Boid

Bird.h

#pragma once
#include "ofMain.h"

class Bird
{
public:
    Bird(vector<Bird>* const, const int, ofColor, vector<Bird>* const, vector<Bird>* const, vector<Bird>* const);
    virtual ~Bird();
    
    virtual void update();
    virtual void draw();
    
    int id;
    float head;
    float tail;
    ofVec2f pos;
    ofVec2f vel;
    ofVec2f acc;
    ofColor ourColor;
    
protected:
    vector<Bird>* pSelfGroup;
    vector<Bird>* pEnemyGroup;
    vector<Bird>* pFriendGroup;
    vector<Bird>* pFriendGroup2;
    
    ofVec2f separationVel;
    ofVec2f alignmentVel;
    ofVec2f cohesionVel;
    ofVec2f groupCenterPos;
};

Bird.cpp

#include "Bird.h"

Bird::Bird( vector<Bird>* const _pSelfGroup, const int _id, const ofColor _ourColor, vector<Bird>* const _pEnemyGroup, vector<Bird>* const _pFriendGroup, vector<Bird>* const _pFriendGroup2 )
{
	pSelfGroup = _pSelfGroup;
	pEnemyGroup = _pEnemyGroup;
	pFriendGroup = _pFriendGroup;
	pFriendGroup2 = _pFriendGroup2;
	id = _id;
	ourColor = _ourColor;
	pos.set( ofRandom(0,ofGetWidth() ) , ofRandom(0,ofGetHeight() ) );
	vel.set( ofRandom(-2,2), ofRandom(-2,2) );
	head = 2;
	tail = head * 4.0;
}

Bird::~Bird()
{
}

void Bird::update()
{
	int separationCount = 0;
	int alignmentCount = 0;
	int cohesionCount = 0;
	separationVel.set(0,0);
	alignmentVel.set(0,0);
	cohesionVel.set(0,0);
	groupCenterPos.set(0,0);

	for(int i = 0; i < pSelfGroup->size(); i++){
		Bird& rAnother = pSelfGroup->at(i);

		if(rAnother.id != id){
			float dist = pos.distance( rAnother.pos );

			if(dist < 10){
				separationVel += pos - rAnother.pos;
				separationCount++;
			}
			else if(dist < 35){
				alignmentVel += rAnother.vel.getNormalized();
				alignmentCount++;
			}
			else if(dist < 60){
				groupCenterPos += rAnother.pos;
				cohesionCount++;
			}
		}
	}

	for(int i = 0; i < pFriendGroup->size(); i++){
		Bird& rAnother = pFriendGroup->at(i);
		float dist = pos.distance( rAnother.pos );

		if(dist < 10){
			separationVel += pos - rAnother.pos;
			separationCount++;
		}
		else if(dist < 35){
			alignmentVel += rAnother.vel.getNormalized();
			alignmentCount++;
		}
		else if(dist < 60){
			groupCenterPos += rAnother.pos;
			cohesionCount++;
		}
	}

	for(int i = 0; i < pFriendGroup2->size(); i++){
		Bird& rAnother = pFriendGroup2->at(i);
		float dist = pos.distance( rAnother.pos );

		if(dist < 10){
			separationVel += pos - rAnother.pos;
			separationCount++;
		}
		else if(dist < 35){
			alignmentVel += rAnother.vel.getNormalized();
			alignmentCount++;
		}
		else if(dist < 60){
			groupCenterPos += rAnother.pos;
			cohesionCount++;
		}
	}

	for(int i = 0; i < pEnemyGroup->size(); i++){
		Bird& rAnother = pEnemyGroup->at(i);
		float dist = pos.distance( rAnother.pos );

		if(dist < 60){
			separationVel += pos - rAnother.pos;
			separationCount++;
		}
	}

	separationVel /= separationCount;
	separationVel.normalize();

	alignmentVel /= alignmentCount;
	alignmentVel.normalize();

	groupCenterPos /= cohesionCount;
	cohesionVel = groupCenterPos - pos;
	cohesionVel.normalize();

	vel += (separationVel*0.15) + (alignmentVel*0.035) + (cohesionVel*0.02);

	vel.scale(1.5);
	pos += vel;

	if( pos.x < 0 ){
		vel.x *= -1;
	}
	else if( pos.x >= ofGetWidth() ){
		vel.x *= -1;
	}
	if( pos.y < 0 ){
		vel.y *= -1;
	}
	else if( pos.y >= ofGetHeight() ){
		vel.y *= -1;
	}
}

void Bird::draw()
{
	ofSetColor(ourColor);
	ofCircle(pos, head);
	ofLine(pos.x + vel.x * tail * 0.5, pos.y + vel.y * tail * 0.5, pos.x - vel.x * tail, pos.y - vel.y * tail);
}

ofApp.h

#pragma once

#include "ofMain.h"
#include "ofGraphics.h"
#include "Bird.h"

class ofApp : public ofBaseApp
{
public:

    void setup();
    void update();
    void draw();
    
    void keyPressed(int key);
    void keyReleased(int key);
    void mouseMoved(int x, int y );
    void mouseDragged(int x, int y, int button);
    void mousePressed(int x, int y, int button);
    void mouseReleased(int x, int y, int button);
    void windowResized(int w, int h);
    void dragEvent(ofDragInfo dragInfo);
    void gotMessage(ofMessage msg);

    vector<Bird> birds1;
    vector<Bird> birds2;
    vector<Bird> birds3;
    vector<Bird> birds4;
    vector<Bird> nullBirds;

	bool active;

};

ofApp.cpp

#include "ofApp.h"

#define BOID1 100
#define BOID2 80
#define BOID3 120
#define BOID4 50

#define BGCOLOR ofColor(0,0,0,32) // black
#define COLOR1 ofColor(255,0,0,255) // red
#define COLOR2 ofColor(0,255,0,255)  // green
#define COLOR3 ofColor(0,255,255,255) //cyan
#define COLOR4 ofColor(255,255,0,255) // yellow

#define FRATE 20

//--------------------------------------------------------------
void ofApp::setup()
{
    ofSetFrameRate(FRATE);
    ofEnableAlphaBlending();
    ofSetBackgroundColor(0,0,0);
    ofSetBackgroundAuto(false);
    ofSetCircleResolution(64);
    ofHideCursor();
    ofSetBackgroundColor(BGCOLOR);
	active = true;

    // self, enemy, friend1, friend2
    birds1.reserve(BOID1);
    for(int i = 0; i < BOID1; i++){
        birds1.push_back(*new Bird( &birds1, i, COLOR1, &birds2, &birds3, &nullBirds));
    }
    birds2.reserve(BOID2);
    for(int i = 0; i < BOID2; i++){
        birds2.push_back(*new Bird( &birds2, i, COLOR2, &nullBirds, &birds3, &nullBirds));
    }
    birds3.reserve(BOID3);
    for(int i = 0; i < BOID3; i++){
        birds3.push_back(*new Bird( &nullBirds, i, COLOR3, &nullBirds, &birds2, &nullBirds));
    }
    birds4.reserve(BOID4);
    for(int i = 0; i < BOID4; i++){
        birds4.push_back(*new Bird( &birds4, i, COLOR4, &birds1, &birds3, &nullBirds));
    }
}

//--------------------------------------------------------------
void ofApp::update()
{
	if(active){
		for(int i = 0; i < birds1.size(); i++){
			birds1[i].update();
		}
		for(int i = 0; i < birds2.size(); i++){
			birds2[i].update();
		}
		for(int i = 0; i < birds3.size(); i++){
			birds3[i].update();
		}
		for(int i = 0; i < birds4.size(); i++){
			birds4[i].update();
		}
	}   
}

//--------------------------------------------------------------
void ofApp::draw()
{
    ofSetColor(BGCOLOR);
    ofRect(0,0, ofGetWidth(),ofGetHeight() );
    
    for(int i = 0; i < birds1.size(); i++){
        birds1[i].draw();
    }
    for(int i = 0; i < birds2.size(); i++){
        birds2[i].draw();
    }
    for(int i = 0; i < birds3.size(); i++){
        birds3[i].draw();
    }
    for(int i = 0; i < birds4.size(); i++){
        birds4[i].draw();
    }
}

//--------------------------------------------------------------
void ofApp::keyPressed(int key){
	switch (key){
	case ' ':
		active = !active;
		break;
	case 'f':
		ofToggleFullscreen();
		break;
	case 's':
		ofShowCursor();
		break;
	case 'h':
		ofHideCursor();
		break;
	default:
		break;
	}
}