The AU Library

Some Animations Made with the AU Library

The AU Library

I wrote the AU Library ("Andrew's Utilities") for Processing because in the course of making animations I found myself writing the same sorts of routines over and over again. So I've written them just once, made them efficient and easy to use, and now I'm sharing the library with you.

Above are four examples of little gif animations that I made with my library; consider these just a taste of what can be done.

Here's an ultra-short summary of them all. See Imaginary Institute Technical Note #3 (download below) for an overview, and the other Tech Notes for motivation, detailed discussions, and full documentation. The library intself includes at least one example program for each of the sections below.

Coin Flip: Flip a fair coin and report whether it came up heads or tails.
Cyclic Lifetime: Support for creating animation loops where objects come and go over time.
Choosing: Choose one object from a list. The objects can have different probabilities for getting chosen.
Distances: Tools for computing distances so that you can freely change the size of your graphics window and things will still look right. Also, a bunch of cool and unusual ways to measure distance.
Easing: A variety of ways to control motion so it looks smooth and even natural, rather than jerky or mechanical.
Quick Blends: Routines for making smooth, natural-looking motion and blends of colors, shapes, or anything else.
Waves: A variety of incredibly handy, repeating patterns for controlling almost anything in space and time.
AUCamera: Makes it easy to create great-looking movies and animated gifs. The results even include high-quality motion blur, so everything moves smoothly and looks natural.
AUCurve/AUBezier: Generate evenly-spaced points along either Bezier or Catmull-Rom curves in 2D, 3D, or any higher number of dimensions. You can also include more data of your own at every curve point, and that gets blended along with the curve's position.
AUField: A 2D array of floats with many handy operations built-in. Great for stroring things like height fields and density maps.
AUMultiField: A group of AUField objects with tons of support. Perfect for color images with and without transparency. You can read your data into or from the screen or an off-screen buffer, modify the colors, compose (overlay) one image on another, and much more. It's perfect for storing any amount of floating-point information on a per-pixel basis, from colors to N-dimensional points, vectors, temperature data, etc. all at once.
AUShuffle: Return the elements of a list, one by one, in random order. When they've all been used, shuffle the list automatically into a new order, and then resume returning them.
AUStepper: A simple but powerful tool for easily creating animations composed of several distinct steps.
AUGlob: A smooth and highly controllable curved blend between two circles.

Installing the AU Library

Installing the library is easy, thanks to Processing's built-in Contribution Manager. Go to the Sketch menu and choose Add Library.... From the list, choose Andrew's Utilities. That's it, you're done!

If you'd rather install the library by hand, download the zip file by clicking here. You can find instructions for manually installing libraries on the web. But unless you have a special reason for installing it manually, I suggest you take the easy and reliable approach and let the Contributions Manager install it for you.

Don't forget to read Tech Note 3 so you can get a good start, and keep in mind that the other tech notes give much more information on each section.

Each section in the library comes with at least one running example to show you how to use the technique in your own code.

Imaginary Institute Technical Reports

I've written a series of technical reports that I hope you'll find useful. You can click on each one to download it in PDF format. Tech Reports 1 and 2 talk about useful ideas for programming in Processing. Tech Report 3 is an overview of the AU Library and a good place to start if you're downloading the library for the first time. Tech Reports 4 through 8 talk about different issues in computer graphics, and how the AU library helps you address them. By contrast to Note 3, which is a general overview, these notes will show you why various sections of the library were created, and contain example code, context and background, and lots of useful information for getting the most out of the library.

1: Solving Geometry: How to solve and program the kinds of geometry problems that often crop up when writing Processing sketches.
2: Trig for Computer Graphics: What the basic trig functions do, and how they provide us with really useful information for making animated and interactive programs.
3: The AU Library: The overview document for the AU Library. If you read nothing else about the AU Library, read this! The other reports for the library, listed below, discuss the motivation for the major pieces of the library, and provides discussion and examples for their use.
4: Blending and Easing: How to make your moving objects appear to move gracefully, and (when you want it), realistically.
5: Waves: A library of many useful waves and curve shapes for modeling and animation.
6: Measuring Distances: How to measure and compute distances in a variety of useful and interesting ways. By using this section of the library, you can freely change the size of your graphics window and your sketch will naturally scale up and down.
7: Fields and Cameras: How to use my implementations of 2D arrays of floats to represent grayscale images, color images, and any other data you might want to storein a grid. It also shows you how to easily create and use a camera object so that you can produce animations that look really nice, thanks to built-in motion blur.
8: Equal Spacing Along Curves: How to use two objects that let you find evenly-spaced points along curves of any number of points. You can also interpolate arbitrary amounts of your own data. Everything comes out seamless and smooth.
9: Quick Reference: A collection of all the AU Library objects, functions, and constants in one place for handy reference.
10: Interpreting Alpha: Everyone uses alpha values to composite images, but what does alpha really describe? Some authors treat it as a color's opacity, others as a pixel's coverage. Most people go back and forth between the two. How can that be right? In this note we look closely at alpha and see what it really represents.
11: Globs: How to create really cool, smoothly-blended shapes between two circles or spheres.