Processing: Creative Coding and Computational Art

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In two dimensions, the surface normal of a vector is really just a line perpendicular to the vector. In three dimensions, the situation is a bit more complicated and requires the use of the cross-product calculation mentioned previously. We’ll look at the cross-product in the book’s final chapter. Calculating the perpendicular line to a vector is very simple. To get the x component of the normal, you simply reverse the sign of the vector’s y component, and to get the y component of the normal, you take the vector’s x component, as illustrated in the last two lines of the previous snippet of code. Be aware, though, that every vector actually has two perpendicular lines, facing opposite directions (once you know one, just reverse its sign to find the other). The block of code that handles most of the real heavy lifting in the draw() function is the following: // normalized incidence vector float incidenceVectorX = -directionX; float incidenceVectorY = -directionY; // detect and handle collision for (int i=0; i
PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART 532 adding the z component into the mix. I’m not going to go into the theory behind the dot product here, but I will discuss it when I cover 3D in Chapter 14. If you just can’t wait, though, Wikipedia has some good stuff to say about it at http://en.wikipedia.org/ wiki/Dot_product. Following the dot product calculation, I calculate the reflection vector, plugging in the values I’ve previously calculated. Finally, I assign the reflection vector to the original direction vector and display the normal at the point of collision. If the code is working, you should see that the angle formed between the base edge normal and the incoming incidence vector is equal to the angle between the outgoing reflection vector and the normal. The remainder of the code handles display window boundary detection and also resets the base’s top edge whenever the ellipse makes contact with the top of the display window. A better way to handle non-orthogonal collisions Although the last example successfully handled angled collisions, there are some challenges in trying to extend this solution to handle object-object collisions as well trying to add simple physics, like gravity and drag. There is another collision solution that ActionScript guru Keith Peters writes about in his excellent book Foundation ActionScript Animation: Making Things Move! Although Keith’s book deals with ActionScript, not Processing, I highly recommend it as a general graphics coding guide. The solution Keith writes about deals with considering angled collisions as a rotated coordinate system problem, instead of focusing on trying to calculate the actual reflection angle. It works like this: if you take any 2D collision, you can always rotate the local coordinates so that the collision happens orthogonally (shown in Figure 11-20). For example, suppose a ball strikes a surface at a 40-degree angle. Rather than trying to calculate the angle of reflection, taking into account both the ball’s incidence vector and the angle of the collision surface, you can rotate the surface and velocity vector (in this case –40 degrees) so that the collision surface is orthogonal (perfectly horizontal or vertical). Once rotated, you can handle the reflection the same way you do with collisions against the edges of the display window—simply reverse the sign of the appropriate velocity vector coordinate; finally, the last step is rotating everything back to where it was prior to the rotation. Figure 11-20. Handling non-orthogonal collisions by rotating coordinates
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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 594 and 595: 12 INTERACTIVITY
Page 596 and 597: } public void mouseClicked(MouseEve
Page 598 and 599: void setup(){ size(400, 400); // in
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Page 606 and 607: As usual, I declare global variable
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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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