Processing: Creative Coding and Computational Art

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Advanced OOP concepts Next, I’ll introduce some advanced OOP concepts, including encapsulation/information hiding, inheritance, composition, interfaces, and polymorphism. These concepts are fundamental to OOP, but they’re somewhat difficult to grasp and even harder to effectively apply. Understanding these concepts becomes increasingly important as your projects increase in size and complexity, especially when you want to create reusable code. If you’re a new coder (and are still recovering from the basic OOP whirlwind tour), you might want to skip this next section (for now). Just be sure to return to it, as you’ll definitely want to know about this stuff to fully leverage the power of Processing and Java. Fortunately, you can learn these concepts incrementally as you progress as a coder. It’s also possible, if you’re anything like me, that you may end up finding this stuff fascinating. Encapsulation and data hiding Encapsulation is one of the more “slippery” terms you’ll stumble across when you begin to learn programming. On the one hand, its meaning in programming is similar to its meaning in English—the encasing or enclosing of something. You can think about the way a function encases lines of code into an invokable unit as a form of encapsulation. One of the benefits of this arrangement is that the interface to a function and the implementation within the function are separated; this allows the implementation to change over time while still maintaining a consistent interface. For example, if I have a function called createPortrait() that initially draws a lousy stick-figure head, over time I can improve the algorithm to generate a more photorealistic head. The user, then, can just keep calling createPortrait() as the interface to the function remains constant, in spite of the improvements made to the guts of the function. In OOP, encapsulation refers to the encasing and grouping of an object’s data fields (properties) with its methods. As mentioned earlier, objects are created from classes, each with its own copies of the properties and methods defined in the class. In classic OOP, you don’t generally interact with an object’s properties directly. Instead, you use the object’s methods to get or set its property values. This principle is referred to as data or information hiding. In Java, for example, you normally use the keyword private when declaring properties to make them inaccessible. You declare methods (which are the structures that users of the class must use to interact with the properties) as public to get and set their values. For example, if I have class that has a name property, I would declare the property as private like this: private String name; And I would create public get and set methods to provide indirect access to the private name property, as follows: public String getName (){ return name; } public void setName (String n){ name = n; } OBJECT-ORIENTED PROGRAMMING 319 8
PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART 320 One of the benefits of data hiding is that dependencies between properties can be better managed. For example, if an object uses the values of a number of properties to calculate something, and users are allowed to go in willy-nilly and change any property values directly, calculations could be adversely affected. However, if you use a method, property values can be both set and checked prior to performing any calculation, improving upon both program efficiency and reliability. All that being said, in Processing, everything is public by default, meaning that to a user of the Processing API, everything is directly accessible. This design decision was made to keep Processing as simple as possible. However, it is possible, especially when working in Java mode, to make your properties private and enforce data hiding. In Chapter 14, you’ll work in Java mode, making your object properties private and using public get and set methods to interact with them. To learn more about this concept, check out http://java.sun.com/ docs/books/tutorial/java/concepts/object.html. Inheritance Inheritance in OOP is the ability of a class A to inherit or extend another class, B, enabling class A to have access to the properties and methods within the extended class B. In this constructed relationship, class B is referred to as the superclass that class A extends, and class A becomes the subclass that extends class B. In addition, class A can add its own additional properties and methods, and even overwrite specific properties and methods of class B (its extended superclass). Inheritance proceeds in a general-to-specific direction. For example, if I have a class called GermanShepherd, I could start with a very general base class, called Mammal, a subclass of Mammal called Quadruped, a subclass of Quadruped called Canine, and a subclass of Canine called GermanShepherd. A Feline class could also inherit from Quadruped, while a Human class might come from a Biped class that inherited from Mammal. Figure 8-1 shows a diagram of this. Figure 8-1. OOP inheritance diagram
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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
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If you run this, you should see a 1
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yspeed*=-1; } } Within the draw() f
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void checkCollisions(int xp, int yp
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createRect(50, 50, 100, 100, 20, 5,
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4 COMPUTER GRAPHICS, THE FUN, EASY
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Some of the reasons coding graphics
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When working in a 3D coordinate sys
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plotted, the vertices are connected
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eally shines. And remember, as you
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need to be stored in memory, and th
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Within each of these application ar
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don’t realize you’re doing it
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Geometry Like algebra, geometry dat
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(second-degree) curve has one turni
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or possibly even a complete crash o
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This linear motion would plot as a
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and began doubling. By step 80, the
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*Simple Repeating Wave Pattern Ira
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float waveGap = 10; float frequency
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a piece of paper and do a little mo
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Interactivity Figure 4-13. Puff Peo
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Events will be covered and implemen
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PROCESSING: CREATIVE CODING AND COM
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6 LINES
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Figure 6-2. Two-point sketch Adding
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Streamlining the sketch with a whil
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type into the sketch. Although the
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Figure 6-7. Randomized particle spr
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Figure 6-9. Multiple randomized par
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Coding a grid To begin, I’ll show
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Notice that you can make the value
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float steps = totalPts+1; int total
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Creating space through fades Your l
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for (int j=0; j
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Figure 6-19. Yin Yang Fade sketch,
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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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Page 324 and 325: Figure 7-35. Bézier Ellipse sketch
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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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