LayoutTests/webgl/2.0.0/resources/webgl_test_files/conformance/ogles/GL/log/log_vec2_vert_xvary01_ref.vert

/*
** Copyright (c) 2012 The Khronos Group Inc.
**
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** "Materials"), to deal in the Materials without restriction, including
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** 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
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*/


attribute vec4 gtf_Color;
attribute vec4 gtf_Vertex;
uniform mat4 gtf_ModelViewProjectionMatrix;
varying vec4 color;

void main (void)
{
	vec2 x = (gtf_Color.rg + 0.01) / 1.01;
	vec2 y = vec2(0.0);
	vec2 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));
	vec2 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, 1.0);
	gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
}