How do you use parent objects in processing?

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println_h..

How do you use parent objects in processing?

in General Discussion • Other • 1 month ago

I am making a game where you are a space ship and there are other space ships that shoot lasers at you. I want the enemies to be able to shoot a laser by making a new laser object and when it reaches the end of he screen or hits its target it does its damage and gets removed from memory (lasers will be in an arraylist because there are multiple types of lasers). I want each laser to be stored in its parent classes array list but i don't know much about parents and childs in programming. I couldn't find a good tutorial anywhere on the processing website either. Can anyone tell me how to use parents and such, or think of a better way to shoot lasers?

Replies(9)

asimes

Re: How do you use parent objects in processing?

1 month ago

I'm not sure what you mean by parent in this context.

Are the lasers all supposed to be different classes? If so then I would say to make a base class (say you call it projectile). Then all of the lasers would be extensions of the base class.

If all the lasers are the same class, then all you need is an ArrayList of that class.

println_h..

Re: How do you use parent objects in processing?

1 month ago

I have a base class where all the lasers extend from. By parent i suppose i mean the ship the laser came from. So in the ship class i have an array list of lasers to be filled with the lasers that are currently in effect. When the lasers "die" they will be removed from that array list. When a laser is shot it will be created and added to the array list. I want the lasers to be shot by the ships and always be a child of the ship that shot the laser. I suppose that it doesn't really matter i could just have one big array list where every laser is stored.

asimes

Re: How do you use parent objects in processing?

1 month ago

Maybe this is helpful, I have a Ship class. Each ship has an ArrayList of Laser. At the moment each ship makes a laser and animates it to go right when the mouse is clicked, you'll replace that with your own code:

ArrayList<Ship> ships = new ArrayList<Ship>();
void setup() {
size(600, 600);
// Make 3 ships
for (int i = 0; i < 3; i++) {
ships.add(new Ship(random(25, width/2), random(25, height-25)));
}
}
void draw() {
background(0);
for (int i = 0; i < ships.size(); i++) {
Ship iShip = ships.get(i);
// Draw the ships. I'm sure you'll do much better :)
ellipse(iShip.x, iShip.y, 50, 50);
for (int j = 0; j < iShip.lasers.size(); j++) {
// Animate all lasers of ship i
iShip.animateLasers();
// Draw each laser j of ship i
Laser jLaser = iShip.lasers.get(j);
ellipse(jLaser.x, jLaser.y, 5, 5);
}
}
}
void mousePressed() {
// Right now I just give each ship a laser
for (int i = 0; i < ships.size(); i++) {
Ship iShip = ships.get(i);
iShip.lasers.add(new Laser(iShip.x, iShip.y));
}
}
class Ship {
float x, y;
// Each ship has lasers
ArrayList<Laser> lasers = new ArrayList<Laser>();
Ship(float inX, float inY) {
x = inX;
y = inY;
}
void animateLasers() {
for (int i = 0; i < lasers.size(); i++) {
lasers.get(i).x += 5.0;
}
}
}
class Laser {
float x, y;
Laser(float inX, float inY) {
x = inX;
y = inY;
}
}

GoToLoop

Re: How do you use parent objects in processing?

1 month ago

Make a composite inheritance inside Ship objects.
That is, instantiate your List< Projectile> inside classes which shoot.

Edit: as asimes did!

println_h..

Re: How do you use parent objects in processing?

1 month ago

Thanks for the help. I really just wanted to understand better how parent classes worked. Not super classes because there is no inheritance there. Thanks for the help though!

println_h..

Re: How do you use parent objects in processing?

1 month ago

Asimes, when you make your array list that holds the lasers, why do you cast it to Laser? Am i correct that you did that, and why couldn't you just have made a normal array list?

asimes

Re: How do you use parent objects in processing?

1 month ago

I get my languages mixed up sometimes. All I remember is that in Processing that if I don't specifically give a type to an ArrayList that later I would have to cast as Laser when I want to use it. It is possible to avoid it, but it is my preference in Processing so that I don't have to do more work with the ArrayList later.

GoToLoop

Re: How do you use parent objects in processing?

1 month ago

W/o specifying what's gonna be stored inside a Collection, every time a get() element for it is issued,
an additional cast operator for its data-type must be stated.
B/c a Collection can stored mixed types in it. It's a Java thing.
To make it for 1 type only, use <> angle brackets when declaring a variable for it.

println_h..

Re: How do you use parent objects in processing?

1 month ago

Thanks, I did not know that. i am getting everything to work now. The game is going to be like geometrywars but with more features. It is a fun project. Thanks for your help.

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