regl

What is regl?

regl is a functional abstraction for WebGL that simplifies the process of creating and managing WebGL contexts and rendering pipelines. It provides a declarative API for defining shaders, buffers, and other WebGL resources, making it easier to build complex graphics applications.

What are regl's main functionalities?

Creating a WebGL Context

This code initializes a new regl instance, which sets up a WebGL context and prepares it for rendering.

const regl = require('regl')();

Drawing a Simple Triangle

This code defines a simple triangle using regl. It specifies the vertex and fragment shaders, the vertex positions, and the draw call. The triangle is drawn in each frame.

const drawTriangle = regl({
  frag: `
  precision mediump float;
  void main () {
    gl_FragColor = vec4(1, 0, 0, 1);
  }
  `,
  vert: `
  precision mediump float;
  attribute vec2 position;
  void main () {
    gl_Position = vec4(position, 0, 1);
  }
  `,
  attributes: {
    position: [
      [-1, 0],
      [0, -1],
      [1, 1]
    ]
  },
  count: 3
});

regl.frame(() => {
  regl.clear({
    color: [0, 0, 0, 1],
    depth: 1
  });
  drawTriangle();
});

Managing Buffers

This code demonstrates how to create and use a buffer in regl. The buffer stores vertex positions, which are then used in the draw call.

const positionBuffer = regl.buffer([
  [-1, 0],
  [0, -1],
  [1, 1]
]);

const drawWithBuffer = regl({
  frag: `
  precision mediump float;
  void main () {
    gl_FragColor = vec4(0, 1, 0, 1);
  }
  `,
  vert: `
  precision mediump float;
  attribute vec2 position;
  void main () {
    gl_Position = vec4(position, 0, 1);
  }
  `,
  attributes: {
    position: positionBuffer
  },
  count: 3
});

regl.frame(() => {
  regl.clear({
    color: [0, 0, 0, 1],
    depth: 1
  });
  drawWithBuffer();
});

Using Uniforms

This code shows how to use uniforms in regl. The uniform 'color' is passed to the fragment shader, allowing dynamic control over the color of the rendered triangle.

const drawWithUniforms = regl({
  frag: `
  precision mediump float;
  uniform vec4 color;
  void main () {
    gl_FragColor = color;
  }
  `,
  vert: `
  precision mediump float;
  attribute vec2 position;
  void main () {
    gl_Position = vec4(position, 0, 1);
  }
  `,
  attributes: {
    position: [
      [-1, 0],
      [0, -1],
      [1, 1]
    ]
  },
  uniforms: {
    color: [0, 0, 1, 1]
  },
  count: 3
});

regl.frame(() => {
  regl.clear({
    color: [0, 0, 0, 1],
    depth: 1
  });
  drawWithUniforms();
});

Other packages similar to regl

three

Three.js is a popular JavaScript library for creating 3D graphics in the browser. It provides a higher-level abstraction compared to regl, making it easier to create complex 3D scenes with less code. However, it may not offer the same level of control and performance optimization as regl.

pixi

PixiJS is a 2D rendering engine that uses WebGL for high-performance graphics. It is designed for creating interactive graphics and games, offering a simpler API compared to regl. While it is more focused on 2D graphics, it can also handle some 3D rendering tasks.

babylonjs

Babylon.js is a powerful, open-source 3D engine that provides a comprehensive set of features for creating 3D applications. It offers a higher-level API than regl, making it easier to get started with 3D graphics, but it may not provide the same fine-grained control over WebGL resources.

README

:crown:

regl

Fast functional WebGL

Docs | Chat | Download | Minified

Example

regl simplifies WebGL programming by removing as much shared state as it can get away with. To do this, it replaces the WebGL API with two fundamental abstractions, resources and commands:

• A resource is a handle to a GPU resident object, like a texture, FBO or buffer.
• A command is a complete representation of the WebGL state required to perform some draw call.

To define a command you specify a mixture of static and dynamic data for the object. Once this is done, regl takes this description and then compiles it into optimized JavaScript code. For example, here is a simple regl program to draw a triangle:

// Calling the regl module with no arguments creates a full screen canvas and
// WebGL context, and then uses this context to initialize a new REGL instance
const regl = require('regl')()

// Calling regl() creates a new partially evaluated draw command
const drawTriangle = regl({

  // Shaders in regl are just strings.  You can use glslify or whatever you want
  // to define them.  No need to manually create shader objects.
  frag: `
    precision mediump float;
    uniform vec4 color;
    void main() {
      gl_FragColor = color;
    }`,

  vert: `
    precision mediump float;
    attribute vec2 position;
    void main() {
      gl_Position = vec4(position, 0, 1);
    }`,

  // Here we define the vertex attributes for the above shader
  attributes: {
    // regl.buffer creates a new array buffer object
    position: regl.buffer([
      [-2, -2],   // no need to flatten nested arrays, regl automatically
      [4, -2],    // unrolls them into a typedarray (default Float32)
      [4,  4]
    ])
    // regl automatically infers sane defaults for the vertex attribute pointers
  },

  uniforms: {
    // This defines the color of the triangle to be a dynamic variable
    color: regl.prop('color')
  },

  // This tells regl the number of vertices to draw in this command
  count: 3
})

// regl.frame() wraps requestAnimationFrame and also handles viewport changes
regl.frame(({time}) => {
  // clear contents of the drawing buffer
  regl.clear({
    color: [0, 0, 0, 0],
    depth: 1
  })

  // draw a triangle using the command defined above
  drawTriangle({
    color: [
      Math.cos(time * 0.001),
      Math.sin(time * 0.0008),
      Math.cos(time * 0.003),
      1
    ]
  })
})

See this example live

More examples

Check out the gallery. The source code of all the gallery examples can be found here.

Setup

regl has no dependencies, so setting it up is pretty easy. There are 3 basic ways to do this:

Live editing

To try out regl right away, you can use the live editor in the gallery.

npm

The easiest way to use regl in a project is via npm. Once you have node set up, you can install and use regl in your project using the following command:

npm i -S regl

For more info on how to use npm, check out the official docs.

Standalone script tag

You can also use regl as a standalone script if you are really stubborn. The most recent versions can be found in the dist/ folder and is also available from npm cdn in both minified and unminified versions.

• Unminified: https://npmcdn.com/regl/dist/regl.js
• Minified: https://npmcdn.com/regl/dist/regl.min.js

There are some difference when using regl in standalone. Because script tags don't assume any sort of module system, the standalone scripts inject a global constructor function which is equivalent to the module.exports of regl:

<!DOCTYPE html>
<html>
  <head>
    <meta content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" name="viewport" />
    <meta charset=utf-8>
  </head>
  <body>
  </body>
  <script language="javascript" src="https://npmcdn.com/regl/dist/regl.js"></script>
  <script language="javascript">
    var regl = createREGL()

    regl.frame(function () {
      regl.clear({
        color: [0, 0, 0, 1]
      })
    })
  </script>
</html>

Why regl

regl just removes shared state from WebGL. You can do anything you could in regular WebGL with little overhead and way less debugging. regl emphasizes the following values:

• Simplicity The interface is concise and emphasizes separation of concerns. Removing shared state helps localize the effects and interactions of code, making it easier to reason about.
• Correctness regl has more than 30,000 unit tests and above 95% code coverage. In development mode, regl performs strong validation and sanity checks on all input data to help you catch errors faster.
• Performance regl uses dynamic code generation and partial evaluation to remove almost all overhead.
• Minimalism regl just wraps WebGL. It is not a game engine and doesn't have opinions about scene graphs or vector math libraries. Any feature in WebGL is accessible, including advanced extensions like multiple render targets or instancing.
• Stability regl takes interface compatibility and semantic versioning seriously, making it well suited for long lived applications that must be supported for months or years down the road. It also has no dependencies limiting exposure to risky or unplanned updates.

Comparisons

While regl is lower level than many 3D engines, code written in it tends to be highly compact and flexible. A comparison of regl to various other WebGL libraries across several tasks can be found here.

Benchmarks

In order to prevent performance regressions, regl is continuously benchmarked. You can run benchmarks locally using npm run bench or check them out online. The results for the last few days can be found here.

These measurements were taken using our custom scripts bench-history and bench-graph. You can read more about them in the development guide.

Projects using regl

The following is an incomplete list of projects using regl:

• 538 Gun Deaths
• Infinite Terrain Demo
• GPGPU Smooth Life
• Summed Area Tables
• GPGPU Fourier Analysis

If you have a project using regl that isn't on this list that you would like to see added, please send us a pull request!

Help Wanted

regl is still under active developement, and anyone willing to contribute is very much welcome to do so. Right now, what we need the most is for people to write examples and demos with the framework. This will allow us to find bugs and deficiencies in the API. We have a list of examples we would like to be implemented here, but you are of course welcome to come up with your own examples. To add an example to our gallery of examples, please send us a pull request!

API docs

regl has extensive API documentation. You can browse the docs online here.

Development

The latest changes in regl can be found in the CHANGELOG.

For info on how to build and test headless, see the contributing guide here

License

All code (c) 2016 MIT License

Development supported by the Freeman Lab and the Howard Hughes Medical Institute (@freeman-lab on GitHub)

Asset licenses

Many examples use creative commons or public domain artwork for illustrative purposes. These assets are not included in any of the redistributable packages of regl.

• Peppers test image for cube comparison is public domain
• Test video (doggie-chromakey.ogv) by L0ckergn0me, used under creative commons license
• Cube maps (posx.jpeg, negx.jpeg, posy.jpeg, negy.jpeg, posz.jpeg, negz.jpeg) by Humus, used under creative commons 3 license
• Environment map of Oregon (ogd-oregon-360.jpg) due to Max Ogden (@maxogd on GitHub)
• DDS test images (alpine_cliff_a, alpine_cliff_a_norm, alpine_cliff_a_spec) taken from the CC0 license 0-AD texture pack by Wildfire games
• Tile set for tile mapping demo (tiles.png) from CC0 licensed cobblestone paths pack
• Audio track for audio.js example is "Bamboo Cactus" by 8bitpeoples. CC BY-ND-NC 1.0 license

Changelog

1.0.0

• Support stencil.op
• Rename stencil op pass to zpass
• Attribute pointers can now use buffer literals
• Implement basic context loss handling
• Add regl.on for hooking events
• Add regl.now(), allows sampling timer at high resolution outside of regl.frame in order to better synchronize DOM events