This is a new converter named IK Angle, designed to facilitate simple inverse kinematics (IK) setups
.cpp and .h file:
converter IK angle.zip (3.5 KB)
demo:
Wow! It looks cool! 
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Age-restricted video (requested by uploader)
Exciting video indeed but I think that the age-restriction is a bit too much 
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hehehe wrong setting 
But it still has the restriction XD
Incredible work! Haven’t seen a custom converter before.
Which Synfig Studio directory should I drop these files? Looking forward to play around with this for myself.
Why in the video did you convert the bone origins to Add valuenode?
Besides, I believe the l1 and l2 can be automatically inferred.
Yes, I once tried to make L1 and L2 automatic using the bone valuenode, but it caused a crash. Maybe it’s not possible to fetch data from itself.
As for why I used ‘add’, it’s because if I use the parent on the bone pole part, it no longer looks correct. The origin is already influenced by the parent bone.
Maybe it can be improved further. The problem is, I don’t know the core of Synfig. I can only go as far as that. Maybe you or someone else can improve that converter.
Latest update: the IK angle can now determine the elbow position from vector data, and the bones can be stretched
demo: https://youtu.be/5yXgffg6n3k?si=94SVqveqSoOvtzIT
file cpp and plugin IK angle: GitHub - zaynopenapp/IK-angle-new-converter-Synfig: new converter Inverse Kinematic in synfig · GitHub
support or coment review PR synfig: feat(converter): new 'IK angle' converter by zaynopenapp · Pull Request #3623 · synfig/synfig · GitHub
test in windows download here: AppVeyor
test in linux donwload appimage 
: https://github.com/BobSynfig/synfig/releases/download/UNOFFICIAL-1.5.5-2026.05.06-test-pr-3623/SynfigStudio-UNOFFICIAL-1.5.5-2026.05.06-linux64-97f56.AppImage
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This NEEDS to be added!! Please SynFig devs pull this into the main software! :o
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Excellent work Zainal, and will be keeping a keen eye on it’s further progress. Happily built a Linux version of Synfig 1.55 with the IK converter in it, but I do hope this gets a commit to the git.
Got my head round how it works easily enough, yet I would suggest some better descriptive tutorials.
Awesome work.. Many thanks.
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Hi @Kegg, hope you’re doing well.
Could you please review this PR?
I’d really appreciate any feedback—especially if there’s anything missing in the script or if you have other ideas for improvement. Thank you! 
UNOFFICIAL AppImage available 
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@BobSynfig Thank you so much for helping create the AppImage. I’ve tried many times to make an AppImage before, but it always failed (it would only run on my own system). It’s definitely not easy to make one. With this AppImage, I hope other users can try new ‘Ik angle’ converter. I will also create more demos in the future. Once again, thank you very much 
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@MGFP Sorry for the late reply. If you want to build Synfig on your own distro, please follow this method first ( feat(converter): new 'IK angle' converter by zaynopenapp · Pull Request #3623 · synfig/synfig · GitHub ). If your OS is Linux, you can try synfig 1.5.5 it directly on (https://github.com/BobSynfig/synfig/releases/download/UNOFFICIAL-1.5.5-2026.05.06-test-pr-3623/SynfigStudio-UNOFFICIAL-1.5.5-2026.05.06-linux64-97f56.AppImage)
@zainal Just done a full build here from your PR… working nicely sir, and love the fact we can now change the color of the bones too.
Hopefully I’ll play around with it more tonight, and do some character animation with it, along with seeing if conflicts occur with the likes of the ‘controller’ plugin.
Equally interested in getting WAYANG plugin a good run through, especially the shapekey side of it, as the potential of automated nuances/shape correction I could add to any character animation is awesome.
One of the things if think worth looking into is being able to add secondary targets for knee/elbow direction hinting.. Not sure how possible this maybe as yet though.
great work mate.. thanks again 
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Thank you for taking the time to review my PR 
. The bone color feature is a bonus. It was originally a separate PR, but it accidentally got merged with the IK angle PR. Hopefully I won’t get banned 
. Still, I believe users need this feature, so let’s support bone color 
Thank you for checking out the WAYANG plugin . This plugin is still in the testing stage, so please be careful and make sure to save your file before using it. Also, to avoid conflicts with exported valuenodes, please unexport them as soon as possible. Don’t worry, the IK angle will still function normally unless the valuenodes become disconnected. You can tell the link is still active by checking the chain icon 
WAYANG plugin: GitHub - zaynopenapp/Wayang: synfig plugin controller shapekey · GitHub
banned.. lol … You deserve a medal. A basic thing I think everyone using bones has craved for many a year.
Haven’t had time as yet to rig something up.. may get time over the weekend to do a little something, kids and Mrs permitting … cheers
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Of course, we can create a flip controller — you can see how to do it here(https://youtu.be/gKZrjq-eJeU). The file
controller flip.sifz (3.1 KB)
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