CODEWITHSUNDEEP
javascripthtml5-canvaswebgl
Nico
Nico

Reputation: 195

Webgl context is null if 2d context is called on canvas

I wrote the following JS code:

var main=function() {
  var CANVAS=document.getElementById("your_canvas");
  CANVAS.width=window.innerWidth;
  CANVAS.height=window.innerHeight;
  //ctx=CANVAS.getContext("2d");
  //ctx.fillText("Hello World",10,50);

  /*========================= GET WEBGL CONTEXT ========================= */
  var GL;
  try {
    GL = CANVAS.getContext("experimental-webgl", {antialias: true});
  } catch (e) {
    alert("You are not webgl compatible :(") ;
    return false;
  }

  var CUBE_VERTEX= GL.createBuffer ();

};

If I uncomment the two commented lines, then the webgl context is NULL. Is this expected ? It's not possible to use 2D context and webgl context on the same canvas ?

Upvotes: 0

Views: 1862

Answers (1)

Bob Wood
Bob Wood

Reputation: 81

This is expected, as webgl basically is a wrapper around opengl, primarily used for accelerated 3D rendering. getContext("experimental-webgl") is essentially telling the browser, that the defined canvas is to be used exclusively by OpenGL/WebGL. (It is possible to use OpenGL/WebGL for 2D, but unless you know what you are doing, you're giving yourself a hard time in doing so.) If you are trying to render text on top of a 3D view, you will have to overlay two different DOM-elements (or render the text with the correct projection in 3D, again hard time-territory).

Upvotes: 2

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