sale of Goods (CISG). You agree to the exclusive jurisdiction of the competent courts of Frankfurt am Main, Germany, in respect of any proceeding, suit or action arising out of or in connection with these Terms of Use, this Site and/or the materials.
Legal Notice
MAXON Computer GmbH
Max-Planck-Str. 20
61381 Friedrichsdorf
Germany
Phone: +49 (0) 6172 / 59 06 0
Fax: +49 (0) 6172 / 59 06 30
General information: info@maxon.de
Sales & Marketing: sales@maxon.de
Press: presse@maxon.de
Authorized company representatives
David McGavran
Court of registration: Amtsgericht Bad Homburg v. d. Höhe
Registration number: HRB 6049
VAT ID number according to § 27 a sales tax law: DE 113864088
Installation
Unzip the downloaded archive to Cinema 4D’s default plugin folder.
Support
Provide your bug reports, test scenes or ideas by writing an email to labs-at-maxon-dot-net
Please keep developing this and other more CAD / technical modelling type tools! Thank you!
don`t work with R21
CoonsMesh 1.0.2 supports R21
Coons Mesh has been updated to work with Cinema 4D R20
R21 Version?
Hi 😉 Dont work in C4D R20 🙁
Yes, as stated earlier the R20 version is not ready, yet. But it will come in the not too distant future. Most likely during November.
R20 Version ?
Yes, a version for R20 will come. It just needs a bit of time.
Nice plugin. Please, where can I download the Py-extrude generator?. Thanks
It’s part of Py-ParametricTools here on MAXON Labs:
https://labs.maxon.net/?p=3158
You described this process as simple as possible. I clearly understood each particular step. Thanks for the submission!
Riccardo, this is an awesome plugin Brah! Very useful and a great addition to workflow man, I appreciate ya dude 😉 😀 Do you have a donation tab? Ya deserve it Brah
Could you make a video tutorial explaining the work-flow with coons mesh ?
Is it possible to work with coons mesh as easily as with patches in 3D MAX ?
In 3D MAX you can directly access any spline control points for tweaking, how is it done in coons ?
https://www.youtube.com/watch?v=HIlgYQWJ2vE
Great plugin!
Feeling honored!
Any plans on making this for R16?
Definively doable. In the next update i’ll try to provide R16 backward compatibility
Legend! 🙂
very useful, but needs some improvments, i would to have generated splines in specific shapes like rectangle with number of points can add on each spline, this allows us to speed up workflow rather than did it manualy
Can be out of the tutorial。
good ! I live it.
This looks good, we have spline patch so will compare. Is there anywhere we can suggest request plugins/issues? Would be great if you could turn on/off takes marks with a drag select like the traffic light system in the object manager. Takes ages if you have a large number of takes (no pun intended).
Hi Emlyn,
thanks for your feedback. For ideas or bug requests of MAXON Labs projects, these comments are the right place. For general feature requests I’d rather recommend the usual way via the Suggestions form on our homepage: https://www.maxon.net/en/support/suggestions/ and bug reports are best reported via our support form: https://www.maxon.net/en/support/how-can-we-help/
Nice plugin!
Having played around with this for only a little while it already feels like a natural addition to the existing modeling toolkit that I will be able to use use on many occasions.
Selecting two splines and then their overlapping points to move a corner of the shape is a bit cumbersome though. Maybe we could have a setting to snap/link endpoints between splines so you don’t have to constantly switch to object mode to select the spline and then back to points mode to select the points you want to manipulate. Hope this makes sense. Great work, thanks!
Very good gave a 5/5, Riccardo do you think it is possible to evolve to something like this:
http://www.dgp.toronto.edu/~shbae/ilovesketch.htm
It looks fantastic! Cinema4D has a sketch spline tool, it would be cool to use this functionality.
The only problem ignores spline depth of the space, as your example of video.
A welcome addition. Thank you!!
Looks awesome, esp. for automotive stuff!
very good, In addition, the splines can be placed as children of the object Coons
What about allowing a 3 spline setup ? Imagine one arc XZ and two arcs XY plane rotated to start and end of XY arc. Splurf can do that even on parametric arcs, Spline patch can to it as well but needs splines ….
Something interesting to add and already on the todo. Thanks for sharing your comment.
I have spline patch and splurf – will be an interesting comparison …