Game Development Reference
In-Depth Information
the z-axis
the xy, xz, and yz planes
Section 1.3.2 describes how to specify the location of a point in the
3D plane using Cartesian (x,y,z) coordinates.
Section 1.3.3 introduces the concepts of left-handed and right-handed
3D coordinate spaces. The main concepts introduced are
the hand rule, an informal definition for left-handed and right-
handed coordinate spaces
differences in rotation in left-handed and right-handed coordi-
nate spaces
how to convert between the two
neither is better than the other, only different
Section 1.3.4 describes some conventions used in this topic.
1.3.1 Extra Dimension, Extra Axis
In 3D, we require three axes to establish a coordinate system. The first
two axes are called the x-axis and y-axis, just as in 2D. (However, it is not
accurate to say that these are the same as the 2D axes; more on this later.)
We call the third axis (predictably) the z-axis. Usually, we set things up so
that all axes are mutually perpendicular, that is, each one is perpendicular
to the others. Figure 1.10 shows an example of a 3D coordinate space.
Figure 1.10
A 3D Cartesian coordinate space
As discussed in Section 1.2.2, it is customary in 2D for +x to point to
the right and +y to point up. (Or sometimes +y may point down, but
 
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