Rigging for Realistic Movement - Game Character Creation with Blender and Unity - page 160

Compare this frame rate to the one in Figure 7.4, where the frame rate rises to 16 fps
while having hundreds of unrigged models onscreen.

Figure 7.4
Unity game screen-
shot with unrigged
zombies

What benchmark tests like these show is that complicated animation rigs can drasti-
cally reduce the frame rate of videogames much more quickly than polygon counts can.
This is why for games much simpler rigs are used.

Bone Anatomy and Relationships
Part of the reason that armatures take up so much memory is the information they hold.
Not only do they tell the modeling environment and game engine how a mesh should
deform, but they also contain information on their relationships with one another.
All bones in Blender have three parts: the head (also called the root), the body, and the
tail (also called the tip), as shown in Figure 7.5. The head/root and tail/tip are both select-
able, which will come in handy later in this chapter.
In Blender, bones can be extruded from one another through either the tail/tip or
head/root of previously created bones. When a new bone is extruded from the tail/tip of
another, it is the child object of the first bone, which is its parent. Parents and children in
3D programs are linked in such a way that child objects follow the transform (position,
rotation, scale) and other attributes of the parent. The parent/child relationship will be
very important in Chapter 9, “Unity Engine Basics,” when you move to the Unity engine.
For now, understand that bones also have a parent/child relationship in that child
bones will follow the rotation of their parent. For example, later in this chapter you will
create an upper arm bone by extruding from the top of the spine. When the spine bone is
rotated along the z-axis, the upper arm will follow to create a realistic shoulder movement
(Figure 7.6).