Initializing arrays within a method

Mysterio1000 · November 2016

I have this code:

PImage[] lol;
PImage thing;

void setup() {
  size(500,300);

  thing = loadImage("c_0.png");
  loadImages(lol, 12);
}

void loadImages(PImage[] p1, int size) {
  p1 = new PImage[size];

  for(int i = 0; i < size; i++) {
    p1[i] = thing;
  }
}

void draw() {
  image(lol[3], 30, 40);
}

However, this gives me a NullPointerException. Why? Can't I initialize the PImages inside a method?

Thank you for any help :)

GoToLoop · November 2016

Parameters are also local variables. Once their function ends, local variables are gone too! :-&

GoToLoop · November 2016

Also, why would you need to have some array filled w/ the the same PImage?! :-/

Mysterio1000 · November 2016

I was trying to create a method for initializing spritesheets. My full code was this:

void loadImages(PImage ss, String ssPath, PImage[] sprites, int sW, int sH, int boxW, int boxH) {
  ss = loadImage(ssPath);
  sprites = new PImage[sW * sH];
  for(int j = 0; j < sH; j++) {
    for(int i = 0; i < sW; i++) {
      sprites[j * sW + i] = ss.get(i * boxW, j * boxH, boxW, boxH);
    }
  }
}

I would run this method like this: loadImages(tileSS, "36086464-ocean-wallpaper.jpg", tileS, 7, 3, 50, 50);

Thank you very much for answering! :)

GoToLoop · November 2016

I'd go w/ something like this: *-:)

// forum.Processing.org/two/discussion/19397/initializing-arrays-within-a-method
// GoToLoop (2016-Nov-29)

static final String FILENAME = "c_0.png";
PImage[] sprites;

void setup() {
  size(500, 300, FX2D);
  smooth(3);
  imageMode(CORNER);

  PImage sheet = loadImage(FILENAME);
  sprites = createTiles(sheet, 7, 3, 50, 50);
}

static final PImage[] createTiles(PImage img, int cols, int rows, int w, int h) {
  PImage[] tiles = new PImage[cols*rows];
  for (int r = 0; r < rows; ++r)  for (int c = 0; c < cols; ++c)
    tiles[cols*r + c] = img.get(c*w, r*h, w, h);
  return tiles;
}

Mysterio1000 · November 2016

Thank you :) :ar!

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