Wire Parameters and Custom Attributes :
Wire Parameters, in conjunction with Custom Attributes can be used to control multiple objects from just one object. We use wire parameters and the parameter wire dialogue ( under the animation menu ) to control the position/rotation/modifier attributes of an object, then we use the parameter editor to set properties that will go on our custom attribute. We'll be using this method for our characters hands, so we can control the rotation of his fingers and thumb, with the same spline that moves and rotates the hand. The Wire Parameters themselves work a bit like the reaction manager, in that we need to state exactly what axis of rotation or position we want the object to move along, but instead of acting out the movements in a recorded actions fashion, we set them to be controlled with spinners or sliders.
We'll begin with a bit of preparation... with the rotate tool selected and on the 'Local' Axis, rotate one of your fingers in the direction in which you want it to rotate. Make a mental note of which axis it rotates on, as we'll need to know this in a short while. Cancel the rotation of the finger by either right clicking once before you release the left mouse button. Or, if you've already committed to the rotation, just 'Undo'.
Now select the Spline that controls the movement of the arm ( and the rotation of the hand ) And put an Attribute Holder on it.
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Now we need to add in an Attribute, to do this we open up the Parameter Editor (
Under the Animation Menu )
Under 'UI Type' in the Attribute roll-out Choose your type and name. I personally prefer the Spinner over the Slider, as with the spinner you can adjust the range via numbers, as well as sliding the arrow bar. The first finger that I will do is the
Index , so name accordingly, and hit the 'Add' button. This will now place the Attribute on our spline in the Attribute Holder modifier.
You can ignore the 'From' and 'To' range for now ( in the parameter editor ) as not only do we not know what kind of range we'll need, we don't even have any movement/rotation yet.
With the Index attribute now loaded into our Attribute Holder, we can set up a Wire Parameter on our finger. With the arm spline still selected, right click it and select Wire Parameters. From the drop down menu. ( or Animation > Wire Parameters > Wire Parameters... )
A new menu will pop up for the spline, in this you need to tell Max that the Modifier ( Attribute holder ) on this object will have influence over the Parameter we previously set. ( Index finger )
When the index option is selected, you need to drag the cursor over to the initial bone of the index finger, click, and set its transform properties.
Once this is done, the Parameter Wiring box will pop up, select its direction of control (right arrow) and hit connect.
You should now be able to adjust the Custom Attribute, and have it effect the rotation of the finger. Only problem is, is that we will be able to rotate the finger more than we really need to.
To make it easier to work with, we need limits so you need to open up the Parameter Editor again and hit the ' Edit/Delete ' button. From here, select your spinner and adjust the 'To' and 'From' ranges. Then hit the 'Apply Changes' button in the Edit window.
I can't say what sort of ranges you will need, but I have gone from 0.0 To 2.0. After you have found your desired ranges, we need to apply the same method to the other bones on the index finger. And also set up new Attributes for the other fingers. It's a basic case of repeating yourself over and over though, so you shouldn't get lost if you've already made it this far.
So with the first finger done, all you need to do is open up the Parameter Editor again, and add in new fingers to the Attribute Holder that is on our spline. I add the extra fingers in after the first one, because this means the ranges wont need to be changed again ( or changed very slightly ) as it will remember our last input for every new finger we create.
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So go ahead and rig up the rest of your fingers, if you're unsure about anything, just go back and follow the previous steps. It's all exactly the same, except for our thumb, Which I will go onto now.
I've included a 'Thumb Roll' in my Attribute Holder, this will allow the thumb to move in a more natural manner, rather than just a standard bone rotate on one axis. It's the same method we used for the other joints on the fingers, except our initial thumb bone gets a different axis of rotation than the last two bones. So the Thumb Roll attribute is reserved solely for the initial bone, whereas the Thumb attribute is for the rotation of the last two bones on the thumb.
Thumb, Fingers, Arm and Hand rotation/movement all in one spline... how about that eh?
Do the same for the other hand. And then we're good to take a crack at Skinning our character up.
One More lesson left and you're free! Time for the Skinning process.
