IK Chain and Rest position - Leg on X-Axis and Rolling toes

Dear BlenderArtists,

I have three questions, and after scouring the internet I am unable to find the answers (perhaps I do not know what to search for).

  1. Rigging: I am working on some dinosaur models, which use the IK-Chain for leg (ie/ chicken leg). Most tutorials which explain rigging use Human legs, which use the foot bone to control the IK and then the foot is kept flat on horizon (x-axis). However, with the chicken-leg, the “foot” bone is higher and the leg is mostly on tip-toes, which should stay flat on the horizon. When I move the Body-Bone (above hips), i find my legs wobble about and do not stay flat on x-axis, however the ankle bone is fixed. Is there a way to correct this so the dinosaur’s tip-toes stay on x-axis?

  2. The other question I have, which is more about animation and posing. If i model my dinosaur in a non-neutral position, can I rig and then create a new resting pose, from which I can create action constraints etc? for example, I want to create an action constraint for the Toes to go from hyper-extension to curled. I have modelled the dinosaur in hyperextension pose, and would like the “neutral” pose to be flat-foot. Is this possible to do? or do i need to model the dinosaur in my desired neutral pose (ie/ start from scratch)?

  3. Animation; is there a way to set a horizon line (ie/ using a plane or mesh), and set bones (ie/ last toes) so that they cannot go below this barrier - always keeping flat footed when animating a walk cycle for example? I find that when I try to eye-ball the horizon line using key frames, there is too much wobbling as a result of the wobbles in Question 1.

Thank you all for your help and advice, Here are some photo’s of my rig (edit mode vs rig; moving the body-bone to see impact of ankle/foot, x-axis):


(I modeled as per wire-frame, and by using action-constraints I have modified the neutral pose to bone pose)


(is there a way to make neutral pose have tip-toes flat on x-axis)


(is there a way to make the toes (tip-toes) respond to the x-axis spending on how i move the Body-bone)

The technical term for those types of legs is digitigrade (humans are plantigrade)
For the IK, you could try including the ‘foot’ segment in the chain and then using a pole target, but I haven’t played around much with digitigrade leg rigging so I’m not sure how accurate that would end up being (so the IK target is effectively the toes).

As for adjusting the rest pose, the easiest way would be to rig first in the current pose, then apply the armature modifier to the mesh. This will change the rest shape of the mesh to the posed shape, you may then want to make a few corrections here depending on how good the skinning was. Then, there is an operator “apply pose as rest pose” (press space to search for it) that you can use when in pose mode in the armature to apply the current pose as the new rest pose.