Add some external dependencies.

extern/EtcLib/Etc/Etc.h

@@ -0,0 +1,47 @@
+/*
+ * 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 "EtcConfig.h"
+#include "EtcImage.h"
+#include "EtcColor.h"
+#include "EtcErrorMetric.h"
+
+#define ETCCOMP_MIN_EFFORT_LEVEL (0.0f)
+#define ETCCOMP_DEFAULT_EFFORT_LEVEL (40.0f)
+#define ETCCOMP_MAX_EFFORT_LEVEL (100.0f)
+
+namespace Etc
+{
+	class Block4x4EncodingBits;
+
+	// C-style inteface to the encoder
+	void Encode(float *a_pafSourceRGBA,
+				unsigned int a_uiSourceWidth,
+				unsigned int a_uiSourceHeight,
+				Image::Format a_format,
+				ErrorMetric a_eErrMetric,
+				float a_fEffort,
+				unsigned int a_uiJobs,
+				unsigned int a_uimaxJobs,
+				unsigned char **a_ppaucEncodingBits,
+				unsigned int *a_puiEncodingBitsBytes,
+				unsigned int *a_puiExtendedWidth,
+				unsigned int *a_puiExtendedHeight,
+				int *a_piEncodingTime_ms, bool a_bVerboseOutput = false);
+
+}