glsl-livecoder

VJ / Live Coding on Atom with GLSL.

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TOC

• Features
• Install
• Commands
• Usage
  • Commands
  • Preset uniform variables
  • Audio Input
  • MIDI Events
  • Loading images / videos
• Author

Features

• GLSL Sandbox style uniform variables
• Load images / videos
• Additional uniform variables useful for live coding
  • Audio input
  • MIDI input
• Auto completion w/ autocomplete-glsl
• Linting w/ linter-glsl

Install

Install glslangValidator

glsl-livecoder requires glslangValidator.
Follow the below steps to install glslangValidator.

macOS

If you are uning macOS, glslangValidator can be installed by homebrew.

brew install glslang

Windows or Linux

If you are uning Windows or Linux, the best way to install glslangValidator is to install Vulkan SDK.
Get the SDK from here:

https://www.lunarg.com/vulkan-sdk/

After that, add installed glslangValidator to your PATH environment variable.
In Windows, glslangValidator will be installed in C:\VulkanSDK\( version )\Bin.

The path of glslangValidator can also be specified in the settings of glsl-livecoder.

Install glsl-livecoder

Just install from Atom GUI or apm.

$ apm install glsl-livecoder

If Atom shows an error like below, try rebuilding the package from 🐞 icon on the footer.

Failed to require the main module of 'glsl-livecoder' because it requires an incompatible native module.
Run `apm rebuild` in the package directory to resolve.

Usage

Commands

glsl-livecoder installs following commands to Atom.

• toggle
  • Start / Stop glsl-livecoder.
• load-shader (key: ctrl-enter)
  • Load the shader on current editor.
• watch-shader (key: ctrl-shift-enter)
  • Watch current tab and load the shader automatically.
• watch-active-editor (key: ctrl-alt-enter)
  • Watch active tab and run watch-shader automatically.
• stop-watching (key: ctrl-.)
  • Stop watch-shader and watch-active-editor.

A typical workflow can be like this:

1. Enable glsl-livecoder by running glsl-liveder:toggle from the Command Palette of Atom.
2. Edit your GLSL code.
3. Hit ctrl-enter to run glsl-livecoder:load-shader.

Preset uniform variables

• float time:
  • The elapsed time since glsl-livecoder has started.
• vec2 resolution
  • The resolution of the screen.
• vec2 mouse
  • Current position of mouse.
  • vec2(0) to vec2(1)
• sampler2D backbuffer
  • Rendered result of last frame.
  • RGBA format
• sampler2D samples
  • Samples of the audio input.
• sampler2D spectrum
  • FFT result of the audio input.
• float volume
  • The volume of the audio input.
• sampler2D midi
  • Last MIDI event for each channel of MIDI devices.
  • x: 2nd byte of the event
  • y: 3rd byte of the event
• sampler2D note
  • States of note numbers of MIDI devices.
  • x: the volume of the note

Audio inputs

You can use audio data of the audio input. These data are obtained by AnalyserNode of Web Audio API.

sampler2D samples stores the most recent 256 frames from the audio input. This is useful for drawing waveforms.

sampler2D spectrum stores the FFT result. This is useful to draw the volume of specific frequency band, such as spectrum visualizer.

float volume is the average of all the frequency bands in spectrum.

See examples for actual usage.

MIDI Events

sampler2D midi stores MIDI events obtained by Web MIDI API. The size of midi is 256x1. Each pixel stores the last event of the corresponding MIDI Events.

For example, texture2D(midi, vec2(144. / 256., 0)).x yields the note number of last note on event of MIDI Channel 1.

• 144. (0x90): note on event of MIDI Channel 1
• .x (2nd byte): Note number

See examples for actual usage.

sampler2D note stores the volumes for each note number The size of midi is 128x1. Each pixel stores the volume of the last event for corresponding MIDI note.

For example, texture2D(note, vec2(60. / 128., 0)).x yields the volume of note C4 (Middle C).

See examples for actual usage.

Loading images / videos

You can load images and videos from local or via URL. To use images / videos, .liverc is required.

• .liverc must be located in your project's root directory.
• .liverc is parsed as JSON5 format
  • You can write comments in .liverc.
• .liverc is loaded on startup and reloaded automatically when you edit it.
• Write image / video paths in IMPORTED property.
  • The structure of .liverc is based on Interactive Shader Format

For example, create .liverc like this:

{
	"IMPORTED": {
		"image1": {
			"PATH": "1.jpg",
		},
		"image2": {
			"PATH": "../2.png",
		},
		"video1": {
			"PATH": "/Users/foo/Movies/1.mp4",
		},
		"video2": {
			"PATH": "http://example.com/2.mp4",
		},
	},
}

Then use it in your GLSL file:

precision mediump float;
uniform vec2 resolution;

uniform sampler2D image1;
uniform sampler2D image2;
uniform sampler2D video1;
uniform sampler2D video2;

void main() {
	vec2 uv = gl_FragCoord.xy / resolution;

	gl_FragColor = (
		texture2D(image1, uv) +
		texture2D(image2, uv) +
		texture2D(video1, uv) +
		texture2D(video2, uv)
  );
}

See these examples for actual usage.

• .liverc
• image.frag
• video.frag

Author

Takayosi Amagi

• Twitter: @amagitakayosi
• GitHub: fand
• Blog: マルシテイア

License

MIT