Help with Space Invaders - moving Aliens down and across (rectangles)

mesiah67

Hi, I'm new here and having a bit of trouble with some basic Space Invaders code.

Here is my code:

    int x = (200);
    int y = (450);

    int a = 0;
    int b = 54;
    int c = 85;

    int xPos = 25;
    int yPos = 25;
    int xdir = 3; 
    int ydir = 40;

    int counter = 0;

    int[][] enemies = generateEnemies();


    int[][] generateEnemies() {
     int[][] enem = new int[54][2];
     int counter = 0;
     for (int xi = 0; xi < 9; xi++) {
       for (int yi = 0; yi < 6; yi++) {
         enem[counter][0] = xi * 50 + xPos;
         enem[counter][1] = yi * 25 + yPos;
         counter++;
        }
      }
      return enem;
    }

    void setup() {
      size(500, 500);
      frameRate(60);
    }

    void draw() {
      background(0);
      player();
      drawEnemies();
      moveEnemiesRight();

    }

    void player() {
      fill(0, 255, 0);
      rect(x, y, 100, 20);
    }

    void drawEnemies() {

      fill(255, 215, 0);
      for (int i = 0; i < 54; i++) {
        rect(enemies[i][0], enemies[i][1], 40, 20);
      }
    }

    void moveEnemiesRight() {
      xPos += 5;
    }

This is super messy and lots of crap going on. This is due to me being very inexperienced in the language. My main problem is that I am unable to make the Enemies move down and across the screen. I tried to adjust their position using the xPos variable but could see it wasn't working and can't seem to see a solution.

Any help or guidance is appreciated. Thank you.

GoToLoop

https://forum.Processing.org/two/discussion/8081/from-several-arrays-to-classes

https://Processing.org/tutorials/objects/

Lord_of_the_Galaxy

Read up about classes and OOP (Object Oriented Programming), GoToLoop has already given you a link to it.

mesiah67

Thanks guys - I have been throuroughly reading the arrays to classes link GoToLoop sent but can't see how that integrates with my generateenemies 2d array. :S

quark

This code will start you off. It has a class called Enemy and a 2D array of Enemy objects. It should get you started but just ask if you don't understand any of the code.

// 10 across (columns) and 4 down (rows)
Enemy[][] enemies = new Enemy[10][4];

void setup() {
  size(500, 500);
  for (int c = 0; c < enemies.length; c++) {
    for (int r = 0; r < enemies[c].length; r++) {
      enemies[c][r] = new Enemy(c * 30 + 60, r * 30 + 50);
    }
  }
}

void draw() {
  background(0);
  for (int c = 0; c < enemies.length; c++) {
    for (int r = 0; r < enemies[c].length; r++) {
      enemies[c][r].display();
    }
  }
}

class Enemy {
  float x, y; // position
  float w, h; // width and height of enemy
  int c;

  Enemy(float px, float py) {
    x = px;
    y = py;
    w = 20;
    h = 15;
    c = color(240, 20, 100);
  }

  void display(){
    noStroke();
    fill(c);
    rect(x,y,w,h);
  }
}

Lord_of_the_Galaxy

Then you need to add moveDownLeft() function to the Enemy class.

mesiah67

How can I space the bricks out further as I changed it to have 10 columns by 6 rows and all of the bricks are squished together? Really appreciate this guys, thank you.

mesiah67

Okay no worries with the spacing now, I've sorted it.

For a a moveDownLeft() function would I be using px and py to translate the aliens around?

mesiah67

I really need help creating a Bullet array to make my ship shoot when I press the spacebar. Here is my current code:

Enemy[][] enemies = new Enemy[9][6];

int rectx = 200;
int recty = 460;
int dir = 1;

Bullet[] b1 = new Bullet[0];

void setup() {
  size(500, 500);
  for (int c = 0; c < enemies.length; c++) {
    for (int r = 0; r < enemies[c].length; r++) {
      enemies[c][r] = new Enemy(c * 50 + 30, r * 30 + 50);
    }
  }
}

void draw() {
  background(0);
  player();
  for (int c = 0; c < enemies.length; c++) {
    for (int r = 0; r < enemies[c].length; r++) {
      enemies[c][r].display();
      enemies[c][r].move();
      if (enemies[c][r].x > 460 || enemies[c][r].x < 0) {
        enemies[c][r].down();
        dir = dir  *= -1;
      }
    }
  }
  for (int b = 0; b < b1.length; b++){
    b1[b].display();
    b1[b].move();
  }
}

class Enemy {
  float x, y; // position
  float w, h; // width and height of enemy
  int c;
  int movespeed = 1;

  Enemy(float px, float py) {
    x = px;
    y = py;
    w = 40;
    h = 20;
    c = color(255, 255, 0);

  }

  void display(){
    noStroke();
    fill(c);
    rect(x,y,w,h);
  }
  void move(){
    this.x = this.x + movespeed * dir;
  }
  void down(){
    this.y += 20;
  }
}

class Bullet {
  float x, y; // position
  float w, h; // width and height of enemy
  int c;
  int movespeed = 3;

  Bullet(float px, float py) {
    x = px;
    y = py;
    w = 10;
    h = 10;
    c = color(255, 0, 0);

  }

  void display(){
    noStroke();
    fill(c);
    ellipse(x,y,w,h);
  }
  void move(){
    this.y = this.y - movespeed * dir;
  }
}

void player(){
  fill(0,255,0);
  rect(rectx,recty,100,20);
}

void keyPressed() {
  if (key == CODED) {
    if (keyCode == LEFT) {
      if (rectx >= 0) {
        rectx -= 5;
      }
    }
    else if (keyCode == RIGHT) {
      if (rectx <= 395) {
        rectx += 5;
      }
    }
    else if (keyCode == ' ') {
      b1 = new Bullet[1];
    } 
  }
}

Lord_of_the_Galaxy

Along completely different lines to the question, why do you need to use a 2D array?? It just seems really useless now, after shifting to OOP.

Lord_of_the_Galaxy

As to the bullets question, you would be better off using ArrayList and not arrays.
Example from Daniel Shiffman - https://processing.org/examples/arraylistclass.html.

Lord_of_the_Galaxy

I also see another potential flaw - a global variable dir that is changed by position of individual instances of the Enemy class. (Line 27)