Explanation of gunswap code

Here's an explanation of the gunswap code as of v6.0.

Siteswap.js

Siteswap.js is the core siteswap parsing library. It exports 1 function:

CreateSiteswap(siteswapStr [, options])

This function takes a set of inputs describing a siteswap and returns a JSON object with calculated properties of the siteswap.

Inputs

siteswapStr is the only required input and is a siteswap string that adheres to the gunswap notation.

options is a JSON object containing additional options.

Examples

var s1 = CreateSiteswap('531');
var s2 = CreateSiteswap('51',{validationOnly:true});
var s3 = CreateSiteswap('441',{beatDuration:.3,dwellRation:.5});

You don't need to specify all of the options. Here are the list of options and their defaults.

validationOnly: true 
Passing in false will prevent the generation of prop positions and rotations.

numSteps: 1000
Defines the size of the prop positions/rotations arrays. A value of 1000 will calculate the props' positions at 1000 equally spaced steps in the full cycle of the pattern.

beatDuration: .2
Defines the length of a single beat in seconds. A value of .2 will result in a 3 ball cascade with throws lasting .6 seconds.

dwellRatio: .5
Defines the amount of time (as a ratio of the beat duration) the a prop is held between throws. The dwell duration cannot exceed the beat duration, hence it's input as a ratio.

props: [{type: 'ball', radius: .05, C: .95}]
Array of props. Valid types are 'ball', 'club' and 'ring'. Obviously radius and C don't really make any sense for clubs/rings. C if the coefficient of restitution (ie. the bounciness) and is just used for determining the ball path in bounce patterns. If the input array length doesn't match the number of props for the pattern the last object in the array is continuously appended or removed to get a match.

dwellPath: 
This requires more explanation - perhaps another blog post soon.

Return object

The CreateSiteswap function returns a big JSON object with the following properties.

siteswap
The same siteswap string that was provided as an input.

validSyntax
validPattern
multiplex
sync
pass
All of the above are just booleans describing the pattern.

numJugglers
numProps
maxHeight
More fairly simple properties of the siteswap.

tosses
Array of tosses that occur at each beat. 

beats
Siteswap string broken down into its component beats.

states
State array used for pattern validation. See previous blog post.

propOrbits
For each prop an array of throws and what beat they occur at. 

propPositions
Array of x,y,z positions for each prop.

jugglerHandPositions
Array of x,y,z positions for each juggler's hands.

jugglers
Array of jugglers and their x,z positions (y is assumed to be 0).

validationOnly
numSteps
beatDuration
dwellDuration
props
dwellPath
The inputs.

errorMessage
If everything worked, this will be undefined. Otherwise this contains any error messages.

The inner workings of this function are an enigma. But the basic flow is:

1. Validate syntax (http://gunswap.blogspot.com/2014/02/using-regex-to-parse-siteswap-strings.html)
2. Validate pattern (http://gunswap.blogspot.com/2014/03/siteswap-validation.html)
3. Generate prop positions (no post yet)

SiteswapAnimator.js

SiteswapAnimator.js handles all the animation. It exports the SiteswapAnimator class.

Constructor

SiteswapAnimator(containerId)

containerId is the div that the canvas will be appended to. The constructor handles all the scene initialization.

Functions

go(siteswap[,options])

This function runs the animation. siteswap is supposed to be the return object from a call to CreateSiteswap. options is a JSON object containing any animation options. It currently just contains a boolean motionBlur.

zoomIn()
zoomOut()
resize(width,height)
updateAnimationSpeed(animationSpeed)
updateCameraMode(cameraMode)

All of the above function should be fairly obvious. animationSpeed is a value from 0 to 1 where 1 is full speed and 0 is paused. cameraMode is either 'sky' or 'juggler'.

Example

var animator = new SiteswapAnimator('myDiv');
animator.go(SiteswapJS.CreateSiteswap('531'));

index.js

This just instantiates a SiteswapAnimator, reads user inputs, and passes the results of a CreateSiteswap call to the animator.

util.js

This contains general helper code.

v6.0

Quick turnaround on this one, though not much to report. Another new layout for the UI along with the ability to change color/type of individual props. Also added motion blur.

v5.0

Version 5:

- Added support for siteswaps up to "z" (for passing use a capital "P")
- Changed dwell duration to dwell ratio
- Animation automatically starts on page load. If you pass in a siteswap in the URL query string then it'll use that siteswap. For example: ydgunz.github.io/gunswap?siteswap=531. Make sure to encode the URI component (just use encodeURIComponent), so to animate 24[54] you would put in ydgunz.github.io/gunswap?siteswap=%5B33%5D.
- Cubic bezier dwell paths! This is one of the ideas that I've been excited about for a while and it's finally coming together. This will need it's own post to explain everything, but the general idea is that using cubic bezier interpolation to define dwell paths will allow patterns like mills mess, factory, etc. I've added a bezier version of the cascade and the 1-count factory (I think some people call this "waterfall"?) to the hand movement select list. More to come on this.
- I spent some time trying to make more of an app out of this so that folks can save patterns. But I'm not really sure where that's going so I stopped. I think I'm going to spend some time documenting the existing code and figuring out how to clean it up some more. Oh the luxuries of a project with no deadline.

v4.0

Haven't posted in a while. Here's what we've got in v4.0:

• Separated siteswap parsing/validation from animation and created a Siteswap.js library that can be used both in the browser and on the server with nodejs. I'm hoping to work on some fancier documentation for the Siteswap.js library so that other folks can use it if they are interested.
• Started using Grunt, Mocha and Travis CI for testing purposes. Grunt is a great Javascript task runner that I really only have set up to watch for changes in the source files and kick off tests, but there's a lot of opportunity there for streamlining some of the development processes. Mocha is the testing framework, pretty simple. Travis CI is an awesome, free, CI platform that runs all my tests on every push to GitHub. 
• I'm really only testing some of the basic siteswap parsing functionality, but I'm pretty happy with the tests so far. I'm not sure how to go about testing the functionality that generates the prop positions/rotations, will have to give that some more thought. Also need to consider how to test the UI. I've played with Watir in the past, but that's all ruby...
• Spent a bunch of time playing with a Mongo/NodeJS/Express/EmbeddedJS stack. Considering adding a DB backend so that people can save their patterns. There's a lot to this though and right now I'm still more interested in just the raw animator.
• Fixed that synchronous halving issue by adding (0,0) to each beat.
• Introduced a new modifier "S" to change the number of prop rotations in the air and the orientation of the throw and spins (only really applicable to clubs and rings). 
• The syntax is <toss>S<# of spins><toss orientation><spin orientation>
• The # of spins represents full 360 degree rotations. This is optional and if it is not present the # of spins will default to floor(<toss>/2). So a toss of 5 would be 2 spins, a toss of 3 would be 1 spin, a toss of 1 would be 0 spins, etc.
• The toss and spin orientation are defined according to Varkor's notation. http://juggle.wikia.com/wiki/Rotation_notation
• Examples:
• 4S04S01S0 - 441 with all flats
• 5S1XY - 5 cascade with 1 helicopter spin thrown with the club facing in the direction of the positive x axis
• Number of bounces is now set the same way as the number of spins, ie. 5B1
• Bounce type now defaults to lift bouncing if you don't specify the bounce type. Thus 5B1 and 5B1L are the same.
• Changed the pass modifier to be a capital "P".
• Added a grass texture map to the floor. Easy and fun. 
• Removed the siteswap explorer and local storage saving option. I think the siteswap explorer deserves to be a separate project and I'll address the saving option when I put a DB backend on this thing.

I know some folks have had trouble with the animator, mostly in Opera and older browser versions. I think I'm going to add a 2-D HTML5 canvas option that doesn't rely on Three.js or WebGL. I've also got a handful of bugs that I should make an effort to log since I haven't actually addressed them yet.

I'm not sure what's next. I know the prop orientation stuff could be way better - more natural angles for club tosses, smoother rotations while the prop is in the dwell path (right now it just jumps), documentation of the syntax. But I'm itching to work on the dwell paths, specifically because I want to try my hand at cubic bezier interpolation. I'd also like to consider more realistic animation of the juggler, but there are a lot of things to consider there. That's a bit more intense on the animation side of things than I think I'm capable of right now.

v3.0 Released

Just published version 3.0. First thought - what's the difference between 3.1 and 4.0? We have this same debate at work and it seems like there's no real solid answer. I think if my next stopping point only includes some bug fixes and refactoring, then it's 3.1. If it's got a bunch of big new features and (yet another) UI change, then I'll call it 4.0.

Anyways, version 3.0 has the following new features:

• Improved UI layout
• Added ring and club prop types
• Added reverse cascade and shower hand movements
• Added a "siteswap explorer" that generates vanilla siteswap patterns based on some user inputs
• Added a save feature using the browser's local storage, so the data wont' persist across browsers and/or machines

I think the next stopping point is going to be a version 3.1 with a bunch of refactoring and bug fixes. There's still that synchronous siteswap "halving" issue and the siteswap explorer doesn't support non-numeric characters. It also kind of gives the user a smoking gun to choke their browser if they generate siteswaps for 8+ beats and max throw height. The help functionality is really lacking, and I think that's because I'm still not sure who the target audience is for this software. If you know your siteswaps and have used something like juggling lab before, then I think this all should be fairly intuitive. If you don't know siteswaps then chances are you're really not interested in this app anyway, so perhaps I don't even try to help that kind of user?

The code is really starting to look like spaghetti. I guess that's the downside to constantly experimenting with different ideas, and not thinking of how the whole thing fits together. I think before I start working on big features for v4.0 (things like customized dwell paths, number of prop rotations in flight, defining where each juggler is in passing patterns) I need to take a step back and re-assess the whole design.

And testing...that didn't last long... I do like the Qunit tests for the siteswap validation component. I think there's some real value to be had there, and I should make sure I spend some time getting that back up to speed. I don't think there's really any sense in automated testing for any of the animation stuff, I'm not even sure how that would work.

Lots of cool stuff here, I'm really pleased with how far this has come since I decided to take the release process more serious. Each release has had its flaws, but actually drawing a line in the sand and saying "this is version 3" feels good.

v2.0 Notes

Reached a good stopping point for v2.0 faster than I expected. I added the following:

• User inputs for beat duration, dwell duration, prop radius and prop coefficient of restitution (ie. bounciness)
• Support for bounce juggling
• Add any number of "B" characters to a single toss to make it a bounce (the number of bounces is the number of B's). Must follow each B with an L (lift), F (force), HL (hyperlift) or HF (hyperforce). So 5 ball lift bounce pattern would be "5BL"
• http://jugglinglab.sourceforge.net/html/ssnotation.html explains the bounce notation I used
• Animated jugglers
• First person camera option
• User input for animation speed

Priorities for the next version:

• Synchronous siteswap "halving" issue
• Alternative dwell paths like reverse cascade, windmill and mills mess
• Alternative props like clubs and rings

Soon I'd like to write a post about my dwell path and flight path interpolation algorithms. Definitely needs explaining because the code is starting to look a little messy.

gunswap v1.0 released!

I am happy to announce that after way too much tinkering and half-complete little scripts, gunswap v1.0 is complete!

All you can do right now is enter a standard siteswap pattern and see it animated in the browser (I've done all my development in Chrome). There is support for vanilla, multiplex, synchronous and passing siteswaps. That lays the groundwork for a lot of cool improvements - what's next?

Version 2 will probably focus mostly on more inputs for configurable parameters. The trick is going to be determining which are the most important. Here are some general categories of input parameters and/or new features:

• Synchronous siteswap "halving" issue. Consider adding (0,0) in between each beat to make throws match up with async siteswap better.
• Environment
• Gravity
• Beat duration
• Dwell ratio
• Props
• Cosmetic properties like size, shape and color
• Consider options for different types of props like clubs and rings
• Coefficient of restitution (if we implement bounce juggling)
• Toss modifiers
• Force/lift bounce
• Rotation of prop (more useful for things like clubs and rings - not really noticeable with balls)
• Dwell path
• Current dwell path is just a circle which has options for center, radius and points of catch/release
• Totally custom dwell paths could be made using some kind of bezier curve algorithm. http://bseth99.github.io/projects/animate/2-bezier-curves.html looks like it has some potential and I think this is how Juggling Lab does it
• Passing
• Define juggler positions
• Allow jugglers to move
• Animation
• 2D option
• Lighting and shading
• Animation speed
• Database backend
• Not sure how interested in this I am, it would be nice to be able to save patterns, but this seems like it would shift the focus of the project