Add some external dependencies.

extern/EtcLib/Etc/EtcColor.h

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2015 The Etc2Comp Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <math.h>
+
+namespace Etc
+{
+
+	inline float LogToLinear(float a_fLog)
+	{
+		static const float ALPHA = 0.055f;
+		static const float ONE_PLUS_ALPHA = 1.0f + ALPHA;
+
+		if (a_fLog <= 0.04045f)
+		{
+			return a_fLog / 12.92f;
+		}
+		else
+		{
+			return powf((a_fLog + ALPHA) / ONE_PLUS_ALPHA, 2.4f);
+		}
+	}
+
+	inline float LinearToLog(float &a_fLinear)
+	{
+		static const float ALPHA = 0.055f;
+		static const float ONE_PLUS_ALPHA = 1.0f + ALPHA;
+
+		if (a_fLinear <= 0.0031308f)
+		{
+			return 12.92f * a_fLinear;
+		}
+		else
+		{
+			return ONE_PLUS_ALPHA * powf(a_fLinear, (1.0f/2.4f)) - ALPHA;
+		}
+	}
+
+	class ColorR8G8B8A8
+	{
+	public:
+
+		unsigned char ucR;
+		unsigned char ucG;
+		unsigned char ucB;
+		unsigned char ucA;
+
+	};
+}