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:

const regl = require('regl')()

// This creates a new partially evaluated draw call.  We flag the dynamic
// parts of the draw call using the special `regl.dynamic` variable
const drawTriangle = 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: regl.buffer([[-2, -2], [4, -2], [4,  4]]))
  },

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

  count: 3
})

regl.frame(() => {
  // clear contents of the drawing buffer
  regl.clear({
    color: [0, 0, 0, 0],
    depth: 1
  })

  // draw a triangle
  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
• Commands
  • Dynamic properties
  • Command properties
    • Shaders
    • Uniforms
    • Attributes
    • Drawing
    • Depth
    • Stencil
    • Blending
    • Polygon offset
    • Culling
    • Miscellaneous parameters
  • Executing commands
    • One-shot rendering
    • Scoped parameters
    • Batch rendering
• Resources
  • Constructors
    • regl.buffer(options)
    • regl.elements(options)
    • regl.texture(options)
    • regl.fbo(options)
  • Updates
  • Destruction
• Other stuff
  • Clear the draw buffer
  • Reading pixels
  • Per-frame callbacks
  • Frame stats
  • Clean up

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