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Drawing complex curves

From: Interactive Data Visualization with Processing

Video: Drawing complex curves

In this movie we're going to learn how to draw curves with an indefinite number of points defining them and you see you can get some very complex sometimes amusing, but always interesting results out of this one. Now I do need to mention that what we're drawing are not Bezier curves, that's a whole separate function, and we'll get to it in the next movie, but you do have some interesting things you can do with this one. I'll start by naming the file with the comment, I'm setting the size of the window, turning on the anti-aliasing.

Drawing complex curves

In this movie we're going to learn how to draw curves with an indefinite number of points defining them and you see you can get some very complex sometimes amusing, but always interesting results out of this one. Now I do need to mention that what we're drawing are not Bezier curves, that's a whole separate function, and we'll get to it in the next movie, but you do have some interesting things you can do with this one. I'll start by naming the file with the comment, I'm setting the size of the window, turning on the anti-aliasing.

And then I'm going turn off the fill if I leave the fill on it get some unexpected results that we've seen with some of the other once, let's put in a noFill. And then what I'm going to do is I'm going to draw a series of curves that all share points, but to make it little easier I'll draw the points first and then draw the curves underneath them. We already know how to draw points all I need is the point function. What I am going to do is I'm going to call strokeWeight and I get that out to about 5 pixels, I'm also going to make this once a bright red, so what I'm going to do is stroke and then I'll use the RGB here, I am not going to go all the way on that, I'm going at 200, 0, 0.

And then what I'm going to do is I'm just going to go ahead and put point and the coordinates for each one; I have a series of them I'm going to get, so I'm just going to copy and paste this information and move each one of them over. First one is at 100, 100, next one be at 150, 150, next one be at 250 and 50, next one is at 300 and 10, next one will be at 400 and 190. These by the way are arbitrarily chosen there is so meaning to this particular coordinates except they're all in the window.

Last one will be 500 and 100. All right, and if I just draw the points there they they are, scattered around the window I may actually make those slightly larger for this particular exercise, I'll take them up to an eight, there we go. Now what I'm going to do is I'm going to run curves that go through every one of these points. They're going to be open curves are not going to loop back around this is going to be a curvy line that goes through each one of these and I'm going to draw few versions with some different parameters, but let's do the first one.

I'm going to copy this information here, because I'm going to need it again and I want the same coordinates, I'm going to paste it right here. Now like we have done with some of the other ones, because there's an arbitrary number of points that can be included, you need to let it know you're starting and finishing a particular shape. So what I'm going to do is I'm going to come up to the top and by the way I'm going to put this as a little comment here this would be black curve. And so I need to specify that is black by putting stroke for the color and zero for black.

And then I'm going to put the strokeWeight as 3 pixels and then I can beginShape. So I type it, it's all lowercase expect for the S which is a capital in shape that makes a bumpy caps. I have the empty parentheses to indicate that there are no arguments in this particular function, and then finish with the semicolon, and then what I do is instead of having point here I need a whole series of arguments called curveVertex.

So, it's like when we did polygons you can make a polygon by adding one vertex to another. This one, it's a curveVertex indicates it handles it a little bit differently. And I'm just going to copy that and replace each of these points. Now an interesting thing about the way the curveVertexes work is that they need a starting point that separate from the original and one way to do this, or at least it has to be specified separately, is you can just duplicate the beginning and the ending.

So I'm repeating the beginning and the ending coordinates that is one way of specifying where it starts and stops. And then I end with endShape. Now I'll just put this one down here and specify that those are the red dots. Now I'm putting the red dots afterwards because I want them to draw on top of the black curve. Again, the order of drawing matters here in terms of things that come later get drawn on top of things that came earlier. So I'm going to save this and there is my default curve.

Not particularly exciting in and of itself, but you see there's some interesting things that you can do with it. Now what I'm going to do right now is I'm going to add an extra parameter to my drawing right here under strokeWeight I'm going to put in curve tightness, we've seen what this can do with just a simple curves earlier, I'm going to put in a zero which you see doesn't really change it and that serves as a starting point for what we're going to do. But now I'm going to draw all of this over again with just changing some of the parameters.

Now the easiest way to do this for me by the way is to just copy and paste, so I'm going to copy all the code for the black curve and I'm going to bring it down. And I'm going to make a gray curve, and so for that one I'm just going to change the fill to 100 that's a medium gray, I'll change maybe the strokeWeight, I'll leave that where it is. And the curve tightness is interesting, well I'm going to change that to a negative 3. Now I Save it and Run it and you can see that we gotten a much wobblier shape, because of that curve tightness.

I should mention that these all have to do with something called Catmull-Rom Spline and that's a mathematical formula for determining the shape that the things go through that the flatness of each line have to do with the point before and after it. But let's draw one more and just to make things a little more interesting, I'll take the gray curve code paste it down here, I'll draw one more, I'll draw a white curve. So that one need a 255, that's all the way white.

And I'm going to give that one a curve tightness of positive 4. Save that and Run that. And you can see it actually loops around backwards through each one, it gets kind of crazy how it goes through. There's a really fascinating thing you can do in terms of joining elements in a sketch using the curve feature here and playing with the tightness factor. Anyhow this is just another way of connecting elements and drawing shapes and processing one of the more interesting ones.

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This video is part of

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

72 video lessons · 12189 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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