Processing: Creative Coding and Computational Art

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The Processing window is divided into horizontal bands of varying height. I’ll deal with each, from the bottom up. The line number, at the very bottom of the window, shows you what line of code you are currently working on, based on your cursor position. The text area gives you verbose feedback about bugs in your code. It can be scary and frustrating to new coders to see all these errors come up in the text area when they first begin coding; rest assured, it happens to all of us. New coders often struggle to even find the errors in their code, and it can seem impossible that a typo or logic error could still possibly exist in code you’ve painstakingly gone through numerous times. The errors will likely also seem annoyingly cryptic, but over time you’ll learn to understand the messages and more quickly track down your bugs. However, there are times when even experienced coders struggle to eradicate bugs. I usually find taking a break helps (as well as screaming obscenities at the top of my lungs). Eventually, you’ll appreciate these verbose error messages and see how valuable they are in the debugging process. Processing also includes two commands, print() and println(), that allow you to output information about your sketch to the text area. The message area gives you quick feedback during saving and exporting, and tells you in plain, simple language about errors in your code. The text editor is where you write your sketch code; it’s essentially your old text editor. If you play with it, you’ll notice that there are clear feedback color cues, showing you what line your cursor is on, what text is selected, and if a word you typed is a legal keyword in the language. The tabs show you what files you are working with. Tabs are really handy when your sketch requires multiple files. At the right side of the tabs area is a right-facing arrow button. Pressing this button opens a pop-up menu that allows you to create and manage your tabs. When you open an existing sketch in Processing, any Java or PDE files in your sketch directory will be automatically put into the tabs layout. The benefit of this will become clearer when you begin to work with external functions and classes. By default, there will always be at least one tab open, with its name at the bottom of the tab pop-up menu. This tab will be your current main sketch PDE file (it’s called a PDE file because .pde is just the suffix that Processing sketches use—it stands for “Processing development environment”). As more tabs are created, you’ll see the new tab names at the bottom of the tabs pop-up menu as well. You can select one of these names by clicking on it to give the tab focus (make it the active window) in the Processing project window. When you click on the tabs arrow button, the pop-up menu allows you to do the following: Create a new tab Rename a tab Delete a tab Hide/unhide a tab Move focus to the previous/next tab THE PROCESSING ENVIRONMENT 147 5
PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART 148 When you create a new tab, you’ll be prompted to give it a name. Processing requires PDE and Java file names to begin with a letter or underscore and contain no spaces. You may use numbers in the name after the initial character, and names should be no more than 64 characters in length. If you try to name a PDE or Java file using an illegal character, Processing will rename your file automatically, converting the illegal character to an underscore. For example, the name function 1 will be renamed function_1. In addition, you have the option of adding a .pde or .java suffix. If no suffix is added, Processing assumes the new file is of type PDE. You won’t see the .pde suffix displayed in the tabs, but if you look in your project directory, you’ll see it there. If you specify .java as a suffix, then the file should be a standard Java file, and you should see the .java suffix in the tab; although the suffix doesn’t come up at the bottom of the tabs pop-up menu. Any other suffix you add will be removed and appended to the root of the name, and the file will be of type PDE. For example, if you accidentally try to save your sketch with the name newfilename.ppe, the full file name will be converted to newfilename_ppe.pde. Again, in the tab, you’ll only see the newfilename_ppe part. Finally, if you hide a tab, it does more than just temporarily change the tab’s visibility. When you run or export your project, if a tab is hidden, then the file associated with the tab will not be compiled or included in the applet subdirectory. The Hide function is a convenient way to ensure that classes and functions not being used in your final sketch do not unnecessarily bloat your program when you compile. If you accidentally hide a tab, but still reference it in your code, the compiler will give you an error—either “No accessible method,” for a missing function; or “Type . . . was not found,” for a missing class. If you look in your sketch directory (see Figure 5-3), you’ll notice that hidden files get appended with .x after the .pde or .java suffix. Figure 5-3. Screen capture of a Processing sketch directory
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IrA GreenberG CreATe CoDe ArT, vIsu
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Processing: Creative Coding and Com
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CONTENTS AT A GLANCE Foreword . . .
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CONTENTS Foreword . . . . . . . . .
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CONTENTS viii The joy of math . . .
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CONTENTS x Applying OOP to shape cr
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CONTENTS xii Environment . . . . .
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FOREWORD If you are like me (and th
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ABOUT THE AUTHOR With an eclectic b
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ACKNOWLEDGMENTS I am very fortunate
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INTRODUCTION Welcome to Processing:
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INTRODUCTION xxii Intended audience
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INTRODUCTION xxiv Setting up Proces
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INTRODUCTION xxvi Hopefully by now
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INTRODUCTION xxviii Figure 3. Scree
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INTRODUCTION xxx New or changed cod
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1 CODE ART
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The problem with a Photoshop filter
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Figure 1-3. Example of ancient art
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then jump 400 years to 1614 and Joh
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fertile imagination remained intact
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As an aside, it’s worth observing
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John Whitney Sr., 1918-1995 John Wh
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algorithms. To learn more about Coh
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landfill/), and Feed (www.potatolan
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periodicals such as Art Journal, Wi
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And many more . . . While I have in
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2 CREATIVE CODING
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I think what was reinforced for me
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customized commands, and run loops.
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of code that work like processing m
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introduced to become larger, more c
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Without getting too geeky, the main
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A framework is just a concept for b
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algorithm in a math class in high s
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frame. The loop keeps running and k
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the time to play at whatever level
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} pts[counter2].y-yg); xg*=-1; coun
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The overall movement was good, but
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Obviously, there are a lot of thing
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} } // generates organic looking br
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3 CODE GRAMMAR 101
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Your first program In most programm
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message comes up on the bar in the
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Since the getBreed() method would r
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Variables Variables are essential t
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It’s because strict typing helps
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Stage 3 adds the gradient: /* title
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Next, I assign values to some primi
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In the first preceding example, add
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Assignment operators The only other
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* title: Bouncing Ball description:
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Animation is a perfect example of t
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if (hunger= starving) { eatAnything
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Ternary operator The last condition
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The items array has 50 places reser
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println(x); x += 1; } while(x
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Figure 3-4. Continuous radial gradi
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int ballCount = 500; int ballSize =
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Hopefully, you were able to success
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function call above*/ // fill(i*255
Page 128 and 129: If you run this, you should see a 1
Page 130 and 131: yspeed*=-1; } } Within the draw() f
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Page 138 and 139: 4 COMPUTER GRAPHICS, THE FUN, EASY
Page 140 and 141: Some of the reasons coding graphics
Page 142 and 143: When working in a 3D coordinate sys
Page 144 and 145: plotted, the vertices are connected
Page 146 and 147: eally shines. And remember, as you
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Page 150 and 151: Within each of these application ar
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Page 154 and 155: Geometry Like algebra, geometry dat
Page 156 and 157: (second-degree) curve has one turni
Page 158 and 159: or possibly even a complete crash o
Page 160 and 161: This linear motion would plot as a
Page 162 and 163: and began doubling. By step 80, the
Page 164 and 165: *Simple Repeating Wave Pattern Ira
Page 166 and 167: float waveGap = 10; float frequency
Page 168 and 169: a piece of paper and do a little mo
Page 170 and 171: Interactivity Figure 4-13. Puff Peo
Page 172: Events will be covered and implemen
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Page 204 and 205: 6 LINES
Page 206 and 207: Figure 6-2. Two-point sketch Adding
Page 208 and 209: Streamlining the sketch with a whil
Page 210 and 211: type into the sketch. Although the
Page 212 and 213: Figure 6-7. Randomized particle spr
Page 214 and 215: Figure 6-9. Multiple randomized par
Page 216 and 217: Coding a grid To begin, I’ll show
Page 218 and 219: Notice that you can make the value
Page 220 and 221: float steps = totalPts+1; int total
Page 222 and 223: Creating space through fades Your l
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coordinates of the line. For exampl
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Figure 6-24. End cap variation exam
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Figure 6-25. Auto Layout sketch Thi
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int xPadding = 150; int yPadding =
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Figure 6-27. Table Layout II sketch
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for (int i=0; i
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This is the same drawTable() functi
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easy. The benefit of internally rec
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I call my custom function makeRect(
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As you might suspect, anti-aliasing
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call scribble function strokeWeight
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else { } // extra line needed to at
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smooth(); float x = random(width);
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Figure 6-36. Concentric Maze sketch
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void setup(){ //these values can be
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Create a Triangle size(400, 400); b
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Figure 6-39. Create 3 Triangles ske
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Poly Pattern I (table structure) /*
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Poly Pattern II (spiral) /* Poly Pa
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Poly Pattern III (polystar) /* Poly
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Figure 6-46. Poly Pattern III (poly
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7 CURVES
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size(200, 200); background(255); in
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You should notice some familiar str
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int margin = height/15; strokeWeigh
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Figure 7-8. Revealing the points ma
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* Curves II Ira Greenberg, December
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lower particle speed ySpeed[i]*=gra
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Figure 7-11. Curves simulating a fo
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Figure 7-13. Damping effect on curv
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particle style strokeWeight(strokeS
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By using functions to organize a pr
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for (int i=0; i
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Figure 7-18. Generating a curve wit
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float x = 0, y = 0; int loopLimit =
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concentric circles size(200, 200);
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Pie charts, although valuable as vi
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curve() and bezier() The next two P
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Next is an interactive example that
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Figure 7-27. Interpolating a Bézie
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ezier(350, 100, 400, 150, 350, 250,
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Figure 7-30. Spline curve using Pro
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curve segments noFill(); // comment
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control handles fill(255); ellipse(
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Figure 7-32. bezier() vs. bezierVer
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curveVertex(92+x, 15); curveVertex(
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strokeWeight(.75); stroke(0); rectM
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Figure 7-35. Bézier Ellipse sketch
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I included one last example (shown
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curveTightness(tightness); beginSha
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Summary Curves, and the math behind
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PROCESSING: CREATIVE CODING AND COM
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10 COLOR AND IMAGING
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left squares fill(255, 120, 0); rec
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the color. Up to this point in the
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} radius*=ratio; ratio-=.1; } } els
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Figure 10-4. Alpha sketch In this e
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A quick review of creating transfor
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* Nematode - stage 1 Ira Greenberg,
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Figure 10-8. Nematode sketch (stage
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Figure 10-9. Finished Nematode sket
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the decreasing wavelengths of the i
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values, just to illustrate the poss
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lerpColor() uses the same approach
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I want to mention two final points
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column for (int i=x; i
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needs to be increased, as radius in
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Figure 10-19. Wave Gradient sketch
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for (int i=0; i
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Figure 10-23. Load an Image sketch
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The image() function has an extra f
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In the last example, I created an a
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Figure 10-27. Simple Image Encrypti
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Figure 10-28. Pixilate sketch The n
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Figure 10-30. Tint sketch Speeding
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* Tint (using bitwise operations) C
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the book that a primitive type is d
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The mask works like an alpha channe
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ect(random(width), random(height),
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This last sketch couldn’t be simp
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separate out and invert component c
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Figure 10-39. GRAY Filter sketch Th
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adius is set high, the blurring can
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lend() PImage Method sketch // both
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Figure 10-45. blend() Function with
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The next sketch utilizes some for l
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In the last example, I used Process
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Inheritance In OOP, inheritance des
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AXIS_VERTICAL from outside the Grad
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y axis if(axis == AXIS_VERTICAL){ f
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calculate differences between color
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c7 = color(0); c8 = color(255); r1
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In the “Imaging” section, you d
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12 INTERACTIVITY
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} public void mouseClicked(MouseEve
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void setup(){ size(400, 400); // in
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initialize x, y x = width/2.0; y =
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float friction = .85; float[]jitter
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nodeYPos = append(nodeYPos, mouseY)
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As usual, I declare global variable
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are filled with black. Using the in
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} } } } } // bottom display window
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color btnUpState = color(200, 200,
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float xSpeed = 0; color movingSquar
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xSpeed-=.2; btn1Background = btnDow
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mouse trails if (isTrailable){ fill
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isTrailsSelected, which changes the
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shapes. The following example, in s
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set initial button background color
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also makes the code a little harder
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stroke(200); rect(eraserBtn[0], era
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} sliderValue = (sliderHandle[0]-sl
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if (!isBrushSelected){ if (mouseX>b
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selection can be active at a time.
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ectBackground = color(255, 0, 0); }
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is smaller (vertically) than the en
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keys 2-8 control number of edges fo
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strokeWeight(strokeWt); float angle
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Summary We began this chapter compa
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A PROCESSING LANGUAGE API
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http://processing.org/. My main obj
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its binary equivalent. I used some
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part of the article as well. My sug
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Example 1: A Java approach void set
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The combination of these two struct
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Example 3: Creating a honeycomb gra
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Conditionals Conditionals and the r
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Shape // top and bottom boundaries
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You’ll notice that by default, th
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start dragging if flag true for (in
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pushMatrix(); rotateY(-frameCount*P
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egular polygon size(400, 400); smoo
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texture(images[3]); vertex(w, -h/2,
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lots of arrays float[]x = new float
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Keyboard Figure A-9. Box Springs sk
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entering CMD). When using a command
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hour hand strokeWeight(2); stroke(5
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In the next example, I use beginRec
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Transformations include moving, sca
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float ang; int rows = 20; int cols
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vertex(-w/2 + shiftX, -h/2 + shiftY
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Lights The Lights section includes
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system, you can try lowering the re
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ankAngle+=bankSpeed; vert = -600 +z
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Setting The Setting section include
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ellipseMode(CORNER); fill(200, 200,
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of this part of the API. These myst
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Image The Image section relates ver
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Loading & Displaying The Loading &
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these elements is the creation of a
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Typography Processing utilizes mult
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This will output a list of all the
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“Operators” will hopefully soun
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The noise() function is an advanced
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B MATH REFERENCE
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After multiplying, you can reduce t
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Here’s an example: When dividing,
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Figure B-1. Using a right triangle
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Here’s how the process works: pic
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In Figure B-5, the point p is at 45
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ect (px, py, 5, 5); stroke(100); li
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manipulation is one area in which b
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the number, as shown in the followi
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Here’s the output: c1 in binary =
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This sketch outputs the following:
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I’m not going to provide examples
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simple-looking paint bucket tool in
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Figure B-7. Color variations filter
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INDEX 776 SYMBOLS AND NUMERICS /* a
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INDEX 778 beginShape function, 209
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INDEX 780 clipping planes, frustum,
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INDEX 782 naming conventions/rules,
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INDEX 784 functions, 440 loadPixels
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INDEX 786 filter function, 452-459
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INDEX 788 minute, 708 modelX/modelY
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INDEX 790 H haptics, 108 has-a rela
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INDEX 792 MouseListener interface,
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INDEX 794 M Mac keyboard shortcuts,
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INDEX 796 classes, 304, 321 constan
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INDEX 798 coding in 3D, 616 mapping
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INDEX 800 procedures see functions
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INDEX 802 Hybrid Shape, 366, 368 Hy
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INDEX 804 radians, converting betwe
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INDEX 806 Nematode sketch, 411, 413
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INDEX 808 text Orbiting Text sketch
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INDEX 810 VERY_HIGH option, encrypt
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