public class Line{
  //member
  float x, y, xEnd, yEnd;
  int alpha;
  int steps;
  float[] scl;
  //constructor
  Line(float x, float y, float xEnd, float yEnd){
    this.x = x;
    this.y = y;
    this.xEnd = xEnd;
    this.yEnd = yEnd;
    alpha = 255;
    steps = 0;
//    scl = new float[steps];
//    scl[0] = 0;
//    for(int i=0; i < steps; i++){
//      float pre = 100000/(i+1);
//      scl[i] = pre/100000;    
//      println(i+" = "+scl[i]);
//    }
  }
  //method
  void setAlpha(int alpha){
    this.alpha = alpha;
    bdraw();
  }
  
  void bdraw(){
    stroke(0, alpha);
//    if(steps > 0){
    if(steps < 20){
      pushMatrix();
      translate(x, y);
//      scale(scl[steps-1]);
//      line(0, 0, (xEnd - x)/steps, (yEnd - y)/steps);
      line(0, 0, ((xEnd - x)/20)*steps, ((yEnd - y)/20)*steps);
      popMatrix();
//      steps--;
      steps++;
    }
    else line(x, y, xEnd, yEnd);
    
  }
  
  void disappear(){
    x = y = xEnd = yEnd = 1000;
    bdraw();
  }
}