Further Explorations - HTML5 Canvas - page 881

uniform mat4 uMVMatrix ;
uniform mat4 uPMatrix ;

varying vec4 vColor ;

void void main ( void void ) {

gl_Position = uPMatrix * uMVMatrix * vec4 ( aVertexPosition , 1.0 );
vColor = aVertexColor ;

}
< /script>

Testing for WebGL support with Modernizr
The structure of the code in this example is much like the other applications we have written
in this topic.However,ithasbeenmodifiedtoworkwiththespecificneedsofthe3Dcontext.
Inthe canvasApp() function, we need to test to see whether the browser has WebGL support.
This is easily accomplished by using the Modernizr.webgl static constant in Modernizr:

iif ( ! webglSupport ()) {
alert ( "Unable to initialize WebGL" );
return return ;

}
function function webglSupport () {

return return Modernizr . webgl ;

}

Initialization in canvasApp()

In canvasApp() , we still get a context, but this time it is the experimental-webgl context.
Also, just like in our other apps, we still call drawScreen() on an interval to render the can-
vas:

var var theCanvas = document . getElementById ( "canvasOne" );

webGLContext = theCanvas . getContext ( "experimental-webgl" );

setInterval ( drawScreen , 33 );

However, there is additional code in canvasApp() required to set up the application to rotate
the cube. A couple of the most important initialization steps are the calls to initShaders()
and initBuffers() :

initShaders ();
initBuffers ();