WebGL 1.0 is based on OpenGL ES 2.0 and provides an API for 3D graphics. It uses the HTML5 canvas element and is accessed using Document Object Model (DOM) interfaces.
Shaders in WebGL are expressed directly in GLSL and passed to the WebGL API as textual strings. The WebGL implementation compiles these shader instructions to GPU code. This code is executed for each and every vertex sent through the API and for each pixel rasterized to the screen.
WebGL evolved out of the Canvas 3D experiments started by Vladimir Vukicevic at Mozilla. Vukicevic first demonstrated a Canvas 3D prototype in 2006. By the end of 2007, both Mozilla and Opera had made their own separate implementations.
In early 2009, the non-profit technology consortium Khronos Group started the WebGL Working Group, with initial participation from Apple, Google, Mozilla, Opera, and others. Version 1.0 of the WebGL specification was released March 2011. As of March 2012, the chair of the working group is Ken Russell.
Early applications of WebGL include Zygote Body. In November 2012 Autodesk announced that they ported most of their applications to the cloud running on local WebGL clients. These applications included Fusion 360 and AutoCAD 360.
Development of the WebGL 2 specification started in 2013 with final in January 2017. This specification is based on OpenGL ES 3.0.
First implementations are in Firefox 51, Chrome 56 and Opera 43.
Almost Native Graphics Layer Engine (ANGLE) is an open source graphic engine which implements WebGL 1.0 (2.0 which closely conforms to ES 3.0) and OpenGL ES 2.0 and 3.0 standards. It is a default backend for both Google Chrome and Mozilla Firefox on Windows platforms and works by translating WebGL and OpenGL calls to available platform-specific APIs. ANGLE currently provides access to OpenGL ES 2.0 and 3.0 to desktop OpenGL, OpenGL ES, Direct3D 9, and Direct3D 11 APIs. ″[Google] Chrome uses ANGLE for all graphics rendering on Windows, including the accelerated Canvas2D implementation and the Native Client sandbox environment.″
WebGL is widely supported by modern browsers. However its availability is dependent on other factors like the GPU supporting it. The official WebGL website offers a simple test page. More detailed information (like what renderer the browser uses, and what extensions are available) is provided at third-party websites.
There also has been a rapid emergence of game engines for WebGL, both 2D and 3D, including Unreal Engine 4 and Unity. The Stage3D/Flash-based Away3D high-level library also has a port to WebGL via TypeScript. A more light-weight utility library that provides just the vector and matrix math utilities for shaders is sylvester.js. It is sometimes used in conjunction with a WebGL specific extension called glUtils.js.
There are also some 2D libraries built on top of WebGL like Cocos2d-x or Pixi.js, which were implemented this way for performance reasons, in a move that parallels what happened with the Starling Framework over Stage3D in the Flash world. The WebGL-based 2D libraries fall back to HTML5 canvas when WebGL is not available.
Like for any other graphics API, creating content for WebGL scenes requires using a regular 3D content creation tool and exporting the scene to a format that is readable by the viewer or helper library. Desktop 3D authoring software such as Blender, Autodesk Maya or SimLab Composer can be used for this purpose. Particularly, Blend4Web allows a WebGL scene to be authored entirely in Blender and exported to a browser with a single click, even as a standalone web page. There are also some WebGL-specific software such as CopperCube and the online WebGL-based editor Clara.io. Online platforms such as Sketchfab and Clara.io allow users to directly upload their 3D models and display them using a hosted WebGL viewer.
Additionally, Mozilla Foundation, in its Firefox browser, has implemented built-in WebGL tools starting with version 27 that allow editing vertex and fragment shaders. A number of other debugging and profiling tools have also emerged.