Add ToT WebGL conformance tests : part 9

conformance/ogles/GL/atan/atan_float_frag_xvaryyvary_ref.frag

Index: conformance/ogles/GL/atan/atan_float_frag_xvaryyvary_ref.frag
===================================================================
--- conformance/ogles/GL/atan/atan_float_frag_xvaryyvary_ref.frag	(revision 0)
+++ conformance/ogles/GL/atan/atan_float_frag_xvaryyvary_ref.frag	(working copy)
@@ -0,0 +1,88 @@
+
+/*
+** 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.
+*/
+
+
+#ifdef GL_ES
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+#endif
+varying vec4 color;
+
+void main (void)
+{
+	const float M_PI = 3.14159265358979323846;
+	float x = 2.0 * (color.g - 0.5);
+	float y = 2.0 * (color.b - 0.5);
+	float atan_c = 0.0;
+	float scale = 1.0;
+	float sign = 1.0;
+	vec4 result = vec4(0.0, 0.0, 0.0, 1.0);
+	const float epsilon = 1.0e-4;
+	
+	// Avoid evaluating atan(0, x) for x < epsilon because it's implementation-dependent
+	if(x > epsilon || abs(y) > epsilon)
+	{
+		if(x < 0.0 ^^ y < 0.0)
+		{
+			sign = -1.0;
+		}
+
+		if(abs(y) <= abs(x))
+		{
+			float c = abs(y / x);
+
+			// Taylors series expansion for atan
+			for(int i = 1; i < 12; i += 2)
+			{
+				atan_c += scale * pow(c, float(i)) / float(i);
+				scale *= -1.0;
+			}
+
+			result = vec4(sign * atan_c / (2.0 * M_PI) + 0.5, 0.0, 0.0, 1.0);
+		}
+		else
+		{
+			float c = abs(x / y);
+
+			// Taylors series expansion for atan
+			for(int i = 1; i < 12; i += 2)
+			{
+				atan_c += scale * pow(c, float(i)) / float(i);
+				scale *= -1.0;
+			}
+
+			result = vec4(sign * (M_PI / 2.0 - atan_c) / (2.0 * M_PI) + 0.5, 0.0, 0.0, 1.0);
+		}
+
+		if(x < 0.0)
+			if(y < 0.0) result.r -= 0.5;
+			else if(y > 0.0) result.r += 0.5;
+	}
+	
+	gl_FragColor = result;
+}
+