Adding the number of boxes

123nqk456

Hi everyone, I have a problem with my project. I want to add more boxes into my project by mousePressed function.

Box[] boxes=new Box[5];
 void setup(){
   size(200,200);
   rectMode(CENTER);
   for(int i=0;i<boxes.length;i++){
     boxes[i]= new Box( random(100),random(100), random(5,15)
     );
   }
 }
  void draw(){
    background(192);
    for(int i=0;i<boxes.length;i++){
      boxes[i].draw();
    }
    for(int j=0;j<boxes.length;j++){
      for(int k=0; k< boxes.length; k++){
        if(j !=k){
          boxes[j].attract(boxes[k]);
        }
      }
    }
  }

  void mousePressed(){
    for(int i=0;i<boxes.length;i++){
      boxes[i].mousePressed();
    }
  }

koogs

code is unreadable

edit post, highlight code, press ctrl-o

koogs

mousePressed needs to add a new Box, the same way it did with the first 5 in setup()

but first you'll have to increase the size of the array.

but tbh, you'd be better off with an ArrayList than with a Box[].

koogs

you are also missing the Box class.

123nqk456

this is my Box Classes:

class Box{
  int frame = 0;
  float posX;
  float posY;
  float movX;
  float movY;
  float side;
  boolean spinning = true;

  Box(float x,float y,float s){
    posX=x;
    posY=y;
    side=s;
    movX=random(-1,1);
    movY=random(-1,1);
  }
   void draw(){
     posX+=movX;
     posY+=movY;
     pushMatrix();
     translate(posX,posY);
     rotate(0.1*frame);
     rect(0,0,side,side);
     if (spinning){
       frame++;
     }
     popMatrix();
   }
     void mousePressed(){
       if (dist(mouseX,mouseY,posX,posY)<side/2){
         spinning = !spinning;
       }
     }


     void attract(Box b){
       float d=dist(posX,posY,b.posX,b.posY);
       float diffX=b.posX-posX;
       float diffY=b.posY-posY;
       movX+=diffX/sq(d);
       movY+=diffY/sq(d);
   }


}

123nqk456

But i can not increase the number of box. I tried to do :

float num ;
Box[] boxes=new Box[num];
..... 
if( mousePressed = true) {
num = num++;
}

but it did not work.... Can you help me?

koogs

line 2 initialises the size of the array to the current value of num, set in line 1. changing num later won't change the size of the array.

there is a method to expand an array, it's in the reference. it is, however, terrible - arrays aren't meant to be extended. which is why i suggested using an ArrayList.

123nqk456

Can you explain for me? How to apply array list in this? I am quite confused now :(

koogs

Box[] boxes=new Box[5];

becomes

ArrayList<Box> boxes = new ArrayList<Box>();

so that's a new ArrayList full of things of type Box. note that it doesn't have a limit to how big it can be, it can handle more than 5.

instead of setting array entries to be new Box you add() them so

boxes[i]= new Box( random(100),random(100), random(5,15));

becomes

boxes.add(new Box( random(100),random(100), random(5,15)));

you can do this as many times as you like, ie within your mousePressed() method.

and accessing them is not boxes[i] but boxes.get(i);

koogs

https://forum.processing.org/two/discussion/8080/why-use-arraylist-instead-of-array-with-append

123nqk456

I tried , but when we change it , we will not use i, will we ?

koogs

for(int i=0;i<boxes.length;i++){
  boxes[i].draw();
}

...

for (int i = 0 ; i < boxes.size() ; i++){
  boxes.get(i).draw();
}

but if all you're using i for is to iterate over all the boxes then you don't need it and can use

for (Box b : boxes) {
  b.draw();
}

123nqk456

To be honest, Have you tested it? although I tried many times and following your induction, It does not work

kfrajer

Implementing @koogs suggestions:

Kf

//Box[] boxes=new Box[5];
ArrayList<Box> boxes = new ArrayList<Box>();
int initBoxNumber=5;

void setup() {
  size(200, 200);
  rectMode(CENTER);
  for (int i=0; i<initBoxNumber; i++) {
    boxes.add(new Box( random(100),random(100), random(5,15)));
  }
}
void draw() {
  background(192);
  for (int i=0; i<boxes.size(); i++) {
    boxes.get(i).draw();
  }
  for (int j=0; j<boxes.size(); j++) {
    for (int k=0; k< boxes.size(); k++) {
      if (j !=k) {
        boxes.get(j).attract(boxes.get(k));
      }
    }
  }
}

void mousePressed() {

  //THESE next lines ... not sure what they are doing....
  //for (int i=0; i<boxes.length; i++) {
  //  boxes[i].mousePressed();
  //}

  //ADDING a new box... you just need to call
  boxes.add(new Box( random(100),random(100), random(5,15)));  //Same line as in setup
}

123nqk456

thank you very very much kfrajer , it is fantastic :D