Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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Hopefully, the rotating castle tower didn’t bring your computer to a standstill. Calculating
all that 3D data in real time is demanding. There are some advanced and frighteningly lowlevel
approaches to optimizing 3D that I won’t go into. However, Processing includes a
really simple way to speed things up, which I’ll look at in the next chapter (sorry to be a
tease). For now, if the code is executing really slowly, try lowering the number of brick layers
and/or increasing the speed of the rotation.
Extrusion
To begin to generate forms such as cylinders, cones, spheres, and toroids (also sometimes
referred to as toruses), it helps to understand the concept of lathing. However, to understand
lathing, you need to understand extrusion (lots of annoying terms, I know). Extrusion
simply pushes 2D geometry into 3D space by adding a depth component to the 2D shape.
For example, a rectangle on the xy plane is extruded into a cube that now exists in xyz
space. Next is a simple interactive extrusion example beginning with a rectangle (shown in
Figure 13-14). Move your mouse right and left to rotate the rectangle, and drag the mouse
up and down to extrude it (remember, dragging requires the mouse button to be pressed).
/* Extrusion Example
move right to left to rotate
drag up and down to extrude
*/
float depth = 0, boxDepth = 0;
float mousePt_Y = 0;
void setup(){
size(500, 300, P3D);
}
void draw(){
background(25);
lights();
fill(100, 100, 175);
stroke(200);
translate(width/2, height/2);
rotateY(radians(mouseX));
box(100, 50, boxDepth);
}
void mouseDragged(){
boxDepth = depth + (mousePt_Y-mouseY);
}
void mousePressed(){
mousePt_Y = mouseY;
}
void mouseReleased(){
depth = boxDepth;
}