Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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OPENGL mode
P3D mode utilizes a software-based 3D engine, meaning that all the 3D calculations are
handled by Java, just as normal 2D calculations are; the 3D math is crunched and converted
to 2D data before being sent to the graphics hardware to draw the image to the
screen. The hardware isn’t even aware the data began life as 3D geometry. However, your
graphics hardware has the capability to crunch numbers, and in fact can do it much faster
than Java. The trick, though, is in communicating directly with the graphics hardware to
speed things up.
OpenGL is a platform-independent library that functions as an interface between your
code and the graphics hardware. OpenGL was developed in 1992 by Silicon Graphics, but
is now overseen by a large group of organizations, under the heading OpenGL
Architecture Review Board. Designed as a set of specifications, OpenGL is platform agnostic
and can be utilized by practically all systems that have OpenGL-accelerated hardware.
Processing and Java interface with OpenGL through JOGL. JOGL, developed by the Game
Technology Group at Sun, is technically considered a Java binding (as in “the ties that
bind”) to OpenGL, and gives Processing sketches that use the OPENGL rendering mode the
ability to render more stuff faster and at larger sizes. However, to benefit from this mode,
you need an OpenGL-accelerated graphics card. Fortunately, most modern machines have
one. To learn more about OpenGL, see www.opengl.org/; and to learn more about JOGL,
see https://jogl.dev.java.net/.
Utilizing the OpenGL library couldn’t be simpler in Processing. Simply select Sketch ➤
Import Library ➤ opengl, which adds an import line to your sketch, and then add the
OPENGL string as a third argument to the size function call: size (800, 600, OPENGL);. The
following 3D example (shown in Figure 5-14) can be run in either P3D or OPENGL rendering
mode; simply change the third size argument from OPENGL to P3D. It is worth trying
both 3D modes to get a sense of how hardware acceleration dramatically impacts performance.
One word of caution to beginners though: 3D programming is difficult—even
Processing’s greatly simplified version. If you’re feeling overwhelmed from information
overload, don’t worry about the 3D renderers. I won’t cover them until the last two chapters
in the book, at which time you’ll be ready. I do recommend running the example to
see what it does. It’s a little complicated, though, so unless you have prior coding experience,
I wouldn’t spend too much time dwelling on it. 3D can be tough, but also pretty
cool.
/*
Space Junk
Ira Greenberg, November 4, 2005
*/
/*need to import opengl library to use OPENGL
rendering mode for hardware acceleration*/
import processing.opengl.*;
//used for oveall rotation
float ang;