<html>
<head>
<meta charset="utf8">
<title>WebGL preserveDrawingbuffer=true</title>
<link type="text/css" href="../../resources/webgl-tutorials.css" rel="stylesheet" />
<style>
canvas { border: 1px solid black; }
</style>
</head>
<body>
<p><canvas id="c" width="400" height="300"></canvas></p>
</body>
<!-- vertex shader -->
<script id="vertex-shader-2d" type="x-shader/x-vertex">
attribute vec4 a_position;
attribute vec4 a_color;
uniform mat4 u_worldViewProjection;
varying vec4 v_color;
void main() {
   gl_Po