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

This repo is an attempt at building new functional abstractions for working with WebGL. It is still experimental, so expect things to change a lot in the near future! If you want to know more about why I am writing this thing and why it looks the way it does, take a look at the rationale.

Why use regl

regl offers the following advantages over raw WebGL code:

• Just one function
• Less state Draw commands in regl are self contained, so you don't have to worry about some other weird subroutine breaking your rendering code
• No bind() In regl, shaders, buffers, textures and fbos are specified declaratively, so there is no need to ever bind() them or unbind them.
• Fewer silent failure If you pass incorrect parameters to some WebGL method, the default behavior is to set an error code and continue on. Because regl commands have more structure, we can do more validation up front without the run time performance cost.
• Sane defaults Many WebGL APIs have redundant or outright broken parameters (for example border in gl.texImage2D or transpose in gl.uniformMatrix4fv). regl wraps these APIs in such a way that you will never have to see this mess.

Simple 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(() => {
  // 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(Date.now() * 0.001),
      Math.sin(Date.now() * 0.0008),
      Math.cos(Date.now() * 0.003),
      1
    ]
  })
})

More examples

Check out the demo gallery

Setup

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

Live editing

To try out regl right away, you can use RequireBin or codepen. The following links should help get you started:

• requirebin
• codepen

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>

Comparisons

TODO implement spinning textured cube in each of the following frameworks

• vs WebGL
• vs gl-* modules from stack.gl
• vs TWGL
• vs THREE.js

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
• Commands
  • Dynamic properties
  • Executing commands
    • One-shot rendering
    • Batch rendering
    • Scoped parameters
  • Parameters
    • Shaders
    • Uniforms
    • Attributes
    • Drawing
    • Framebuffer
    • Depth buffer
    • Blending
    • Stencil
    • Polygon offset
    • Culling
    • Front face
    • Dithering
    • Line width
    • Color mask
    • Sample coverage
    • Scissor
    • Viewport
• Resources
  • Basic usage
    • Updating a resource
    • Destroying a resource
  • Types
    • regl.buffer(options)
    • regl.elements(options)
• Other features
  • Clear the draw buffer
  • Reading pixels
  • Per-frame callbacks
  • Frame stats
  • WebGL capabilities
  • Clean up
  • Context loss

Contributing

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

License

(c) 2016 MIT License

Supported by the Freeman Lab and the Howard Hughes Medical Institute

Changelog

0.1.0

• Actually kind of works now!
• All draw state and WebGL state except textures, renderbuffers and frame buffers wrapped
• Changed the arguments to dynamic functions. Now they take (args, batchId, stats) instead of (frameCount, batchId)
• Tons of code generation improvements and bug fixing
• Unit tests!
• Code coverage metrics! (not good yet)
• API docs!