Cameras - Game Programming Algorithms and Techniques - page 193

Some follow cameras very rigidly trail the target, whereas others have some
amount of springiness. Some allow the player to manually rotate the camera while
in follow mode, whereas others don't. Some might even let the player instantly
flip the camera to observe what's behind them. There are many different ways this
type of camera may ultimately be implemented.
Cutscene Cameras
An increasing number of games have cutscenes —that is, scenes that cut away
from the actual gameplay in order to advance the story of the game in some man-
ner. To implement a cutscene in a 3D game, at a minimum there needs to be a
system to specify a series of fixed cameras while the animation plays. But most
cutscenes use more cinematic devices such as panning and moving the camera,
and in order to do this, some sort of spline system is typically also utilized, which
we'll discuss later in the chapter.
Perspective Projections
As discussed in Chapter 4 , a perspective projection is one that has depth percep-
tion. That is to say, as objects become further and further away from the camera,
they appear smaller and smaller. We briefly touched on the parameters that drive
the perspective projection in Chapter 4 , but now it's time to look at this topic in
more detail.
Field of View
The amount of the world that is visible at any one time is expressed as an angle
known as the field of view (FOV). As humans, our pair of eyes affords us nearly
a 180° field of view, though not with an equal amount of clarity. The binocular
field of view, which is what can be seen with both eyes simultaneously, is approx-
imately 120°. The rest of our field of view is in the peripheral, which is good at
detecting movement but not necessarily able to effectively focus.
Field of view is an important consideration when setting up the perspective pro-
jection because an incorrect field of view can lead to eye strain, or worse, motion
sickness for certain players. To see how this comes into play, let's first take a look
at the field of view for a console gamer playing on an HDTV.
The recommended viewing distance for an HDTV varies depending on who you
ask, but THX recommends taking the diagonal measurement and multiplying it
by 1.2. So a 50” television should be viewed from approximately 60” (or 5').
With this distance, the television has a viewing angle of approximately 40°, which