A brief analysis of differences between OpenGL ES directive in WebGL and C version instruction in IOS

A brief analysis of differences between OpenGL ES directive in WebGL and C version instruction in IOS

The beautiful Life of the Sun Vulcan (http://blog.csdn.net/opengl_es)

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The difference between the OpenGL ES directive in WebGL and the C directive in IOS is that, as a whole, it should be omitted from the GL prefix in the WebGL version of the directive, for example:

    Glenable (gl_cull_face);    Glfrontface (GL_CW);

    Gl.enable (GL. Cull_face);    Gl.frontface (GL. CW);

From the above example, it can be seen that the C version of the use of the global function, process-oriented usage, so there is no object;

In WebGL, a method encapsulated in an object is invoked in the form of a GL object (an instance of a WebGL object) to invoke the corresponding C-version of the package contained in a WebGL object, so omitting the GL prefix for the C-version directive is understandable.

As for the GL object, it is created as follows:

var gl;function initgl (Canvas) {    try {        gl = canvas.getcontext ("Experimental-webgl");        Gl.viewportwidth = Canvas.width;        Gl.viewportheight = canvas.height;    } catch (E) {    }    if (!GL) {        alert ("Could not initialise WebGL, sorry:-(");}    }

The canvas in the code above is a new label in HTML5, typically used to get a 2d context for drawing, and in the WebGL era, a new implementation has been added to support WebGL.

    var canvas = document.getElementById ("Lesson13-canvas");

<canvas id= "Lesson13-canvas" style= "Border:none;" width= "height=" ></canvas>

More differences, follow-up constantly found, and then at any time to add in.