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Chapter 11 Animation Composition
the perception is that the book is not moving. This is because you are seeing it
relative to your own frame of reference. You, the car, and the book are traveling at
the same speed. If you held up the book, a person on the side of the road would
see the book moving even though the book is not moving from your perspective.
In video games, perception is determined by the camera. In a side-scrolling
2D game, the camera is looking at objects from the side. Motion is perceived as
left, right, up, and down. In a top-down 2D game, the camera location is above
the game looking down. In this view, motion is perceived as North, South,
East, and West. In a first-person shooter (FPS) game, the entire game map
moves with each step of the player character. Motion is perceived as all objects
moving while the player remains still. The player’s view remains centered on
the screen.
Translation
The most basic of all movement types is translation motion.
Translation
is the movement from one point to another. This is simple right-left, up-
down, and in-out movement. If a ball is located in the Cartesian coordinate
system at the coordinate (0,0,0) and it is translated to coordinate (5,0,0),
the ball has moved five units from the origin on the X axis. This is shown in
Figure 11-2.
Translation is very important in video game design. Each object on the
screen is plotted using the coordinate system. A collision occurs when two
objects have the same coordinates. Game designers must create collision
detection for all of the interactive objects in the scene.
Figure 11-1.
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A car has a positive acceleration vector when it is speeding up.
Positive Acceleration Vector
Velocity Vector
Negative Acceleration Vector
Velocity Vector