Processing: Creative Coding and Computational Art

Before moving on, try experimenting with the values for xSpeed, gravity, damping, and
friction. You should easily be able to simulate different gravities (as you’d encounter on
different planets), as well as different materials for the rectangle and ground surface. For
example, to simulate a lead block being dropped on the moon and landing on a rough surface,
you could try the following settings:
speedX = 1;
gravity = .02;
damping = .85;
friction = .6;
To simulate a lacrosse ball landing on Jupiter on a super smooth, slick surface, try the
following:
speedX = 5;
gravity = .98;
damping = .75;
friction = .99;
Figure 11-8 shows these two scenarios side by side, without a background() call in draw().
Figure 11-8. Simple Motion Physics I sketch
Converting this sketch of a single bouncing rectangle with naturalesque physics to many
rectangles is as easy as creating arrays for each of the individual variables and adding for
loops within the setup() and draw() functions. That being said, all the array syntax can
look a little intimidating.
In addition to the arrays, I added three variables (shapeCount, birthRate, and sprayWidth)
to control how the rectangles are born. Without controlling the birthrate, all the rectangles
would be born at the same time, creating a much less interesting effect than the spray
effect we get in the sketch. Also, by using the sprayWidth variable in setting the xSpeed[]
values, I can control the width of the spray. Output from the sketch is shown in Figure 11-9.
MOTION
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