@maptalks/regl

v3.5.1

Published

14 days ago

regl is a fast functional WebGL framework.

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webgl stackgl regl gl graphics computer graphics opengl glsl data flow reactive functional

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.

If you are using npm, you may also want to try budo which is a live development server.

Run time error checking and browserify

By default if you compile regl with browserify then all error messages and run time checks are removed. This is done to reduce the size of the final bundle. If you are developing an application, you should run browserify using the --debug flag in order to enable error messages. This will also generate source maps which make reading the source code of your application easier.

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:

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!

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
Matcap (spheretexture.jpg) by Ben Simonds. CC 3 license.
Normal map (normaltexture.jpg) by rubberduck. CC0 license.

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