Processing: Creative Coding and Computational Art

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vFinal[0].vx = ((b[0].m - b[1].m) * vTemp[0].vx + 2 * b[1].m * vTemp[1].vx) / (b[0].m + b[1].m); vFinal[0].vy = vTemp[0].vy; // final rotated velocity for b[0] vFinal[1].vx = ((b[1].m - b[0].m) * vTemp[1].vx + 2 * b[0].m * vTemp[0].vx) / (b[0].m + b[1].m); vFinal[1].vy = vTemp[1].vy; // hack to avoid clumping bTemp[0].x += vFinal[0].vx; bTemp[1].x += vFinal[1].vx; /* Rotate ball positions and velocities back Reverse signs in trig expressions to rotate in the opposite direction */ // rotate balls Ball[] bFinal = { new Ball(), new Ball() }; bFinal[0].x = cosine * bTemp[0].x - sine * bTemp[0].y; bFinal[0].y = cosine * bTemp[0].y + sine * bTemp[0].x; bFinal[1].x = cosine * bTemp[1].x - sine * bTemp[1].y; bFinal[1].y = cosine * bTemp[1].y + sine * bTemp[1].x; // update balls to screen position b[1].x = b[0].x + bFinal[1].x; b[1].y = b[0].y + bFinal[1].y; b[0].x = b[0].x + bFinal[0].x; b[0].y = b[0].y + bFinal[0].y; // update velocities v[0].vx = cosine * vFinal[0].vx - sine * vFinal[0].vy; v[0].vy = cosine * vFinal[0].vy + sine * vFinal[0].vx; v[1].vx = cosine * vFinal[1].vx - sine * vFinal[1].vy; v[1].vy = cosine * vFinal[1].vy + sine * vFinal[1].vx; } } Figure 11-26. 2D Collision Using Conservation of Momentum sketch MOTION 559 11
PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART 560 OK, hopefully we’re still on speaking terms. Part of the reason this function is so long, with a slew of temporary object arrays, is that I wanted to make all the processes as explicit as possible. There are many ways of optimizing this code and reducing the number of lines; however, that economy comes with a cost of potential confusion. (Again, Keith Peters’s book discusses a bunch of these optimizations, so I encourage you to take a look at it for a deeper discussion on this topic.) I added a lot of comments directly within the code to help you decipher it. In addition, I’ll provide a brief overview. The code in the function combines a number of concepts we’ve looked at throughout this chapter, including vectors, coordinate rotation, and of course the law of conservation of momentum. I began the function by assigning the vector described by the distance between the two balls to bVect. I used this vector to determine the angle of rotation between the balls, as well as to define the reference point for rotation. Vectors, you’ll remember, tell us about both direction and magnitude. I calculated the magnitude of bVect (assigned to bVectMag) and used it to determine when the balls were colliding, since the vector between the balls is also conveniently the distance between the balls. By plugging the components of bVect into the atan2() function, I was able to find the angle (in radians) of the vector’s rotation, which is precisely the value you need to rotate the ball and velocity coordinates, allowing you to treat the 2D collision between the balls as a 1D (orthogonal) collision. When rotating the ball and velocity coordinates, you don’t want to rotate in reference to the screen origin, but rather locally around the point of collision. I accomplished this by using bVect (the vector describing the distance between the balls) as the reference point of rotation. The two lines I’m referring to are the following (please note that I created a bunch of temporary Ball and Vect2D arrays (including bTemp) in the function to try to help clarify the different steps in the collision process): bTemp[1].x = cosine * bVect.vx + sine * bVect.vy; bTemp[1].y = cosine * bVect.vy - sine * bVect.vx; b[1] will rotate around b[0], setting the vector between them perfectly horizontal. Thus, b[0] will act, in a sense, as the origin for the rotation, so I don’t need to assign any value to bTemp[0].x and bTemp[0].y, which were both automatically assigned 0.0 when bTemp[0] was instantiated (since float values—which the x and y properties are—default to 0.0 when declared). Next, I rotated the velocities, which should be self-explanatory, using the good old long form trig expressions. The rotated velocities were assigned to the vTemp objects. Next, the ugly conservation of momentum expressions come into play. Notice that I only used them to find the final rotated velocities along the x-axis. The velocities along the y-axis were calculated previously, so I simply assigned vTemp.vy to vFinal.vy (for both objects).
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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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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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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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Page 539 and 540: PROCESSING: CREATIVE CODING AND COM
Page 589: PROCESSING: CREATIVE CODING AND COM
Page 594 and 595: 12 INTERACTIVITY
Page 596 and 597: } public void mouseClicked(MouseEve
Page 598 and 599: void setup(){ size(400, 400); // in
Page 600 and 601: initialize x, y x = width/2.0; y =
Page 602 and 603: float friction = .85; float[]jitter
Page 604 and 605: nodeYPos = append(nodeYPos, mouseY)
Page 606 and 607: As usual, I declare global variable
Page 608 and 609: are filled with black. Using the in
Page 610 and 611: } } } } } // bottom display window
Page 612 and 613: color btnUpState = color(200, 200,
Page 614 and 615: float xSpeed = 0; color movingSquar
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Page 624 and 625: set initial button background color
Page 626 and 627: also makes the code a little harder
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Page 630 and 631: } sliderValue = (sliderHandle[0]-sl
Page 632 and 633: if (!isBrushSelected){ if (mouseX>b
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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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