Lesson #5 -Ants

INTRODUCTION

In this sketch we are going to create independent agents who draw for us. We will learn how to manage a large number of objects on the screen using only a little code.

SKETCH #5

This sketch using the concept of an object. Object-oriented programming (OOP) makes clean, human-readable code that is easily adaptable. Open Processing to a blank sketch. Click on the arrow to the right of the tab at the top of the Processing window and select "New Tab":

Now switch to the new tab you just created.

At the top of the tab we are going to define a new object. Class names are capitalized to distinguish them from variables:

• class RobotAnt {

float x = 0; //after we define a new class we will set its location and color using variables

float y = 0;

color col = 0;

Finally, we define how the RobotAnts will move:

• void crawl() {

x+= random(-1,1); //randomly move forward then backwards by 1 pixel

y+ = random(-1,1); //same

noStroke();

fill(col);

rect( x, y, 1, 1);

}

} //this bracket corresponds to the bracket next to the class name all of the code is under that.

Switch back to the first tab. First we initialize the objects we are going to use:

RobotAnt dave = new RobotAnt(); // here we initialized dave we say we are going to have an ant called dave from that class

RobotAnt frank = new RobotAnt();

Next we declare an object variable to determine how many ants we are going to make.

int antCount = 1000; // we are going to make 1000 ants using a new variable for the object

We are also going to set up a list called an array:

RobotAnt[] antList; //tell processing to expect an array called antList

...and now setup()

void setup() {

size(600,600);

background(255);

dave.x = width/2;

dave.y = height/2;

frank.x = width/2;

frank.y = height/2;

//populate the array so we can create ants

antList = new RobotAnt[antCount]; //make the array for new ants

for ( int i = 0; i < antCount; i ++) { //count the ants for us starting at 0 and less than 1000

println(i); //tell us what number we are at

RobotAnt newbie = new RobotAnt();

newbie.x = width/2;

newbie.y = width/2;

newbie.col = color(random(255), random(255), random(255));

antList[i] = newbie;

}

}

The void draw() portion of the code makes the ants leave a trail. Notice how it references back to the capabilities defined in the RobotAnt class:

void draw() {

dave.crawl();

frank.crawl();

for (int i = 0; i < antCount; i ++) {

antList[i].crawl();

}

}

Your finished project has the main code in the first tab and the RobotAnt class in the second tab.

More information:

Use the "Find in Reference" command and explore these commands:

• class