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72 Getting Started with Processing
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}
float mx = map(mouseX, 0, width, 60, 180);
line(mx, 0, mx, height); // Black line
The map() function makes the code easy to read, because the
minimum and maximum values are clearly written as the
parameters. In this example, mouseX values between 0 and width
are converted to a number from 60 (when mouseX is 0) up to 180
(when mouseX is width). You’ll find the useful map() function in
many examples throughout this book.
Robot 3: Response
This program uses the variables introduced in Robot 2 (see
“Robot 2: Variables” on page 47) and makes it possible to
change them while the program runs so that the shapes
respond to the mouse. The code inside the draw() block runs
many times each second. At each frame, the variables defined
in the program change in response to the mouseX and mouse
Pressed variables.
The mouseX value controls the position of the robot with an easing
technique so that movements are less instantaneous and
feel more natural. When a mouse button is pressed, the values
of neckHeight and bodyHeight change to make the robot short: