Game Development Reference
In-Depth Information
Figure 3.3
Vector addition and the parallelogram rule.
Notice how there are two permutations: one where is the first vector and one
where is the first vector. But regardless of the configuration, the result is the
same. This is known as the
parallelogram rule
, and it holds because vector addi-
tion is commutative, just like addition between two real numbers:
Subtraction
In vector subtraction, the components of two vectors are subtracted from each oth-
er.
To geometrically subtract two vectors, draw them such that both vectors' tails are
at the same position, as in
Figure 3.4(a)
. Then construct a vector from the head
of one vector to the head of the other. Because subtraction isn't commutative, the
order is significant. The best way to remember this is that if you want the resultant
vector to go
from to
, the calculation is
.
