Hydra

Set of tools for livecoding networked visuals. Inspired by analog modular synthesizers, these tools are an exploration into using streaming over the web for routing video sources and outputs in realtime.

Hydra uses multiple framebuffers to allow dynamically mixing, compositing, and collaborating between connected browser-visual-streams. Coordinate and color transforms can be applied to each output via chained functions.

Note: experimental/in development. Right now only works on Chrome or Chromium, on machines with WebGL. I welcome pull requests as well as comments, ideas, and bugs in the issues section =]

For more information, see getting started, getting started pdf en español, tutorials and examples, the complete list of functions, gallery of user-generated sketches, or a a talk about the motivations for creating hydra.

Note: this repository is for the online version of hydra. Other pieces of hydra are published as separate modules:

• hydra-synth: synth engine of hydra as a standalone npm module
• atom-hydra: use hydra within atom
• rtc-patch-bay: networking logic of hydra as a standalone npm module

Getting started

Go to https://hydra-editor.glitch.me

• CTRL-Enter: run a line of code
• CTRL-Shift-Enter: run all code on screen
• ALT-Enter: run a block
• CTRL-Shift-H: hide or show code
• CTRL-Shift-F: format code using Prettier
• CTRL-Shift-S: Save screenshot and download as local file
• CTRL-Shift-G: Share to twitter (if available). Shares to @hydra_patterns

All code can be run either from the in-browser text editor or from the browser console.

Check @hydra_patterns for patterns folks have shared as an easy way to get started.

Basic functions

render an oscillator with parameters frequency, sync, and rgb offset:

osc(20, 0.1, 0.8).out()

rotate the oscillator 0.8 radians:

osc(20, 0.1, 0.8).rotate(0.8).out()

pixelate the output of the above function:

osc(20, 0.1, 0.8).rotate(0.8).pixelate(20, 30).out()

show webcam output:

s0.initCam() // initialize a webcam in source buffer s0
src(s0).out() // render source buffer s0

If you have more than one camera connected, you can select the camera using an index:

s0.initCam(1) // initialize a webcam in source buffer s0

webcam kaleidoscope:

s0.initCam() // initialize a webcam in source buffer s0
src(s0).kaleid(4).out() // render the webcam to a kaleidoscope

You can also composite multiple sources together:

osc(10)
  .rotate(0.5)
  .diff(osc(200))
  .out()

By default, the environment contains four separate output buffers that can each render different graphics. The outputs are accessed by the variables o0, o1, o2, and o3.

to render to output buffer o1:

osc().out(o1)
render(o1) // render the contents of o1

If no output is specified in out(), the graphics are rendered to buffer o0. to show all render buffers at once:

render()

The output buffers can then be mixed and composited to produce what is shown on the screen.

s0.initCam() // initialize a webcam in source buffer s0
src(s0).out(o0) // set the source of o0 to render the buffer containing the webcam
osc(10, 0.2, 0.8).diff(o0).out(o1) // initialize a gradient in output buffer o1, composite with the contents of o0
render(o1) // render o1 to the screen

The composite functions blend(), diff(), mult(), and add() perform arithmetic operations to combine the input texture color with the base texture color, similar to photoshop blend modes.

modulate(texture, amount) uses the red and green channels of the input texture to modify the x and y coordinates of the base texture. More about modulation at: https://lumen-app.com/guide/modulation/

osc(21, 0).modulate(o1).out(o0)
osc(40).rotate(1.57).out(o1)

Passing functions as variables

Each parameter can be defined as a function rather than a static variable. For example,

osc(function(){return 100 * Math.sin(time * 0.1)}).out()

modifies the oscillator frequency as a function of time. (Time is a global variable that represents the milliseconds that have passed since loading the page). This can be written more concisely using es6 syntax:

osc(() => (100 * Math.sin(time * 0.1))).out()

Desktop capture

To use screen capture or a browser tab as an input texture, you must first install the chrome extension for screensharing, and restart chrome. Desktop capture can be useful for inputing graphics from another application, or a video or website in another browser tab. It can also be used to create interesting feedback effects.

To install, go to chrome://extensions Click "Load unpacked extension", and select the "extensions" folder in "screen-capture-extension" in this repo. Restart chrome. The extension should work from now on without needing to reinstall.

select a screen tab to use as input texture:

s0.initScreen()

render screen tab:

s0.initScreen()
src(s0).out()

Connecting to remote streams

Any hydra instance can use other instances/windows containing hydra as input sources, as long as they are connected to the internet and not blocked by a firewall. Hydra uses webrtc (real time webstreaming) under the hood to share video streams between open windows. The included module rtc-patch-bay manages connections between connected windows, and can also be used as a standalone module to convert any website into a source within hydra. (See standalone camera source below for example.)

To begin, open hydra simultaneously in two separate windows. In one of the windows, set a name for the given patch-bay source:

pb.setName("myGraphics")

The title of the window should change to the name entered in setName().

From the other window, initiate "myGraphics" as a source stream.

s0.initStream("myGraphics")

render to screen:

s0.initStream("myGraphics")
src(s0).out()

The connections sometimes take a few seconds to be established; open the browser console to see progress. To list available sources, type the following in the console:

pb.list()

Running locally

To run locally, you must have nodejs and npm installed. Install from: https://nodejs.org/en/

open terminal and enter directory

cd hydra

install dependencies:

npm install -d

run server

npm run start

go to https://localhost:8000 in the browser

Audio Responsiveness (experimental)

FFT functionality is available via an audio object accessed via "a". The editor uses https://github.com/meyda/meyda for audio analysis. To show the fft bins,

a.show()

Set number of fft bins:

a.setBins(6)

Access the value of the leftmost (lowest frequency) bin:

a.fft[0]

Use the value to control a variable:

osc(10, 0, () => (a.fft[0]*4))
  .out()

It is possible to calibrate the responsiveness by changing the minimum and maximum value detected. (Represented by blur lines over the fft). To set minimum value detected:

a.setCutoff(4)

Setting the scale changes the range that is detected.

a.setScale(2)

The fft[] will return a value between 0 and 1, where 0 represents the cutoff and 1 corresponds to the maximum.

You can set smoothing between audio level readings (values between 0 and 1). 0 corresponds to no smoothing (more jumpy, faster reaction time), while 1 means that the value will never change.

a.setSmooth(0.8)

To hide the audio waveform:

a.hide()

MIDI (experimental)

MIDI controllers can work with Hydra via WebMIDI an example workflow is at /docs/midi.md .

API

There is an updated list of functions at /docs/funcs.md.

As well as in the source code for hydra-synth.

Changelog between v0 and v1:

• Syntax change from 'o0.osc()' to 'osc().out(o0)'. Note: old syntax still works
• multiple generator functions can be composited into each other: osc(10) .rotate(0.5) .diff(osc(200).rotate(0.2)) .out()
• Buffer can be an input to itself: osc(40, 0.1, 1) .modulate(src(o0), 0.1) .scale(1.1) .rotate(0.04) .out(o0)
• Multiple cameras can be specified using s0.initCam(1)
• synth logic exists as a separate module, hydra-synth
• added preliminary fft capability
• fixed some bugs in editor and camera

Libraries and tools used:

• Regl: functional webgl
• glitch.io: hosting for sandbox signalling server
• codemirror: browser-based text editor
• simple-peer

Inspiration:

• Space-Time Dynamics in Video Feedback (1984). video and paper by Jim Crutchfield about using analog video feedback to model complex systems.
• Satellite Arts Project (1977) - Kit Galloway and Sherrie Rabinowitz
• Sandin Image Processor
• kynd - reactive buffers experiment

Related projects:

• Lumen app (osx application)
• Vsynth (package for MaxMSP)
• VEDA (VJ system within atom)
• The Force