Processing: Creative Coding and Computational Art

lower particle speed
ySpeed[i]*=gravity;
// keep particle from sliding out of window
y[i]=height;
}
This expression slowly reduces the particle’s velocity (ySpeed) until it is very near zero.
However, because ySpeed will actually never reach zero, I am forced to add the final
assignment, y[i]=height, which keeps the particles from slowly creeping off the bottom
of the screen. I’ll revisit this issue again in more detail in Chapter 11. As always, play with
the code. If you comment out this last assignment, you should notice the output is a little
lower in relation to the display window.
In the next example (shown in Figure 7-11), I pushed this particle effect a little further,
utilizing a new material property, more randomization, and additional display edge detection.
There’s nothing really new in the example, but it should reveal some more of the
interesting effects you can get coding curved motion. This example can take a long time to
render—up to 30 seconds. Decreasing the strokeWtMin and strokeWtMax argument values
will speed things up. However, on some systems, too small a value may make the curves
undetectable.
/*
Curves III
Ira Greenberg, December 4, 2005
// this takes some time to render
*/
// changeable variables
int particles = 125;
int timeLimit = 2000;
float particleSpan = 2;
float accelMin = .005;
float accelMax = .2;
float strokeWtMin = 1.25;
float strokeWtMax = 1.6;
float materialMin = .25;
float materialMax = .99;
float gravity = .9;
// not meant to be changed
int timer;
float[]x = new float[particles];
float[]y = new float[particles];
float[]xSpeed = new float[particles];
float[]ySpeed = new float[particles];
float[]accel = new float[particles];
float[]material = new float[particles];
float[]strokeWts = new float[particles];
CURVES
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