Hair Weights

Because the hair joints are not symmetrical, we can't rely on weighting the left side and mirroring the weights across for the right.

NOTE

Before continuing with the work in this section, It's important that you are entirely finished with all Mirror Weights operations on this character. If you proceed with any nonsymmetrical work and then notice problems that require remirroring, you'll have to redo all your nonsymmetical work. In addition, it's a good idea to keep saving your work as you go, so you can easily refer back to some previous weights if you make a mistake.

At this point it would be useful to turn on the base skeleton so you can see the positions of the hair joints.

1.	As shown in Figure 14.41a, move the individual controllers for the hair outside the head. Figure 14.41. Fully weight each strand of hair to its closest joint. TIP You can quickly turn off all the icons by going to the view's Show menu and disabling NURBs Curves.
2.	Select the character mesh and open the Paint Skin Weights tool, highlighting the first hair joint, Hair_A (Figure 14.41b).
3.	With both Value and Opacity set to 1, begin to paint over the polygonal strands of hair that are closest to the joint. Start on the outside and work your way in, making sure you don't paint too far up the head (Figure 14.41c).
4.	Repeat these steps for the remaining strands of hair, weighting them fully to their closest joints (Figure 14.41d).
5.	At present, if the hair moves, it will look quite rigid because we have fixed the vertices rigidly to each joint (Figure 14.42, left). To help free the hair, allowing it to flow more naturally, paint over the strands again, but this time use the Smooth paint operation (Figure 14.42, right). Figure 14.42. Smooth out each strand of hair, allowing the hair more movement.

Our aim was to give Kila's hair some life, "unlocking" it from her head, and we have achieved that. You can now animate the controls, and the hair will follow smoothly.

You have one more step to complete the weighting process on Kila, and that is to remove any small weights that have been applied as you worked. While painting the weights, you may have applied smaller weighting values to other joints without really noticing. These are often relics of using the Paint Skin Weights tool's Smooth or Replace paint operations. Upon export into the game engine, these might be removed, but if they are not they could have an impact on the processing power of the system.

So let's get rid of them. Select the character mesh and go to Skin > Edit Smooth Skin > Prune Small Weights. The default value of 0.01 will work well in most cases, but to be safe, save your scene before applying this to your model. Any values below 0.01 will be reset to 0, and the remaining weights will be normalized to add up to 1.