Boid flocking algorithm
in
Programming Questions
•
2 years ago
The following code I began playing with from openprocessing.org. I'm interested in emergent systems and flocking patterns. It is interesting to me that flocks of birds and schools of fish will behave as a unit based on subtle cues. I used to think this happens less with people. Now I would argue that it happens across the board, with people, with the spread of ideas, etc. What I would like to do with this code is draw in another boid of a different color (we'll say green because it is a cool and natural color). This boid will not be controlled by the flocking algorithm but will move randomly. However, when it gets very close to another boid it will turn that boid green which will then spread throughout the flock, one by one. That being said, I'm not sure how to write the code to make this happen yet. Any pointers would be greatly appreciated.
int initBoidNum = 100; //amount of boids to start the program with
BoidList flock1;//,flock2;//,flock3;
float zoom=800;
boolean smoothEdges = false;
void setup()
{
size(800,600,P3D);
//create and fill the list of boids
flock1 = new BoidList(initBoidNum,0);
//flock2 = new BoidList(0,0);
//flock3 = new BoidList(100,128);
}
void draw()
{
//clear screen
beginCamera();
camera();
rotateX(map(mouseY,0,height,0,
rotateY(map(mouseX,width,0,0,
translate(0,0,zoom);
endCamera();
background(#75E8ED);
noFill();
stroke(#75E8ED);
line(0,0,300,0,height,300);
line(0,0,900,0,height,900);
line(0,0,300,width,0,300);
line(0,0,900,width,0,900);
line(width,0,300,width,height,
line(width,0,900,width,height,
line(0,height,300,width,
line(0,height,900,width,
line(0,0,300,0,0,900);
line(0,height,300,0,height,
line(width,0,300,width,0,900);
line(width,height,300,width,
flock1.run();
//flock2.run();
//flock3.run();
if(smoothEdges)
smooth();
else
noSmooth();
}
void keyPressed()
{
switch (keyCode)
{
case UP: zoom-=10; break;
case DOWN: zoom+=10; break;
}
switch (key)
{
case 's': smoothEdges = !smoothEdges; break;
}
}
//new tab
class Boid
{
//fields
PVector pos,vel,acc,ali,coh,sep; //pos, velocity, and acceleration in a vector datatype
float neighborhoodRadius; //radius in which it looks for fellow boids
float maxSpeed = 4; //maximum magnitude for the velocity vector
float maxSteerForce = .1; //maximum magnitude of the steering vector
float h; //hue
//constructors
Boid(PVector inPos)
{
pos = new PVector();
pos.set(inPos);
vel = new PVector(random(-1,1),random(-
acc = new PVector(0,0,0);
neighborhoodRadius = 200;
}
Boid(PVector inPos,PVector inVel,float r)
{
pos = new PVector();
pos.set(inPos);
vel = new PVector();
vel.set(inVel);
acc = new PVector(0,0);
neighborhoodRadius = r;
}
void run(ArrayList bl)
{
//acc.add(steer(new PVector(mouseX,mouseY,300),
flock(bl);
move();
checkBounds();
render();
}
/////-----------behaviors-----
void flock(ArrayList bl)
{
ali = alignment(bl);
coh = cohesion(bl);
sep = seperation(bl);
acc.add(PVector.mult(ali,1));
acc.add(PVector.mult(coh,3));
acc.add(PVector.mult(sep,1));
}
void scatter()
{
}
////--------------------------
void move()
{
vel.add(acc); //add acceleration to velocity
vel.limit(maxSpeed); //make sure the velocity vector magnitude does not exceed maxSpeed
pos.add(vel); //add velocity to position
acc.mult(0); //reset acceleration
}
void checkBounds()
{
if(pos.x>width) pos.x=0;
if(pos.x<0) pos.x=width;
if(pos.y>height) pos.y=0;
if(pos.y<0) pos.y=height;
if(pos.z>900) pos.z=300;
if(pos.z<300) pos.z=900;
}
void render()
{
pushMatrix();
translate(pos.x,pos.y,pos.z);
rotate(atan2(vel.y,vel.x)); //rotate drawing matrix to direction of velocity
//rotateZ(asin(vel.z/vel.mag()
stroke(#FF2E78, 100);
noFill();
//ellipse(0,0,
noStroke();
fill(#FFB700, 100);
//draw triangle
beginShape(TRIANGLES);
vertex(3,0);
vertex(-3,2);
vertex(-3,-2);
endShape();
box(10);
popMatrix();
}
//steering. If arrival==true, the boid slows to meet the target. Credit to Craig Reynolds
PVector steer(PVector target,boolean arrival)
{
PVector steer = new PVector(); //creates vector for steering
if(!arrival)
{
steer.set(PVector.sub(target,
steer.limit(maxSteerForce); //limits the steering force to maxSteerForce
}
else
{
PVector targetOffset = PVector.sub(target,pos);
float distance=targetOffset.mag();
float rampedSpeed = maxSpeed*(distance/100);
float clippedSpeed = min(rampedSpeed,maxSpeed);
PVector desiredVelocity = PVector.mult(targetOffset,(
steer.set(PVector.sub(
}
return steer;
}
//avoid. If weight == true avoidance vector is larger the closer the boid is to the target
PVector avoid(PVector target,boolean weight)
{
PVector steer = new PVector(); //creates vector for steering
steer.set(PVector.sub(pos,
if(weight)
steer.mult(1/sq(PVector.dist(
//steer.limit(maxSteerForce); //limits the steering force to maxSteerForce
return steer;
}
PVector seperation(ArrayList boids)
{
PVector posSum = new PVector(0,0,0);
PVector repulse;
for(int i=0;i<boids.size();i++)
{
Boid b = (Boid)boids.get(i);
float d = PVector.dist(pos,b.pos);
if(d>0&&d<=neighborhoodRadius)
{
repulse = PVector.sub(pos,b.pos);
repulse.normalize();
repulse.div(d);
posSum.add(repulse);
}
}
return posSum;
}
PVector alignment(ArrayList boids)
{
PVector velSum = new PVector(0,0,0);
int count = 0;
for(int i=0;i<boids.size();i++)
{
Boid b = (Boid)boids.get(i);
float d = PVector.dist(pos,b.pos);
if(d>0&&d<=neighborhoodRadius)
{
velSum.add(b.vel);
count++;
}
}
if(count>0)
{
velSum.div((float)count);
velSum.limit(maxSteerForce);
}
return velSum;
}
PVector cohesion(ArrayList boids)
{
PVector posSum = new PVector(0,0,0);
PVector steer = new PVector(0,0,0);
int count = 0;
for(int i=0;i<boids.size();i++)
{
Boid b = (Boid)boids.get(i);
float d = dist(pos.x,pos.y,b.pos.x,b.
if(d>0&&d<=neighborhoodRadius)
{
posSum.add(b.pos);
count++;
}
}
if(count>0)
{
posSum.div((float)count);
}
steer = PVector.sub(posSum,pos);
steer.limit(maxSteerForce);
return steer;
}
}
//new tab
class BoidList
{
ArrayList boids; //will hold the boids in this BoidList
float h; //for color
BoidList(int n,float ih)
{
boids = new ArrayList();
h = ih;
for(int i=0;i<n;i++)
boids.add(new Boid(new PVector(width/2,height/2,600))
}
void add()
{
boids.add(new Boid(new PVector(width/2,height/2)));
}
void addBoid(Boid b)
{
boids.add(b);
}
void run()
{
for(int i=0;i<boids.size();i++) //iterate through the list of boids
{
Boid tempBoid = (Boid)boids.get(i); //create a temporary boid to process and make it the current boid in the list
tempBoid.h = h;
tempBoid.run(boids); //tell the temporary boid to execute its run method
}
}
}
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