Game Development Reference
In-Depth Information
Let's see what a typical trajectory under the gravity-only model looks like. We'll assume
that the y-components of motion are zero, so the trajectory will be restricted to the x-z plane.
Here are the initial conditions that will be used:
x
=
0
m
z
=
0
m
v
=
15
m/s
v
=
20
m/s
0
0
x
0
z
0
The x- and z-locations as a function of time are computed using Equations (5.8a) and
(5.8c). The resulting trajectory profile is shown in Figure 5-3.
Figure 5-3.
A typical trajectory under the gravity-only model
You might recognize the shape of the curve shown in Figure 5-3 as a parabola. One char-
acteristic of the gravity-only model is that it will always generate a parabolic-shaped trajectory.
The gravity-only trajectory is symmetrical in many ways. If the projectile is fired from a flat
surface, the amount of time the projectile takes going up is the same as the amount of time it
will take coming back down. The horizontal distance the projectile travels on the way up is the
same as the horizontal distance it travels on the way down.
