Hey all,

I'm using some code I borrowed from Max Kaufman

His code can create basically a piece of cord or string or whatever you want to call it that is affected by gravity as it falls down the screen.  Great for what I wanted to do, which is create three separate ribbons that I can control the length, position, and other properties of.  However, I can't figure out how to make a Ribbon class that connects to this code.  What he was doing before was creating a line using a for statement in the draw function; however, that can't make 3 individual and independently manipulable objects.  

Anyway here is the code.  Any help would be much appreciated.



//VECTOR CLASS/////////////////////////////////////
class Vector
{
 float x,y;
 Vector(float u, float v)
 {
   x = u;
   y = v;
 }
 void add(Vector V)
 {
   x += V.x;
   y += V.y;
 }
 void scale(float Scalar)
 {
   x *= Scalar;
   y *= Scalar;
 }
 void setEqual(Vector V)
 {
   x = V.x;
   y = V.y;
 }
}

//FORCE CLASS/////////////////////////////////////
abstract class Force
{
 abstract Vector forceOn(DynamicNode N);
}

//GRAVITY CLASS/////////////////////////////////////
class Gravity extends Force
{
 float acceleration=0.25f;
 Vector forceOn(DynamicNode N)
 {
   return new Vector(0.0f,acceleration*N.mass);
 }
}

//SPRING CLASS/////////////////////////////////////
class Spring extends Force
{
 float restLength=1.0f, stiffness=1.0f;
 DynamicNode a,b;
 Spring (DynamicNode left, DynamicNode right)
 {
   a = left;
   b = right;
   a.addForce(this);
   b.addForce(this);
 }
 Vector forceOn(DynamicNode N1)
 {
   DynamicNode N2;
   if (N1==a) N2 = b;
   else if (N1 == b) N2 = a;
   else return new Vector(0.0f, 0.0f);
   float dx = N2.position.x-N1.position.x;
   float dy = N2.position.y-N1.position.y;
   float displacement = sqrt(dx*dx+dy*dy);
   if (displacement == 0) return new Vector(0.0f, 0.0f);
   float magnitude = stiffness*(displacement-restLength)/displacement;
   return new Vector(dx*magnitude, dy*magnitude);
 }
}


//POINT CLASS/////////////////////////////////////
class Point
{
 float x,y;
 Point(float u, float v)
 {
   x = u;
   y = v;
 }
 void displace(Vector V)
 {
   x += V.x;
   y += V.y;
 }
}


//DYNAMICNODE CLASS/////////////////////////////////////
class DynamicNode {

 Point position = new Point(0.0f,0.0f);
 float mass = 1.0f;
 boolean pinned;

 float dampening = 1.0f;
 Force[] myForces = new Force[0];
 Vector netForce = new Vector(0.0f,0.0f);
 Vector velocity = new Vector(0.0f,0.0f);
 Vector acceleration = new Vector(0.0f, 0.0f);
 void addForce(Force F)
 {
   Force[] newForces = new Force[myForces.length+1];
   arraycopy(myForces,0,newForces,0,myForces.length);
   newForces[newForces.length-1] = F;
   myForces = newForces;
 }
 void computeForce()
 {
   netForce.x = 0;
   netForce.y = 0;
   for (int i=0; i<myForces.length; i++){
     netForce.add(myForces[i].forceOn(this));
   }
 }


 void update()
 {
   if (!pinned){
     acceleration.setEqual(netForce);
     acceleration.scale(1.0f/mass);
     velocity.add(acceleration);
     velocity.scale(dampening);
     position.displace(velocity);

   }
 }


}