Game Development Reference
In-Depth Information
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the z-axis
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the xy, xz, and yz planes
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Section 1.3.2
describes how to specify the location of a point in the
3D plane using Cartesian (x,y,z) coordinates.
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Section 1.3.3
introduces the concepts of left-handed and right-handed
3D coordinate spaces. The main concepts introduced are
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the hand rule, an informal definition for left-handed and right-
handed coordinate spaces
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differences in rotation in left-handed and right-handed coordi-
nate spaces
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how to convert between the two
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neither is better than the other, only different
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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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