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

regl

regl is a fast functional reactive abstraction for WebGL.

Example

In regl, there are 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 colored 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.

Setup

regl has no dependencies, so setting it up is pretty easy

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 under the releases tab. To do this, add the following script tag to your HTML:

<script src="[some cdn tbd]/regl.min.js"></script>

Why use regl?

regl is basically all of WebGL without all of the shared state. You can do anything you could in regular WebGL with little overhead and way less debugging.

Comparisons

In this section, we show how you can implement a spinning textured cube in regl, and compare it with other WebGL frameworks.

regl

const regl = require('../regl')()
const mat4 = require('gl-mat4')

var cubePosition = [
  [-0.5, +0.5, +0.5], [+0.5, +0.5, +0.5], [+0.5, -0.5, +0.5], [-0.5, -0.5, +0.5], // positive z face.
  [+0.5, +0.5, +0.5], [+0.5, +0.5, -0.5], [+0.5, -0.5, -0.5], [+0.5, -0.5, +0.5], // positive x face
  [+0.5, +0.5, -0.5], [-0.5, +0.5, -0.5], [-0.5, -0.5, -0.5], [+0.5, -0.5, -0.5], // negative z face
  [-0.5, +0.5, -0.5], [-0.5, +0.5, +0.5], [-0.5, -0.5, +0.5], [-0.5, -0.5, -0.5], // negative x face.
  [-0.5, +0.5, -0.5], [+0.5, +0.5, -0.5], [+0.5, +0.5, +0.5], [-0.5, +0.5, +0.5], // top face
  [-0.5, -0.5, -0.5], [+0.5, -0.5, -0.5], [+0.5, -0.5, +0.5], [-0.5, -0.5, +0.5]  // bottom face
]

var cubeUv = [
  [0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], // positive z face.
  [0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], // positive x face.
  [0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], // negative z face.
  [0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], // negative x face.
  [0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], // top face
  [0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0]  // bottom face
]

const cubeElements = [
  [2, 1, 0], [2, 0, 3],       // positive z face.
  [6, 5, 4], [6, 4, 7],       // positive x face.
  [10, 9, 8], [10, 8, 11],    // negative z face.
  [14, 13, 12], [14, 12, 15], // negative x face.
  [18, 17, 16], [18, 16, 19], // top face.
  [20, 21, 22], [23, 20, 22]  // bottom face
]

const drawCube = regl({
  frag: `
  precision mediump float;
  varying vec2 vUv;
  uniform sampler2D tex;
  void main () {
    gl_FragColor = texture2D(tex,vUv);
  }`,
  vert: `
  precision mediump float;
  attribute vec3 position;
  attribute vec2 uv;
  varying vec2 vUv;
  uniform mat4 projection, view;
  void main() {
    vUv = uv;
    gl_Position = projection * view * vec4(position, 1);
  }`,
  attributes: {
    position: cubePosition,
    uv: cubeUv
  },
  elements: cubeElements,
  uniforms: {
    view: ({tick}) => {
      const t = 0.01 * tick
      return mat4.lookAt([],
                         [5 * Math.cos(t), 2.5 * Math.sin(t), 5 * Math.sin(t)],
                         [0, 0.0, 0],
                         [0, 1, 0])
    },
    projection: ({viewportWidth, viewportHeight}) =>
      mat4.perspective([],
                       Math.PI / 4,
                       viewportWidth / viewportHeight,
                       0.01,
                       10),
    tex: regl.prop('texture')
  }
})

require('resl')({
  manifest: {
    texture: {
      type: 'image',
      src: 'assets/lena.png',
      parser: (data) => regl.texture({
        data: data,
        mag: 'linear',
        min: 'linear'
      })
    }
  },
  onDone: ({texture}) => {
    regl.frame(() => {
      regl.clear({
        color: [0, 0, 0, 255],
        depth: 1
      })
      drawCube({texture})
    })
  }
})

Raw WebGL

<!doctype html>
<html>
  <head>
    <title>WebGL Textured Cube Demo</title>
    <script type="text/javascript">
/* global Image, alert, requestAnimationFrame */
var canvas
var gl
var cubePositionBuffer
var cubeUvBuffer
var cubeElementsBuffers
var cubeTexture
var shaderProgram
var cubePositionAttribute
var cubeUvAttribute
var projectionUniformLocation
var viewUniformLocation
var tick
function start () {
  canvas = document.getElementById('glcanvas')
  tick = 0
  initWebGL(canvas)
  if (gl) {
    gl.clearColor(0.0, 0.0, 0.0, 1.0)
    gl.enable(gl.DEPTH_TEST)
    gl.enable(gl.CULL_FACE)
    initShaders()
    initBuffers()
    initTextures()
    // start RAF
    requestAnimationFrame(drawScene)
  }
}
function initWebGL () {
  try {
    gl = canvas.getContext('experimental-webgl')
  } catch (e) {
  }
  if (!gl) {
    alert('Unable to initialize WebGL. Your browser may not support it.')
  }
}
function initBuffers () {
  cubePositionBuffer = gl.createBuffer()
  gl.bindBuffer(gl.ARRAY_BUFFER, cubePositionBuffer)
  var cubePosition = [
    // positive z face.
      -0.5, +0.5, +0.5,
      +0.5, +0.5, +0.5,
      +0.5, -0.5, +0.5,
      -0.5, -0.5, +0.5,
    // positive x face
      +0.5, +0.5, +0.5,
      +0.5, +0.5, -0.5,
      +0.5, -0.5, -0.5,
      +0.5, -0.5, +0.5,
    // negative z face
      +0.5, +0.5, -0.5,
      -0.5, +0.5, -0.5,
      -0.5, -0.5, -0.5,
      +0.5, -0.5, -0.5,
    // negative x face.
      -0.5, +0.5, -0.5,
      -0.5, +0.5, +0.5,
      -0.5, -0.5, +0.5,
      -0.5, -0.5, -0.5,
    // top face
      -0.5, +0.5, -0.5,
      +0.5, +0.5, -0.5,
      +0.5, +0.5, +0.5,
      -0.5, +0.5, +0.5,
    // bottom face
      -0.5, -0.5, -0.5,
      +0.5, -0.5, -0.5,
      +0.5, -0.5, +0.5,
      -0.5, -0.5, +0.5
  ]
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(cubePosition), gl.STATIC_DRAW)
  cubeUvBuffer = gl.createBuffer()
  gl.bindBuffer(gl.ARRAY_BUFFER, cubeUvBuffer)
  var cubeUv = [
    // positive z face.
    0.0, 0.0,
    1.0, 0.0,
    1.0, 1.0,
    0.0, 1.0,
    // positive x face.
    0.0, 0.0,
    1.0, 0.0,
    1.0, 1.0,
    0.0, 1.0,
    // negative z face.
    0.0, 0.0,
    1.0, 0.0,
    1.0, 1.0,
    0.0, 1.0,
    // negative x face.
    0.0, 0.0,
    1.0, 0.0,
    1.0, 1.0,
    0.0, 1.0,
    // top face
    0.0, 0.0,
    1.0, 0.0,
    1.0, 1.0,
    0.0, 1.0,
    // bottom face
    0.0, 0.0,
    1.0, 0.0,
    1.0, 1.0,
    0.0, 1.0
  ]
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(cubeUv), gl.STATIC_DRAW)
  cubeElementsBuffers = gl.createBuffer()
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeElementsBuffers)
  var cubeElements = [
    // positive z face.
    2, 1, 0,
    2, 0, 3,
    // positive x face.
    6, 5, 4,
    6, 4, 7,
    // negative z face.
    10, 9, 8,
    10, 8, 11,
    // negative x face.
    14, 13, 12,
    14, 12, 15,
    // top face.
    18, 17, 16,
    18, 16, 19,
    // bottom face
    20, 21, 22,
    23, 20, 22
  ]
  gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeElements), gl.STATIC_DRAW)
}
function initTextures () {
  cubeTexture = gl.createTexture()
  var cubeImage = new Image()
  cubeImage.onload = function () {
    gl.bindTexture(gl.TEXTURE_2D, cubeTexture)
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, cubeImage)
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
  }
  cubeImage.src = '../example/assets/lena.png'
}
function drawScene () {
  tick++
  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
  // bind buffers.
  gl.bindBuffer(gl.ARRAY_BUFFER, cubePositionBuffer)
  gl.vertexAttribPointer(cubePositionAttribute, 3, gl.FLOAT, false, 0, 0)
  gl.bindBuffer(gl.ARRAY_BUFFER, cubeUvBuffer)
  gl.vertexAttribPointer(cubeUvAttribute, 2, gl.FLOAT, false, 0, 0)
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeElementsBuffers)
  // set texture.
  gl.activeTexture(gl.TEXTURE0)
  gl.bindTexture(gl.TEXTURE_2D, cubeTexture)
  // set uniforms
  gl.uniform1i(gl.getUniformLocation(shaderProgram, 'tex'), 0)
  const t = 0.01 * tick
  var perspectiveMatrix = perspective(45, 640.0 / 480.0, 0.1, 100.0)
  gl.uniformMatrix4fv(projectionUniformLocation, false, new Float32Array(perspectiveMatrix))
  gl.uniformMatrix4fv(viewUniformLocation, false, new Float32Array(
    lookAt(
      [5 * Math.cos(t), 2.5 * Math.sin(t), 5 * Math.sin(t)],
      [0, 0.0, 0],
      [0, 1, 0])))
  gl.drawElements(gl.TRIANGLES, 36, gl.UNSIGNED_SHORT, 0)
  requestAnimationFrame(drawScene)
}
function initShaders () {
  var fragmentShader = getShader(gl, 'shader-fs')
  var vertexShader = getShader(gl, 'shader-vs')
  shaderProgram = gl.createProgram()
  gl.attachShader(shaderProgram, vertexShader)
  gl.attachShader(shaderProgram, fragmentShader)
  gl.linkProgram(shaderProgram)
  if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
    alert('Unable to initialize the shader program: ' + gl.getProgramInfoLog(shaderProgram))
  }
  gl.useProgram(shaderProgram)
  cubePositionAttribute = gl.getAttribLocation(shaderProgram, 'position')
  gl.enableVertexAttribArray(cubePositionAttribute)
  cubeUvAttribute = gl.getAttribLocation(shaderProgram, 'uv')
  gl.enableVertexAttribArray(cubeUvAttribute)
  projectionUniformLocation = gl.getUniformLocation(shaderProgram, 'projection')
  viewUniformLocation = gl.getUniformLocation(shaderProgram, 'view')
}
function getShader (gl, id) {
  var e = document.getElementById(id)
  if (!e) {
    return null
  }
  var sourceCode = e.firstChild.textContent
  var shader
  if (e.type === 'x-shader/x-fragment') {
    shader = gl.createShader(gl.FRAGMENT_SHADER)
  } else if (e.type === 'x-shader/x-vertex') {
    shader = gl.createShader(gl.VERTEX_SHADER)
  } else {
    return null
  }
  gl.shaderSource(shader, sourceCode)
  gl.compileShader(shader)
  if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
    alert('An error occurred compiling the shaders: ' + gl.getShaderInfoLog(shader))
    return null
  }
  return shader
}
// Taken from gl-mat4
// https://github.com/stackgl/gl-mat4/blob/master/lookAt.js
function lookAt (eye, center, up) {
  var x0, x1, x2, y0, y1, y2, z0, z1, z2, len
  var eyex = eye[0]
  var eyey = eye[1]
  var eyez = eye[2]
  var upx = up[0]
  var upy = up[1]
  var upz = up[2]
  var centerx = center[0]
  var centery = center[1]
  var centerz = center[2]
  z0 = eyex - centerx
  z1 = eyey - centery
  z2 = eyez - centerz
  len = 1 / Math.sqrt(z0 * z0 + z1 * z1 + z2 * z2)
  z0 *= len
  z1 *= len
  z2 *= len
  x0 = upy * z2 - upz * z1
  x1 = upz * z0 - upx * z2
  x2 = upx * z1 - upy * z0
  len = Math.sqrt(x0 * x0 + x1 * x1 + x2 * x2)
  if (!len) {
    x0 = 0
    x1 = 0
    x2 = 0
  } else {
    len = 1 / len
    x0 *= len
    x1 *= len
    x2 *= len
  }
  y0 = z1 * x2 - z2 * x1
  y1 = z2 * x0 - z0 * x2
  y2 = z0 * x1 - z1 * x0
  len = Math.sqrt(y0 * y0 + y1 * y1 + y2 * y2)
  if (!len) {
    y0 = 0
    y1 = 0
    y2 = 0
  } else {
    len = 1 / len
    y0 *= len
    y1 *= len
    y2 *= len
  }
  return [
    x0, y0, z0, 0,
    x1, y1, z1, 0,
    x2, y2, z2, 0,
    -(x0 * eyex + x1 * eyey + x2 * eyez),
    -(y0 * eyex + y1 * eyey + y2 * eyez),
    -(z0 * eyex + z1 * eyey + z2 * eyez),
    1
  ]
}
// Taken from gl-mat4
// https://github.com/stackgl/gl-mat4/blob/master/perspective.js
function perspective (fovy, aspect, near, far) {
  var f = 1.0 / Math.tan(fovy / 2)
  var nf = 1 / (near - far)
  return [
    f / aspect, 0.0, 0.0, 0.0,
    0.0, f, 0.0, 0.0,
    0.0, 0.0, (far + near) * nf, -1.0,
    0.0, 0.0, (2 * far * near) * nf, 0.0
  ]
}
    </script>

    <script id="shader-fs" type="x-shader/x-fragment">
  precision mediump float;
  varying vec2 vUv;
  uniform sampler2D tex;
  void main () {
    gl_FragColor = texture2D(tex,vUv);
  }
    </script>

    <script id="shader-vs" type="x-shader/x-vertex">
  precision mediump float;
  attribute vec3 position;
  attribute vec2 uv;
  varying vec2 vUv;
  uniform mat4 projection, view;
  void main() {
    vUv = uv;
    gl_Position = projection * view * vec4(position, 1);
  }
    </script>
  </head>
  <body onload="start()">
    <canvas id="glcanvas" width="640" height="480">
      Your browser doesn't appear to support the <code>&lt;canvas&gt;</code> element.
    </canvas>
  </body>
</html>

stack.gl

TODO

gl-react

TODO

TWGL

TODO

three.js

TODO

Benchmarks

You can run benchmarks locally using npm run bench or check them out here:

• Interactive benchmarks

API

• Initialization * As a fullscreen canvas * From a container div * From a canvas * From a WebGL context
  • Initialization options
• Commands
  • Executing commands
    • One-shot rendering
    • Batch rendering
    • Scoped commands
  • Inputs
    • Context
    • Props
    • this
  • Parameters
    • Shaders
    • Uniforms
    • Attributes
    • Drawing
    • Render target
    • Depth buffer
    • Blending
    • Stencil
    • Polygon offset
    • Culling
    • Front face
    • Dithering
    • Line width
    • Color mask
    • Sample coverage
    • Scissor
    • Viewport
• Resources
  • Buffers
    • Constructor
    • Update
    • Destroy
  • Elements
    • Constructor
    • Update
    • Destroy
  • Textures
    • Constructor
    • Update
    • Destroy
  • Cube maps
    • Constructor
    • Update
    • Destroy
  • Render buffers
    • Constructor
    • Update
    • Destroy
  • Frame buffers
    • Constructor
    • Update
    • Destroy
  • Cubic frame buffers
    • Constructor
    • Update
    • Destroy
• Other features
  • Clear the draw buffer
  • Reading pixels
  • Per-frame callbacks
  • Device capabilities and limits
  • Performance metrics
  • Clean up
  • Context loss
  • Unsafe escape hatch
• Tips
  • Reuse resources (buffers, elements, textures, etc.)
  • Preallocate memory
  • Debug vs release
  • Context loss mitigation

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.

• 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

0.9.0

• Add performance monitoring hooks for commands. Now tracks draw call count, cpu time and gpu time (if disjoint timer extension supported).
• Performance monitoring hooks for commands can be enabled/disabled using the profile property.
• Finish API documentation for framebuffers
• Optimize constructors/updates for framebuffers
• More test cases for framebuffers
• Clean up renderbuffer constructor and improve test coverage
• Added resize method to textures, renderbuffers and framebuffers
• Added global performance monitoring hooks via regl.stats
• Rename count context variable to tick
• Remove deltaTime context variable
• Uniform validation fixes
• Texture construction fixes
• Improved test coverage for uniform variables