Cannot add 'cycles modifier' to F-curve

My character mode can walk but I would like my character to walk indefinitely. It walks nicely over a span of two extremes (where the feet contact the ground).
To walk indefinitely further without adding key frames, I decided to add the ‘cycles modifier’ at the end of the second extreme. I focused on the ikfoot.L and added the modifier. But the system would not add the same modifier to ikfoot.R. Reason given in the Console: “the cycles modifier can only be first in stack.”

What on earth does that mean? What is the stack being referred to?
I’d be grateful for an explanation.

The Cycles Modifier MUST be at top of the list of F-Curve Modifiers. Just add it FIRST so it is at the top of the list. If you already have a Modifier there, delete it then add the Cycles - then add back the one you deleted.

Cheer, Clock.

Thanks, Clock. I noticed that for foot.R, none of the F-curve modifiers work, not just ‘cycles’ [the space under modifiers goes semi-opaque].
I next noticed

  • for foot.L the f-curve shows the key frames (black spots) ON the curve
  • for foot.R, the black spots are confined to the horizontal line at o mark but none on the curve itself.
    Quite a mystery to me.

Any further light will be appreciated. [screenshots attached]


it’s locked (See the little padlock) I think you just click it to toggle.

Thanks, Photox, for the suggestion. It is true the last item in the F-curve list, the ikfk foot switch, can be clicked to open or close but it makes no difference to the F-curve or the cycles mod.
There is something else at work and I am baffled.

It’s time to post the blend file for us to look at me thinks…

I am not seeing the Modifiers list in your screenshot so I cannot comment on them…

You can make a copy of your blend file, then take out all that is not needed to show the problem, like all the meshes for example, then post it here or to and post the link here.

Cheers, Clock.

Right - I have just uploaded the Blend file Walk-full walk (one loop)


W1 walk- full walk (one loop).blend (4.57 MB)

Great - I will look at it tomorrow.

Cheers, Clock.

OK sorry for the delay!

On first look you seem to have baked the F-Curve for Y location of the right foot IK target - you need to go back to a previous unbaked version I suspect, unless you can clear the bake, I don’t know how you might clear the bake…

Also you are keyframing scale all the time on your bones - no need to keyframe this unless you alter it! I think you are using I key then selecting LocRotScale - you can simply keyframe the things you really need by just RMB-click in the Transform boxes and select “Insert Single Keyframe” for one box only, or “Insert Keyframes” to do all three in the class.

To get your head around F-Curve Modifiers - just use a simple animation on a simple mesh and experiment with them. I would simply move a cube in X and Z - a bounce while moving along, then play with that.

Cheers, Clock.

On your F curve you have the modifiers turned off. Click the little wrench on the Y location on your foot IK.r and you will then see a godzillion modifiers on that F curve. Clean it up by deleting all that garbage and just put the cycle on it and you should be ready to add a root location constant move to get her walking. May need the same thing on the other non body parts. If you get stuck, post back. Been there done that. When you do your root move with constant interpolation you can use your NLA to get a longer walk.

Sorry, Clock, for the delay in returning to you. I got occupied with something else.
I tend to overdo the i key for key framing. I’ll do as you say - perhaps just locrot. (I am also aware of the auto key.)

Thanks so much, Stilltrying! Those wrenches are staring in the face but I just wondered what they were for!
I just clicked the ikfoot.r wrench and voila the mods were back. What relief !
But I noticed that the F-curve had turned into a series of steps!!
I just tried again. Frame 1 was Ok but for later frames, the right foot wouldn’t budge and just kept stretching.
So nice of you to check again if I need help again. It’s 1.30 am now and will retire.
Meanwhile I am attaching the image of the F-curve for the right foot.


Again. In your F curve, delete all the F curve modifiers. Your looking at a step modifier with a big step. Don’t need it. Delete them all and add back the cycle as the only one and then the offset. Images help a little, but please post back the blend if you get stuck again. Look in the panel on the right side of the graph under Modifiers.

Stilltrying, you’ve saved me again.
Going down the Mod list, I could see that the step-modifier had appeared unannounced.
But why did it appear without being enabled? [ A defect of the Blender code??]
As suggested, I deleted the modifiers, leaving only the Cycles one.
I set ‘no cycles’ Before and ‘repeat with offset’ After
Now the f-curves looked OK and the black spots (for key frames) also appeared on the foot.R curve, which they didn’t before.

A couple of questions if I may:

  1. Is there any need to set a number for the frame range (eg 400) or just leave it 0?
  2. The model (keyed to frame 32) now walks OK for another 120 frames or so. After frame 32, her hair and underwear get left behind and the model begins to lean forward. After frame 100 or so, the left foot is stuck behind !!
  3. More disturbing: the arms stop swinging from frame 32 (end of my loop) [Please comment on this]

So it seems that despite the modifier, the walk cannot go on forever. Pity. Blender’s coding flaw?
I recall you did suggest NLA for a longer walk. I’ve also seen a couple of efforts which did use NLA in the end.

I’ll be most grateful for your comments.

Again, if you don’t post a blend where your at, I have no way of knowing what you have done. I really don’t want to play guessing games. With Blender, it has been my experience that most of the problems I have encountered are between the keyboard and the floor.

I am posting the Blend file


W1 walk- #full walk (one loop) for StillTry.blend (4.56 MB)

1.The frame range is used to put the cycle animation within certain frames. So what are you doing? If you use the NLA, you won’t need frame ranges at all you will simply move the strips where you want and repeat as needed. Also, why have you checked the influence in the modifiers?
2. Look in the dope sheet for the answer to your second question. The “action” you keyed on the mesh stops at frame 32.
A better method is to parent this mesh to the armature and weight paint it to the head bone. That way you don’t have to key frame it. Search google for how to rig hair. I’ll let you diagnose underwear, eyes, etc. Take a look at some of Dan Pro’s tutorials.
3. So you didn’t keyframe anything past 32 on the arms or didn’t do anything with the f-curves. Reason it out. Better yet why do all that extra work? Hint, repeating animations.

I would suggest that you spend a couple of bucks and get some basic animation books for Blender. I would recommend a small investment in something like Traditional Blender by Hess or Blender 2.5 Character Animation Cookbook by Vasconcelos. They helped me alot. As far as your current project, You need to plan out what you want and what you are doing. I don’t understand why you want to animate forever. How many frames is that? You see the issue? There is a limit in all software either by code or by equipment. Or do you just want to repeat the animation like a walk cycle which is continually playing the animation?

I would start with your model and its size and clear your mesh transformations to start with (look at the Blender units which are normally metric and figure out why you need a model 30 meters or so high model) and then look at your rigging, (the parts of your model need to go with your rig) look up Humane Rigging, and try to understand your rig.

I know this is not what you want to hear, but references have walks and walk cycles in them using similar rigs. Your off base and need to do a little research on your own. As far as starting Blender, my first animation was pretty bad and I’m still trying to match some of the great animators on this forum. They graciously gave their time to comment and that actually helped. Made me realize that I had a lot to learn and needed to use Google a lot. I still do and therefore am stilltrying. If you have the bucks, invest in Blender Cookie. This will save you a ton of time and time is worth something.

The fact is an indefinite walk is achievable. Otherwise what’s the point of the cycles modifier?
It has been done by Nathan Engdhal in his Anim Fundamentals series with his model called Clive.
Also done by V Vasconcelos in his book chapter 9 where a chap keeps walking forever looking at his watch now & then.
Maybe CG Cookie is the answer.