Post Nine

Creating the bones & rigging the legs.

In this post I will start to create the bones that will form to provide the basis for my character rig. To access the bone creation tools click systems-create-bones. In any view port I clicked once to create a bone then every time I click again another bone will be created, to finish the line of bones I right click and the nub is created, this ends the line or you can add bones later on from this nub if you wish to do so.
Once the line of bones has been created, I can modify the length width and size of fins, by using the Bone Edit Mode, found at animation-Bone tools. This will bring up a panel where you can modify all the necessary parameters. Basically the first thing to do was to line my character up in the top view port against the grid.
With my character lined up I started to create the pones for my characters legs, setting up the fins as I go, and making sure to rename all the parts so it makes selecting bones later on easily done. With one leg done I used the mirror tool in the bone edit mode, and created an exact copy, and renamed all the parts accordingly
The next part was to start to create the spine bones, all four of them, one for the neck and one for the head, name them etc. I started at the hips and worked up towards the head.One bit you must watch out for when doing it this way is that I need the spline and the legs to remain separate. When I start the spine it kept trying to connect to the bones already created, to work around this I created it a part behind the mesh then moved it into shape afterwards.
Again the fins are the hardest part to sort out, and require the most tweaking. Making sure the bone is wide enough and the fins widen it further, when I was happy with the outcome I carried on with the bones for the rest of the rig.
The arms came next, three sections for the arm, one for the palm and two bones and a nub for each of the fingers and thumb. I deleted the nub for the thumb as I won’t be needing it.
I will not be animating the hands much maybe only to hold the skateboard, if my character does a trick requiring him to do such a thing, so I tried to keep it all very simple. I used the mirror again to create the other side and renamed all the objects correctly as this will save time selecting the lot afterwards.
The final rig is complete. Now all that is left to do is setting up the IK chains; IK stands for inverse kinematics, this allows to control an entire chain by moving a child in the chain, an IK chain is a control object that allows manipulation of bones with the IK method. When it is created it appears as a crosshairs, it has special properties but if you were to click the modify tab nothing would show as most of the controls are shown on the motion panel.

Creating the IK chains for the feet; select the right calf and rotate the calf so it bends like a normal knee, this bend helps the Ik chain figure out which way it should bend, if I was to leave the leg straight it might bend in any direction unlike a normal human leg. Now select the thigh bone then choose animation > IK Solvers > HI Solver and select the right foot bone. This creates an IK chain, I created two more from the foot to the toe and the toe to the nub. Then I repeated the process for the other leg, then I renamed the IK chains to a more sensible name.
Now my chains for the legs are complete, I have 3 Ik chains for each of the legs. Now I must link the chains together, I select the first IK chain created the heel and chain to the ball, the ball to the toe and the toe to the nub and repeat the process for the other leg. To check they are all working in an hierarchy I can press the ‘h’ key to select an object and by checking the box display sub tree this shows the chains links have worked.
My legs have bones and IK chains animating my character at this stage would not be a good idea, to lift and bend well theres not much to it, but to stand on tip toes I would have to rotate all the chains individually and that’s just the leg parts, so I have decided to add a control object or two, this object would be customised to be able to move and rotate and bend the bones as they would in a human leg, it gets a bit complicated here but I managed to work the process out.

In 3ds Max one can use a box as a custom tool to do such a thing. To find the parameters to set the box up as a control object one has to navigate to Animation > Parameter Editor. This lets us connect the custom attribute to another value in the rig, First we need an extra object to control the rig, and shapes are a cool way to do this, they do not render so that’s one good aspect to consider and you don’t have to remember to hide it before rendering, in addition they use less geometry. I could use helpers such as points or dummies, but a box will be easier to create.
I have created a box underneath the foot and named it as the controlling object, copy it and position that under the other foot, and rename that one too. Now select the IKToe chain and link it to the box. Now I set the custom attribute to roll the feet. A range of 90 degrees will be used. In the parameter roll out for custom attribute I change the name to roll, set the float UI options range to 90 degrees and click add. Now on the modifier panel we can see the new parameter called roll.
Now I will use to reaction Manager to set up the Master and slaves, and the reactions for the custom Roll Attribute. I will try to explain this as best as I can but it can be rather confusing to start with, Choose Animation > Reaction Manager. In the dialog box, click add master then select the contrl box and then from the pop up menu select object, box, custom attributes, roll. Now select the IKBall and the IKToe and click the add selected and from that pop up menu select transform, IK goal, rotation, X rotation. This adds the two rotation parameters as slaves the first state has roll 0 and both chins in the rest position.
On the modify panel I pin the stack so as to show the roll parameter all the time, Now to create the reaction, one when the roll is 60 the heel will come off the ground and another 90 to have the foot in its fully rolled position. First thing to do is click the Create Mode in the reaction manager, then find the roll parameter on the modify panel and change to 60, then rotate the IKBall to 45 degrees then click Create state, then change roll to 90, rotate the IKToe to 80degress on the x axis, then rotate the ball back to 70 degrees to straighten the foot out, then click Create State. Turn off create mode. Now test the reactions by changing the roll parameter in the modify panel, if all goes well you should be able to see the foot roll smoothly as you change the roll.
This conclude this part of the Rigging process, in the next part I will sort some controls out for the spine, to twist and bend it, controls for the arms and finally the head, and hopefully when I have created these; moving, rotating and twisting the bones should be made easy just by moving the control objects I create.