I'm working on a sketch that for now will start in 2 dimensions.

I want to start very simple and just create an array of arrows across the canvas pointing to 90 degrees. This part I can accomplish very easily with nested for loop.

The second part is to create the attractor. I'm really a beginner when it comes to particle fields. I've had a look at the Traer physics library but I could really really really use a little guidance or a solid reference material to turn to when I'm baffled.

I've been hacking apart whatever I can find but I still can't get away from a mode of thinking where the vector field is going to displayed at a individual moment. I'm lost on how I would create a field where the attractor could be something like the mouse pointer.

Man ... I just had a flash in my head that there's already a proessing example I've seen somehwere that shows a screen of arrows following the cursor.

eeehhhh, that could be the reference I need! anyone remember? I'm gonna go searh.

found it on the alpha site. of course it's some more of Robert Hodgin's beautiful work, albeit early (2003 it looks like!!!) I guess it's fitting since I've been on flight404.com for at least a portion of every few hours. haha.

I'm still not finding a way to keep the field stationery. I want to visualize the forces instead of simulate the motion I guess? Just show the initial trajectory for each vector.

Thanks in advance, all suggestions welcome!

Hi

I just put together the simplest form of "point to mouse" script I could think off.
Hope it can help you a little to adjust some of the larger flocking/Vector3D examples.

Code:

float deltaX;
float deltaY;
float radian;
float degree;
Arrow arrow;

void setup()
{
  size(300, 300);
  arrow = new Arrow();  
}

void draw()
{
   deltaX = mouseX - width/2;  //arrow.x
   deltaY = mouseY - height/2;   //arrow.y
   radian = atan2(deltaY, deltaX);
   //degree = radian * 180/PI; //not needed as rotation takes radians
   arrow.update(radian);
}
 

and this small fellow...not pretty I know..

Code:

class Arrow
{
  float rotation;
  
  Arrow()
  {

  }
  
  void update(float rotation)
  {
    background(2555);
    pushMatrix();
    translate(width/2, height/2);
    rotate(rotation);
    rect(0, 0, 50, 10);
    popMatrix();
  }
}
 

From here on I would say it is something like finding the distance from the mouse/attractor to the vector/arrow and calculate if the vector should react or not.
Something like toxi's Vector class or the new Vector class added to processing 1.0 could handle all those calculations for you.