Adding custom attributes and controllers - Part 1


Having skinned the character, it was now time to take care of the IK and FK chains blending and add the (custom) controls for the rig. Adding a set of manipulators (controllers) is important because it ‘…makes it easy to animate by the animators’ whilst not adding any would result in ‘…making the pipeline of character animation more time-consuming, difficult and problematic’ (Bhati, Karbasi, Mahesar and Waqas, 2015). It all comes down to how easy an animator can control individual bones and bone chains, as instead without any controllers even selecting a bone would take much longer. However, the subject goes lengths beyond that with certain bones having bound to them certain reactions, constraints (limits) and more.

I have started the process by freezing and hiding the mesh first, as using or interacting with it was not necessary for this task. Following an extensive online video guide I’ve found, I have started by creating an IK chain (using the ‘HI Solver’ option under the ‘Animation’ tab) between two bones, namely the left heel and the left thigh. What that did was to link the movement of a bone to the other, so that when the heel was raised the thigh followed on a logical pattern determined by the algorithms the tool was based on. The result in question can be seen below:



The blue star like figure in the GIF above is the result of an IK chain between two bones. It is called an IK goal and it is used in moving the bones as described above. So now instead of selecting the heel bone you would select the goal, recreating the IK movement as established. For the same result I have then chained the ‘ball’ to the heel and the toe to the ball in the logical order.

To make the animator’s job easier which results in a lot of saved time, custom shapes are then attributed to the IK chains (to the goals). These shapes are called helpers and they can come in any type of shape or form, colour or size, all depending on the animators’ needs. I have so created a few green, wireframe cubes that can be selected instead of the goals, making everything easier. These cubes have been carefully aligned (using the ‘Align’ tool) to the joints as seen in the next image.



The helpers were then linked (using the ‘Link’ tool) to their respective IK goals. One of the helpers was linked to two IK goals instead, to create the ‘Heel peel’ effect where rotating the helper would make the heel follow the ball of the foot. The effect can be seen below:



 The next step was creating a main foot controller with the help of the line tool under the create panel. I have drawn a shape and adjusted its corners to look like a rectangle. It was then placed underneath the shoe sole like an outline and bound to the heel helper. The foot controller was now usable. Rotating or translating the controller would make all the affected bones to follow as affected by their respective IK solvers.

Adding custom attributes was the next task. An ‘attribute holder’ modifier was added to the foot controller. Then the parameter editor was opened using the key combination ‘Alt+1’. I have then added all the necessary foot interactions as custom attributes. For example, instead of selecting the toe helper to rotate it I could now look for the ‘Toe twist’ attribute in the list on the right, simplifying the process.



After creating the attributes list, reactions were now to be added. In the reaction manager window (under the ‘Animation’ tab) I have selected each attribute in the list and added a custom reaction, such as adding a Zero Euler XYZ rotation on the Z axis for the Heel Peel attribute. Doing so allowed me to input the constraints for the slider:

  • -          If the slider was on 100% (or 10), the heel would be lifted to a 60° angle (-60° in this case due to the axis orientation).
  • -          Similarly, if the slider was on 0 then the heel would stay in its resting state. Any in-between value would be calculated by the existent algorithms.



So as I said, using the reaction manager I have added a custom reaction to each individual attribute created earlier. I have then inserted the limits (or constraints) of each attribute so that it won’t allow for twisting the toe more than it’s naturally possible, for example. At the end I have tested each slider to make sure the bones motion was correct and each custom attribute was working properly.

References:
Bhati, Z., Waqas, A., Karbasi, M. and Mahesar, A.W. (2015). A Wire Parameter and Reaction Manager based Biped Character Setup and Rigging Technique in 3Ds Max for Animation. International Journal of Computer Graphics & Animation, 5(2), pp.21–36.

YouTube. (2012). Rigging a Character in 3ds Max - Part 4 - Foot Reactions. [online] Available at:https://www.youtube.com/watch?v=glL0_EJKiaE&index=28&list=PLnKw1txyYzRlxh1-BT4CifPXC5TBg2vUd [Accessed 6 Feb. 2019].

 YouTube. (2012). Rigging a Character in 3ds Max - Part 3 - Custom Foot Attributes. [online] Available at: https://www.youtube.com/watch?v=8f6Xs79T-TA&list=PLnKw1txyYzRlxh1-BT4CifPXC5TBg2vUd&index=27 [Accessed 6 Feb. 2019].

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