Why can't you generate the array in setup()?

1. int cols = 10;
2. int rows = 10;
3. int[]ArrayX = new int[rows];
4. int[]ArrayY = new int[rows];
5. void setup() {
6.   size (600, 300);
7.   for (int i = 0; i < cols; i++) {
8.     for (int j = 0; j < rows; j++) {
9.       int x = (int) random(-10, 10);
10.       int y = (int) random(-10, 10);
11.       ArrayX[i] = x + 10*i;
12.       ArrayY[j] = y + 10*j;
13.     }
14.   }
15. }
16. 
    
17. void draw() {
18.   background (127);
19.   noStroke();
20.   fill(0);
21.   for (int i = 0; i < cols; i++) {
22.     for (int j = 0; j < rows; j++) {
23.       ellipse(ArrayX[i], ArrayY[j], 3, 3);
24.     }
25.   }
26. }

This is what setup() is for! The contents of setup() only run once, and then draw runs continuously.

1. int cols = 10;
2. int rows = 10;
3. int[]ArrayX = new int[rows];
4. int[]ArrayY = new int[rows];
5. 
   
6. void setup() {
7.   size (600, 300);
8.   for (int i = 0; i < cols; i++) {
9.       for (int j = 0; j < rows; j++) {
10.         int x = (int) random(-10, 10); 
11.         int y = (int) random(-10, 10); 
12.         ArrayX[i] = x + 10*i; 
13.         ArrayY[j] = y + 10*j;
14.       }
15.     } 
16. }
17. 
    
18. void draw() {
19.   background (127);
20.   noStroke();
21.   fill(0);
22.   for (int i = 0; i < cols; i++) {
23.     for (int j = 0; j < rows; j++) {
24.       ellipse(ArrayX[i], ArrayY[j], 3, 3);
25.     }
26.   }
27. } 

I thought if I did it that way that I'd have a problem passing values into draw{} but obviously they're global so that's ok.

It's works now.

Thanks to you both for your help.

Shane

Hi,

I can't quite figure out why the dots are not random. The dots in the first column have the same x coordinate and same with dots in the second column. Likewise with the dots across: the first row all have the same y coordinate?

Here's the code,

1. int cols = 2;
2. int rows = 2;
3. int[]ArrayX = new int[rows];
4. int[]ArrayY = new int[cols];
5. void setup() {
6.   size (600, 300);
7.   for (int i = 0; i < cols; i++) {
8.     for (int j = 0; j < rows; j++) {
9.       ArrayX[i] = (int) random(0, 10) + i*10; 
10.       ArrayY[j] = (int) random(0, 10) + j*10;
11.     }
12.   }
13. }
14. void draw() {
15.   background (127);
16.   stroke(0);
17.   fill(0);                       
18.   for (int i = 0; i < cols; i++) {
19.     for (int j = 0; j < rows; j++) {
20.       ellipse(ArrayX[i], ArrayY[j], 3, 3);
21.     }
22.   }
23. }

The following does what I want, but I can't apply it to above so that I get the coordinated into the arrays.

1. for (int i = 0; i < 100; i += 10) {
2.   for (int j = 0; j < 100; j += 10) {
3.     float r = random(-5, 5);
4.     ellipse(i+r, j+r, 5, 5);
5.   }
6. }

Thanks,

Shane

it's not necessary to have a double for loop

1. int numDots = 40;
2. // int rows = 2;
3. int[]ArrayX = new int[numDots];
4. int[]ArrayY = new int[numDots];
5. void setup() {
6.   size (600, 300);
7.   for (int i = 0; i < numDots; i++) {
8.     ArrayX[i] = (int) random(0, width); // (int) random(0, 10) + i*10;
9.     ArrayY[i] = (int) random(0, height); // (int) random(0, 10) + j*10;
10.   }
11. }
12. void draw() {
13.   background (127);
14.   stroke(0);
15.   fill(0);                      
16.   for (int i = 0; i < numDots; i++) {
17.     ellipse(ArrayX[i], ArrayY[i], 3, 3);
18.   }
19. }

Hi Chrisir,

This is so much simpler and I like the way I can just put in the number of dots to decide how dense it should be.

Thanks very much for your help,

Shane