CODEWITHSUNDEEP
arraysimageprocessing
alter718
alter718

Reputation: 31

Extracting an image from an array in Processing

Does anyone have any suggestions on what might be going wrong with this code? I'm trying to load tiles of images into a large array and then display them. Later on I'll shuffle the pieces. The issue I'm running into is seen near the bottom. I have a for loop that should plug the value of i into the output array and display the relevant image at that index value. Instead I get a null pointer exception. If I replace the letter i with an integer it works perfectly. What could be preventing processing from passing that value if i into the array? Any thoughts? Thanks. 

int tileSize = 100;
PImage out; PImage sample;
PImage img;
PImage img2;
String[] imageNames = {"arctic_fox.jpg", "bbridge_in_the_am.jpg", "Kali2.jpg"};
PImage[] images = new PImage[imageNames.length];
//PImage[] output = new PImage[((1440/tileSize)*imageNames.length)*(900/tileSize)];
PImage[] output = new PImage[2000];

int tintScale = 200;
void setup() {
  fullScreen();
  for (int i=0; i < imageNames.length; i++) {
    String imageName = imageNames[i];
    images[i] = loadImage(imageName);
  }
  out = createImage(width, height, RGB);  
  noLoop();
  println("test");
}
void draw() {
  background(0);
  println(width, height);
  println(output.length);
  int counter=0;
  for (int i = 0; i < imageNames.length; i++) {
    img = loadImage(imageNames[i]);
    img.resize(0,900);
    for (int y=0; y<img.height; y+=tileSize) {
      for (int x=0; x<img.width; x+=tileSize/3) {
        sample = img.get(x, y, tileSize, tileSize);
        output[counter] = sample;
        tint(255, tintScale);
        counter++;
        //println(counter);
        //image(out, random(0, width-img_x), random(0, height-img_y));
      }
      //image(output[i],30,30);
    }
  }
  for (int i=0;i<output.length;i++){
    image(output[30],i*tileSize,i*tileSize);
  }
  //for (int y=0; y<out.height; y+=tileSize) {
  //  for (int x=0; x<out.width; x+=tileSize) {
  //    i = 800;
  //    //tint(255, tintScale);
  //    image(output[i], x, y);

  //  }
  //}
}

Upvotes: 1

Views: 1233

Answers (1)

J.D.
J.D.

Reputation: 4561

I hope you solved it, but this is the problem:

PImage[] output = new PImage[2000];

You are initializing the array with 2000 null values, and then enter less then 300 tiles. That's why you get a null pointer error. You have to calculate how large your array will be before you initialize it. Or perhaps better, use an arraylist:

  ArrayList<PImage> output = new ArrayList<PImage>();

  //to add a tile:
  output.add(sample);

  //to draw all tile:
  for(int i = 0; i< output.size();i++)
  {
   image(output[i],i*tileSize,i*tileSize); 
  }

You can read more about arraylists here

Final note: as Kevin Workman says, loadImage() and this process of dividing into tiles does not belong in 'void draw()'. It should be in setup() or in a separate function, called from setup().

Upvotes: 1

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