import java.awt.Graphics;
import java.awt.Color;
import Punto;

public class Muelle
{
   private Punto pto1, pto2; // puntos limite
   private double k;         // cte de recuperacion
   private double l0;        // longitud propia
   private double gamma;     // amortiguamiento

   public Muelle( Punto p1, Punto p2 )
   {
      pto1 = p1;
      pto2 = p2;
      double ix = pto1.q[0]-pto2.q[0];
      double iy = pto1.q[1]-pto2.q[1];
      k = 1.0;
      l0 = Math.sqrt(ix*ix + iy*iy);
      gamma = 0.0;
   }

   public void setCoef( double k )
   {
      this.k = k;
   }

   public void setAmortig( double g )
   {
      gamma = g;
   }

   public void dibujar( Graphics g )
   {
      g.setColor(Color.red);
      g.drawLine(pto1.panX,pto1.panY,pto2.panX,pto2.panY);
/*
      cx[0] = pto1.panX;
      cy[0] = pto1.panY;
      cx[5] = pto2.panX;
      cy[5] = pto2.panY;
      double ix = (cx[5]-cx[0])/16.0;
      double iy = (cy[5]-cy[0])/16.0;
      cx[1] = cx[0] + (int) Math.round( 2*ix-iy);
      cx[2] = cx[0] + (int) Math.round( 6*ix+iy);
      cx[3] = cx[0] + (int) Math.round(10*ix-iy);
      cx[4] = cx[0] + (int) Math.round(14*ix+iy);

      cy[1] = cy[0] + (int) Math.round( 2*iy-ix);
      cy[2] = cy[0] + (int) Math.round( 6*iy+ix);
      cy[3] = cy[0] + (int) Math.round(10*iy-ix);
      cy[4] = cy[0] + (int) Math.round(14*iy+ix);
      g.drawPolyline(cx,cy,6);
*/
   }

   public void fuerzas( )
   {
      double ix = pto1.qc[0] - pto2.qc[0];
      double iy = pto1.qc[1] - pto2.qc[1];
      double l = Math.sqrt(ix*ix + iy*iy);
      double fk  = k*(l - l0)/l;
      double fx = fk*ix;
      double fy = fk*iy;
      double ca1 = 2.0*gamma*pto1.masa;
      double ca2 = 2.0*gamma*pto2.masa;
      pto1.fx -= fx + pto1.qc[2]*ca1;
      pto1.fy -= fy + pto1.qc[3]*ca1;
      pto2.fx += fx - pto2.qc[2]*ca2;
      pto2.fy += fy - pto2.qc[3]*ca2;
   }

   public void tensionNula( )
   {
      double ix = pto1.q[0]-pto2.q[0];
      double iy = pto1.q[1]-pto2.q[1];
      l0 = Math.sqrt(ix*ix + iy*iy);
   }
}