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

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19 19.1 Data Streams “ I’m mad as hell and I’m not going to take this anymore! ” —Howard Beale, Network In this chapter: – Sockets. – Servers. – Clients. – Multi-user processing. – Serial input. Synchronous vs. Asynchronous Data Streams 357 In Chapter 18, we looked at how we can request the raw source of a URL using loadStrings( ), the simpleML library, or the XML library. You make the request, sit back, and await the results. You may have noticed that this process does not happen instantaneously. Sometimes the program may pause for seconds (or even minutes) while a web page or XML document loads. Th is is due to the length of time required for what Processing performs behind the scenes—an HTTP request. HTTP stands for “ Hypertext Transfer Protocol, ” a request/response protocol for the transfer of information on the world wide web. Let’s consider, for a moment, what we mean by “ request/response. ” Perhaps you wake up one morning and think to yourself that a vacation, say in Tuscany, is in order. You turn on your computer, launch a web browser, type www.google.com in the address bar, and enter “ romantic getaway Tuscany villa ” . You, the client , made a request, and it is the job of google, the server , to provide a response. The Client : Just to introduce myself, I'm Firefox, the web browser, and I have a request . I was wondering if you might be so kind as to send me your web page about vacation villas in Tuscany? [Dramatic Pause] The Server: Sure, no problem, here is my response . It's really just a whole lot of bytes, but if you read it as html you'll see it's a nicely formatted page about Tuscany vacation rentals. Enjoy! Oh, can you let me know that you received it ok? Got it, thanks! The Client: [The Client and the Server shake hands.] Th e above process is known as an asynchronous request and response, bi-directional communication between a server and a client where the server responds at its leisure. Th e connection is established temporarily in order to transfer the web page after which it is promptly closed. In terms of sending information along the world wide web, this methodology is perfectly adequate. Nevertheless, imagine if you were to use asynchronous communication in a multiplayer game. It would
358 Learning Processing be a disaster. Having to open and close the connection every time one player sends a message to another would result in huge delays and lag between movements. For multiuser applications in Processing where we need near real-time communication, a diff erent type of connection is used, a synchronous one known as a socket connection. Synchronous communication is also necessary for live performance applications that need real-time interaction between elements. See Figure 19.1 . Client fi g. 19.1 response request SERVER request Client response request response request response Client Asynchronous Request (e.g., asking for a web page) Client SERVER Client Socket Connection (e.g., chat) Continuous Socket, bi = 2 directional A network socket connection is a continuous connection between two programs across a network. Sockets are used for multi-user applications, such as games, instant messenger, and chat (among other things). Th ey consist of an IP address—the numeric address of a machine on the network—and a port number— a number used to route information from one program to another. We can use sockets in Processing to write programs that can communicate with each other in real-time. To do this, we will use the built-in net library ( processing.net ) to create servers and clients connecting via sockets. 19.2 Creating a Server In order to create a server, we need to choose a port number. Any client that wants to connect to the server will need to know this number. Port numbers range from 0 to 65,536 and any number is fair game, however, ports 0 through 1,024 are usually reserved for common services, so it is best to avoid those. If you are unsure, a google search will turn up information on whether the port is likely used by another application. For our purposes, we will use the port 5,204 (this is the same port used in the Processing net library reference that you would fi nd at processing.org ). To create a server, we must fi rst import the library and create an instance of a Server object.
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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
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Arrays 151 Now comes the hard part.
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9.7 Arrays 153 Exercise 9-7: Rewrit
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9.8 Interactive Objects Arrays 155
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Check if point is inside of Stripe
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alls[i].gravity(); balls[i].move();
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Draw Zoog's arms with a for loop fo
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Lesson Five Putting It All Together
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10 10.1 Algorithms “ Lather. Rins
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Translating the preceding algorithm
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void draw() { background(255); stro
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Example 10-2: Bouncing ball class c
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Now that the function is complete,
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10.6 // Constructor Ball(float temp
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Algorithms 177 With the above logic
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Drop() { r = 8; // All raindrops ar
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Example 10-7: Drops one at a time /
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Algorithms 183 Notice how every sin
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oolean intersecting = ball1.interse
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} void setLocation(float tempX, flo
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Algorithms 189 It is important to r
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11 Debugging “ Th e diff erence b
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Debugging 193 Once all the code is
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12 Libraries “ If truth is beauty
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or /Applications/Processing 0135/ c
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Lesson Six The World Revolves Aroun
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13 Mathematics Mathematics 201 “
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Mathematics 203 Th erefore, modulo
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Th e probability of a coin fl ippin
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13.6 Perlin Noise Mathematics 207 O
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Mathematics 209 How quickly we incr
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It is fairly intuitive for us to th
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fi g. 13.9 y-axis sine(theta) � y
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Example 13-6: Oscillation float the
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Mathematics 217 In 1975, Benoit Man
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Mathematics 219 said about recursio
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Mathematics 221 A two-dimensional a
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Example 13-10: Two-dimensional arra
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} void display() { } // FILL IN Mat
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14 14.1 Translation and Rotation (i
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Our fi rst instinct might be to add
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Example 14-3: A rectangle moving al
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When using the OPENGL mode, you mus
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Translation and Rotation (in 3D!) 2
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14.5 fill(150,150); vertex(-t, t,-t
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14.6 Example 14-5: Rectangle rotati
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fill(0,100); // Note the use of pus
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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
Page 326 and 327: Exercise 17-2: Loop through and pri
Page 328 and 329: 17.3 Displaying Text Text 309 We wi
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Page 332 and 333: X = �50 fi g. 17.4 float w = text
Page 334 and 335: Example 17-4: Text mirror import pr
Page 336 and 337: textFont(f); // Set the font transl
Page 338 and 339: Exercise 17-9: Using textWidth( ) ,
Page 340 and 341: Example 17-7: Boxes along a curve P
Page 342 and 343: Text 323 Exercise 17-10: Create a s
Page 344 and 345: 18 Data Input “ A million monkeys
Page 346 and 347: Example 18-1: User input PFont f; /
Page 348 and 349: Data Input 329 Th e reverse of spli
Page 350 and 351: Example 18-2: Graphing comma separa
Page 352 and 353: Data Input 333 Th e rollover( ) fun
Page 354 and 355: 18.4 diameter = diameter_; } // Tru
Page 356 and 357: } // Find the index of the end tag
Page 358 and 359: void mousePressed() { // Increment
Page 360 and 361: 18.6 for (int i = 0; i < kinglear.l
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Page 366 and 367: Requests for XML data are made via
Page 368 and 369: 18.8 Using the Processing XML Libra
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Page 372 and 373: Example 18-10: A Yahoo search impor
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Page 378 and 379: import processing.net.* ; Server se
Page 380 and 381: Data Streams 361 Once the server is
Page 382 and 383: 19.4 void draw() { background(255);
Page 384 and 385: Data Streams 365 must be networked
Page 386 and 387: Data Streams 367 will send X , Y co
Page 388 and 389: Data Streams 369 Here is the full S
Page 390 and 391: Here is the entire client sketch: 1
Page 392 and 393: Data Streams 373 Serial communicati
Page 394 and 395: Data Streams 375 of information, ca
Page 396 and 397: Corresponding Arduino code: int sen
Page 398 and 399: Lesson Nine Making Noise 20 Sound 2
Page 400 and 401: 20 Sound “ Check. Check. Check 1.
Page 402 and 403: void setup() { Sonia.start(this); }
Page 404 and 405: void mousePressed() { // If the use
Page 406 and 407: Sound 387 check and see if a sound
Page 408 and 409: Is a point inside the doorbell (use
Page 410 and 411: Pressing the mouse stops and starts
Page 412 and 413: 20.6 void draw() { background(255,1
Page 414 and 415: In code, this translates to: // If
Page 416 and 417: 21 Exporting “ Wait a minute. I t
Page 418 and 419: Th is code can be inserted anywhere
Page 420 and 421: void setup() { size(400, 400); begi
Page 422 and 423: Exporting 403 save( ) takes one arg
Page 424 and 425: 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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