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Writing a while loop

From: Interactive Data Visualization with Processing

Video: Writing a while loop

Processing provides you with several different ways of repeating code and automating elements of your sketch. One method for doing this is what's called a while loop. Now the while loop in Processing seemed a functional differently than others where you can say for instance, while the water level is below 10 feet, do this; when it's above, do this. I'm going to show you an example of how you can use a while loop to produce a particular drawing. I'm going to copy in a palette.

Writing a while loop

Processing provides you with several different ways of repeating code and automating elements of your sketch. One method for doing this is what's called a while loop. Now the while loop in Processing seemed a functional differently than others where you can say for instance, while the water level is below 10 feet, do this; when it's above, do this. I'm going to show you an example of how you can use a while loop to produce a particular drawing. I'm going to copy in a palette.

I'm going to use this one up top. This is from the palette text document that's included in the exercise files. So there I've got my color palette and I'm going to also put in a variable, a float variable that I'm calling the limiter. Then I'm going to create my first block of code which is set up. I put the size of the window, 600x200. I'll going to put in the background color which is palette the first color which has index number 0.

I'll turn on the anti-aliasing. Then I'm also going to change this strokeWeight to 5 pixels. I'm going to have noFill in the shapes that I'm going to draw and then I'm actually going to adjust the frameRate for the sketch, although that may not make a difference in how it works. The second block is the draw and this is where I'm going to put the while. What I do is I specify while=(limiter<100). So it starts at 0 and I'll go up to 100.

It will stop when it gets there. While it is less than a hundred execute this other code. Now you notice I actually have a nested loop. I have second inside of curly brackets within the draw. That's fine. You can have as many as you want going in and out as long as you remember to close all of them which is why I draw the closing one as soon as I draw the opening one. So what I'm going to do now is I'm going to set the stroke to come from the palette, but I'm going to use a random value here where I do the (1, 5) and when that gets truncated as cast into an integer that will become (1, 4). There we go.

It takes a little while to close all of those markers and then I'm going to put in random variables for the coordinates. I want the X to be anywhere in the width of the drawing. I want the height to be anywhere in the height of the drawing. I want to size, the diameter, to be somewhere between (20, 200) and then I'm going to put ellipse centered on X, Y, D, D as its dimensions.

Then I need to include an update for the limiter variable that the condition that the while is running on. In this case I'm going to put limiter is plus or equal (+=) to a random increment. So it's going to add a certain amount of every time, but its not going to be the same amount. I'm going to say somewhere between (-1, +2). So we will generally go up and hit the limit of a hundred eventually. When I save this and run it we're not going to see anything until it's finished, because what's going to happen is the draw is not going to go through until this while loop has completed.

So we're just going to take a moment and it's going to pop up with a finished drawing. And there we go. What is drawn is a number of circles. It maybe a 100. It depends on how the random increment went on. But it just kept calculated more and more circles positions on until the limiter reached a particular value, which I set to 100, and then it stopped. So that's one way of using a while loop in Processing. It's a way of automating and repeating a particular function that you want to use a number of times and it lets you get more elaborate drawing than you would be able to do by hand-coding everything.

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This video is part of

Image for Interactive Data Visualization with Processing
Interactive Data Visualization with Processing

72 video lessons · 12211 viewers

Barton Poulson
Author

 
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  1. 3m 16s
    1. Welcome
      58s
    2. What you should know
      1m 22s
    3. Using the exercise files
      56s
  2. 11m 51s
    1. Overview of data visualization
      11m 51s
  3. 11m 53s
    1. Installing Processing
      3m 38s
    2. Overview of Processing
      4m 5s
    3. Exploring libraries
      4m 10s
  4. 1h 1m
    1. Basic setup
      7m 31s
    2. Drawing points
      4m 37s
    3. Drawing lines
      5m 6s
    4. Drawing ellipses and circles
      5m 24s
    5. Drawing arcs
      6m 54s
    6. Drawing rectangles and squares
      4m 58s
    7. Drawing quadrangles
      3m 25s
    8. Drawing triangles
      2m 55s
    9. Drawing polygons
      3m 37s
    10. Drawing simple curves
      4m 54s
    11. Drawing complex curves
      6m 46s
    12. Drawing Bézier curves
      5m 38s
  5. 54m 3s
    1. Introduction to variables
      10m 44s
    2. Understanding variable scope
      6m 53s
    3. Modifying variables
      9m 8s
    4. Creating arrays
      9m 53s
    5. Modifying arrays
      6m 37s
    6. Creating strings
      7m 3s
    7. Modifying strings
      3m 45s
  6. 1h 2m
    1. Incorporating randomness
      7m 59s
    2. Using Perlin noise
      4m 24s
    3. Shuffling with Java
      3m 30s
    4. Specifying line attributes
      8m 2s
    5. Changing placement modes
      5m 45s
    6. Understanding color attributes and functions
      4m 16s
    7. Exploring color spaces
      7m 44s
    8. Using color palettes
      7m 5s
    9. Transforming the grid
      8m 38s
    10. Exploring the attribute matrix
      5m 33s
  7. 52m 7s
    1. Building code blocks
      5m 57s
    2. Writing a while loop
      3m 52s
    3. Using for loops
      5m 35s
    4. Creating conditionals
      14m 50s
    5. Working with easing
      10m 51s
    6. Creating spirals
      11m 2s
  8. 18m 55s
    1. Mouse tracking
      3m 54s
    2. Hovering and clicking
      11m 16s
    3. Understanding keyboard interaction
      3m 45s
  9. 27m 32s
    1. Specifying fonts
      6m 43s
    2. Using images
      5m 51s
    3. Playing a video loop
      6m 20s
    4. Exporting video
      3m 47s
    5. Adding sound
      4m 51s
  10. 20m 49s
    1. Creating functions
      11m 48s
    2. Creating classes and objects
      9m 1s
  11. 31m 10s
    1. Using embedded data
      5m 26s
    2. Working with appended text data
      6m 4s
    3. Working with appended tabular data
      10m 26s
    4. Reading XML data
      9m 14s
  12. 48m 17s
    1. Generating dot plots
      11m 11s
    2. Building scatter plots
      10m 0s
    3. Making line plots
      9m 55s
    4. Creating bar charts
      9m 12s
    5. Checking out examples of maps, hierarchies, and networks
      7m 59s
  13. 20m 57s
    1. Introducing some principles of 2D design
      13m 44s
    2. Understanding color theory
      7m 13s
  14. 24m 46s
    1. Interacting with zooming, rotating, and sliding
      6m 26s
    2. Implementing slicing
      6m 47s
    3. Using rollovers
      5m 58s
    4. Introducing the GUI libraries
      5m 35s
  15. 10m 35s
    1. Sharing via OpenProcessing and other sites
      3m 19s
    2. Saving as a desktop application
      2m 42s
    3. Saving as JavaScript
      1m 47s
    4. Saving as an Android application
      2m 47s
  16. 2m 38s
    1. Where to go from here
      2m 38s

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