How (not) to apply a skin to a skeleton

To create a character for a game, we need to apply a body structure that fits the intended role in the game. For example, a male wizard has a different body than a female elf, and both are completely different to a human blacksmith. Therefore, the skin needs to reflect the amount of muscle and fat on the body of the model to appear plausible.

Naive model skinning

The naive way of applying a skin to a character skeleton is by using constant distances from the start and end of a node. This works if the entire model moves, but if individual nodes are rotated or translated, the character body will be distorted in an unwanted manner. In Figure 9.4, you can see the effect of the rotation of the middle and right nodes of a part of a functional character:

Figure 9.4. Naive idea of applying the skin to moving nodes gone wrong

Nodes are shown as blue arrows, vertices are red dots, and the skin is depicted by the red...