void dragSegment(int i, float xin, float yin) {
      float dx = xin - x[i];
      float dy = yin - y[i];
      float angle = atan2(dy, dx);  
      x[i] = xin - cos(angle) * segLength;
      y[i] = yin - sin(angle) * segLength;
      //stroke(23, 79, 4, 220);
      
      pushMatrix();
      translate(x[i], y[i]);
      rotate(angle);
      
      color c;
      
      if ( i % 3 == 1 )
        c = color(0, 0, 0, 255);
      else if ( i % 3 == 2 )
        c = color(255, 255, 0, 255);
      else
        c = color(255, 0, 0, 255);
    
      stroke( c );
      strokeWeight(10);
      line(0, 0, segLength, 0);
      
      if ( i == x.length - 1 )
      {
        fill( c );
        noStroke();
        beginShape(TRIANGLES);
        vertex(0, 5);
        vertex(-2 * segLength, 0);
        vertex(0, -5);
        endShape();
      }
      
      if ( i == 0 )
      {
       // stroke(0, 255);
       noStroke();
       fill(0, 255);
       ellipse(segLength, -2, 3, 3);
       ellipse(segLength, 2, 3, 3);
        //point(segLength, -2);
        //point(segLength, 2);
      }
      
      popMatrix();
  }