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Incorporating randomness

From: Interactive Data Visualization with Processing

Video: Incorporating randomness

One of the great things about Processing is that you can incorporate randomness into your sketches. This actually makes them seem much more alive and much more interesting, and I am going to show you how to use the randomness functions in a few different ways to create a more interesting sketch. First thing I am going to do is I am just going to come and put a comment here. Then I am going to create a sketch. Now what I want to do is I want to create a what's called a dynamic sketch and I'll talk more about this little bit later. But I need to have two blocks of code.

Incorporating randomness

One of the great things about Processing is that you can incorporate randomness into your sketches. This actually makes them seem much more alive and much more interesting, and I am going to show you how to use the randomness functions in a few different ways to create a more interesting sketch. First thing I am going to do is I am just going to come and put a comment here. Then I am going to create a sketch. Now what I want to do is I want to create a what's called a dynamic sketch and I'll talk more about this little bit later. But I need to have two blocks of code.

The first one is a block that provides some setup information, this is the stuff that runs only once in the code. And in this, is where I am going to put the size 600x200 again, do the anti-aliasing, I'm actually going to do no fill on the shapes I am going to draw. I am going to be using ellipses, circles actually. And I'll do stroke weight, I am going to make them a little thick, to 5 pixels, we have done that before. And I think that's the essentials of my information here.

What I am going to do next, is come down and create a block for draw, and this is code that cycles through up to 60 frames per second, until you tell it to stop. And what I'm going to do on this one, is I'm going to draw ellipses but what I want to do is I want to put them in random places, and I want to have them have randomized diameters and even random colors. So the way I am going to do this is, I am going to create a few different variables, I am going to have x and y and d and d, I'll show you how I will create those.

First thing I'll do is I am going to create a floating variable. Float is for decimal places and since the random function produces decimal places, I am just going to leave it exactly as it is. I am going to have the variable called x and I enter the function random and if you want to go from 0 up to particular value, all you need to do is put the higher limit. And in this case, since x gives the across values on the drawing, I am just going to put width. So it means anywhere on the x values from 0 up to as big as the window is.

In this case, it's 600 pixels. I am going to do a similar thing for the y. I am going to put random, so at this time I put height and so that also starts at 0 and goes up to the maximum value of the height of the window. And then for the diameter, I am going to do a little differently because I want to specify both a lower and an upper limit. I think I am going as small as 30 pixels in diameter and as large as 300 pixels in diameter. And you may recall, that guarantees me that, those larger ones will be drawn at least partly off the screen.

Processing doesn't mind, it will draw it wherever you want it. That is enough to draw with black and so I am just going to save this and run it as a test. Okay, I have got few things is, it's really fast and so what I am going to do, again Processing runs up to 60 frames per second, but I can slow down here with a command called frame rate and I'll put at about five frames per second and we'll try it again. Okay, now it's a little slower but it is black on gray. Now there's a few ways of working with that.

What I am going to do is I am going to put random colors in and I'm going to do that with stroke. And what I need is three components, an r for Red and Green and a Blue and I am just going to put random values in for each one of them. I am going to do random 255 that's for Red, random 255 for Green and random 255 for Blue. And then I have a second parenthesis () to close off the whole thing and it semi colon (;). And now every ellipsis, every circle will be drawn with a different color.

Cool. So now we have some colors. On the other hand, what we have is completely unregulated color variation, it may be that you want just a few different colors to show up. And to do that there's a neat little trick that involves using random integers and arrays of colors. So I am going to close that and what I am going to do is, I am going to come up to the top of the sketch and I'm going to create an array of colors that I am going to use. So color is the variable type, I'll put the opening and closing square brackets [] to indicate that it's an array, and this particular palette, I've found is called rainbow.

It's actually muted colors actually. And what I'm going to do, I got the equals in the wrong place, sorry. So I have color, that has the variable type, the brackets indicates an array. Rainbow is the name of the array, then equals and then I am just going to put right here and curly brackets several hex codes. So the first one is ffffcd, it's a very light color in the background. The next one is CC5C54 next one is F69162 and one after that is 85A562 and the last one I am going to have is 7AB5DB. Great, and so now I have got five different colors in my array, I can close that with {} and put (;).

And now what I am going to do is I am going to start calling on those particular colors. Now, the first ones are very light-colored. I am going to make that my background color. So I am going to come down here and I am going to put in lower case, background. Now, I don't have to copy that code. I could if I wanted but a neat way to do it is to use the array function. So I put rainbow, and then to indicate that I want the first one in there, I put square brackets and then 0, that's its index number and that will give me that color background. And then if I want to draw on the index numbers one, two, three and four, I can use a random function to get from those.

So I am going to actually comment that one function out, and instead what I'm going to do is, I'm going to use a stroke and I need to put a color in here. I need to put the Hex code. What I'm going to do though is I'm going to say that I'm going to use the rainbow and then I need to give the index number. Now the index number is going to be a random number from one to four, and the way I get that, this is going to involve just a little bit of back and forth here. As I put random, and to get 1 to 4, I can do 1 and I am going to do up to 5, now that's because 5 is an exclusive limit, it goes actually from 1.000 to 4.999.

And then what happens is, if I cast the variable, because for index numbers I need integers, I come back here and I put the whole thing in parentheses () like that and if I go here, you can just see, which ones these correspond to. On the other hand, I see that for index numbers, it needs to be in square brackets []. So I need to take that one and put it in a square bracket and close this one with a square bracket and then I need one more closing parenthesis for the color function. So it's kind of a mishmash there with parenthesis, parenthesis, square bracket parenthesis but as that's the way it needs to do to get nested.

As so what that will do, is it will pull one of those palette colors down and the ellipses would be in those colors. I am going to save this and I am going to run it like this. And now you see there's only four different colors that are showing up and this is kind of nice because they're all chosen to be coordinated with the background color and with each other. And that's the general idea of Processing the random function. In the next two videos, I am going to show you a couple of variations on this. One is a very short one about how to shuffle information using a Java command and another one is a different kind of randomness, it's called Perlin Noise.

Show transcript

This video is part of

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

72 video lessons · 13920 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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