Processing: Creative Coding and Computational Art

I included one last example (shown in Figure 7-37) on how to create an elliptical spline plot
using shape() and shapeVertex(). I also included a more generalized spline ellipse–
creation function. Notice how the curveTightness settings affect the different curves,
creating interesting path details. Similarly to the bezier() example, I initially populate the
coordinate arrays with ellipse point data, using some trig expressions. However, unlike
bezier(), I’m not burdened with anchor and control points. When drawing the closed
curves, I followed the control point order I covered earlier in the chapter. This is not terribly
intuitive, so it might help to mess with the node order in the curve() functions a little
to see how it affects the curve. I implemented the first ellipse using curve(), and the second
using curveVertex(). I’m not sure which is easier—probably curveVertex(), since it
uses a shorter parameter list. The problem with the initial ellipse plots is that they are
hard-coded for four points and can’t easily be customized. Thus, I created a more general
spline ellipse function as well, allowing you to control the number of points, as well as the
x and y position, radius, and curve tightness, among other properties. The function is used
to generate the two inner curves. This modular approach will be looked at in more depth
in the next chapter, as you begin to apply some object-oriented approaches to the examples.
/*
Curve Ellipse
Ira Greenberg, December 20, 2005
revised November 15, 2006
*/
float radius = 165;
float angle = 0;
//outer circle
float[]cx = new float[4];
float[]cy = new float[4];
//middle circle
float[]cx2 = new float[4];
float[]cy2 = new float[4];
void setup(){
size(400, 400);
background(255);
strokeWeight(1.5);
smooth();
for (int i =0; i