Game Development Reference

In-Depth Information

CHAPTER 6

Projectiles

This chapter is the first in a series of chapters that discuss specific real-world phenomena

and systems, such as projectile motion and airplanes, with the goal of giving you a solid

understanding of their real-life behavior. This understanding will help you to model

these or similar systems accurately in your games. Instead of relying on purely idealized

formulas, we'll present a wide variety of practical formulas and data that you can use.

We've chosen the examples in this and later chapters to illustrate common forces and

phenomena that exists in many systems, not just the ones we'll be discussing here. For

example, while
Chapter 16
, “Ships and Boats,” discusses buoyancy in detail, buoyancy

is not limited to ships; any object immersed in a fluid experiences buoyant forces. The

same applies for the topics discussed in this chapter and
Chapter 15
,
Chapter 17
,
Chap‐

ter 18
, and
Chapter 19
.

Once you understand what's supposed to happen with these and similar systems, you'll

be in a better position to interpret your simulation results to determine if they make

sense—that is, if they are realistic enough. You'll also be better educated on what factors

are most important for a given system such that you can make appropriate simplifying

assumptions to help ease your effort. Basically, when designing and optimizing your

code, you'll know where to cut things out without sacrificing realism. This gets into the

subject of
parameter tuning
.

Over the next few chapters, we want to give you enough of an understanding of certain

physical phenomenon such that you can tune your models for the desired behavior. If

you are modeling several similar objects in your simulation but want each one to behave

slightly differently, then you have to tune the forces that get applied to each object in

order to achieve the varying behavior. Since forces govern the behavior of objects in

your simulations, we'll be focusing on force calculations with the intent of showing you

how and why certain forces are what they are instead of simply using the idealized

formulas discussed in
Chapter 3
. Parameter tuning isn't just limited to tuning your

model's behavior—it also involves dealing with numerical issues, such as numerical