Add ETC1/ETC2 compression support though etc2comp.

Remove rg-etc1 code. Also updated travis to use ubuntu 14.04.

Fixes #8457.

1 files changed, 1819 insertions, 0 deletions

diff --git a/thirdparty/etc2comp/EtcBlock4x4Encoding_RGB8A1.cpp b/thirdparty/etc2comp/EtcBlock4x4Encoding_RGB8A1.cpp
new file mode 100644
index 0000000000..ba2b42fb05
--- /dev/null
+++ b/thirdparty/etc2comp/EtcBlock4x4Encoding_RGB8A1.cpp
@@ -0,0 +1,1819 @@
+/*
+ * 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.
+ */
+
+/*
+EtcBlock4x4Encoding_RGB8A1.cpp contains:
+	Block4x4Encoding_RGB8A1
+	Block4x4Encoding_RGB8A1_Opaque
+	Block4x4Encoding_RGB8A1_Transparent
+
+These encoders are used when targetting file format RGB8A1.
+
+Block4x4Encoding_RGB8A1_Opaque is used when all pixels in the 4x4 block are opaque
+Block4x4Encoding_RGB8A1_Transparent is used when all pixels in the 4x4 block are transparent
+Block4x4Encoding_RGB8A1 is used when there is a mixture of alphas in the 4x4 block
+
+*/
+
+#include "EtcConfig.h"
+#include "EtcBlock4x4Encoding_RGB8A1.h"
+
+#include "EtcBlock4x4.h"
+#include "EtcBlock4x4EncodingBits.h"
+#include "EtcBlock4x4Encoding_RGB8.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+namespace Etc
+{
+	
+	// ####################################################################################################
+	// Block4x4Encoding_RGB8A1
+	// ####################################################################################################
+
+	float Block4x4Encoding_RGB8A1::s_aafCwOpaqueUnsetTable[CW_RANGES][SELECTORS] =
+	{
+		{ 0.0f / 255.0f, 8.0f / 255.0f, 0.0f / 255.0f, -8.0f / 255.0f },
+		{ 0.0f / 255.0f, 17.0f / 255.0f, 0.0f / 255.0f, -17.0f / 255.0f },
+		{ 0.0f / 255.0f, 29.0f / 255.0f, 0.0f / 255.0f, -29.0f / 255.0f },
+		{ 0.0f / 255.0f, 42.0f / 255.0f, 0.0f / 255.0f, -42.0f / 255.0f },
+		{ 0.0f / 255.0f, 60.0f / 255.0f, 0.0f / 255.0f, -60.0f / 255.0f },
+		{ 0.0f / 255.0f, 80.0f / 255.0f, 0.0f / 255.0f, -80.0f / 255.0f },
+		{ 0.0f / 255.0f, 106.0f / 255.0f, 0.0f / 255.0f, -106.0f / 255.0f },
+		{ 0.0f / 255.0f, 183.0f / 255.0f, 0.0f / 255.0f, -183.0f / 255.0f }
+	};
+
+	// ----------------------------------------------------------------------------------------------------
+	//
+	Block4x4Encoding_RGB8A1::Block4x4Encoding_RGB8A1(void)
+	{
+		m_pencodingbitsRGB8 = nullptr;
+		m_boolOpaque = false;
+		m_boolTransparent = false;
+		m_boolPunchThroughPixels = true;
+
+	}
+	Block4x4Encoding_RGB8A1::~Block4x4Encoding_RGB8A1(void) {}
+	// ----------------------------------------------------------------------------------------------------
+	// initialization prior to encoding
+	// a_pblockParent points to the block associated with this encoding
+	// a_errormetric is used to choose the best encoding
+	// a_pafrgbaSource points to a 4x4 block subset of the source image
+	// a_paucEncodingBits points to the final encoding bits
+	//
+	void Block4x4Encoding_RGB8A1::InitFromSource(Block4x4 *a_pblockParent,
+													ColorFloatRGBA *a_pafrgbaSource,
+													unsigned char *a_paucEncodingBits,
+													ErrorMetric a_errormetric)
+	{
+
+		Block4x4Encoding_RGB8::InitFromSource(a_pblockParent,
+			a_pafrgbaSource,
+			a_paucEncodingBits,
+			a_errormetric);
+
+		m_boolOpaque = a_pblockParent->GetSourceAlphaMix() == Block4x4::SourceAlphaMix::OPAQUE;
+		m_boolTransparent = a_pblockParent->GetSourceAlphaMix() == Block4x4::SourceAlphaMix::TRANSPARENT;
+		m_boolPunchThroughPixels = a_pblockParent->HasPunchThroughPixels();
+
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			if (m_pafrgbaSource[uiPixel].fA >= 0.5f)
+			{
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+			}
+			else
+			{
+				m_afDecodedAlphas[uiPixel] = 0.0f;
+			}
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// initialization from the encoding bits of a previous encoding
+	// a_pblockParent points to the block associated with this encoding
+	// a_errormetric is used to choose the best encoding
+	// a_pafrgbaSource points to a 4x4 block subset of the source image
+	// a_paucEncodingBits points to the final encoding bits of a previous encoding
+	//
+	void Block4x4Encoding_RGB8A1::InitFromEncodingBits(Block4x4 *a_pblockParent,
+														unsigned char *a_paucEncodingBits,
+														ColorFloatRGBA *a_pafrgbaSource,
+														ErrorMetric a_errormetric)
+	{
+
+
+		InitFromEncodingBits_ETC1(a_pblockParent,
+			a_paucEncodingBits,
+			a_pafrgbaSource,
+			a_errormetric);
+
+		m_pencodingbitsRGB8 = (Block4x4EncodingBits_RGB8 *)a_paucEncodingBits;
+
+		// detect if there is a T, H or Planar mode present
+		int iRed1 = m_pencodingbitsRGB8->differential.red1;
+		int iDRed2 = m_pencodingbitsRGB8->differential.dred2;
+		int iRed2 = iRed1 + iDRed2;
+
+		int iGreen1 = m_pencodingbitsRGB8->differential.green1;
+		int iDGreen2 = m_pencodingbitsRGB8->differential.dgreen2;
+		int iGreen2 = iGreen1 + iDGreen2;
+
+		int iBlue1 = m_pencodingbitsRGB8->differential.blue1;
+		int iDBlue2 = m_pencodingbitsRGB8->differential.dblue2;
+		int iBlue2 = iBlue1 + iDBlue2;
+
+		if (iRed2 < 0 || iRed2 > 31)
+		{
+			InitFromEncodingBits_T();
+		}
+		else if (iGreen2 < 0 || iGreen2 > 31)
+		{
+			InitFromEncodingBits_H();
+		}
+		else if (iBlue2 < 0 || iBlue2 > 31)
+		{
+			Block4x4Encoding_RGB8::InitFromEncodingBits_Planar();
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// initialization from the encoding bits of a previous encoding assuming the encoding is an ETC1 mode.
+	// if it isn't an ETC1 mode, this will be overwritten later
+	//
+	void Block4x4Encoding_RGB8A1::InitFromEncodingBits_ETC1(Block4x4 *a_pblockParent,
+		unsigned char *a_paucEncodingBits,
+		ColorFloatRGBA *a_pafrgbaSource,
+		ErrorMetric a_errormetric)
+	{
+		Block4x4Encoding::Init(a_pblockParent, a_pafrgbaSource,
+			a_errormetric);
+
+		m_pencodingbitsRGB8 = (Block4x4EncodingBits_RGB8 *)a_paucEncodingBits;
+
+		m_mode = MODE_ETC1;
+		m_boolDiff = true;
+		m_boolFlip = m_pencodingbitsRGB8->differential.flip;
+		m_boolOpaque = m_pencodingbitsRGB8->differential.diff;
+
+		int iR2 = m_pencodingbitsRGB8->differential.red1 + m_pencodingbitsRGB8->differential.dred2;
+		if (iR2 < 0)
+		{
+			iR2 = 0;
+		}
+		else if (iR2 > 31)
+		{
+			iR2 = 31;
+		}
+
+		int iG2 = m_pencodingbitsRGB8->differential.green1 + m_pencodingbitsRGB8->differential.dgreen2;
+		if (iG2 < 0)
+		{
+			iG2 = 0;
+		}
+		else if (iG2 > 31)
+		{
+			iG2 = 31;
+		}
+
+		int iB2 = m_pencodingbitsRGB8->differential.blue1 + m_pencodingbitsRGB8->differential.dblue2;
+		if (iB2 < 0)
+		{
+			iB2 = 0;
+		}
+		else if (iB2 > 31)
+		{
+			iB2 = 31;
+		}
+
+		m_frgbaColor1 = ColorFloatRGBA::ConvertFromRGB5(m_pencodingbitsRGB8->differential.red1, m_pencodingbitsRGB8->differential.green1, m_pencodingbitsRGB8->differential.blue1);
+		m_frgbaColor2 = ColorFloatRGBA::ConvertFromRGB5((unsigned char)iR2, (unsigned char)iG2, (unsigned char)iB2);
+
+		m_uiCW1 = m_pencodingbitsRGB8->differential.cw1;
+		m_uiCW2 = m_pencodingbitsRGB8->differential.cw2;
+
+		Block4x4Encoding_ETC1::InitFromEncodingBits_Selectors();
+
+		Decode_ETC1();
+
+		CalcBlockError();
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// initialization from the encoding bits of a previous encoding if T mode is detected
+	//
+	void Block4x4Encoding_RGB8A1::InitFromEncodingBits_T(void)
+	{
+		m_mode = MODE_T;
+
+		unsigned char ucRed1 = (unsigned char)((m_pencodingbitsRGB8->t.red1a << 2) +
+								m_pencodingbitsRGB8->t.red1b);
+		unsigned char ucGreen1 = m_pencodingbitsRGB8->t.green1;
+		unsigned char ucBlue1 = m_pencodingbitsRGB8->t.blue1;
+
+		unsigned char ucRed2 = m_pencodingbitsRGB8->t.red2;
+		unsigned char ucGreen2 = m_pencodingbitsRGB8->t.green2;
+		unsigned char ucBlue2 = m_pencodingbitsRGB8->t.blue2;
+
+		m_frgbaColor1 = ColorFloatRGBA::ConvertFromRGB4(ucRed1, ucGreen1, ucBlue1);
+		m_frgbaColor2 = ColorFloatRGBA::ConvertFromRGB4(ucRed2, ucGreen2, ucBlue2);
+
+		m_uiCW1 = (m_pencodingbitsRGB8->t.da << 1) + m_pencodingbitsRGB8->t.db;
+
+		Block4x4Encoding_ETC1::InitFromEncodingBits_Selectors();
+
+		DecodePixels_T();
+
+		CalcBlockError();
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// initialization from the encoding bits of a previous encoding if H mode is detected
+	//
+	void Block4x4Encoding_RGB8A1::InitFromEncodingBits_H(void)
+	{
+		m_mode = MODE_H;
+
+		unsigned char ucRed1 = m_pencodingbitsRGB8->h.red1;
+		unsigned char ucGreen1 = (unsigned char)((m_pencodingbitsRGB8->h.green1a << 1) +
+									m_pencodingbitsRGB8->h.green1b);
+		unsigned char ucBlue1 = (unsigned char)((m_pencodingbitsRGB8->h.blue1a << 3) +
+								(m_pencodingbitsRGB8->h.blue1b << 1) +
+								m_pencodingbitsRGB8->h.blue1c);
+
+		unsigned char ucRed2 = m_pencodingbitsRGB8->h.red2;
+		unsigned char ucGreen2 = (unsigned char)((m_pencodingbitsRGB8->h.green2a << 1) +
+									m_pencodingbitsRGB8->h.green2b);
+		unsigned char ucBlue2 = m_pencodingbitsRGB8->h.blue2;
+
+		m_frgbaColor1 = ColorFloatRGBA::ConvertFromRGB4(ucRed1, ucGreen1, ucBlue1);
+		m_frgbaColor2 = ColorFloatRGBA::ConvertFromRGB4(ucRed2, ucGreen2, ucBlue2);
+
+		// used to determine the LSB of the CW
+		unsigned int uiRGB1 = (unsigned int)(((int)ucRed1 << 16) + ((int)ucGreen1 << 8) + (int)ucBlue1);
+		unsigned int uiRGB2 = (unsigned int)(((int)ucRed2 << 16) + ((int)ucGreen2 << 8) + (int)ucBlue2);
+
+		m_uiCW1 = (m_pencodingbitsRGB8->h.da << 2) + (m_pencodingbitsRGB8->h.db << 1);
+		if (uiRGB1 >= uiRGB2)
+		{
+			m_uiCW1++;
+		}
+
+		Block4x4Encoding_ETC1::InitFromEncodingBits_Selectors();
+
+		DecodePixels_H();
+
+		CalcBlockError();
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// for ETC1 modes, set the decoded colors and decoded alpha based on the encoding state
+	//
+	void Block4x4Encoding_RGB8A1::Decode_ETC1(void)
+	{
+
+		const unsigned int *pauiPixelOrder = m_boolFlip ? s_auiPixelOrderFlip1 : s_auiPixelOrderFlip0;
+
+		for (unsigned int uiPixelOrder = 0; uiPixelOrder < PIXELS; uiPixelOrder++)
+		{
+			ColorFloatRGBA *pfrgbaCenter = uiPixelOrder < 8 ? &m_frgbaColor1 : &m_frgbaColor2;
+			unsigned int uiCW = uiPixelOrder < 8 ? m_uiCW1 : m_uiCW2;
+
+			unsigned int uiPixel = pauiPixelOrder[uiPixelOrder];
+
+			float fDelta;
+			if (m_boolOpaque)
+				fDelta = Block4x4Encoding_ETC1::s_aafCwTable[uiCW][m_auiSelectors[uiPixel]];
+			else 
+				fDelta = s_aafCwOpaqueUnsetTable[uiCW][m_auiSelectors[uiPixel]];
+
+			if (m_boolOpaque == false && m_auiSelectors[uiPixel] == TRANSPARENT_SELECTOR)
+			{
+				m_afrgbaDecodedColors[uiPixel] = ColorFloatRGBA();
+				m_afDecodedAlphas[uiPixel] = 0.0f;
+			}
+			else
+			{
+				m_afrgbaDecodedColors[uiPixel] = (*pfrgbaCenter + fDelta).ClampRGB();
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+			}
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// for T mode, set the decoded colors and decoded alpha based on the encoding state
+	//
+	void Block4x4Encoding_RGB8A1::DecodePixels_T(void)
+	{
+
+		float fDistance = s_afTHDistanceTable[m_uiCW1];
+		ColorFloatRGBA frgbaDistance(fDistance, fDistance, fDistance, 0.0f);
+
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			switch (m_auiSelectors[uiPixel])
+			{
+			case 0:
+				m_afrgbaDecodedColors[uiPixel] = m_frgbaColor1;
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+				break;
+
+			case 1:
+				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 + frgbaDistance).ClampRGB();
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+				break;
+
+			case 2:
+				if (m_boolOpaque == false)
+				{
+					m_afrgbaDecodedColors[uiPixel] = ColorFloatRGBA();
+					m_afDecodedAlphas[uiPixel] = 0.0f;
+				}
+				else
+				{
+					m_afrgbaDecodedColors[uiPixel] = m_frgbaColor2;
+					m_afDecodedAlphas[uiPixel] = 1.0f;
+				}
+				break;
+
+			case 3:
+				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 - frgbaDistance).ClampRGB();
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+				break;
+			}
+
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// for H mode, set the decoded colors and decoded alpha based on the encoding state
+	//
+	void Block4x4Encoding_RGB8A1::DecodePixels_H(void)
+	{
+
+		float fDistance = s_afTHDistanceTable[m_uiCW1];
+		ColorFloatRGBA frgbaDistance(fDistance, fDistance, fDistance, 0.0f);
+
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			switch (m_auiSelectors[uiPixel])
+			{
+			case 0:
+				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor1 + frgbaDistance).ClampRGB();
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+				break;
+
+			case 1:
+				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor1 - frgbaDistance).ClampRGB();
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+				break;
+
+			case 2:
+				if (m_boolOpaque == false)
+				{
+					m_afrgbaDecodedColors[uiPixel] = ColorFloatRGBA();
+					m_afDecodedAlphas[uiPixel] = 0.0f;
+				}
+				else
+				{
+					m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 + frgbaDistance).ClampRGB();
+					m_afDecodedAlphas[uiPixel] = 1.0f;
+				}
+				break;
+
+			case 3:
+				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 - frgbaDistance).ClampRGB();
+				m_afDecodedAlphas[uiPixel] = 1.0f;
+				break;
+			}
+
+		}
+
+	}
+
+
+	// ----------------------------------------------------------------------------------------------------
+	// perform a single encoding iteration
+	// replace the encoding if a better encoding was found
+	// subsequent iterations generally take longer for each iteration
+	// set m_boolDone if encoding is perfect or encoding is finished based on a_fEffort
+	//
+	// RGB8A1 can't use individual mode
+	// RGB8A1 with transparent pixels can't use planar mode
+	//
+	void Block4x4Encoding_RGB8A1::PerformIteration(float a_fEffort)
+	{
+		assert(!m_boolOpaque);
+		assert(!m_boolTransparent);
+		assert(!m_boolDone);
+
+		switch (m_uiEncodingIterations)
+		{
+		case 0:
+			PerformFirstIteration();
+			break;
+
+		case 1:
+			TryDifferential(m_boolMostLikelyFlip, 1, 0, 0);
+			break;
+
+		case 2:
+			TryDifferential(!m_boolMostLikelyFlip, 1, 0, 0);
+			if (a_fEffort <= 39.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 3:
+			Block4x4Encoding_RGB8::CalculateBaseColorsForTAndH();
+			TryT(1);
+			TryH(1);
+			if (a_fEffort <= 49.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 4:
+			TryDegenerates1();
+			if (a_fEffort <= 59.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 5:
+			TryDegenerates2();
+			if (a_fEffort <= 69.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 6:
+			TryDegenerates3();
+			if (a_fEffort <= 79.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 7:
+			TryDegenerates4();
+			m_boolDone = true;
+			break;
+
+		default:
+			assert(0);
+			break;
+		}
+
+		m_uiEncodingIterations++;
+
+		SetDoneIfPerfect();
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// find best initial encoding to ensure block has a valid encoding
+	//
+	void Block4x4Encoding_RGB8A1::PerformFirstIteration(void)
+	{
+		Block4x4Encoding_ETC1::CalculateMostLikelyFlip();
+
+		m_fError = FLT_MAX;
+
+		TryDifferential(m_boolMostLikelyFlip, 0, 0, 0);
+		SetDoneIfPerfect();
+		if (m_boolDone)
+		{
+			return;
+		}
+		TryDifferential(!m_boolMostLikelyFlip, 0, 0, 0);
+		SetDoneIfPerfect();
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// mostly copied from ETC1
+	// differences:
+	//		Block4x4Encoding_RGB8A1 encodingTry = *this;
+	//
+	void Block4x4Encoding_RGB8A1::TryDifferential(bool a_boolFlip, unsigned int a_uiRadius, 
+													int a_iGrayOffset1, int a_iGrayOffset2)
+	{
+
+		ColorFloatRGBA frgbaColor1;
+		ColorFloatRGBA frgbaColor2;
+
+		const unsigned int *pauiPixelMapping1;
+		const unsigned int *pauiPixelMapping2;
+
+		if (a_boolFlip)
+		{
+			frgbaColor1 = m_frgbaSourceAverageTop;
+			frgbaColor2 = m_frgbaSourceAverageBottom;
+
+			pauiPixelMapping1 = s_auiTopPixelMapping;
+			pauiPixelMapping2 = s_auiBottomPixelMapping;
+		}
+		else
+		{
+			frgbaColor1 = m_frgbaSourceAverageLeft;
+			frgbaColor2 = m_frgbaSourceAverageRight;
+
+			pauiPixelMapping1 = s_auiLeftPixelMapping;
+			pauiPixelMapping2 = s_auiRightPixelMapping;
+		}
+
+		DifferentialTrys trys(frgbaColor1, frgbaColor2, pauiPixelMapping1, pauiPixelMapping2, 
+								a_uiRadius, a_iGrayOffset1, a_iGrayOffset2);
+
+		Block4x4Encoding_RGB8A1 encodingTry = *this;
+		encodingTry.m_boolFlip = a_boolFlip;
+
+		encodingTry.TryDifferentialHalf(&trys.m_half1);
+		encodingTry.TryDifferentialHalf(&trys.m_half2);
+
+		// find best halves that are within differential range
+		DifferentialTrys::Try *ptryBest1 = nullptr;
+		DifferentialTrys::Try *ptryBest2 = nullptr;
+		encodingTry.m_fError = FLT_MAX;
+
+		// see if the best of each half are in differential range
+		int iDRed = trys.m_half2.m_ptryBest->m_iRed - trys.m_half1.m_ptryBest->m_iRed;
+		int iDGreen = trys.m_half2.m_ptryBest->m_iGreen - trys.m_half1.m_ptryBest->m_iGreen;
+		int iDBlue = trys.m_half2.m_ptryBest->m_iBlue - trys.m_half1.m_ptryBest->m_iBlue;
+		if (iDRed >= -4 && iDRed <= 3 && iDGreen >= -4 && iDGreen <= 3 && iDBlue >= -4 && iDBlue <= 3)
+		{
+			ptryBest1 = trys.m_half1.m_ptryBest;
+			ptryBest2 = trys.m_half2.m_ptryBest;
+			encodingTry.m_fError = trys.m_half1.m_ptryBest->m_fError + trys.m_half2.m_ptryBest->m_fError;
+		}
+		else
+		{
+			// else, find the next best halves that are in differential range
+			for (DifferentialTrys::Try *ptry1 = &trys.m_half1.m_atry[0];
+			ptry1 < &trys.m_half1.m_atry[trys.m_half1.m_uiTrys];
+				ptry1++)
+			{
+				for (DifferentialTrys::Try *ptry2 = &trys.m_half2.m_atry[0];
+				ptry2 < &trys.m_half2.m_atry[trys.m_half2.m_uiTrys];
+					ptry2++)
+				{
+					iDRed = ptry2->m_iRed - ptry1->m_iRed;
+					bool boolValidRedDelta = iDRed <= 3 && iDRed >= -4;
+					iDGreen = ptry2->m_iGreen - ptry1->m_iGreen;
+					bool boolValidGreenDelta = iDGreen <= 3 && iDGreen >= -4;
+					iDBlue = ptry2->m_iBlue - ptry1->m_iBlue;
+					bool boolValidBlueDelta = iDBlue <= 3 && iDBlue >= -4;
+
+					if (boolValidRedDelta && boolValidGreenDelta && boolValidBlueDelta)
+					{
+						float fError = ptry1->m_fError + ptry2->m_fError;
+
+						if (fError < encodingTry.m_fError)
+						{
+							encodingTry.m_fError = fError;
+
+							ptryBest1 = ptry1;
+							ptryBest2 = ptry2;
+						}
+					}
+
+				}
+			}
+			assert(encodingTry.m_fError < FLT_MAX);
+			assert(ptryBest1 != nullptr);
+			assert(ptryBest2 != nullptr);
+		}
+
+		if (encodingTry.m_fError < m_fError)
+		{
+			m_mode = MODE_ETC1;
+			m_boolDiff = true;
+			m_boolFlip = encodingTry.m_boolFlip;
+			m_frgbaColor1 = ColorFloatRGBA::ConvertFromRGB5((unsigned char)ptryBest1->m_iRed, (unsigned char)ptryBest1->m_iGreen, (unsigned char)ptryBest1->m_iBlue);
+			m_frgbaColor2 = ColorFloatRGBA::ConvertFromRGB5((unsigned char)ptryBest2->m_iRed, (unsigned char)ptryBest2->m_iGreen, (unsigned char)ptryBest2->m_iBlue);
+			m_uiCW1 = ptryBest1->m_uiCW;
+			m_uiCW2 = ptryBest2->m_uiCW;
+
+			m_fError = 0.0f;
+			for (unsigned int uiPixelOrder = 0; uiPixelOrder < PIXELS / 2; uiPixelOrder++)
+			{
+				unsigned int uiPixel1 = pauiPixelMapping1[uiPixelOrder];
+				unsigned int uiPixel2 = pauiPixelMapping2[uiPixelOrder];
+
+				unsigned int uiSelector1 = ptryBest1->m_auiSelectors[uiPixelOrder];
+				unsigned int uiSelector2 = ptryBest2->m_auiSelectors[uiPixelOrder];
+
+				m_auiSelectors[uiPixel1] = uiSelector1;
+				m_auiSelectors[uiPixel2] = ptryBest2->m_auiSelectors[uiPixelOrder];
+
+				if (uiSelector1 == TRANSPARENT_SELECTOR)
+				{
+					m_afrgbaDecodedColors[uiPixel1] = ColorFloatRGBA();
+					m_afDecodedAlphas[uiPixel1] = 0.0f;
+				}
+				else
+				{
+					float fDeltaRGB1 = s_aafCwOpaqueUnsetTable[m_uiCW1][uiSelector1];
+					m_afrgbaDecodedColors[uiPixel1] = (m_frgbaColor1 + fDeltaRGB1).ClampRGB();
+					m_afDecodedAlphas[uiPixel1] = 1.0f;
+				}
+
+				if (uiSelector2 == TRANSPARENT_SELECTOR)
+				{
+					m_afrgbaDecodedColors[uiPixel2] = ColorFloatRGBA();
+					m_afDecodedAlphas[uiPixel2] = 0.0f;
+				}
+				else
+				{
+					float fDeltaRGB2 = s_aafCwOpaqueUnsetTable[m_uiCW2][uiSelector2];
+					m_afrgbaDecodedColors[uiPixel2] = (m_frgbaColor2 + fDeltaRGB2).ClampRGB();
+					m_afDecodedAlphas[uiPixel2] = 1.0f;
+				}
+
+				float fDeltaA1 = m_afDecodedAlphas[uiPixel1] - m_pafrgbaSource[uiPixel1].fA;
+				m_fError += fDeltaA1 * fDeltaA1;
+				float fDeltaA2 = m_afDecodedAlphas[uiPixel2] - m_pafrgbaSource[uiPixel2].fA;
+				m_fError += fDeltaA2 * fDeltaA2;
+			}
+
+			m_fError1 = ptryBest1->m_fError;
+			m_fError2 = ptryBest2->m_fError;
+			m_boolSeverelyBentDifferentialColors = trys.m_boolSeverelyBentColors;
+			m_fError = m_fError1 + m_fError2;
+
+			// sanity check
+			{
+				int iRed1 = m_frgbaColor1.IntRed(31.0f);
+				int iGreen1 = m_frgbaColor1.IntGreen(31.0f);
+				int iBlue1 = m_frgbaColor1.IntBlue(31.0f);
+
+				int iRed2 = m_frgbaColor2.IntRed(31.0f);
+				int iGreen2 = m_frgbaColor2.IntGreen(31.0f);
+				int iBlue2 = m_frgbaColor2.IntBlue(31.0f);
+
+				iDRed = iRed2 - iRed1;
+				iDGreen = iGreen2 - iGreen1;
+				iDBlue = iBlue2 - iBlue1;
+
+				assert(iDRed >= -4 && iDRed < 4);
+				assert(iDGreen >= -4 && iDGreen < 4);
+				assert(iDBlue >= -4 && iDBlue < 4);
+			}
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// mostly copied from ETC1
+	// differences:
+	//		uses s_aafCwOpaqueUnsetTable
+	//		color for selector set to 0,0,0,0
+	//
+	void Block4x4Encoding_RGB8A1::TryDifferentialHalf(DifferentialTrys::Half *a_phalf)
+	{
+
+		a_phalf->m_ptryBest = nullptr;
+		float fBestTryError = FLT_MAX;
+
+		a_phalf->m_uiTrys = 0;
+		for (int iRed = a_phalf->m_iRed - (int)a_phalf->m_uiRadius;
+		iRed <= a_phalf->m_iRed + (int)a_phalf->m_uiRadius;
+			iRed++)
+		{
+			assert(iRed >= 0 && iRed <= 31);
+
+			for (int iGreen = a_phalf->m_iGreen - (int)a_phalf->m_uiRadius;
+			iGreen <= a_phalf->m_iGreen + (int)a_phalf->m_uiRadius;
+				iGreen++)
+			{
+				assert(iGreen >= 0 && iGreen <= 31);
+
+				for (int iBlue = a_phalf->m_iBlue - (int)a_phalf->m_uiRadius;
+				iBlue <= a_phalf->m_iBlue + (int)a_phalf->m_uiRadius;
+					iBlue++)
+				{
+					assert(iBlue >= 0 && iBlue <= 31);
+
+					DifferentialTrys::Try *ptry = &a_phalf->m_atry[a_phalf->m_uiTrys];
+					assert(ptry < &a_phalf->m_atry[DifferentialTrys::Half::MAX_TRYS]);
+
+					ptry->m_iRed = iRed;
+					ptry->m_iGreen = iGreen;
+					ptry->m_iBlue = iBlue;
+					ptry->m_fError = FLT_MAX;
+					ColorFloatRGBA frgbaColor = ColorFloatRGBA::ConvertFromRGB5((unsigned char)iRed, (unsigned char)iGreen, (unsigned char)iBlue);
+
+					// try each CW
+					for (unsigned int uiCW = 0; uiCW < CW_RANGES; uiCW++)
+					{
+						unsigned int auiPixelSelectors[PIXELS / 2];
+						ColorFloatRGBA	afrgbaDecodedColors[PIXELS / 2];
+						float afPixelErrors[PIXELS / 2] = { FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX,
+							FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX };
+
+						// pre-compute decoded pixels for each selector
+						ColorFloatRGBA afrgbaSelectors[SELECTORS];
+						assert(SELECTORS == 4);
+						afrgbaSelectors[0] = (frgbaColor + s_aafCwOpaqueUnsetTable[uiCW][0]).ClampRGB();
+						afrgbaSelectors[1] = (frgbaColor + s_aafCwOpaqueUnsetTable[uiCW][1]).ClampRGB();
+						afrgbaSelectors[2] = ColorFloatRGBA();
+						afrgbaSelectors[3] = (frgbaColor + s_aafCwOpaqueUnsetTable[uiCW][3]).ClampRGB();
+
+						for (unsigned int uiPixel = 0; uiPixel < 8; uiPixel++)
+						{
+							ColorFloatRGBA *pfrgbaSourcePixel = &m_pafrgbaSource[a_phalf->m_pauiPixelMapping[uiPixel]];
+							ColorFloatRGBA frgbaDecodedPixel;
+
+							for (unsigned int uiSelector = 0; uiSelector < SELECTORS; uiSelector++)
+							{
+								if (pfrgbaSourcePixel->fA < 0.5f)
+								{
+									uiSelector = TRANSPARENT_SELECTOR;
+								}
+								else if (uiSelector == TRANSPARENT_SELECTOR)
+								{
+									continue;
+								}
+
+								frgbaDecodedPixel = afrgbaSelectors[uiSelector];
+
+								float fPixelError;
+								
+								fPixelError = CalcPixelError(frgbaDecodedPixel, m_afDecodedAlphas[a_phalf->m_pauiPixelMapping[uiPixel]],
+																	*pfrgbaSourcePixel);
+
+								if (fPixelError < afPixelErrors[uiPixel])
+								{
+									auiPixelSelectors[uiPixel] = uiSelector;
+									afrgbaDecodedColors[uiPixel] = frgbaDecodedPixel;
+									afPixelErrors[uiPixel] = fPixelError;
+								}
+
+								if (uiSelector == TRANSPARENT_SELECTOR)
+								{
+									break;
+								}
+							}
+						}
+
+						// add up all pixel errors
+						float fCWError = 0.0f;
+						for (unsigned int uiPixel = 0; uiPixel < 8; uiPixel++)
+						{
+							fCWError += afPixelErrors[uiPixel];
+						}
+
+						// if best CW so far
+						if (fCWError < ptry->m_fError)
+						{
+							ptry->m_uiCW = uiCW;
+							for (unsigned int uiPixel = 0; uiPixel < 8; uiPixel++)
+							{
+								ptry->m_auiSelectors[uiPixel] = auiPixelSelectors[uiPixel];
+							}
+							ptry->m_fError = fCWError;
+						}
+
+					}
+
+					if (ptry->m_fError < fBestTryError)
+					{
+						a_phalf->m_ptryBest = ptry;
+						fBestTryError = ptry->m_fError;
+					}
+
+					assert(ptry->m_fError < FLT_MAX);
+
+					a_phalf->m_uiTrys++;
+				}
+			}
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// try encoding in T mode
+	// save this encoding if it improves the error
+	//
+	// since pixels that use base color1 don't use the distance table, color1 and color2 can be twiddled independently
+	// better encoding can be found if TWIDDLE_RADIUS is set to 2, but it will be much slower
+	//
+	void Block4x4Encoding_RGB8A1::TryT(unsigned int a_uiRadius)
+	{
+		Block4x4Encoding_RGB8A1 encodingTry = *this;
+
+		// init "try"
+		{
+			encodingTry.m_mode = MODE_T;
+			encodingTry.m_boolDiff = true;
+			encodingTry.m_boolFlip = false;
+			encodingTry.m_fError = FLT_MAX;
+		}
+
+		int iColor1Red = m_frgbaOriginalColor1_TAndH.IntRed(15.0f);
+		int iColor1Green = m_frgbaOriginalColor1_TAndH.IntGreen(15.0f);
+		int iColor1Blue = m_frgbaOriginalColor1_TAndH.IntBlue(15.0f);
+
+		int iMinRed1 = iColor1Red - (int)a_uiRadius;
+		if (iMinRed1 < 0)
+		{
+			iMinRed1 = 0;
+		}
+		int iMaxRed1 = iColor1Red + (int)a_uiRadius;
+		if (iMaxRed1 > 15)
+		{
+			iMinRed1 = 15;
+		}
+
+		int iMinGreen1 = iColor1Green - (int)a_uiRadius;
+		if (iMinGreen1 < 0)
+		{
+			iMinGreen1 = 0;
+		}
+		int iMaxGreen1 = iColor1Green + (int)a_uiRadius;
+		if (iMaxGreen1 > 15)
+		{
+			iMinGreen1 = 15;
+		}
+
+		int iMinBlue1 = iColor1Blue - (int)a_uiRadius;
+		if (iMinBlue1 < 0)
+		{
+			iMinBlue1 = 0;
+		}
+		int iMaxBlue1 = iColor1Blue + (int)a_uiRadius;
+		if (iMaxBlue1 > 15)
+		{
+			iMinBlue1 = 15;
+		}
+
+		int iColor2Red = m_frgbaOriginalColor2_TAndH.IntRed(15.0f);
+		int iColor2Green = m_frgbaOriginalColor2_TAndH.IntGreen(15.0f);
+		int iColor2Blue = m_frgbaOriginalColor2_TAndH.IntBlue(15.0f);
+
+		int iMinRed2 = iColor2Red - (int)a_uiRadius;
+		if (iMinRed2 < 0)
+		{
+			iMinRed2 = 0;
+		}
+		int iMaxRed2 = iColor2Red + (int)a_uiRadius;
+		if (iMaxRed2 > 15)
+		{
+			iMinRed2 = 15;
+		}
+
+		int iMinGreen2 = iColor2Green - (int)a_uiRadius;
+		if (iMinGreen2 < 0)
+		{
+			iMinGreen2 = 0;
+		}
+		int iMaxGreen2 = iColor2Green + (int)a_uiRadius;
+		if (iMaxGreen2 > 15)
+		{
+			iMinGreen2 = 15;
+		}
+
+		int iMinBlue2 = iColor2Blue - (int)a_uiRadius;
+		if (iMinBlue2 < 0)
+		{
+			iMinBlue2 = 0;
+		}
+		int iMaxBlue2 = iColor2Blue + (int)a_uiRadius;
+		if (iMaxBlue2 > 15)
+		{
+			iMinBlue2 = 15;
+		}
+
+		for (unsigned int uiDistance = 0; uiDistance < TH_DISTANCES; uiDistance++)
+		{
+			encodingTry.m_uiCW1 = uiDistance;
+
+			// twiddle m_frgbaOriginalColor2_TAndH
+			// twiddle color2 first, since it affects 3 selectors, while color1 only affects one selector
+			//
+			for (int iRed2 = iMinRed2; iRed2 <= iMaxRed2; iRed2++)
+			{
+				for (int iGreen2 = iMinGreen2; iGreen2 <= iMaxGreen2; iGreen2++)
+				{
+					for (int iBlue2 = iMinBlue2; iBlue2 <= iMaxBlue2; iBlue2++)
+					{
+						for (unsigned int uiBaseColorSwaps = 0; uiBaseColorSwaps < 2; uiBaseColorSwaps++)
+						{
+							if (uiBaseColorSwaps == 0)
+							{
+								encodingTry.m_frgbaColor1 = m_frgbaOriginalColor1_TAndH;
+								encodingTry.m_frgbaColor2 = ColorFloatRGBA::ConvertFromRGB4((unsigned char)iRed2, (unsigned char)iGreen2, (unsigned char)iBlue2);
+							}
+							else
+							{
+								encodingTry.m_frgbaColor1 = ColorFloatRGBA::ConvertFromRGB4((unsigned char)iRed2, (unsigned char)iGreen2, (unsigned char)iBlue2);
+								encodingTry.m_frgbaColor2 = m_frgbaOriginalColor1_TAndH;
+							}
+
+							encodingTry.TryT_BestSelectorCombination();
+
+							if (encodingTry.m_fError < m_fError)
+							{
+								m_mode = encodingTry.m_mode;
+								m_boolDiff = encodingTry.m_boolDiff;
+								m_boolFlip = encodingTry.m_boolFlip;
+
+								m_frgbaColor1 = encodingTry.m_frgbaColor1;
+								m_frgbaColor2 = encodingTry.m_frgbaColor2;
+								m_uiCW1 = encodingTry.m_uiCW1;
+
+								for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+								{
+									m_auiSelectors[uiPixel] = encodingTry.m_auiSelectors[uiPixel];
+									m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
+								}
+
+								m_fError = encodingTry.m_fError;
+							}
+						}
+					}
+				}
+			}
+
+			// twiddle m_frgbaOriginalColor1_TAndH
+			for (int iRed1 = iMinRed1; iRed1 <= iMaxRed1; iRed1++)
+			{
+				for (int iGreen1 = iMinGreen1; iGreen1 <= iMaxGreen1; iGreen1++)
+				{
+					for (int iBlue1 = iMinBlue1; iBlue1 <= iMaxBlue1; iBlue1++)
+					{
+						for (unsigned int uiBaseColorSwaps = 0; uiBaseColorSwaps < 2; uiBaseColorSwaps++)
+						{
+							if (uiBaseColorSwaps == 0)
+							{
+								encodingTry.m_frgbaColor1 = ColorFloatRGBA::ConvertFromRGB4((unsigned char)iRed1, (unsigned char)iGreen1, (unsigned char)iBlue1);
+								encodingTry.m_frgbaColor2 = m_frgbaOriginalColor2_TAndH;
+							}
+							else
+							{
+								encodingTry.m_frgbaColor1 = m_frgbaOriginalColor2_TAndH;
+								encodingTry.m_frgbaColor2 = ColorFloatRGBA::ConvertFromRGB4((unsigned char)iRed1, (unsigned char)iGreen1, (unsigned char)iBlue1);
+							}
+
+							encodingTry.TryT_BestSelectorCombination();
+
+							if (encodingTry.m_fError < m_fError)
+							{
+								m_mode = encodingTry.m_mode;
+								m_boolDiff = encodingTry.m_boolDiff;
+								m_boolFlip = encodingTry.m_boolFlip;
+
+								m_frgbaColor1 = encodingTry.m_frgbaColor1;
+								m_frgbaColor2 = encodingTry.m_frgbaColor2;
+								m_uiCW1 = encodingTry.m_uiCW1;
+
+								for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+								{
+									m_auiSelectors[uiPixel] = encodingTry.m_auiSelectors[uiPixel];
+									m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
+								}
+
+								m_fError = encodingTry.m_fError;
+							}
+						}
+					}
+				}
+			}
+
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// find best selector combination for TryT
+	// called on an encodingTry
+	//
+	void Block4x4Encoding_RGB8A1::TryT_BestSelectorCombination(void)
+	{
+
+		float fDistance = s_afTHDistanceTable[m_uiCW1];
+
+		unsigned int auiBestPixelSelectors[PIXELS];
+		float afBestPixelErrors[PIXELS] = { FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX,
+			FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX };
+		ColorFloatRGBA	afrgbaBestDecodedPixels[PIXELS];
+		ColorFloatRGBA afrgbaDecodedPixel[SELECTORS];
+
+		assert(SELECTORS == 4);
+		afrgbaDecodedPixel[0] = m_frgbaColor1;
+		afrgbaDecodedPixel[1] = (m_frgbaColor2 + fDistance).ClampRGB();
+		afrgbaDecodedPixel[2] = ColorFloatRGBA();
+		afrgbaDecodedPixel[3] = (m_frgbaColor2 - fDistance).ClampRGB();
+
+		// try each selector
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			unsigned int uiMinSelector = 0;
+			unsigned int uiMaxSelector = SELECTORS - 1;
+
+			if (m_pafrgbaSource[uiPixel].fA < 0.5f)
+			{
+				uiMinSelector = 2;
+				uiMaxSelector = 2;
+			}
+
+			for (unsigned int uiSelector = uiMinSelector; uiSelector <= uiMaxSelector; uiSelector++)
+			{
+				float fPixelError = CalcPixelError(afrgbaDecodedPixel[uiSelector], m_afDecodedAlphas[uiPixel],
+													m_pafrgbaSource[uiPixel]);
+
+				if (fPixelError < afBestPixelErrors[uiPixel])
+				{
+					afBestPixelErrors[uiPixel] = fPixelError;
+					auiBestPixelSelectors[uiPixel] = uiSelector;
+					afrgbaBestDecodedPixels[uiPixel] = afrgbaDecodedPixel[uiSelector];
+				}
+			}
+		}
+		
+
+		// add up all of the pixel errors
+		float fBlockError = 0.0f;
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			fBlockError += afBestPixelErrors[uiPixel];
+		}
+
+		if (fBlockError < m_fError)
+		{
+			m_fError = fBlockError;
+
+			for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+			{
+				m_auiSelectors[uiPixel] = auiBestPixelSelectors[uiPixel];
+				m_afrgbaDecodedColors[uiPixel] = afrgbaBestDecodedPixels[uiPixel];
+			}
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// try encoding in H mode
+	// save this encoding if it improves the error
+	//
+	// since all pixels use the distance table, color1 and color2 can NOT be twiddled independently
+	// TWIDDLE_RADIUS of 2 is WAY too slow
+	//
+	void Block4x4Encoding_RGB8A1::TryH(unsigned int a_uiRadius)
+	{
+		Block4x4Encoding_RGB8A1 encodingTry = *this;
+
+		// init "try"
+		{
+			encodingTry.m_mode = MODE_H;
+			encodingTry.m_boolDiff = true;
+			encodingTry.m_boolFlip = false;
+			encodingTry.m_fError = FLT_MAX;
+		}
+
+		int iColor1Red = m_frgbaOriginalColor1_TAndH.IntRed(15.0f);
+		int iColor1Green = m_frgbaOriginalColor1_TAndH.IntGreen(15.0f);
+		int iColor1Blue = m_frgbaOriginalColor1_TAndH.IntBlue(15.0f);
+
+		int iMinRed1 = iColor1Red - (int)a_uiRadius;
+		if (iMinRed1 < 0)
+		{
+			iMinRed1 = 0;
+		}
+		int iMaxRed1 = iColor1Red + (int)a_uiRadius;
+		if (iMaxRed1 > 15)
+		{
+			iMinRed1 = 15;
+		}
+
+		int iMinGreen1 = iColor1Green - (int)a_uiRadius;
+		if (iMinGreen1 < 0)
+		{
+			iMinGreen1 = 0;
+		}
+		int iMaxGreen1 = iColor1Green + (int)a_uiRadius;
+		if (iMaxGreen1 > 15)
+		{
+			iMinGreen1 = 15;
+		}
+
+		int iMinBlue1 = iColor1Blue - (int)a_uiRadius;
+		if (iMinBlue1 < 0)
+		{
+			iMinBlue1 = 0;
+		}
+		int iMaxBlue1 = iColor1Blue + (int)a_uiRadius;
+		if (iMaxBlue1 > 15)
+		{
+			iMinBlue1 = 15;
+		}
+
+		int iColor2Red = m_frgbaOriginalColor2_TAndH.IntRed(15.0f);
+		int iColor2Green = m_frgbaOriginalColor2_TAndH.IntGreen(15.0f);
+		int iColor2Blue = m_frgbaOriginalColor2_TAndH.IntBlue(15.0f);
+
+		int iMinRed2 = iColor2Red - (int)a_uiRadius;
+		if (iMinRed2 < 0)
+		{
+			iMinRed2 = 0;
+		}
+		int iMaxRed2 = iColor2Red + (int)a_uiRadius;
+		if (iMaxRed2 > 15)
+		{
+			iMinRed2 = 15;
+		}
+
+		int iMinGreen2 = iColor2Green - (int)a_uiRadius;
+		if (iMinGreen2 < 0)
+		{
+			iMinGreen2 = 0;
+		}
+		int iMaxGreen2 = iColor2Green + (int)a_uiRadius;
+		if (iMaxGreen2 > 15)
+		{
+			iMinGreen2 = 15;
+		}
+
+		int iMinBlue2 = iColor2Blue - (int)a_uiRadius;
+		if (iMinBlue2 < 0)
+		{
+			iMinBlue2 = 0;
+		}
+		int iMaxBlue2 = iColor2Blue + (int)a_uiRadius;
+		if (iMaxBlue2 > 15)
+		{
+			iMinBlue2 = 15;
+		}
+
+		for (unsigned int uiDistance = 0; uiDistance < TH_DISTANCES; uiDistance++)
+		{
+			encodingTry.m_uiCW1 = uiDistance;
+
+			// twiddle m_frgbaOriginalColor1_TAndH
+			for (int iRed1 = iMinRed1; iRed1 <= iMaxRed1; iRed1++)
+			{
+				for (int iGreen1 = iMinGreen1; iGreen1 <= iMaxGreen1; iGreen1++)
+				{
+					for (int iBlue1 = iMinBlue1; iBlue1 <= iMaxBlue1; iBlue1++)
+					{
+						encodingTry.m_frgbaColor1 = ColorFloatRGBA::ConvertFromRGB4((unsigned char)iRed1, (unsigned char)iGreen1, (unsigned char)iBlue1);
+						encodingTry.m_frgbaColor2 = m_frgbaOriginalColor2_TAndH;
+
+						// if color1 == color2, H encoding issues can pop up, so abort
+						if (iRed1 == iColor2Red && iGreen1 == iColor2Green && iBlue1 == iColor2Blue)
+						{
+							continue;
+						}
+
+						encodingTry.TryH_BestSelectorCombination();
+
+						if (encodingTry.m_fError < m_fError)
+						{
+							m_mode = encodingTry.m_mode;
+							m_boolDiff = encodingTry.m_boolDiff;
+							m_boolFlip = encodingTry.m_boolFlip;
+
+							m_frgbaColor1 = encodingTry.m_frgbaColor1;
+							m_frgbaColor2 = encodingTry.m_frgbaColor2;
+							m_uiCW1 = encodingTry.m_uiCW1;
+
+							for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+							{
+								m_auiSelectors[uiPixel] = encodingTry.m_auiSelectors[uiPixel];
+								m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
+							}
+
+							m_fError = encodingTry.m_fError;
+						}
+					}
+				}
+			}
+
+			// twiddle m_frgbaOriginalColor2_TAndH
+			for (int iRed2 = iMinRed2; iRed2 <= iMaxRed2; iRed2++)
+			{
+				for (int iGreen2 = iMinGreen2; iGreen2 <= iMaxGreen2; iGreen2++)
+				{
+					for (int iBlue2 = iMinBlue2; iBlue2 <= iMaxBlue2; iBlue2++)
+					{
+						encodingTry.m_frgbaColor1 = m_frgbaOriginalColor1_TAndH;
+						encodingTry.m_frgbaColor2 = ColorFloatRGBA::ConvertFromRGB4((unsigned char)iRed2, (unsigned char)iGreen2, (unsigned char)iBlue2);
+
+						// if color1 == color2, H encoding issues can pop up, so abort
+						if (iRed2 == iColor1Red && iGreen2 == iColor1Green && iBlue2 == iColor1Blue)
+						{
+							continue;
+						}
+
+						encodingTry.TryH_BestSelectorCombination();
+
+						if (encodingTry.m_fError < m_fError)
+						{
+							m_mode = encodingTry.m_mode;
+							m_boolDiff = encodingTry.m_boolDiff;
+							m_boolFlip = encodingTry.m_boolFlip;
+
+							m_frgbaColor1 = encodingTry.m_frgbaColor1;
+							m_frgbaColor2 = encodingTry.m_frgbaColor2;
+							m_uiCW1 = encodingTry.m_uiCW1;
+
+							for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+							{
+								m_auiSelectors[uiPixel] = encodingTry.m_auiSelectors[uiPixel];
+								m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
+							}
+
+							m_fError = encodingTry.m_fError;
+						}
+					}
+				}
+			}
+
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// find best selector combination for TryH
+	// called on an encodingTry
+	//
+	void Block4x4Encoding_RGB8A1::TryH_BestSelectorCombination(void)
+	{
+
+		// abort if colors and CW will pose an encoding problem
+		{
+			unsigned int uiRed1 = (unsigned int)m_frgbaColor1.IntRed(255.0f);
+			unsigned int uiGreen1 = (unsigned int)m_frgbaColor1.IntGreen(255.0f);
+			unsigned int uiBlue1 = (unsigned int)m_frgbaColor1.IntBlue(255.0f);
+			unsigned int uiColorValue1 = (uiRed1 << 16) + (uiGreen1 << 8) + uiBlue1;
+
+			unsigned int uiRed2 = (unsigned int)m_frgbaColor2.IntRed(255.0f);
+			unsigned int uiGreen2 = (unsigned int)m_frgbaColor2.IntGreen(255.0f);
+			unsigned int uiBlue2 = (unsigned int)m_frgbaColor2.IntBlue(255.0f);
+			unsigned int uiColorValue2 = (uiRed2 << 16) + (uiGreen2 << 8) + uiBlue2;
+
+			unsigned int uiCWLsb = m_uiCW1 & 1;
+
+			if ((uiColorValue1 >= (uiColorValue2 & uiCWLsb)) == 0 ||
+				(uiColorValue1 < (uiColorValue2 & uiCWLsb)) == 1)
+			{
+				return;
+			}
+		}
+
+		float fDistance = s_afTHDistanceTable[m_uiCW1];
+
+		unsigned int auiBestPixelSelectors[PIXELS];
+		float afBestPixelErrors[PIXELS] = { FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX,
+											FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX };
+		ColorFloatRGBA	afrgbaBestDecodedPixels[PIXELS];
+		ColorFloatRGBA afrgbaDecodedPixel[SELECTORS];
+
+		assert(SELECTORS == 4);
+		afrgbaDecodedPixel[0] = (m_frgbaColor1 + fDistance).ClampRGB();
+		afrgbaDecodedPixel[1] = (m_frgbaColor1 - fDistance).ClampRGB();
+		afrgbaDecodedPixel[2] = ColorFloatRGBA();;
+		afrgbaDecodedPixel[3] = (m_frgbaColor2 - fDistance).ClampRGB();
+
+
+		// try each selector
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			unsigned int uiMinSelector = 0;
+			unsigned int uiMaxSelector = SELECTORS - 1;
+
+			if (m_pafrgbaSource[uiPixel].fA < 0.5f)
+			{
+				uiMinSelector = 2;
+				uiMaxSelector = 2;
+			}
+
+			for (unsigned int uiSelector = uiMinSelector; uiSelector <= uiMaxSelector; uiSelector++)
+			{
+				float fPixelError = CalcPixelError(afrgbaDecodedPixel[uiSelector], m_afDecodedAlphas[uiPixel],
+													m_pafrgbaSource[uiPixel]);
+
+				if (fPixelError < afBestPixelErrors[uiPixel])
+				{
+					afBestPixelErrors[uiPixel] = fPixelError;
+					auiBestPixelSelectors[uiPixel] = uiSelector;
+					afrgbaBestDecodedPixels[uiPixel] = afrgbaDecodedPixel[uiSelector];
+				}
+			}
+		}
+		
+
+		// add up all of the pixel errors
+		float fBlockError = 0.0f;
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			fBlockError += afBestPixelErrors[uiPixel];
+		}
+
+		if (fBlockError < m_fError)
+		{
+			m_fError = fBlockError;
+
+			for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+			{
+				m_auiSelectors[uiPixel] = auiBestPixelSelectors[uiPixel];
+				m_afrgbaDecodedColors[uiPixel] = afrgbaBestDecodedPixels[uiPixel];
+			}
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// try version 1 of the degenerate search
+	// degenerate encodings use basecolor movement and a subset of the selectors to find useful encodings
+	// each subsequent version of the degenerate search uses more basecolor movement and is less likely to
+	//		be successfull
+	//
+	void Block4x4Encoding_RGB8A1::TryDegenerates1(void)
+	{
+
+		TryDifferential(m_boolMostLikelyFlip, 1, -2, 0);
+		TryDifferential(m_boolMostLikelyFlip, 1, 2, 0);
+		TryDifferential(m_boolMostLikelyFlip, 1, 0, 2);
+		TryDifferential(m_boolMostLikelyFlip, 1, 0, -2);
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// try version 2 of the degenerate search
+	// degenerate encodings use basecolor movement and a subset of the selectors to find useful encodings
+	// each subsequent version of the degenerate search uses more basecolor movement and is less likely to
+	//		be successfull
+	//
+	void Block4x4Encoding_RGB8A1::TryDegenerates2(void)
+	{
+
+		TryDifferential(!m_boolMostLikelyFlip, 1, -2, 0);
+		TryDifferential(!m_boolMostLikelyFlip, 1, 2, 0);
+		TryDifferential(!m_boolMostLikelyFlip, 1, 0, 2);
+		TryDifferential(!m_boolMostLikelyFlip, 1, 0, -2);
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// try version 3 of the degenerate search
+	// degenerate encodings use basecolor movement and a subset of the selectors to find useful encodings
+	// each subsequent version of the degenerate search uses more basecolor movement and is less likely to
+	//		be successfull
+	//
+	void Block4x4Encoding_RGB8A1::TryDegenerates3(void)
+	{
+
+		TryDifferential(m_boolMostLikelyFlip, 1, -2, -2);
+		TryDifferential(m_boolMostLikelyFlip, 1, -2, 2);
+		TryDifferential(m_boolMostLikelyFlip, 1, 2, -2);
+		TryDifferential(m_boolMostLikelyFlip, 1, 2, 2);
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// try version 4 of the degenerate search
+	// degenerate encodings use basecolor movement and a subset of the selectors to find useful encodings
+	// each subsequent version of the degenerate search uses more basecolor movement and is less likely to
+	//		be successfull
+	//
+	void Block4x4Encoding_RGB8A1::TryDegenerates4(void)
+	{
+
+		TryDifferential(m_boolMostLikelyFlip, 1, -4, 0);
+		TryDifferential(m_boolMostLikelyFlip, 1, 4, 0);
+		TryDifferential(m_boolMostLikelyFlip, 1, 0, 4);
+		TryDifferential(m_boolMostLikelyFlip, 1, 0, -4);
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// set the encoding bits based on encoding state
+	//
+	void Block4x4Encoding_RGB8A1::SetEncodingBits(void)
+	{
+		switch (m_mode)
+		{
+		case MODE_ETC1:
+			SetEncodingBits_ETC1();
+			break;
+
+		case MODE_T:
+			SetEncodingBits_T();
+			break;
+
+		case MODE_H:
+			SetEncodingBits_H();
+			break;
+
+		case MODE_PLANAR:
+			Block4x4Encoding_RGB8::SetEncodingBits_Planar();
+			break;
+
+		default:
+			assert(false);
+		}
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// set the encoding bits based on encoding state if ETC1 mode
+	//
+	void Block4x4Encoding_RGB8A1::SetEncodingBits_ETC1(void)
+	{
+
+		// there is no individual mode in RGB8A1
+		assert(m_boolDiff);
+
+		int iRed1 = m_frgbaColor1.IntRed(31.0f);
+		int iGreen1 = m_frgbaColor1.IntGreen(31.0f);
+		int iBlue1 = m_frgbaColor1.IntBlue(31.0f);
+
+		int iRed2 = m_frgbaColor2.IntRed(31.0f);
+		int iGreen2 = m_frgbaColor2.IntGreen(31.0f);
+		int iBlue2 = m_frgbaColor2.IntBlue(31.0f);
+
+		int iDRed2 = iRed2 - iRed1;
+		int iDGreen2 = iGreen2 - iGreen1;
+		int iDBlue2 = iBlue2 - iBlue1;
+
+		assert(iDRed2 >= -4 && iDRed2 < 4);
+		assert(iDGreen2 >= -4 && iDGreen2 < 4);
+		assert(iDBlue2 >= -4 && iDBlue2 < 4);
+
+		m_pencodingbitsRGB8->differential.red1 = iRed1;
+		m_pencodingbitsRGB8->differential.green1 = iGreen1;
+		m_pencodingbitsRGB8->differential.blue1 = iBlue1;
+
+		m_pencodingbitsRGB8->differential.dred2 = iDRed2;
+		m_pencodingbitsRGB8->differential.dgreen2 = iDGreen2;
+		m_pencodingbitsRGB8->differential.dblue2 = iDBlue2;
+
+		m_pencodingbitsRGB8->individual.cw1 = m_uiCW1;
+		m_pencodingbitsRGB8->individual.cw2 = m_uiCW2;
+
+		SetEncodingBits_Selectors();
+
+		// in RGB8A1 encoding bits, opaque replaces differential
+		m_pencodingbitsRGB8->differential.diff = !m_boolPunchThroughPixels;
+
+		m_pencodingbitsRGB8->individual.flip = m_boolFlip;
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// set the encoding bits based on encoding state if T mode
+	//
+	void Block4x4Encoding_RGB8A1::SetEncodingBits_T(void)
+	{
+		static const bool SANITY_CHECK = true;
+
+		assert(m_mode == MODE_T);
+		assert(m_boolDiff == true);
+
+		unsigned int uiRed1 = (unsigned int)m_frgbaColor1.IntRed(15.0f);
+		unsigned int uiGreen1 = (unsigned int)m_frgbaColor1.IntGreen(15.0f);
+		unsigned int uiBlue1 = (unsigned int)m_frgbaColor1.IntBlue(15.0f);
+
+		unsigned int uiRed2 = (unsigned int)m_frgbaColor2.IntRed(15.0f);
+		unsigned int uiGreen2 = (unsigned int)m_frgbaColor2.IntGreen(15.0f);
+		unsigned int uiBlue2 = (unsigned int)m_frgbaColor2.IntBlue(15.0f);
+
+		m_pencodingbitsRGB8->t.red1a = uiRed1 >> 2;
+		m_pencodingbitsRGB8->t.red1b = uiRed1;
+		m_pencodingbitsRGB8->t.green1 = uiGreen1;
+		m_pencodingbitsRGB8->t.blue1 = uiBlue1;
+
+		m_pencodingbitsRGB8->t.red2 = uiRed2;
+		m_pencodingbitsRGB8->t.green2 = uiGreen2;
+		m_pencodingbitsRGB8->t.blue2 = uiBlue2;
+
+		m_pencodingbitsRGB8->t.da = m_uiCW1 >> 1;
+		m_pencodingbitsRGB8->t.db = m_uiCW1;
+
+		// in RGB8A1 encoding bits, opaque replaces differential
+		m_pencodingbitsRGB8->differential.diff = !m_boolPunchThroughPixels;
+
+		Block4x4Encoding_ETC1::SetEncodingBits_Selectors();
+
+		// create an invalid R differential to trigger T mode
+		m_pencodingbitsRGB8->t.detect1 = 0;
+		m_pencodingbitsRGB8->t.detect2 = 0;
+		int iRed2 = (int)m_pencodingbitsRGB8->differential.red1 + (int)m_pencodingbitsRGB8->differential.dred2;
+		if (iRed2 >= 4)
+		{
+			m_pencodingbitsRGB8->t.detect1 = 7;
+			m_pencodingbitsRGB8->t.detect2 = 0;
+		}
+		else
+		{
+			m_pencodingbitsRGB8->t.detect1 = 0;
+			m_pencodingbitsRGB8->t.detect2 = 1;
+		}
+
+		if (SANITY_CHECK)
+		{
+			iRed2 = (int)m_pencodingbitsRGB8->differential.red1 + (int)m_pencodingbitsRGB8->differential.dred2;
+
+			// make sure red overflows
+			assert(iRed2 < 0 || iRed2 > 31);
+		}
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// set the encoding bits based on encoding state if H mode
+	//
+	// colors and selectors may need to swap in order to generate lsb of distance index
+	//
+	void Block4x4Encoding_RGB8A1::SetEncodingBits_H(void)
+	{
+		static const bool SANITY_CHECK = true;
+
+		assert(m_mode == MODE_H);
+		assert(m_boolDiff == true);
+
+		unsigned int uiRed1 = (unsigned int)m_frgbaColor1.IntRed(15.0f);
+		unsigned int uiGreen1 = (unsigned int)m_frgbaColor1.IntGreen(15.0f);
+		unsigned int uiBlue1 = (unsigned int)m_frgbaColor1.IntBlue(15.0f);
+
+		unsigned int uiRed2 = (unsigned int)m_frgbaColor2.IntRed(15.0f);
+		unsigned int uiGreen2 = (unsigned int)m_frgbaColor2.IntGreen(15.0f);
+		unsigned int uiBlue2 = (unsigned int)m_frgbaColor2.IntBlue(15.0f);
+
+		unsigned int uiColor1 = (uiRed1 << 16) + (uiGreen1 << 8) + uiBlue1;
+		unsigned int uiColor2 = (uiRed2 << 16) + (uiGreen2 << 8) + uiBlue2;
+
+		bool boolOddDistance = m_uiCW1 & 1;
+		bool boolSwapColors = (uiColor1 < uiColor2) ^ !boolOddDistance;
+
+		if (boolSwapColors)
+		{
+			m_pencodingbitsRGB8->h.red1 = uiRed2;
+			m_pencodingbitsRGB8->h.green1a = uiGreen2 >> 1;
+			m_pencodingbitsRGB8->h.green1b = uiGreen2;
+			m_pencodingbitsRGB8->h.blue1a = uiBlue2 >> 3;
+			m_pencodingbitsRGB8->h.blue1b = uiBlue2 >> 1;
+			m_pencodingbitsRGB8->h.blue1c = uiBlue2;
+
+			m_pencodingbitsRGB8->h.red2 = uiRed1;
+			m_pencodingbitsRGB8->h.green2a = uiGreen1 >> 1;
+			m_pencodingbitsRGB8->h.green2b = uiGreen1;
+			m_pencodingbitsRGB8->h.blue2 = uiBlue1;
+
+			m_pencodingbitsRGB8->h.da = m_uiCW1 >> 2;
+			m_pencodingbitsRGB8->h.db = m_uiCW1 >> 1;
+		}
+		else
+		{
+			m_pencodingbitsRGB8->h.red1 = uiRed1;
+			m_pencodingbitsRGB8->h.green1a = uiGreen1 >> 1;
+			m_pencodingbitsRGB8->h.green1b = uiGreen1;
+			m_pencodingbitsRGB8->h.blue1a = uiBlue1 >> 3;
+			m_pencodingbitsRGB8->h.blue1b = uiBlue1 >> 1;
+			m_pencodingbitsRGB8->h.blue1c = uiBlue1;
+
+			m_pencodingbitsRGB8->h.red2 = uiRed2;
+			m_pencodingbitsRGB8->h.green2a = uiGreen2 >> 1;
+			m_pencodingbitsRGB8->h.green2b = uiGreen2;
+			m_pencodingbitsRGB8->h.blue2 = uiBlue2;
+
+			m_pencodingbitsRGB8->h.da = m_uiCW1 >> 2;
+			m_pencodingbitsRGB8->h.db = m_uiCW1 >> 1;
+		}
+
+		// in RGB8A1 encoding bits, opaque replaces differential
+		m_pencodingbitsRGB8->differential.diff = !m_boolPunchThroughPixels;
+
+		Block4x4Encoding_ETC1::SetEncodingBits_Selectors();
+
+		if (boolSwapColors)
+		{
+			m_pencodingbitsRGB8->h.selectors ^= 0x0000FFFF;
+		}
+
+		// create an invalid R differential to trigger T mode
+		m_pencodingbitsRGB8->h.detect1 = 0;
+		m_pencodingbitsRGB8->h.detect2 = 0;
+		m_pencodingbitsRGB8->h.detect3 = 0;
+		int iRed2 = (int)m_pencodingbitsRGB8->differential.red1 + (int)m_pencodingbitsRGB8->differential.dred2;
+		int iGreen2 = (int)m_pencodingbitsRGB8->differential.green1 + (int)m_pencodingbitsRGB8->differential.dgreen2;
+		if (iRed2 < 0 || iRed2 > 31)
+		{
+			m_pencodingbitsRGB8->h.detect1 = 1;
+		}
+		if (iGreen2 >= 4)
+		{
+			m_pencodingbitsRGB8->h.detect2 = 7;
+			m_pencodingbitsRGB8->h.detect3 = 0;
+		}
+		else
+		{
+			m_pencodingbitsRGB8->h.detect2 = 0;
+			m_pencodingbitsRGB8->h.detect3 = 1;
+		}
+
+		if (SANITY_CHECK)
+		{
+			iRed2 = (int)m_pencodingbitsRGB8->differential.red1 + (int)m_pencodingbitsRGB8->differential.dred2;
+			iGreen2 = (int)m_pencodingbitsRGB8->differential.green1 + (int)m_pencodingbitsRGB8->differential.dgreen2;
+
+			// make sure red doesn't overflow and green does
+			assert(iRed2 >= 0 && iRed2 <= 31);
+			assert(iGreen2 < 0 || iGreen2 > 31);
+		}
+
+	}
+
+	// ####################################################################################################
+	// Block4x4Encoding_RGB8A1_Opaque
+	// ####################################################################################################
+
+	// ----------------------------------------------------------------------------------------------------
+	// perform a single encoding iteration
+	// replace the encoding if a better encoding was found
+	// subsequent iterations generally take longer for each iteration
+	// set m_boolDone if encoding is perfect or encoding is finished based on a_fEffort
+	//
+	void Block4x4Encoding_RGB8A1_Opaque::PerformIteration(float a_fEffort)
+	{
+		assert(!m_boolPunchThroughPixels);
+		assert(!m_boolTransparent);
+		assert(!m_boolDone);
+
+		switch (m_uiEncodingIterations)
+		{
+		case 0:
+			PerformFirstIteration();
+			break;
+
+		case 1:
+			Block4x4Encoding_ETC1::TryDifferential(m_boolMostLikelyFlip, 1, 0, 0);
+			break;
+
+		case 2:
+			Block4x4Encoding_ETC1::TryDifferential(!m_boolMostLikelyFlip, 1, 0, 0);
+			break;
+
+		case 3:
+			Block4x4Encoding_RGB8::TryPlanar(1);
+			break;
+
+		case 4:
+			Block4x4Encoding_RGB8::TryTAndH(1);
+			if (a_fEffort <= 49.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 5:
+			Block4x4Encoding_ETC1::TryDegenerates1();
+			if (a_fEffort <= 59.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 6:
+			Block4x4Encoding_ETC1::TryDegenerates2();
+			if (a_fEffort <= 69.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 7:
+			Block4x4Encoding_ETC1::TryDegenerates3();
+			if (a_fEffort <= 79.5f)
+			{
+				m_boolDone = true;
+			}
+			break;
+
+		case 8:
+			Block4x4Encoding_ETC1::TryDegenerates4();
+			m_boolDone = true;
+			break;
+
+		default:
+			assert(0);
+			break;
+		}
+
+		m_uiEncodingIterations++;
+		SetDoneIfPerfect();
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	// find best initial encoding to ensure block has a valid encoding
+	//
+	void Block4x4Encoding_RGB8A1_Opaque::PerformFirstIteration(void)
+	{
+		
+		// set decoded alphas
+		// calculate alpha error
+		m_fError = 0.0f;
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			m_afDecodedAlphas[uiPixel] = 1.0f;
+
+			float fDeltaA = 1.0f - m_pafrgbaSource[uiPixel].fA;
+			m_fError += fDeltaA * fDeltaA;
+		}
+
+		CalculateMostLikelyFlip();
+
+		m_fError = FLT_MAX;
+
+		Block4x4Encoding_ETC1::TryDifferential(m_boolMostLikelyFlip, 0, 0, 0);
+		SetDoneIfPerfect();
+		if (m_boolDone)
+		{
+			return;
+		}
+		Block4x4Encoding_ETC1::TryDifferential(!m_boolMostLikelyFlip, 0, 0, 0);
+		SetDoneIfPerfect();
+		if (m_boolDone)
+		{
+			return;
+		}
+		Block4x4Encoding_RGB8::TryPlanar(0);
+		SetDoneIfPerfect();
+		if (m_boolDone)
+		{
+			return;
+		}
+		Block4x4Encoding_RGB8::TryTAndH(0);
+		SetDoneIfPerfect();
+	}
+
+	// ####################################################################################################
+	// Block4x4Encoding_RGB8A1_Transparent
+	// ####################################################################################################
+
+	// ----------------------------------------------------------------------------------------------------
+	// perform a single encoding iteration
+	// replace the encoding if a better encoding was found
+	// subsequent iterations generally take longer for each iteration
+	// set m_boolDone if encoding is perfect or encoding is finished based on a_fEffort
+	//
+	void Block4x4Encoding_RGB8A1_Transparent::PerformIteration(float )
+	{
+		assert(!m_boolOpaque);
+		assert(m_boolTransparent);
+		assert(!m_boolDone);
+		assert(m_uiEncodingIterations == 0);
+
+		m_mode = MODE_ETC1;
+		m_boolDiff = true;
+		m_boolFlip = false;
+
+		m_uiCW1 = 0;
+		m_uiCW2 = 0;
+
+		m_frgbaColor1 = ColorFloatRGBA();
+		m_frgbaColor2 = ColorFloatRGBA();
+
+		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++)
+		{
+			m_auiSelectors[uiPixel] = TRANSPARENT_SELECTOR;
+
+			m_afrgbaDecodedColors[uiPixel] = ColorFloatRGBA();
+			m_afDecodedAlphas[uiPixel] = 0.0f;
+		}
+
+		CalcBlockError();
+
+		m_boolDone = true;
+		m_uiEncodingIterations++;
+
+	}
+
+	// ----------------------------------------------------------------------------------------------------
+	//
+}