Add ToT WebGL conformance tests : part 9

conformance/ogles/GL/atan/atan_vec2_vert_xvaryyvary.vert

Index: conformance/ogles/GL/atan/atan_vec2_vert_xvaryyvary.vert
===================================================================
--- conformance/ogles/GL/atan/atan_vec2_vert_xvaryyvary.vert	(revision 0)
+++ conformance/ogles/GL/atan/atan_vec2_vert_xvaryyvary.vert	(working copy)
@@ -0,0 +1,51 @@
+
+/*
+** 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_Vertex;
+attribute vec4 gtf_Color;
+uniform mat4 gtf_ModelViewProjectionMatrix;
+varying vec4 color;
+
+void main (void)
+{
+	const float M_PI = 3.14159265358979323846;
+	vec2 x = 2.0 * (gtf_Color.gg - 0.5);
+	vec2 y = 2.0 * (gtf_Color.bb - 0.5);
+	const float epsilon = 1.0e-4;
+	color = vec4(0.0, 0.0, 0.0, 1.0);
+	
+	// Avoid evaluating atan(0, x) for x < epsilon because it's implementation-dependent
+	if(x[0] > epsilon || abs(y[0]) > epsilon)
+	{
+		color[0] = atan(y[0], x[0]) / (2.0 * M_PI) + 0.5;
+	}
+
+	if(x[1] > epsilon || abs(y[1]) > epsilon)
+	{
+		color[1] = atan(y[1], x[1]) / (2.0 * M_PI) + 0.5;
+	}
+	
+	gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
+}