Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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P3D mode
P3D mode gives you access to a custom 3D engine in Processing. A 3D engine is just software
(no oil or gears) that allows you to deal with a z-axis, in addition to the standard
x- and y-axes. In 3D, geometry is calculated in three dimensions, which is just a simple
math problem for a computer. However, the darn computer screen is only 2D, so the
engine has to translate the 3D data back to a 2D screen projection. In the real world, we
perceive images decreasing in size as they move farther away from us. We can simulate this
virtually (both with traditional materials and through software) by using a system of
perspective. I’m sure some of you remember doing simple two and three-point perspective
exercises in an intro art class. Perspective works similarly in P3D mode, but without the
need to grab a ruler or get your hands dirty. 3D-to-2D projections on the computer are
generally tied to the concept of a virtual camera, which is capable of very wide-angle views
(in which things are large, close, and often distorted—think fish-eye lens) as well as very
distant views.
Besides virtual camera capabilities, P3D has virtual lights and simple texture mapping
(image mapping), allowing an image to be attached to the points (vertices) of 3D geometry.
This capability, called u-v mapping, allows image maps on the geometry to move with
the form. P3D mode is built for speed, a little at the expense of rendering quality.
However, P3D mode is a great and relatively easy way to begin experimenting with coding
3D with a minimal amount of code and complexity. The following short example rotates
three concentric polyhedra (polyhedra are basically 3D polygons) and also responds to
both the x and y mouse positions. Figure 5-13 shows the output of the sketch.
/*
Rotating Polyhedra
Ira Greenberg, November 3, 2005
*/
//declare variables
float rotY;
float rotX;
void setup(){
size (400, 400, P3D);
frameRate(30);
}
void draw(){
background(255);
/* ensures shapes are drawn at the
center of the display window. In addition,
mouse y postion controls the distance
the shapes are drawn along the z-axis.
As the shapes moves further into space,
they will diminish in size*/
translate(width/2, height/2, mouseY-100);