In this video, we will be creating the hind leg of the quadruped with IK/FK blend, twist effectors and custom parameters. This process used in the video will be very similar to the one used when rigging the front leg, seen in the previous two videos.

Download the scene file created in this video below. You can create your own rig from scratch by following along this tutorial series, or just grab one of the accompanying scene files that are available in each chapter and continue!


  • Txeroki 3 years, 4 months ago  | 

    Hey there,

    Great tutorials and videos, I'm really learning a lot!

    So after I did this one yesterday, I followed along and have everything the same, and the setup is the same for the hind and frontleg. Everything seemed fine yesterday when I hit save, and now I open it up and the hindleg is in IK mode just like I left it, but when I slide the Hindleg IkFk switch to 0 to put it into FK mode, the entire leg rotates backwards and inwards instead of staying in the same position. The front leg stays in the same position when I switch between IK and FK, as it should, but not the hindleg.

    I have searched to see if maybe there are some transforms that are not 0 but it is all clean both in IK and FK and I have also tried rebinding the Kin CHOPS nodes Blend parameter. When I disconect the Blend parameter the bones go back to the correct position, but when I paste relative references again, if the switch is in IK (i.e. equals 1) the leg stays ok, but when I switch it back to FK the leg rotates again to the same position. And if I bind it again in FK (switch value = 0) the leg is wrong and only goes back to the correct pose when I switch to IK. So basically there is some offset rotations somewhere (bones or controllers) between IK and FK.

    Yesterday when I set it up the first time it was working fine, but it seems that after saving and reopening the file something changes inexplicably. Using Houdini 16.5.268 apprentice.

    I also noticed that after I did the earlier front leg tutorials, everything was ok and I saved the file, then opened it next day and then some of the nodes had an error saying "bad reference in parameter....", for example in the Blend nodes and also the Controllers Display Channel which was bound to the IKFK rev. So I reconnected all these and all the errors were fixed. It's just that it seams that Houdini has trouble "remembering things", so to speak. And now there are no bad references messages, but the hindleg FK position is messed up. So I really don't know what to expect because it works just fine the first time around, and then without changing anything I open the file the next day and things are screwed by themselves....

    Anyway,I appreciate these videos and any help or advice about the screwed up hindleg FK rotations. I will continue on with the series as well as I can....:)

  • blaabjerg 3 years, 4 months ago  | 

    Hi Txeroki,

    That seems very strange, but since the leg flips around when you blend the IK FK setup, there is definitely a parent somewhere that does not share the same transform values. If you are only having the problem on the hind leg and not on the front leg I am pretty sure it must be a typo somewhere in your references. Either check every step of the leg rig or try to rebuild. The good thing about rigging in Houdini is that it's very procedural so you almost only need to create the leg once, and after that you can re-purpose it again and again.

  • alutaroma 3 years, 4 months ago  | 

    Parent the lefthindlegroottothefirstnullandparentthefirstnulltothelefthindlegfemurboneandparentthelefthindlegfemurbonetothesecondnullandparendthesecondnulltothelefthindlegkneebonethenparendthehindlegkneebonetothethirdnullandparentthethirdnulltothelefthindlegankleboneandparentthelefthindlegankletothefourthnullandparendthefourthnulltothelefthindlegfoot bone xD

Please log in to leave a comment.