Add `etcpak` library for faster ETC/ETC2/S3TC imports.

- `etc` module was renamed to `etcpak` and modified to use the new library.
- PKM importer is removed in the process, it's obsolete.
- Old library `etc2comp` is removed.
- S3TC compression no longer done via `squish` (but decompression still is).
- Slight modifications to etcpak sources for MinGW compatibility,
  to fix LLVM `-Wc++11-narrowing` errors, and to allow using vendored or
  system libpng.

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

1 files changed, 0 insertions, 64 deletions

diff --git a/thirdparty/etc2comp/EtcMath.cpp b/thirdparty/etc2comp/EtcMath.cpp
deleted file mode 100644
index 096d5f7ab9..0000000000
--- a/thirdparty/etc2comp/EtcMath.cpp
+++ /dev/null
@@ -1,64 +0,0 @@
-/*
- * 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.
- */
-
-#include "EtcConfig.h"
-#include "EtcMath.h"
-
-namespace Etc
-{
-
-	// ----------------------------------------------------------------------------------------------------
-	// calculate the line that best fits the set of XY points contained in a_afX[] and a_afY[]
-	// use a_fSlope and a_fOffset to define that line
-	//
-	bool Regression(float a_afX[], float a_afY[], unsigned int a_Points,
-					float *a_fSlope, float *a_fOffset)
-	{
-		float fPoints = (float)a_Points;
-
-		float fSumX = 0.0f;
-		float fSumY = 0.0f;
-		float fSumXY = 0.0f;
-		float fSumX2 = 0.0f;
-
-		for (unsigned int uiPoint = 0; uiPoint < a_Points; uiPoint++)
-		{
-			fSumX += a_afX[uiPoint];
-			fSumY += a_afY[uiPoint];
-			fSumXY += a_afX[uiPoint] * a_afY[uiPoint];
-			fSumX2 += a_afX[uiPoint] * a_afX[uiPoint];
-		}
-
-		float fDivisor = fPoints*fSumX2 - fSumX*fSumX;
-
-		// if vertical line
-		if (fDivisor == 0.0f)
-		{
-			*a_fSlope = 0.0f;
-			*a_fOffset = 0.0f;
-			return true;
-		}
-
-		*a_fSlope = (fPoints*fSumXY - fSumX*fSumY) / fDivisor;
-		*a_fOffset = (fSumY - (*a_fSlope)*fSumX) / fPoints;
-
-		return false;
-	}
-
-	// ----------------------------------------------------------------------------------------------------
-	//
-
-} // namespace Etc