Let's take a look at these two figures (fig. 1a & 1b) and see how these correspond to
what you'll see in trueSpace when you are working with the joints. You see that there is
an arc with two closing ends, plus you see the line extending from the center-point. These
two images will be important to refer back to when we are adjusting the joints for the
shoulders and the hips. As they stand alone, you'll see that these are what we refer to as
1 Dimensional Hinge Joints. But, when put together (one in the vertical plane and
one in the horizontal plane) we get a 2 Dimensional Spherical Joint. 
TFigure 1a shows the 1D Hinge Joint part along the horizontal plane. This one part of the
joint will restrict motion along the horizontal plane. This is similar to your forward and
backward reaching ability. Picture your arm outstretched to the side, like the one in
Figure 1a, and that you can only move it so far back and so far forwards -- these are the
limits. The same for Figure 1b... You can only move your arm so much up and down. Take a
moment to see how other joints in your body can be "bent". It is important to know
how each joint works. Once you understand them, let's move on. |
