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→WebGL section
[add 3D FFT visualizer]
'''WebGL Introduction'''<br />
The introduction of the <canvas> tag into the HTML5 specification allowed Processing to be ported to JavaScript, thus enabling users to run 2D sketches within the browser without additional plug-ins. At the time when porting began, there still was no plug-in free method of delivering 3D content. This limited Processing.js to 2D until WebGL was introduced. Once WebGL was implemented on pre-release versions of Firefox, Safari and Chrome, it became a viable candidate for use in Processing.js to render 3D sketches. Additionally, since WebGL closely matches OpenGL which is used by Processing, it substantially aided the porting process.
WebGL first began as an experimental add-on for Firefox developed at Mozilla. It was later adopted by the Khronos group who manage the OpenGL specifications. It is a JavaScript API which provides a subset of the functionality of OpenGL ES 2.0. The interface is relatively simple, yet it still provides enough functionality to emulate almost all of Processing's 3D functions. WebGL continues go through interface changes and revisions.
'''Differences'''<br />
The matter of porting Processing (which uses OpenGL) was simplified because the WebGL interface is similar that of OpenGL, but there are a number of differences between the interfaces. Arguably, the single largest difference between WebGL and OpenGL is that like OpenGL ES 2.0, the fixed-function pipeline was been removed. Because of this, not all Processing source code could not be ported directly. Instead, user-defined vertex and fragment shaders were necessary to write for lighting operations. Since some shapes in Processing aren't lit, a few shaders were written. One shader exists for lit objects such as boxes and spheres, another less complex shader was written for unlit objects such as lines and points.
The following shaders are used for rendering unlit shapes specified with begin/end function calls.
"varying vec4 vFrontColor;" +
"attribute vec3 aVertex;" +
" gl_Position = uProjection * uView * vec4(aVertex, 1.0);" +
"}";
</pre>
fragment shader:
<pre>
ifdef"GLfESf GL_ES\n" +
"prehighpn highp float;\n" endif"#endif\n" +
"void main(void){" +glrFragColoragCvFrontColorntColor;" +
"}";
</pre>
Examinishadersshaders reveals some of the idiosyncrasWebGLf WebGgl The gl_Color keyword is considered invalid. Instead, users must create their own varying vector. Furthermore, a preprocessor statement to set float types to use high precision is also required. These are some examples of changes to the specifications changes which were introduced over time.
