Learning Processing: A Beginner's Guide to Programming Images ...

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13 Mathematics Mathematics 201 “ If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is. ” —John von Neumann “ If you were cosine squared, I’d be sine squared, because together we’d be one. ” —Anonymous In this chapter: – Probability. – Perlin noise. – Trigonometry. – Recursion. Here we are. Th e fundamentals are fi nished and we are going to start looking at some more sophisticated topics in Processing . You may fi nd there is less of a story to follow from chapter to chapter. Nonetheless, although the concepts do not necessarily build on each other as fl uidly as they did previously, the chapters are ordered with a step-by-step learning approach in mind. Everything we do from here on out will still employ the same fl ow structure of setup( ) and draw( ) . We will continue to use functions from the Processing library and algorithms made of conditional statements and loops, and organize sketches with an object-oriented approach in mind. At this point, however, the descriptions will assume a knowledge of these essential topics and I encourage you to return to earlier chapters to review as needed. 13.1 Mathematics and Programming Did you ever start to feel the sweat beading on your forehead the moment your teacher called you up to the board to write out the solution to the latest algebra assignment? Does the mere mention of the word “ calculus ” cause a trembling sensation in your extremities? Relax, there is no need to be afraid. Th ere is nothing to fear, but the fear of mathematics itself. Perhaps at the beginning of reading this book, you feared computer programming. I certainly hope that, by now, any terrifi ed sensations associated with code have been replaced with feelings of serenity. Th is chapter aims to take a relaxed and friendly approach to a few useful topics from mathematics that will help us along the journey of developing Processing sketches. You know, we have been using math all along. For example, we have likely had an algebraic expression on almost every single page since learning variables. x = x + 1;
202 Learning Processing And most recently, in Chapter 10, we tested intersection using the Pythagorean Th eorem. float d = dist(x1,x2,y1,y2); Th ese are just a few examples we have seen so far and as you get more and more advanced, you may even fi nd yourself online, late at night, googling “ Sinusoidal Spiral Inverse Curve. ” For now, we will start with a selection of useful mathematical topics. 13.2 Modulus We begin with a discussion of the modulo operator , written as a percent sign, in Processing. Modulus is a very simple concept (one that you learned without referring to it by name when you fi rst studied division) that is incredibly useful for keeping a number within a certain boundary (a shape on the screen, an index value within the range of an array, etc.) Th e modulo operator calculates the remainder when one number is divided by another. It works with both integers and fl oats. 20 divided by 6 equals 3 remainder 2. (In other words: 6*3 � 2 � 18 � 2 � 20.) therefore: 20 modulo 6 equals 2 or 20 % 6 � 2 Here are a few more, with some blanks for you to fi ll in. 17 divided by 4 equals 4 remainder 1 17 % 4 � 1 3 divided by 5 equals 0 remainder 3 3 % 5 � 3 10 divided by 3.75 equals 2 remainder 2.5 10.0 % 3.75 � 2.5 100 divided by 50 equals ___________ remainder ______ _________ 100 % 40 � ____________ 9.25 divided by 0.5 equals ___________ remainder _______________ 9.25 % 0.5 � ______ _____ You will notice that if A � B % C , A can never be larger than C . Th e remainder can never be larger than the divisor. 0 % 3 � 0 1 % 3 � 1 2 % 3 � 2 3 % 3 � 0 4 % 3 � 1 etc .
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Learning Processing A Beginner’s
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Learning Processing A Beginner’s
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Contents Acknowledgments vii Introd
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Acknowledgments In the fall of 2001
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Introduction What is this book? Th
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Introduction xi While both of these
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Introduction xiii Th e book is desi
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Introduction xv Th is book’s web
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Introductory Exercise: Write instru
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Lesson One The Beginning 1 Pixels 2
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1 Pixels “ A journey of a thousan
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1.2 Simple Shapes Pixels 5 Th e vas
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0 1 2 3 4 5 6 7 8 9 fi g. 1.9 top l
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1.3 Pixels 9 Exercise 1-3: Reverse
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Example 1-2: noFill ( ) background(
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fi g. 1.19 Pixels 13 Exercise 1-5:
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colorMode(RGB,100); Pixels 15 Th e
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2 2.1 Processing “ Computers in t
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fi g. 2.2 Once you have opened the
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Let’s write a fi rst example ( se
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Line 9 fi g. 2.6 Processing is case
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fi g. 2.7 Processing 25 Processing
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Example 2-1: Zoog again size(200,20
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Processing 29 To see the applet wor
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3 3.1 Interaction “ Always rememb
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Let’s look at what will surely be
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3.3 Variation with the Mouse Intera
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Draw Zoog's eyes fill(0); ellipse(8
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3.4 Mouse Clicks and Key Presses In
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Draw Zoog's eyes fill(mo useX,0,mou
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Lesson Two Everything You Need to K
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4 4.1 Variables “ All of the book
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4.2 Variable Declaration and Initia
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A variable can also be initialized
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x = 5; x = a + b; x = y - 10 * 20;
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void draw() { // Draw the backgroun
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4.6 Random: Variety is the spice of
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4.7 Example 4-7: Filling variables
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5 5.1 Conditionals Conditionals 59
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Finally, for testing multiple condi
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Conditionals 63 It is worth pointin
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Conditionals 65 Getting into the ha
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Our fi rst instinct might be to wri
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5.5 Multiple Rollovers Conditionals
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Conditionals 71 We can then check t
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5.7 Conditionals 73 Exercise 5-8: E
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Reversing the Polarity of a Number
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One way to solve this problem is to
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Display the square fill(0); noStrok
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6 Loops “ Repetition is the reali
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Loops 83 (see Chapter 5). However,
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while (y < 100) { // Loop! } 3. Wha
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while (x < = endLegs) { line(x,y,x,
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Th e same exact loop can be program
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Loops 91 Th is was a nice simplifi
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6.6 Loop Inside the Main Loop Loops
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6.7 float distance = abs(mouseX - i
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Draw Zoog's legs stroke(0); line(x-
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Lesson Three Organization 7 Functio
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7 7.1 Functions “ When it’s all
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7.2 “ User Defi ned ” Functions
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Example 5-6: Bouncing ball // Decla
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7.5 Functions 107 Exercise 7-3: Tak
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Functions 109 It should be fairly a
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int globalX = 0; int globalY = 100;
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void setup() { println( "a"); funct
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If we did not include a return stat
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7.8 Zoog Reorganization Zoog is now
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void draw() { } background(0); // D
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8 8.1 Objects “ No object is so b
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Setup: Draw: Initialize car color.
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Objects 125 • The Class Name—Th
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Objects 127 One other thing; with t
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fi g. 8.1 fi g. 8.2 fi g. 8.4 fi g.
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Objects 131 Nevertheless, this is q
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void draw() { } background(100); ba
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Objects 135 modular, reusable packa
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Lesson Three Project Step 1. Take y
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Lesson Four More of the Same 9 Arra
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9 Arrays “ I might repeat to myse
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Car myCar80 Car myCar81 Car myCar82
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9.3 Declaring and Creating an Array
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9.4 Initializing an Array One way t
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Example 9-5: Using a for loop to in
Page 170 and 171: Arrays 151 Now comes the hard part.
Page 172 and 173: 9.7 Arrays 153 Exercise 9-7: Rewrit
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Page 176 and 177: Check if point is inside of Stripe
Page 178 and 179: alls[i].gravity(); balls[i].move();
Page 180 and 181: Draw Zoog's arms with a for loop fo
Page 182 and 183: Lesson Five Putting It All Together
Page 184 and 185: 10 10.1 Algorithms “ Lather. Rins
Page 186 and 187: Translating the preceding algorithm
Page 188 and 189: void draw() { background(255); stro
Page 190 and 191: Example 10-2: Bouncing ball class c
Page 192 and 193: Now that the function is complete,
Page 194 and 195: 10.6 // Constructor Ball(float temp
Page 196 and 197: Algorithms 177 With the above logic
Page 198 and 199: Drop() { r = 8; // All raindrops ar
Page 200 and 201: Example 10-7: Drops one at a time /
Page 202 and 203: Algorithms 183 Notice how every sin
Page 204 and 205: oolean intersecting = ball1.interse
Page 206 and 207: } void setLocation(float tempX, flo
Page 208 and 209: Algorithms 189 It is important to r
Page 210 and 211: 11 Debugging “ Th e diff erence b
Page 212 and 213: Debugging 193 Once all the code is
Page 214 and 215: 12 Libraries “ If truth is beauty
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Page 218 and 219: Lesson Six The World Revolves Aroun
Page 222 and 223: Mathematics 203 Th erefore, modulo
Page 224 and 225: Th e probability of a coin fl ippin
Page 226 and 227: 13.6 Perlin Noise Mathematics 207 O
Page 228 and 229: Mathematics 209 How quickly we incr
Page 230 and 231: It is fairly intuitive for us to th
Page 232 and 233: fi g. 13.9 y-axis sine(theta) � y
Page 234 and 235: Example 13-6: Oscillation float the
Page 236 and 237: Mathematics 217 In 1975, Benoit Man
Page 238 and 239: Mathematics 219 said about recursio
Page 240 and 241: Mathematics 221 A two-dimensional a
Page 242 and 243: Example 13-10: Two-dimensional arra
Page 244 and 245: } void display() { } // FILL IN Mat
Page 246 and 247: 14 14.1 Translation and Rotation (i
Page 248 and 249: Our fi rst instinct might be to add
Page 250 and 251: Example 14-3: A rectangle moving al
Page 252 and 253: When using the OPENGL mode, you mus
Page 254 and 255: Translation and Rotation (in 3D!) 2
Page 256 and 257: 14.5 fill(150,150); vertex(-t, t,-t
Page 258 and 259: 14.6 Example 14-5: Rectangle rotati
Page 266 and 267: fill(0,100); // Note the use of pus
Page 268 and 269: 14.9 Example 14-17: Nested push and
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stroke(0); fill(175); ellipse(0,0,d
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Lesson Seven Pixels Under a Microsc
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15 Images Images 255 “ Politics w
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And yet: PImage img = loadImage( "f
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15.3 My Very First Image Processing
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Images 261 Even better, if we just
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Images 263 // Create a grayscale co
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Images 265 15.6 Intro to Image Proc
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Images 267 Since we are altering th
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15.9 More on fi lter( ): fi lter(mo
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Images 271 Example 15-13 performs a
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Example 15-14: “ Pointillism ”
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16 16.1 Video “ I have no memory.
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Video 277 Th e above line of code i
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void draw() { // Check to see if a
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16.3 Recorded Video Video 281 Displ
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16.4 Video 283 Exercise 16-3: Using
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Video 285 For every square at colum
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} } // Each rect is colored white w
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16.5 Video as Sensor, Computer Visi
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Now, we are ready to compare the co
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16.6 Video 293 Exercise 16-5: Take
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void setup() { size(320,240); video
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Example 16-13: Simple motion detect
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16.8 // Step 4, compare colors (pre
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Lesson Seven Project Develop a soft
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Lesson Eight The Outside World 17 T
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17 17.1 Text “ I could entertain
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Exercise 17-2: Loop through and pri
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17.3 Displaying Text Text 309 We wi
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println(PFont.list()); For demonstr
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X = �50 fi g. 17.4 float w = text
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Example 17-4: Text mirror import pr
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textFont(f); // Set the font transl
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Exercise 17-9: Using textWidth( ) ,
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Example 17-7: Boxes along a curve P
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Text 323 Exercise 17-10: Create a s
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18 Data Input “ A million monkeys
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Example 18-1: User input PFont f; /
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Data Input 329 Th e reverse of spli
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Example 18-2: Graphing comma separa
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Data Input 333 Th e rollover( ) fun
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18.4 diameter = diameter_; } // Tru
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} // Find the index of the end tag
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void mousePressed() { // Increment
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18.6 for (int i = 0; i < kinglear.l
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Create and make an asynchronous req
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� student � � id � 002 �
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Requests for XML data are made via
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18.8 Using the Processing XML Libra
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XMLElement diameterElement = childr
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Example 18-10: A Yahoo search impor
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However, if you request a URL on a
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19 19.1 Data Streams “ I’m mad
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import processing.net.* ; Server se
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Data Streams 361 Once the server is
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19.4 void draw() { background(255);
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Data Streams 365 must be networked
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Data Streams 367 will send X , Y co
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Data Streams 369 Here is the full S
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Here is the entire client sketch: 1
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Data Streams 373 Serial communicati
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Data Streams 375 of information, ca
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Corresponding Arduino code: int sen
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Lesson Nine Making Noise 20 Sound 2
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20 Sound “ Check. Check. Check 1.
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void setup() { Sonia.start(this); }
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void mousePressed() { // If the use
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Sound 387 check and see if a sound
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Is a point inside the doorbell (use
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Pressing the mouse stops and starts
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20.6 void draw() { background(255,1
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In code, this translates to: // If
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21 Exporting “ Wait a minute. I t
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Th is code can be inserted anywhere
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void setup() { size(400, 400); begi
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Exporting 403 save( ) takes one arg
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Exporting 405 Example 21-5 records
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Lesson Ten Beyond Processing 22 Adv
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22 Advanced Object-Oriented Program
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class Point { float x,y; Point(floa
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Advanced Object-Oriented Programmin
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Advanced Object-Oriented Programmin
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class Circle extends Shape { // inh
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for (int i = 0; i < dogs.length; i
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22.5 Example 22-2: Polymorphism //
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23 23.1 Java “ I l o ve c off ee,
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Java 425 instead of Processing , sp
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fi g. 23.2 Java 427 Just as with th
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Particle p = parray[i]; p.run(); p.
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Hint: Add a function that returns a
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Example 23-4: Super fancy ArrayList
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Java 435 It is sad when these error
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Th e tutorials will cover the same
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Appendix: Common Errors Appendix 43
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Error: No accessible fi eld named
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void draw() { thing.display(); } Co
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Error: Perhaps you wanted the overl
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Index AIFF (Audio Interchange File
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Fill( ) function 10 , 11 , 256 , 30
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One-dimensional Perlin noise 208 OP
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solar system, processing 247-9 vert
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