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.ojack.xyz

• 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)

use a video as a source:

s0.initVideo("https://media.giphy.com/media/AS9LIFttYzkc0/giphy.mp4")
src(s0).out()

use an image as a source:

s0.initImage("https://upload.wikimedia.org/wikipedia/commons/2/25/Hydra-Foto.jpg")
src(s0).out()

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

Open a dialog to select a screen tab to use as input texture:

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()

Using p5.js with hydra

// Initialize a new p5 instance It is only necessary to call this once
p5 = new P5() // {width: window.innerWidth, height:window.innerHeight, mode: 'P2D'}

// draw a rectangle at point 300, 100
p5.rect(300, 100, 100, 100)

// Note that P5 runs in instance mode, so all functions need to start with the variable where P5 was initialized (in this case p5)
// reference for P5: https://P5js.org/reference/
// explanation of instance mode: https://github.com/processing/P5.js/wiki/Global-and-instance-mode

// When live coding, the "setup()" function of P5.js has basically no use; anything that you would have called in setup you can just call outside of any function.

p5.clear()

for(var i = 0; i < 100; i++){
  p5.fill(i*10, i%30, 255)
  p5.rect(i*20, 200, 10,200)
}

// To live code animations, you can redefine the draw function of P5 as follows:
// (a rectangle that follows the mouse)
p5.draw = () => {
  p5.fill(p5.mouseX/5, p5.mouseY/5, 255, 100)
  p5.rect(p5.mouseX, p5.mouseY, 30, 150)
}

// To use P5 as an input to hydra, simply use the canvas as a source:
s0.init({src: p5.canvas})

// Then render the canvas
src(s0).repeat().out()

Loading external scripts

The await loadScript() function lets you load other packaged javascript libraries within the hydra editor. Any javascript code can run in the hydra editor.

Here is an example using Three.js from the web editor:

await loadScript("https://threejs.org/build/three.js")

scene = new THREE.Scene()
camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000)

renderer = new THREE.WebGLRenderer()
renderer.setSize(width, height)
geometry = new THREE.BoxGeometry()
material = new THREE.MeshBasicMaterial({color: 0x00ff00})
cube = new THREE.Mesh(geometry, material);
scene.add(cube)
camera.position.z = 1.5

// 'update' is a reserved function that will be run every time the main hydra rendering context is updated
update = () => {
  cube.rotation.x += 0.01;
  cube.rotation.y += 0.01;
  renderer.render( scene, camera );
}

s0.init({ src: renderer.domElement })

src(s0).repeat().out()

And here is an example loading the Tone.js library:

await loadScript("https://unpkg.com/tone")

synth = new Tone.Synth().toDestination();
synth.triggerAttackRelease("C4", "8n");

Running locally

To run locally, you must have nodejs, yarn and npm installed. Install node and npm from: https://nodejs.org/en/. Once you have node and npm installed, you can install yarn globally by running the following from the command line:

npm install --global yarn

To run, open terminal and enter the directory of the hydra source code:

cd hydra

install dependencies:

yarn install

run server

yarn serve

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

Using submodules

If you would like to run all projects on the hydra website (such as the documentation, garden, and api documentation), you must also clone the repos added as submodules, i.e.:

git clone --recurse-submodules https://github.com/hydra-synth/hydra.git

To add current submodules to an existing checked-out version of the repo:

git submodule update --init

To pull latest versions of submodules:

git submodule foreach git pull origin main  

To develop

Edit frontend/public/index.html to load 'bundle.js' rather than 'bundle.min.js'

Run development server

yarn dev

Generate locally-signed certificates

(For development) Run the following from the terminal

openssl req -x509 -out backend/certs/certificate.pem -keyout backend/certs/key.pem \
  -newkey rsa:2048 -nodes -sha256 \
  -subj '/CN=localhost' -extensions EXT -config <( \
   printf "[dn]\nCN=localhost\n[req]\ndistinguished_name = dn\n[EXT]\nsubjectAltName=DNS:localhost\nkeyUsage=digitalSignature\nextendedKeyUsage=serverAuth")

Audio Responsiveness

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

See CHANGELOG.md for recent changes.

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