Chap7/render3.html

<!DOCTYPE html>
<html>

<script id="vertex-shader1" type="x-shader/x-vertex">

attribute  vec4 vPosition;

void main() 
{
    gl_Position = vPosition;
} 
</script>

<script id="vertex-shader2" type="x-shader/x-vertex">

attribute vec4 vPosition;
attribute vec2 vTexCoord;

varying vec2 fTexCoord;

void main()
{

gl_Position = vPosition;
fTexCoord = vTexCoord;

}
</script>

<script id="fragment-shader1" type="x-shader/x-fragment">

precision mediump float;

void
main()
{
    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);

}
</script>
<script id="fragment-shader2" type="x-shader/x-fragment">

precision mediump float;

varying  vec2 fTexCoord;

uniform sampler2D texture;

void main() 
{ 
    float s = 4.0;
    float d = 1.0/1024.0;
    float x = fTexCoord.x;
    float y = fTexCoord.y;
    gl_FragColor = (texture2D( texture, vec2(x+d, y))
                   +texture2D( texture, vec2(x, y+d))
                   +texture2D( texture, vec2(x-d, y))
                   +texture2D( texture, vec2(x, y-d)))/s;
                 
} 

</script>


<script type="text/javascript" src="../Common/webgl-utils.js"></script>
<script type="text/javascript" src="../Common/initShaders.js"></script>
<script type="text/javascript" src="../Common/MV.js"></script>
<script type="text/javascript" src="render3.js"></script>

<body>
<canvas id="gl-canvas" width="1024" height="1024">
Oops ... your browser doesn't support the HTML5 canvas element
</canvas>
</body>
</html>