Btukfyl

So I have a row of 3 tea cups that I want to generate in a single for loop. Depending on the value of 'count', it will show either an PImage "emptyCup" or "fullCup". The code mostly works, but the graphical order from the rows is not what I want.

Here is the loop in a nutshell.

int count = 2;

int width = 210;

int length = 180;



for (int i = 1; i <= 3; i++) {

  if (i <= 3) {

    length = length1;

  } else if ((3 <= i) && (i <= 6)) {

    length = length2;

  } else {

    length = length3;

  }

   if ((i <= count)) {

     image(fullCup, (width * (i % 3)), length);

     println("FULL CUP: Count = " + count + ", i = " + i);

   } else {

     println("EMPTY CUP: Count = " + count + ", i = " + i);

     image(emptyCup, (width * (i % 3)), length);

   }

}

The following should give me the following output, where [o] is a full cup and [ ] is an empty one:

[o] [o] [ ] 

instead it gives me this:

[ ] [o] [o]

Likewise, if I change "count" to 4, and continue the for-loop to 6, then I would get this:

[o] [o] [o]

[ ] [o] [ ]

I'm aware my use of the modulus operator isn't getting me what I want, but I can't put my finger on what I should be saying instead. Any advice?

I hope you found the answer by now, but I'll answer it anyway.

This is a classic case of an error caused by bad programming habits. You may be new at this and I don't mean this in a bad way, but so you can learn from it ;)

First off, 'width' and 'length' are keywords in Processing, that should not be assigned, only read out.

Second, it is custom to start a for-loop at 0, unless there is a specific reason. This is because of how a computer works and because it makes the logic in the rest of the code easier. For example the modulus.

This is also the error your code.

• The first cup is drawn at x = width*(1%3) = width


• The second cup is drawn at x = width*(2%3) = 2*width


• The third cup is drawn at x = width*(3%3) = 0*width=0

The logic used is not wrong, but based on a for-loop that starts at 0.

This code does what you want. It draws the first image at x=0 and y=0. If necessary you can add an offset.

void setup() {

  PImage fullCup = loadImage("fullCup.jpg");

  PImage emptyCup = loadImage("emptyCup.jpg");

  size(800, 800);



  int count = 4;

  int numberOfCups = 6;

  int img_width = 210;

  int img_length = 180;



  for (int i = 0; i < numberOfCups; i++) {

    if (i < count) {

      image(fullCup, img_width * (i % 3), img_length*(i/3));

    } else {

      image(emptyCup, img_width * (i % 3), img_length*(i/3));

    }

  }

}