Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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Figure 3-7. Random rectangles
This example begins to reveal the power of functions. By passing, or inputting, different
values to the function, you can generate very different results. Functions create efficiencies
by helping you avoid writing redundant code. They also free you from having to write
all your code linearly, from top bottom, in your sketch. Once you define a function, you
can call it when you need it, as well as multiple times, as I did in the last example. The next
sketch uses Processing’s built-in draw() function to move a box across the screen.
Processing’s draw() function is called automatically when you include it in your sketch.
The draw() function increments the value of two speed variables I created (xspeed and
yspeed), which are assigned to two position variables I created (xpos and ypos). xpos and
ypos control the x and y positions of the box.
// simple ball
int xpos, ypos;
int xspeed=3;
int yspeed=5;
void setup(){
size(400, 400);
}
void draw(){
background(0);
rect(xpos, ypos, 10, 10);
xpos+=xspeed;
ypos+=yspeed;
if (xpos>=width-10 || xpos=width-10 || ypos