Day2_WalkerAttractionApp.cpp

#include "cinder/app/App.h"
#include "cinder/app/RendererGl.h"
#include "cinder/gl/gl.h"
#include "Walker.h"

using namespace ci;
using namespace ci::app;
using namespace std;

class Day2_WalkerAttractionApp : public App {
  public:
    void prepareSettings( Settings *settings );
	void setup() override;
	void mouseDown( MouseEvent event ) override;
	void update() override;
	void draw() override;
    
    Walker *mWalker1;
    Walker *mWalker2;
};

void Day2_WalkerAttractionApp::prepareSettings( Settings *settings )
{
    settings->setWindowSize( 640, 320 );
}

void Day2_WalkerAttractionApp::setup()
{
    mWalker1 = new Walker();
    mWalker2 = new Walker();
}

void Day2_WalkerAttractionApp::mouseDown( MouseEvent event )
{
}

void Day2_WalkerAttractionApp::update()
{
    mWalker1->step(*mWalker2);
    mWalker2->step(*mWalker1);
}

void Day2_WalkerAttractionApp::draw()
{
//	gl::clear( Color( 0, 0, 0 ) );
    gl::clear( Color( 0, 0, 0 ) );
    mWalker1->display();
    mWalker2->display();
}

CINDER_APP( Day2_WalkerAttractionApp, RendererGl )

Walker.cpp

//
//  Walker.cpp
//  Walker
//
//  Created by Kat Sullivan on 12/12/17.
//
//

#include "Walker.h"
#include "cinder/Rand.h"

using namespace ci;
using namespace ci::app;
using namespace std;

Walker::Walker() {
    Rand::randomize();
    x = randInt(getWindowWidth());
    y = randInt(getWindowHeight());
}

void Walker::display() {
    cinder::gl::color(1.0, 0.0, 0.0);
    cinder::gl::drawSolidEllipse(vec2(x,y), 1.0, 1.0);
}

void Walker::step(Walker w) {
    int stepX=0;
    int stepY=0;
    
    if (w.x - this->x > 0) {
        stepX = randInt(-1,3);
    } else if(w.x - this->x < 0) {
        stepX = randInt(-2,2);
    }
    
    if (w.y - this->y > 0) {
        stepY = randInt(-1,3);
    } else if(w.y - this->y < 0) {
        stepY = randInt(-2,2);
    }
    
    this->x += stepX;
    this->y += stepY;
}

Walker.h

//
//  Walker.h
//  Walker
//
//  Created by Kat Sullivan on 12/12/17.
//
//

#pragma once

class Walker {
public:
    int x;
    int y;
    Walker();
    void display();
    void step(Walker w);
};