class square{
  float[] v = new float[4];

  square(){
    for(int i=0;i<4;i++){
      v[i]=0.0f;
    }
  }

  square(float v0, float v1, float v2, float v3){
    v[0]=v0;
    v[1]=v1;
    v[2]=v2;
    v[3]=v3;  
  }

  int determineType(float treshold){
    int lv0,lv1,lv2,lv3;
    lv0=lv1=lv2=lv3=0;
    if (v[0]<=treshold) lv0=1;
    if (v[1]<=treshold) lv1=2;  
    if (v[2]<=treshold) lv2=4;
    if (v[3]<=treshold) lv3=8;
    return lv0+lv1+lv2+lv3;
  };

  void update(float v0, float v1, float v2, float v3){
    v[0]=v0;
    v[1]=v1;
    v[2]=v2;
    v[3]=v3;  
  }
  void draw(float offsetx, float offsety, float scale, float treshold){
    int type = determineType(treshold);
    beginShape(LINES);
    switch (type){
    case 0:
      break;
    case 1:

      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
      break;
    case 2:
 
      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
      break;
    case 3:
 
      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);

      break;
    case 4:

      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);
      break;
    case 5:

      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
 
      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);
      break;
    case 6:
 
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);

      break;
    case 7:

      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);

      break;
    case 8:
      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);
      break;
    case 9:
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);
      break;
    case 10:
      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);
      break;
    case 11:
      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);
      vertex(offsetx+interpolate(v[3],v[2],treshold)*scale,offsety+scale);
      break;
    case 12:
      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);
      break;
    case 13:
      vertex(offsetx+scale,offsety+interpolate(v[1],v[2],treshold)*scale);
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
      break;
    case 14:
      vertex(offsetx,offsety+interpolate(v[0],v[3],treshold)*scale);
      vertex(offsetx+interpolate(v[0],v[1],treshold)*scale,offsety);
      break;
    case 15:
      break;
    default:
      break;


    }
    endShape();
  }

  float interpolate(float xi, float xj, float treshold){
    return( (treshold-xi)/(xj-xi));

  }



}