Hello. I have tried over a dozen times. According to this blendercookie tutorial (http://cgcookie.com/blender/lessons/creating-a-spider-part-02/ time mark 25.08 give or take) I should be able to set a working ik to the second segment of the leg.
but the ik bone, at the tip of the leg is loose. i tried to parent the bone that is supposed to be liked to it. but that also didn’t work.
Could i please get some advice.
Thx
D
spiderIKIssues.blend (882 KB)
quick update. on the leg i removed the ik bone. added an ik restraint to each remaining bone each with a chain length of 1
so i got the little guy rigged. but wish i could better control the ik for the legs. as is i have to position each bone,
Could i please get some advice on how to improve the ik to help w/the aniation?
thx
D
additionally what is that lime green “no sync” button at the bottom?
thx
Attachments
spiderIKIssues.blend (1010 KB)
Bone Stiffness. As is true in many walks of life, a bone’s stiffness is important.:eek:
I have attached a blend file, with two armatures rigged as they should be for your legs, one has bone stiffness added the other doesn’t. Both are animated the same - they behave differently. They also show a foolproof way to build and IK chain, with the “Control” bone being the one you move to animate the chain. The bones have “XYZ Euler” rotation set, also a good idea for this type of rig. To set IK stiffness, go to the the bones “Bone” pane, when in Pose Mode, then the Inverse Kinematics sub-pane to set values, you can lock a bone so it won’t rotate at all, useful in making steam engines where you don’t want the cylinder to move. Set the bone’s rotation mode in the same main pane, Transform sub pane in Pose Mode.
You will note that control bone has a small extruded extension called control-IK to which the IK constraint for the last leg bone is targeted, this is because IK constraints work against the tail of a bone and you need the tail of your control bone free so you can move it. Simply grab the Control bone to move the rig manually.
ik-chains.blend (445 KB)
Cheers and happy new year. Clock.
PS - nice model…
I prefer your first armature, clockmender. I locked the y and z axis on the last two bones keeping the x axis free in the inverse kinematics menu. (The two after what would be the bone that connects to the body.) No bone stiffness needed in this case, IMHO.
Many ways to skin a cat and all that. 
I have just looked at your model - ALL your IK’s are wrong, sorry, but it is so, none of them have a target assigned, hence the red colour. An IK chain is just that - a chain or bones with an IK constraint on the last bone targeted at it’s control bone or an extrusion of that, or some other object, so you can grab and move, or rotate the controlling bone, object. Also bones ltj, rtj, llj & rlj are all the wrong way round - they should have their tails towards your “head” bone and their heads pointing towards the end of the jaw structures - that way your can pose them correctly, these should also be an IK chain (see my comment on “waist” and “Abdomen” bones below). I would put the armature(s) on a separate layer to the meshes, so you can work on them without the mesh being in the way, (yes, I know about “Hide”, but it’s still easier). If you don’t want your “la.001, etc.” bones to move in relation to the head, lock their IK stiffnesses or take them out completely and just parent the last leg bones to the head bone.
Your bones “Waist” and “Abdomen” should ideally be an IK chain, with a control set (“control” bone plus “control-IK”) at the end, as on my armatures in my previously attached blend file, so you just have to move the abdomen to control the waist. set the chain length here to 2, so the head bone is not affected, and set stiffness values for your “waist” bone to get a realistic movement. If you set the chain length to 0, the IK chain goes right back to the last connected bone, use another number to set the chain limit for how far back the IK chain effects other bones.
IK Constraints In General:
On an IK constraint you MUST set the target, it can be an armature or mesh/empty, in the case of an armature, you then have the option to select the desired bone. You should put the IK constraint on the LAST bone in the chain ONLY, the other connected bones will then be affected up to the last one or a subset depending on whether chain length is set to either 0 or some other number, indicating the number of bones in the chain you want to influence. Just to reiterate, an IK constraint targets the tail of a bone, so you must have a tail available, which, if you want to move, must be connected to a separate bone with a free tail. You could of course use an “empty” here as the target, you can then animate the chain by moving the target “empty”. I have updated my blend file to show this as another option - just move the “empty” to see it working, you will note that “bone.003” is not moved, because it has its IK stiffnesses locked and “bone.004” is not affected, because the chain length stops at “bone.003” (chain length of the constraint on “bone.002” is 4 and bone.004 is the fifth in the connected chain). I have not bothered to name my bones in a good manner - you can always do this yourself. Hope this helps you, sorry to point out all the errors, but that’s partly what we are here for…
ik-chains.blend (453 KB)
Clearly you are not scared of spiders!
Cheers. Clock.
Thanks Danpro - I have not locked these as I assumed the originator wanted to “walk” the legs by moving the control in my Y axis as well. The second option was merely to demonstrate the effect of bone stiffness, or one of them at least (teehee). Also the originator’s model had a leg-to-body connecting bone, which I did not add to my rig, but I take on board what you have said.
Happy New Year to you!
Cheers. Clock.
pdxDaniela,
As an example of the lengths we go to in order to help you, I have just been watching a spider crawl up my study wall and no, I did not squash it, Mrs. Clockmender would never forgive me - she is petrified of mice, but thinks spiders are “lovely and cute” before adding “two thing that you are not” :-(, anyway I digress, back to the spider, before carefully gathering it up in my hand and placing it outside - on the bird feeding table (“Cute your way to of this Mr. la-di-da-lovely-bl**dy spider!”), I noticed that it walked with a very stiff-legged gait, or at least it did until the first sparrow caught sight of it… So with this in mind, I would probably advise that you set fairly high stiffness values for the last two bones, i.e. those furthest away from the body, in your leg IK chains and let the nearest large bone rotate more freely against the small stub bone connecting the leg to head. This way I think your walking motion for the spider will be more life-like.
Cheers. Clock.
clockmender thank you for you help. that is really going the distance. actually this would be pretty much my second try at rigging/animating anything(first was years, year? ago) so feel free to point out errors & give advice(100% sure errors will abound )
As for spiders not at all crazy about them or most insect, but ever since starting this project i can now actually look at the images for ref w/out wincing. Picked them because they can scare people.
I was following a tutorial on how to rig this by david ward on cgcookie, but i noticed some of the ui & info has changed in the current blender releases and it was making it a bit confusing for me.
Thank you also on the kind words about the model but it is a quick & dirty one, low poly so i can take it into unity 3d. Soon as it is done (gave myself a week to complete the very very basic u3d environment, an extra week for the extra cheese)will drop a line.
btw…“clock”?
DanPro …good grief…No cat skinning.
& http://iwantanimage.blogspot.com/2015/01/blender-to-unity3d-part41.html
Soon as this thing is done & i have a working junior in u3d i’d be happy to add any extra details you’d advise to the blog post.
btw. there is one thing that is driving me up the wall. i have no probs on my laptop. but when i work on my desktop & use the ctrl+alt+s to scale the bone in edit mode it doesn’t recognize the command at all.
where can i manually set the scale for the bones. so they are wider along the x axis?
I spent a good chunk of time looking for it yesterday but couldn’t find it.
(hp/windows btw)
thx
D
ctrl+alt+s to scale the bone in edit mode
In Edit Mode - put your cursor at the centre of scaling, usually the tail end, select 3D cursor mode for pivot point, select the bone, key “s x 2 CR” without the quotes, this will scale the bone 2 times in its X axis. This approach works for any computer, any scaling operation, even with Wind’ohs (spit) teehee.
btw…“clock”?
I mend old clocks, such as Grandfather clocks in my spare time, when I’m not feeding spiders to the local bird population…
nope, tried, thanks for the suggestion. think it must be the keyboard. works on my laptop.
back to work for me!
Everyone have a great day
D
Say have already tried to fix this w/several new bones but i am still running into the same problem.
how can fix this so the leg will curl up and not forward?
thank you
D
ps i did a ctrl + n to recalculate the roll on the global z-axis several times but i see the legs on the right hand side do not want to do that.
http://www.pasteall.org/blend/33621
I made a quick rig to test out a theory I had using one bone control for a three bone chain. You can move the leg control and it will stick anywhere you place it. To get some control over the bend angles of the leg, I added copy rotation constraints to the upper leg bones. This allows you to rotate the controller on the local x and z axis (r+ xx or zz) to fine tune the direction of the leg bends.
I also used limits and locked some of the rotation axis on the bones in the inverse kinematics menu. Each is different, so look at the bones in the file for examples.
Good luck!
D,
Please use Octahedral display for your armature - then I and you, can tell which way round the bones are! I always align my bones Global X axis - don’t know why, I just do and it always works for me like that. It does look like all the bones Z axes are pointing up though… Probably another issue, like wrong axes locked in IK stiffnesses menu? wrong Limit Rotation constraint? Now I am guessing… Probably a good idea to take a peek at DanPro’s rig, which I will do tomorrow - it’s getting near my bed time in the UK.
DanPro,
I’ll look at your file tomorrow - just cooking an animation on my Mac, and an even bigger one on my server, so no free Blender just now. and I am getting tired, must be getting old…
Take care all. Clock.
One last thing I thought of; you are starting off with all the bones dead straight - how do they know which way to bend, Try and Internet search for Humane Rigging tutorial, it recommends slight bends in bones so when you rotate or move them they take the path of least resistance and go the way you want. Just a thought, what do you think DanPro?
DanPro, thank you will try it out.
Clockmender. I don’t believe you can segment a octahedral (tried) but as am new to this rigging thing i could be crazy wrong.
Will try this again & update tomorrow.
Cheers all
D
Hello again - here is your model using Octahedral display: 
That’s how I knew your jaw bones where the wrong direction…
Cheers. Tick-Tock.
DanPro - Yes I like your rig.
thx all will try to get this working in u3d and post a pic later on today.
D
Hello DanPro & Clockmender. I got a quick update here
got the spider going and spawining. And was able to add a run animation to it. Thanks again for the help.
D