Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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the rotateVertices() function; there are certainly other ways to implement this. Before
you move on to the cube example, I strongly recommend you play/experiment with this
one for a while.
I’ll reuse the Point3D and Cube classes to build the next example. I’ll need to create
another method to handle the combined 3D rotations. I could redesign the Cube class and
add the new rotation method directly in there. But a much better a way to deal with
adding the new method is to create a new class as a subclass of the Cube class. This
approach gives me the benefit of using the original class without having to alter it, still
allowing me to extend its capabilities. As discussed earlier in the book, the term inheritance
in OOP is used to describe this extending approach. Although I could have gone into
my original Cube class and added a rotation method, it’s best practice to not edit existing
classes, as other dependent classes could be adversely affected. The following code gives
the completed example (shown in Figure 13-12). I didn’t include the Point3D or Cube class
code, just the new SpinnyCube class (Cube subclass); so don’t forget to add the Point3D
and Cube classes before running the example. (Remember, you can either create a new tab
for each class, or simply paste the classes beneath your current sketch code.)
// Rotation of a Custom Cube Around the X-, Y-, and Z-Axes
// custom Cube reference variable
SpinnyCube c1;
// array to hold different face colors
color[]quadBG = new color[6];
void setup(){
size(400, 400, P3D);
quadBG[0] = color(175, 30, 30, 255);
quadBG[1] = color(30, 175, 30, 255);
quadBG[2] = color(30, 30, 175, 255);
quadBG[3] = color(175, 175, 30, 255);
quadBG[4] = color(175, 30, 175, 255);
quadBG[5] = color(175, 87, 30, 255);
//instantiate cube
c1 = new SpinnyCube(200, 200, 200);
}
void draw(){
background(100);
translate(width/2, height/2);
if (mousePressed){
//interactive rotation
c1.spinnyRotateX(mouseY);
c1.spinnyRotateY(mouseX);
}
else {