Add ToT WebGL conformance tests : part 9

conformance/ogles/GL/log2/log2_float_frag_xvary01_ref.frag

+
+/*
+** 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
+precision mediump float;
+#endif
+varying vec4 color;
+const float ln2 = 0.69314718055994530941723212145818;
+
+
+
+void main (void)
+{
+        float x = (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 / ln2;
+
+        gl_FragColor = vec4(y / -8.0, 0.0, 0.0, 1.0);
+}