Blender Tutorial 33 - IK Controllers and Bone rolls

in this tutorial we're going to talk about simple ik controllers and also we're going to talk about bone rolls and what those are so um following on from the previous tutorial I've taken this a step back so we have an Armature here but it's not sorry my Pivot Point needs to be changed to the median point it's not parented two or the mesh isn't parented to the Armature yet so the Armature doesn't deform the mesh um so the reason I've kind of taken that a step back is when you're going to be using ik controllers it's important to pre-bend the joints that are be going to be controlled with ik controllers and what ik stands for is inverse kinematics meaning kind of backward movement so rather than go through and say I want to pose this arm in this particular way so that the arm is raised up like the person's taking an oath here I have to start at the upper arm then move to the forearm then move and pose the hand that's called forward kinematics basically I move from the top of the chain downward with uh inverse kinematics I control it more like a puppet so I'm going to put a control on the wrist and it will allow me to kind of grab the wrist and move a chain of Bones meaning the forearm and the upper arm in this instance and they'll they'll kind of all move to follow that controller and it's important to pre-bend the joints this uh this model has some good pre-bend in the elbows you see the elbows just slightly bent there and the knee is slightly bent so that my ik controllers I know which direction the joint is intended to bend so in order to create an ik controller we can now go through and we'll just we'll parent the mesh here so selection orders always child meets your parent so we select the child first shift click to select the Armature and then hit Ctrl p and we're going to go through and select our Armature deform option with automatic weights you can see just like we mentioned in the previous tutorial that that now put a bunch of vertex groups into our mesh data and it also added an Armature deformation modifier in the modifier stack so now if we go into pose mode you can see that we are deforming the mesh and that's working reasonably well so we're just kind of going to leave it as it is um on the Armature I'm going to now tab into edit mode and I'm going to create my controls my ik controls so I'm going to select this the tip of the forearm bone right at the wrist there and I'm going to extrude and I still have my x-axis mirror option in my tool options but now I'm going to extrude a control backward and you'll see because we're mirrored that extruded one on both sides so I'm going to rename this bone instead of forearm underscore l.001 I'm going to rename this and I'm going to start a naming schema here for bones that don't directly deform the mesh and that is going to be my control bone so Ctrl underscore ik underscore hand underscore l and that's the schema I'm going to use so we'll rename the other one Ctrl underscore ik underscore hand underscore r so that those stay mirrored and um I'm going to go forward and parent this incorrectly so that you can kind of see the result because that's a really common error here and then I'll correct it so that you can see what the what the correct parenting should be now that we have this in place let's control tab back into pose mode and we're going to add a bone constraint onto this forearm bone here so when we're in pose mode that option those properties show up over here bone constraint properties we're going to add an inverse kinematics bone constraint and that of course changes the color of our bone here the target is going to be our Armature and you'll see we have a new kind of a sub object here that bone is if I just search for control or CT then I get my ik hand controller here and that changes the bone color here as well it turns yellow when its targets actually have usable data in there okay so um the next thing I need to do is I need to define a chain length so the chain length in this instance is going to be two bones that I'm going to control with this target one is the forearm and two is the upper arm so you'll notice that when I type that two I get a little dotted line from the one end of the chain to the other so basically from wrist to shoulder now and other than the incorrect parenting that should be enough to now control this arm but if I tap G you'll see that nothing moves here and that is because this control bone is parented to the forearm bone because I extruded it out of the tip so it's a child of the forearm and the forearm has been told by this ik bone constraint to follow that Target bone so it's circular they're trying to follow each other and that doesn't work so I I try to grab this bone and just nothing happens so in order to fix that let's just tab into edit mode really quickly and since we're mirrored this will fix both sides I'm going to clear the parent on this ik controller and just hit alt p we'll hit clear parent now we'll tab back to pose mode and if I move this bone around now you can see that it moves the whole chain it moves the upper arm and the lower arm and of course the hand is a child of those bones so it comes with it and that's a really handy way to move things around so that's an ik constraint and we're also going to create a pull Target so I'm going to tab back into edit mode what a pull Target is is it allows us a little more Precision when we're working with IKS by providing a target for our mid joint in this case the elbow to aim at so we're going to create a bone back here in the back we're going to hit shift d and duplicate this ik controller and we want to put it far enough back that the elbow can't pass it because if the elbow passes its Target then it will flip around the other direction trying to aim at it um and let's just kind of move these in so they're sort of right behind the elbows let's rename these so this is going to be control underscore pull underscore elbow underscore l and we'll do the same thing over here control underscore pull underscore elbow underscore r kind of click back and forth and make sure those names look like they are the same other than the underscore R and underscore L and they are so now go back into pose mode and we will modify our inverse kinematics constraint here to have a pull Target and again we're just going to specify the Armature and that that option gives us a sub option well which bone so again we can look for our control bones and I'm going to choose control pull elbow l and quite often you get this twisting and that needs to be corrected by just adding a pole angle and in this instance the pole angle is going to be minus 90. and now I can once again move this object around and the elbow is going to aim it's going to try to point toward that pull Target if I move the pull Target then I move the direction that the elbow is aiming so if I for instance put that pull Target clear down here and then move the arm around you can see that that elbow tries to point downward okay so that's an ik con controller with a pull Target the last thing we're going to talk about here is bone rolls so I'm going to reset our poses alt R clears rotations alt G clears our movements and ALT s clears any scaling operations we've done in pose mode and I'm going to tab back into edit mode now so each bone in edit mode under our just item transforms here it has a roll value now in order to see what that role should be we need to go and go into our Armature properties and in our viewport display check the box for the axes and I like to move these axes about halfway down the bone so that you can see them and what we're going to do here is we're going to try to get most of these bones uh their most prominent kind of default Bend we want to be along the x-axis so you can see like the head bone and the spine bones here those are all the x-axis is pointing right out the side you can imagine if that were a hinge pin that's the direction they would rotate around that pin and that's the direction we want them to rotate but some of our axes are not really quite working that way and actually the arm's looking pretty good which is a little bit surprising the hand bone here is not looking quite right so let's whoop selected the wrong one let's select that hand bone and then we're just going to drag this roll option so that that x-axis sort of looks like if this if this hand were to close around it it would grip it like a handlebar basically and then of course our legs are really messed up here so let's uh let's correct those roles so that X kind of sticks out the back so that if the leg moves back and forth and it looks like actually a roll of zeros about right there if the leg were to move back and forth or if the knee were to bend in this instance with the shin it would see you know what I want it out farther than that here we go it would bend around that x-axis without injuring the knee um so let's fix our foot it's good let's fix our toes and you really only have to fix one side if you've gotten your naming conventions right and you have everything mirrored properly you only have to fix one side and the other side will fix as well and that looks a lot better so the reason that we need those x-axis lined up is that later on when we get to using bone constraints and things like that we need to be able to be consistent in bending the bones around a particular axis and that will help us an awful lot it won't be arbitrary it'll be a controlled parameter so those are ik controllers and Bone rolls and I hope that's helpful happy blending

Channel: Alex Chamberlain

Views: 2,887

Keywords: Blender, 3D, rig, animation, how to, IK, Inverse, Kinematics, Roll

Id: tXaMfKnfzFw

Length: 12min 51sec (771 seconds)

Published: Wed Jan 18 2023