processing

name	processing
description	Processing (Java) creative coding reference and patterns. Use when: writing Processing sketches, using PApplet API (setup/draw lifecycle, shape primitives, transformations, color), working with P3D/P2D renderers, handling input events, using Processing libraries (oscP5, minim, toxiclibs), debugging rendering or performance, converting between Processing and Java idioms.

Processing (Java) Skill

When to Use

• Writing or editing .pde sketch files
• Using Processing drawing primitives, transformations, or 3D rendering
• Integrating Processing libraries (oscP5, minim, sound, video, etc.)
• Debugging frame rate, rendering artifacts, or memory issues
• Structuring multi-file Processing sketches

Processing Sketch Structure

A Processing sketch is a folder containing .pde files. The main file must share the folder's name. Additional .pde files define classes and are automatically combined at compile time.

my_sketch/
├── my_sketch.pde       # Main file: setup(), draw(), event handlers
├── MyClass.pde         # Additional class
└── AnotherClass.pde    # Another class

Lifecycle

void setup() { }   // Called once at start
void draw() { }    // Called every frame (default 60 fps)

• setup(): Initialize size/renderer, load resources, set initial state
• draw(): Clear background, update state, render frame
• Use frameRate(n) to change target FPS
• Use noLoop() / loop() to pause/resume the draw loop

Renderers

Renderer	Usage	Notes
Default (JAVA2D)	size(800, 600)	2D, good for simple sketches
P2D	size(800, 600, P2D)	OpenGL-accelerated 2D
P3D	size(800, 600, P3D)	3D with lighting, camera, depth
fullScreen()	fullScreen(P3D)	Full screen with specified renderer

Drawing Primitives

// 2D shapes
point(x, y);
line(x1, y1, x2, y2);
rect(x, y, w, h);
ellipse(x, y, w, h);
arc(x, y, w, h, start, stop);
triangle(x1, y1, x2, y2, x3, y3);
quad(x1, y1, x2, y2, x3, y3, x4, y4);

// Curves
bezier(x1, y1, cx1, cy1, cx2, cy2, x2, y2);
curve(x1, y1, x2, y2, x3, y3, x4, y4);

// 3D shapes
box(size);
sphere(radius);

Transformations

pushMatrix();
translate(x, y, z);
rotate(angle);          // radians
rotateX(angle);
rotateY(angle);
rotateZ(angle);
scale(s);
popMatrix();            // Always pair with pushMatrix()

Color & Style

color c = color(r, g, b);          // RGB
color c = color(r, g, b, a);       // RGBA (a = alpha/opacity)
fill(c);
noFill();
stroke(c);
noStroke();
strokeWeight(w);
background(r, g, b);
lerpColor(c1, c2, amt);            // Interpolate between colors

Math Utilities

map(value, low1, high1, low2, high2);   // Remap value range
lerp(start, stop, amt);                  // Linear interpolation
constrain(val, min, max);
dist(x1, y1, x2, y2);
radians(degrees);
sin(angle); cos(angle); tan(angle);
random(low, high);
noise(x); noise(x, y);                   // Perlin noise

Input Events

void mousePressed() { }
void mouseReleased() { }
void mouseDragged() { }
void keyPressed() { }
void keyReleased() { }
// Built-in variables: mouseX, mouseY, pmouseX, pmouseY, key, keyCode

Common Libraries

oscP5 (OSC Protocol)

import oscP5.*;
OscP5 oscP5;

void setup() {
    oscP5 = new OscP5(this, 8000);  // Listen on port 8000
}

void oscEvent(OscMessage msg) {
    if (msg.checkAddrPattern("/address")) {
        String s = msg.get(0).stringValue();
        float f = msg.get(1).floatValue();
        int i = msg.get(2).intValue();
    }
}

Thread Safety

Processing's draw() runs on the animation thread. OSC callbacks (oscEvent) run on a separate network thread. Use thread-safe collections when sharing data:

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
List<MyObject> objects = new CopyOnWriteArrayList<MyObject>();

Performance Tips

• Call background() each frame to clear (or use semi-transparent background for trails: background(0, 40))
• Remove offscreen/dead objects from lists to prevent memory leaks
• Minimize object allocations inside draw()
• Use println() sparingly in draw() — it slows rendering
• Prefer P2D/P3D over default renderer for complex scenes
• Use hint(DISABLE_DEPTH_TEST) / hint(ENABLE_DEPTH_TEST) in P3D when mixing 2D and 3D

Running Sketches

Processing sketches can be run via:

• Processing IDE (PDE): Open the main .pde file and click Run
• processing-java CLI: processing-java --sketch=/path/to/sketch --run