Processing: Creative Coding and Computational Art

The Sprocket Creator sketch is similar to the Polygon Creator sketch. The main difference
is the few extra trig expressions in the makeSprocket() function. Instead of plotting vertices
at equal angle rotations, each spoke of the sprocket is composed of three vertices.
The first and second share the same radius and are the outer edge of the spoke. The third
vertex is an inner radius, and is at the base between each spoke. Notice also that I used
two different angle values. I somewhat arbitrarily defined the angle between the two
spoke vertices (within the spoke) as twice as large as the angle between the spokes. The
final angle incrementation (angle+=ang2) ensures that there is symmetry between each
spoke.
As reading descriptions like this can be confusing, I suggest playing with the sketch and
creating some of your own sprockets. You might also want to try to spin your own shape
by modifying the existing drawSprocket() method.
Creating hybrid shapes
The beginShape() and endShape() functions allow you to combine straight and curved
lines to form hybrid shapes. Once you introduce curves into to your shapes, calculating
coordinates can get a little tricky. It often helps to break the problem down into more
manageable sections—in the next two example sketches, I do just that. In the first sketch,
I hack out a list of coordinates (using magic numbers) and individual drawing function calls
that create a hybrid shape. In the second sketch, I develop a more general plotting algorithm,
removing all the magic numbers. Here’s the initial code in all its magic number glory
(see Figure 9-19):
// Hybrid Shape
size(600, 600);
curveTightness(-.4);
smooth();
beginShape();
curveVertex(200, -300);
curveVertex(200, 100);
curveVertex(400, 100);
curveVertex(400, -300);
vertex(500, 100);
vertex(500, 200);
curveVertex(800, 200);
curveVertex(500, 200);
curveVertex(500, 400);
curveVertex(800, 400);
vertex(500, 500);
vertex(400, 500);
SHAPES
365
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