text: 
  /*
  ** Copyright (c) 2012 The Khronos Group Inc.
  **
  ** Permission is hereby granted, free of charge, to any person obtaining a
  ** copy of this software and/or associated documentation files (the
  ** "Materials"), to deal in the Materials without restriction, including
  ** without limitation the rights to use, copy, modify, merge, publish,
  ** distribute, sublicense, and/or sell copies of the Materials, and to
  ** permit persons to whom the Materials are furnished to do so, subject to
  ** the following conditions:
  **
  ** The above copyright notice and this permission notice shall be included
  ** in all copies or substantial portions of the Materials.
  **
  ** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  ** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  ** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  ** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  ** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  ** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
  */
  
  
  attribute vec4 gtf_Color;
  attribute vec4 gtf_Vertex;
  uniform mat4 gtf_ModelViewProjectionMatrix;
  varying vec4 color;
  
  void main (void)
  {
  	float x = (gtf_Color.r + 0.01) / 1.01;
  	float y = 0.0;
  	float z;   // x-1 / x+1
  	int n = 50;
  
  	// ln(x) = 2[x-1 + 1 (x-1)^3 + 1 (x-1)^5 + ...] for x > 0
  	//          [x+1   3 (x+1)     5 (x+1)        ]
  	// Note: z will always be negative between 0.01 and 1.0 and
  	// so will y since it is raised to an odd power, and the shader spec
  	// does not support pow(-x, y) where y is not a compile time constant
  	z = abs((x - 1.0) / (x + 1.0));
  	float p = z;
  	for(int i = 1; i <= 101; i += 2)
  	{
  		y += p / float(i);
  		p *= z * z;
  	}
  	y *= -2.0;
  
  	color = vec4(y / -4.61, 0.0, 0.0, 1.0);
  	gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
  }
  