path: root/thirdparty/etc2comp/EtcBlock4x4Encoding_RGB8.cpp

/*
 * 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_RGB8.cpp

Block4x4Encoding_RGB8 is the encoder to use for the ETC2 extensions when targetting file format RGB8.  
This encoder is also used for the ETC2 subset of file format RGBA8.

Block4x4Encoding_ETC1 encodes the ETC1 subset of RGB8.

*/

#include "EtcBlock4x4Encoding_RGB8.h"
#include "EtcConfig.h"

#include "EtcBlock4x4.h"
#include "EtcBlock4x4EncodingBits.h"
#include "EtcMath.h"

#include <assert.h>
#include <float.h>
#include <stdio.h>
#include <string.h>
#include <limits>

namespace Etc {
float Block4x4Encoding_RGB8::s_afTHDistanceTable[TH_DISTANCES] =
		{
		  3.0f / 255.0f,
		  6.0f / 255.0f,
		  11.0f / 255.0f,
		  16.0f / 255.0f,
		  23.0f / 255.0f,
		  32.0f / 255.0f,
		  41.0f / 255.0f,
		  64.0f / 255.0f
		};

// ----------------------------------------------------------------------------------------------------
//
Block4x4Encoding_RGB8::Block4x4Encoding_RGB8(void) {

	m_pencodingbitsRGB8 = nullptr;
}

Block4x4Encoding_RGB8::~Block4x4Encoding_RGB8(void) {}
// ----------------------------------------------------------------------------------------------------
// 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_RGB8::InitFromEncodingBits(Block4x4 *a_pblockParent,
		unsigned char *a_paucEncodingBits,
		ColorFloatRGBA *a_pafrgbaSource,
		ErrorMetric a_errormetric) {

	// handle ETC1 modes
	Block4x4Encoding_ETC1::InitFromEncodingBits(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
	if (m_pencodingbitsRGB8->differential.diff) {
		int iRed1 = (int)m_pencodingbitsRGB8->differential.red1;
		int iDRed2 = m_pencodingbitsRGB8->differential.dred2;
		int iRed2 = iRed1 + iDRed2;

		int iGreen1 = (int)m_pencodingbitsRGB8->differential.green1;
		int iDGreen2 = m_pencodingbitsRGB8->differential.dgreen2;
		int iGreen2 = iGreen1 + iDGreen2;

		int iBlue1 = (int)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) {
			InitFromEncodingBits_Planar();
		}
	}
}

// ----------------------------------------------------------------------------------------------------
// initialization from the encoding bits of a previous encoding if T mode is detected
//
void Block4x4Encoding_RGB8::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_RGB8::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();
}

// ----------------------------------------------------------------------------------------------------
// initialization from the encoding bits of a previous encoding if Planar mode is detected
//
void Block4x4Encoding_RGB8::InitFromEncodingBits_Planar(void) {

	m_mode = MODE_PLANAR;

	unsigned char ucOriginRed = m_pencodingbitsRGB8->planar.originRed;
	unsigned char ucOriginGreen = (unsigned char)((m_pencodingbitsRGB8->planar.originGreen1 << 6) +
												  m_pencodingbitsRGB8->planar.originGreen2);
	unsigned char ucOriginBlue = (unsigned char)((m_pencodingbitsRGB8->planar.originBlue1 << 5) +
												 (m_pencodingbitsRGB8->planar.originBlue2 << 3) +
												 (m_pencodingbitsRGB8->planar.originBlue3 << 1) +
												 m_pencodingbitsRGB8->planar.originBlue4);

	unsigned char ucHorizRed = (unsigned char)((m_pencodingbitsRGB8->planar.horizRed1 << 1) +
											   m_pencodingbitsRGB8->planar.horizRed2);
	unsigned char ucHorizGreen = m_pencodingbitsRGB8->planar.horizGreen;
	unsigned char ucHorizBlue = (unsigned char)((m_pencodingbitsRGB8->planar.horizBlue1 << 5) +
												m_pencodingbitsRGB8->planar.horizBlue2);

	unsigned char ucVertRed = (unsigned char)((m_pencodingbitsRGB8->planar.vertRed1 << 3) +
											  m_pencodingbitsRGB8->planar.vertRed2);
	unsigned char ucVertGreen = (unsigned char)((m_pencodingbitsRGB8->planar.vertGreen1 << 2) +
												m_pencodingbitsRGB8->planar.vertGreen2);
	unsigned char ucVertBlue = m_pencodingbitsRGB8->planar.vertBlue;

	m_frgbaColor1 = ColorFloatRGBA::ConvertFromR6G7B6(ucOriginRed, ucOriginGreen, ucOriginBlue);
	m_frgbaColor2 = ColorFloatRGBA::ConvertFromR6G7B6(ucHorizRed, ucHorizGreen, ucHorizBlue);
	m_frgbaColor3 = ColorFloatRGBA::ConvertFromR6G7B6(ucVertRed, ucVertGreen, ucVertBlue);

	DecodePixels_Planar();

	CalcBlockError();
}

// ----------------------------------------------------------------------------------------------------
// 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_RGB8::PerformIteration(float a_fEffort) {
	assert(!m_boolDone);

	switch (m_uiEncodingIterations) {
		case 0:
			Block4x4Encoding_ETC1::PerformFirstIteration();

			//@TODO@ Restrict here compression to ETC1 to speed up compression in low quality
			if (m_boolDone) {
				break;
			}
			TryPlanar(0);
			SetDoneIfPerfect();
			if (m_boolDone) {
				break;
			}
			TryTAndH(0);

			break;

		case 1:
			Block4x4Encoding_ETC1::TryDifferential(m_boolMostLikelyFlip, 1, 0, 0);
			break;

		case 2:
			Block4x4Encoding_ETC1::TryIndividual(m_boolMostLikelyFlip, 1);
			break;

		case 3:
			Block4x4Encoding_ETC1::TryDifferential(!m_boolMostLikelyFlip, 1, 0, 0);
			break;

		case 4:
			Block4x4Encoding_ETC1::TryIndividual(!m_boolMostLikelyFlip, 1);
			break;

		case 5:
			TryPlanar(1);
			if (a_fEffort <= 49.5f) {
				m_boolDone = true;
			}
			break;

		case 6:
			TryTAndH(1);
			if (a_fEffort <= 59.5f) {
				m_boolDone = true;
			}
			break;

		case 7:
			Block4x4Encoding_ETC1::TryDegenerates1();
			if (a_fEffort <= 69.5f) {
				m_boolDone = true;
			}
			break;

		case 8:
			Block4x4Encoding_ETC1::TryDegenerates2();
			if (a_fEffort <= 79.5f) {
				m_boolDone = true;
			}
			break;

		case 9:
			Block4x4Encoding_ETC1::TryDegenerates3();
			if (a_fEffort <= 89.5f) {
				m_boolDone = true;
			}
			break;

		case 10:
			Block4x4Encoding_ETC1::TryDegenerates4();
			m_boolDone = true;
			break;

		default:
			assert(0);
			break;
	}

	m_uiEncodingIterations++;

	SetDoneIfPerfect();
}

// ----------------------------------------------------------------------------------------------------
// try encoding in Planar mode
// save this encoding if it improves the error
//
void Block4x4Encoding_RGB8::TryPlanar(unsigned int a_uiRadius) {
	Block4x4Encoding_RGB8 encodingTry = *this;

	// init "try"
	{
		encodingTry.m_mode = MODE_PLANAR;
		encodingTry.m_boolDiff = true;
		encodingTry.m_boolFlip = false;
	}

	encodingTry.CalculatePlanarCornerColors();

	encodingTry.DecodePixels_Planar();

	encodingTry.CalcBlockError();

	if (a_uiRadius > 0) {
		encodingTry.TwiddlePlanar();
	}

	if (encodingTry.m_fError < m_fError) {
		m_mode = MODE_PLANAR;
		m_boolDiff = true;
		m_boolFlip = false;
		m_frgbaColor1 = encodingTry.m_frgbaColor1;
		m_frgbaColor2 = encodingTry.m_frgbaColor2;
		m_frgbaColor3 = encodingTry.m_frgbaColor3;

		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {
			m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
		}

		m_fError = encodingTry.m_fError;
	}
}

// ----------------------------------------------------------------------------------------------------
// try encoding in T mode or H mode
// save this encoding if it improves the error
//
void Block4x4Encoding_RGB8::TryTAndH(unsigned int a_uiRadius) {

	CalculateBaseColorsForTAndH();

	TryT(a_uiRadius);

	TryH(a_uiRadius);
}

// ----------------------------------------------------------------------------------------------------
// calculate original values for base colors
// store them in m_frgbaOriginalColor1 and m_frgbaOriginalColor2
//
void Block4x4Encoding_RGB8::CalculateBaseColorsForTAndH(void) {

	bool boolRGBX = m_pblockParent->GetImageSource()->GetErrorMetric() == ErrorMetric::RGBX;

	ColorFloatRGBA frgbaBlockAverage = (m_frgbaSourceAverageLeft + m_frgbaSourceAverageRight) * 0.5f;

	// find pixel farthest from average gray line
	unsigned int uiFarthestPixel = 0;
	float fFarthestGrayDistance2 = 0.0f;
	unsigned int uiTransparentPixels = 0;
	for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {
		// don't count transparent
		if (m_pafrgbaSource[uiPixel].fA == 0.0f && !boolRGBX) {
			uiTransparentPixels++;
		} else {
			float fGrayDistance2 = CalcGrayDistance2(m_pafrgbaSource[uiPixel], frgbaBlockAverage);

			if (fGrayDistance2 > fFarthestGrayDistance2) {
				uiFarthestPixel = uiPixel;
				fFarthestGrayDistance2 = fGrayDistance2;
			}
		}
	}
	// a transparent block should not reach this method
	assert(uiTransparentPixels < PIXELS);

	// set the original base colors to:
	//		half way to the farthest pixel and
	//		the mirror color on the other side of the average
	ColorFloatRGBA frgbaOffset = (m_pafrgbaSource[uiFarthestPixel] - frgbaBlockAverage) * 0.5f;
	m_frgbaOriginalColor1_TAndH = (frgbaBlockAverage + frgbaOffset).QuantizeR4G4B4();
	m_frgbaOriginalColor2_TAndH = (frgbaBlockAverage - frgbaOffset).ClampRGB().QuantizeR4G4B4(); // the "other side" might be out of range

	// move base colors to find best fit
	for (unsigned int uiIteration = 0; uiIteration < 10; uiIteration++) {
		// find the center of pixels closest to each color
		float fPixelsCloserToColor1 = 0.0f;
		ColorFloatRGBA frgbSumPixelsCloserToColor1;
		float fPixelsCloserToColor2 = 0.0f;
		ColorFloatRGBA frgbSumPixelsCloserToColor2;
		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {
			// don't count transparent pixels
			if (m_pafrgbaSource[uiPixel].fA == 0.0f) {
				continue;
			}

			float fGrayDistance2ToColor1 = CalcGrayDistance2(m_pafrgbaSource[uiPixel], m_frgbaOriginalColor1_TAndH);
			float fGrayDistance2ToColor2 = CalcGrayDistance2(m_pafrgbaSource[uiPixel], m_frgbaOriginalColor2_TAndH);

			ColorFloatRGBA frgbaAlphaWeightedSource = m_pafrgbaSource[uiPixel] * m_pafrgbaSource[uiPixel].fA;

			if (fGrayDistance2ToColor1 <= fGrayDistance2ToColor2) {
				fPixelsCloserToColor1 += m_pafrgbaSource[uiPixel].fA;
				frgbSumPixelsCloserToColor1 = frgbSumPixelsCloserToColor1 + frgbaAlphaWeightedSource;
			} else {
				fPixelsCloserToColor2 += m_pafrgbaSource[uiPixel].fA;
				frgbSumPixelsCloserToColor2 = frgbSumPixelsCloserToColor2 + frgbaAlphaWeightedSource;
			}
		}
		if (fPixelsCloserToColor1 == 0.0f || fPixelsCloserToColor2 == 0.0f) {
			break;
		}

		ColorFloatRGBA frgbAvgColor1Pixels = (frgbSumPixelsCloserToColor1 * (1.0f / fPixelsCloserToColor1)).QuantizeR4G4B4();
		ColorFloatRGBA frgbAvgColor2Pixels = (frgbSumPixelsCloserToColor2 * (1.0f / fPixelsCloserToColor2)).QuantizeR4G4B4();

		if (frgbAvgColor1Pixels.fR == m_frgbaOriginalColor1_TAndH.fR &&
				frgbAvgColor1Pixels.fG == m_frgbaOriginalColor1_TAndH.fG &&
				frgbAvgColor1Pixels.fB == m_frgbaOriginalColor1_TAndH.fB &&
				frgbAvgColor2Pixels.fR == m_frgbaOriginalColor2_TAndH.fR &&
				frgbAvgColor2Pixels.fG == m_frgbaOriginalColor2_TAndH.fG &&
				frgbAvgColor2Pixels.fB == m_frgbaOriginalColor2_TAndH.fB) {
			break;
		}

		m_frgbaOriginalColor1_TAndH = frgbAvgColor1Pixels;
		m_frgbaOriginalColor2_TAndH = frgbAvgColor2Pixels;
	}
}

// ----------------------------------------------------------------------------------------------------
// 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_RGB8::TryT(unsigned int a_uiRadius) {
	Block4x4Encoding_RGB8 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_RGB8::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] = m_frgbaColor2;
	afrgbaDecodedPixel[3] = (m_frgbaColor2 - fDistance).ClampRGB();

	// try each selector
	for (unsigned int uiSelector = 0; uiSelector < SELECTORS; uiSelector++) {
		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {

			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 T 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_RGB8::TryH(unsigned int a_uiRadius) {
	Block4x4Encoding_RGB8 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_RGB8::TryH_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 + fDistance).ClampRGB();
	afrgbaDecodedPixel[1] = (m_frgbaColor1 - fDistance).ClampRGB();
	afrgbaDecodedPixel[2] = (m_frgbaColor2 + fDistance).ClampRGB();
	afrgbaDecodedPixel[3] = (m_frgbaColor2 - fDistance).ClampRGB();

	// try each selector
	for (unsigned int uiSelector = 0; uiSelector < SELECTORS; uiSelector++) {
		for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {

			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];
		}
	}
}

// ----------------------------------------------------------------------------------------------------
// use linear regression to find the best fit for colors along the edges of the 4x4 block
//
void Block4x4Encoding_RGB8::CalculatePlanarCornerColors(void) {
	ColorFloatRGBA afrgbaRegression[MAX_PLANAR_REGRESSION_SIZE];
	ColorFloatRGBA frgbaSlope;
	ColorFloatRGBA frgbaOffset;

	// top edge
	afrgbaRegression[0] = m_pafrgbaSource[0];
	afrgbaRegression[1] = m_pafrgbaSource[4];
	afrgbaRegression[2] = m_pafrgbaSource[8];
	afrgbaRegression[3] = m_pafrgbaSource[12];
	ColorRegression(afrgbaRegression, 4, &frgbaSlope, &frgbaOffset);
	m_frgbaColor1 = frgbaOffset;
	m_frgbaColor2 = (frgbaSlope * 4.0f) + frgbaOffset;

	// left edge
	afrgbaRegression[0] = m_pafrgbaSource[0];
	afrgbaRegression[1] = m_pafrgbaSource[1];
	afrgbaRegression[2] = m_pafrgbaSource[2];
	afrgbaRegression[3] = m_pafrgbaSource[3];
	ColorRegression(afrgbaRegression, 4, &frgbaSlope, &frgbaOffset);
	m_frgbaColor1 = (m_frgbaColor1 + frgbaOffset) * 0.5f; // average with top edge
	m_frgbaColor3 = (frgbaSlope * 4.0f) + frgbaOffset;

	// right edge
	afrgbaRegression[0] = m_pafrgbaSource[12];
	afrgbaRegression[1] = m_pafrgbaSource[13];
	afrgbaRegression[2] = m_pafrgbaSource[14];
	afrgbaRegression[3] = m_pafrgbaSource[15];
	ColorRegression(afrgbaRegression, 4, &frgbaSlope, &frgbaOffset);
	m_frgbaColor2 = (m_frgbaColor2 + frgbaOffset) * 0.5f; // average with top edge

	// bottom edge
	afrgbaRegression[0] = m_pafrgbaSource[3];
	afrgbaRegression[1] = m_pafrgbaSource[7];
	afrgbaRegression[2] = m_pafrgbaSource[11];
	afrgbaRegression[3] = m_pafrgbaSource[15];
	ColorRegression(afrgbaRegression, 4, &frgbaSlope, &frgbaOffset);
	m_frgbaColor3 = (m_frgbaColor3 + frgbaOffset) * 0.5f; // average with left edge

	// quantize corner colors to 6/7/6
	m_frgbaColor1 = m_frgbaColor1.QuantizeR6G7B6();
	m_frgbaColor2 = m_frgbaColor2.QuantizeR6G7B6();
	m_frgbaColor3 = m_frgbaColor3.QuantizeR6G7B6();
}

// ----------------------------------------------------------------------------------------------------
// try different corner colors by slightly changing R, G and B independently
//
// R, G and B decoding and errors are independent, so R, G and B twiddles can be independent
//
// return true if improvement
//
bool Block4x4Encoding_RGB8::TwiddlePlanar(void) {
	bool boolImprovement = false;

	while (TwiddlePlanarR()) {
		boolImprovement = true;
	}

	while (TwiddlePlanarG()) {
		boolImprovement = true;
	}

	while (TwiddlePlanarB()) {
		boolImprovement = true;
	}

	return boolImprovement;
}

// ----------------------------------------------------------------------------------------------------
// try different corner colors by slightly changing R
//
bool Block4x4Encoding_RGB8::TwiddlePlanarR() {
	bool boolImprovement = false;

	Block4x4Encoding_RGB8 encodingTry = *this;

	// init "try"
	{
		encodingTry.m_mode = MODE_PLANAR;
		encodingTry.m_boolDiff = true;
		encodingTry.m_boolFlip = false;
	}

	int iOriginRed = encodingTry.m_frgbaColor1.IntRed(63.0f);
	int iHorizRed = encodingTry.m_frgbaColor2.IntRed(63.0f);
	int iVertRed = encodingTry.m_frgbaColor3.IntRed(63.0f);

	for (int iTryOriginRed = iOriginRed - 1; iTryOriginRed <= iOriginRed + 1; iTryOriginRed++) {
		// check for out of range
		if (iTryOriginRed < 0 || iTryOriginRed > 63) {
			continue;
		}

		encodingTry.m_frgbaColor1.fR = ((iTryOriginRed << 2) + (iTryOriginRed >> 4)) / 255.0f;

		for (int iTryHorizRed = iHorizRed - 1; iTryHorizRed <= iHorizRed + 1; iTryHorizRed++) {
			// check for out of range
			if (iTryHorizRed < 0 || iTryHorizRed > 63) {
				continue;
			}

			encodingTry.m_frgbaColor2.fR = ((iTryHorizRed << 2) + (iTryHorizRed >> 4)) / 255.0f;

			for (int iTryVertRed = iVertRed - 1; iTryVertRed <= iVertRed + 1; iTryVertRed++) {
				// check for out of range
				if (iTryVertRed < 0 || iTryVertRed > 63) {
					continue;
				}

				// don't bother with null twiddle
				if (iTryOriginRed == iOriginRed && iTryHorizRed == iHorizRed && iTryVertRed == iVertRed) {
					continue;
				}

				encodingTry.m_frgbaColor3.fR = ((iTryVertRed << 2) + (iTryVertRed >> 4)) / 255.0f;

				encodingTry.DecodePixels_Planar();

				encodingTry.CalcBlockError();

				if (encodingTry.m_fError < m_fError) {
					m_mode = MODE_PLANAR;
					m_boolDiff = true;
					m_boolFlip = false;
					m_frgbaColor1 = encodingTry.m_frgbaColor1;
					m_frgbaColor2 = encodingTry.m_frgbaColor2;
					m_frgbaColor3 = encodingTry.m_frgbaColor3;

					for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {
						m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
					}

					m_fError = encodingTry.m_fError;

					boolImprovement = true;
				}
			}
		}
	}

	return boolImprovement;
}

// ----------------------------------------------------------------------------------------------------
// try different corner colors by slightly changing G
//
bool Block4x4Encoding_RGB8::TwiddlePlanarG() {
	bool boolImprovement = false;

	Block4x4Encoding_RGB8 encodingTry = *this;

	// init "try"
	{
		encodingTry.m_mode = MODE_PLANAR;
		encodingTry.m_boolDiff = true;
		encodingTry.m_boolFlip = false;
	}

	int iOriginGreen = encodingTry.m_frgbaColor1.IntGreen(127.0f);
	int iHorizGreen = encodingTry.m_frgbaColor2.IntGreen(127.0f);
	int iVertGreen = encodingTry.m_frgbaColor3.IntGreen(127.0f);

	for (int iTryOriginGreen = iOriginGreen - 1; iTryOriginGreen <= iOriginGreen + 1; iTryOriginGreen++) {
		// check for out of range
		if (iTryOriginGreen < 0 || iTryOriginGreen > 127) {
			continue;
		}

		encodingTry.m_frgbaColor1.fG = ((iTryOriginGreen << 1) + (iTryOriginGreen >> 6)) / 255.0f;

		for (int iTryHorizGreen = iHorizGreen - 1; iTryHorizGreen <= iHorizGreen + 1; iTryHorizGreen++) {
			// check for out of range
			if (iTryHorizGreen < 0 || iTryHorizGreen > 127) {
				continue;
			}

			encodingTry.m_frgbaColor2.fG = ((iTryHorizGreen << 1) + (iTryHorizGreen >> 6)) / 255.0f;

			for (int iTryVertGreen = iVertGreen - 1; iTryVertGreen <= iVertGreen + 1; iTryVertGreen++) {
				// check for out of range
				if (iTryVertGreen < 0 || iTryVertGreen > 127) {
					continue;
				}

				// don't bother with null twiddle
				if (iTryOriginGreen == iOriginGreen &&
						iTryHorizGreen == iHorizGreen &&
						iTryVertGreen == iVertGreen) {
					continue;
				}

				encodingTry.m_frgbaColor3.fG = ((iTryVertGreen << 1) + (iTryVertGreen >> 6)) / 255.0f;

				encodingTry.DecodePixels_Planar();

				encodingTry.CalcBlockError();

				if (encodingTry.m_fError < m_fError) {
					m_mode = MODE_PLANAR;
					m_boolDiff = true;
					m_boolFlip = false;
					m_frgbaColor1 = encodingTry.m_frgbaColor1;
					m_frgbaColor2 = encodingTry.m_frgbaColor2;
					m_frgbaColor3 = encodingTry.m_frgbaColor3;

					for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {
						m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
					}

					m_fError = encodingTry.m_fError;

					boolImprovement = true;
				}
			}
		}
	}

	return boolImprovement;
}

// ----------------------------------------------------------------------------------------------------
// try different corner colors by slightly changing B
//
bool Block4x4Encoding_RGB8::TwiddlePlanarB() {
	bool boolImprovement = false;

	Block4x4Encoding_RGB8 encodingTry = *this;

	// init "try"
	{
		encodingTry.m_mode = MODE_PLANAR;
		encodingTry.m_boolDiff = true;
		encodingTry.m_boolFlip = false;
	}

	int iOriginBlue = encodingTry.m_frgbaColor1.IntBlue(63.0f);
	int iHorizBlue = encodingTry.m_frgbaColor2.IntBlue(63.0f);
	int iVertBlue = encodingTry.m_frgbaColor3.IntBlue(63.0f);

	for (int iTryOriginBlue = iOriginBlue - 1; iTryOriginBlue <= iOriginBlue + 1; iTryOriginBlue++) {
		// check for out of range
		if (iTryOriginBlue < 0 || iTryOriginBlue > 63) {
			continue;
		}

		encodingTry.m_frgbaColor1.fB = ((iTryOriginBlue << 2) + (iTryOriginBlue >> 4)) / 255.0f;

		for (int iTryHorizBlue = iHorizBlue - 1; iTryHorizBlue <= iHorizBlue + 1; iTryHorizBlue++) {
			// check for out of range
			if (iTryHorizBlue < 0 || iTryHorizBlue > 63) {
				continue;
			}

			encodingTry.m_frgbaColor2.fB = ((iTryHorizBlue << 2) + (iTryHorizBlue >> 4)) / 255.0f;

			for (int iTryVertBlue = iVertBlue - 1; iTryVertBlue <= iVertBlue + 1; iTryVertBlue++) {
				// check for out of range
				if (iTryVertBlue < 0 || iTryVertBlue > 63) {
					continue;
				}

				// don't bother with null twiddle
				if (iTryOriginBlue == iOriginBlue && iTryHorizBlue == iHorizBlue && iTryVertBlue == iVertBlue) {
					continue;
				}

				encodingTry.m_frgbaColor3.fB = ((iTryVertBlue << 2) + (iTryVertBlue >> 4)) / 255.0f;

				encodingTry.DecodePixels_Planar();

				encodingTry.CalcBlockError();

				if (encodingTry.m_fError < m_fError) {
					m_mode = MODE_PLANAR;
					m_boolDiff = true;
					m_boolFlip = false;
					m_frgbaColor1 = encodingTry.m_frgbaColor1;
					m_frgbaColor2 = encodingTry.m_frgbaColor2;
					m_frgbaColor3 = encodingTry.m_frgbaColor3;

					for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {
						m_afrgbaDecodedColors[uiPixel] = encodingTry.m_afrgbaDecodedColors[uiPixel];
					}

					m_fError = encodingTry.m_fError;

					boolImprovement = true;
				}
			}
		}
	}

	return boolImprovement;
}

// ----------------------------------------------------------------------------------------------------
// set the encoding bits based on encoding state
//
void Block4x4Encoding_RGB8::SetEncodingBits(void) {

	switch (m_mode) {
		case MODE_ETC1:
			Block4x4Encoding_ETC1::SetEncodingBits();
			break;

		case MODE_T:
			SetEncodingBits_T();
			break;

		case MODE_H:
			SetEncodingBits_H();
			break;

		case MODE_PLANAR:
			SetEncodingBits_Planar();
			break;

		default:
			assert(false);
	}
}

// ----------------------------------------------------------------------------------------------------
// set the encoding bits based on encoding state for T mode
//
void Block4x4Encoding_RGB8::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;

	m_pencodingbitsRGB8->t.diff = 1;

	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 for H mode
//
// colors and selectors may need to swap in order to generate lsb of distance index
//
void Block4x4Encoding_RGB8::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;
	}

	m_pencodingbitsRGB8->h.diff = 1;

	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);
	}
}

// ----------------------------------------------------------------------------------------------------
// set the encoding bits based on encoding state for Planar mode
//
void Block4x4Encoding_RGB8::SetEncodingBits_Planar(void) {
	static const bool SANITY_CHECK = true;

	assert(m_mode == MODE_PLANAR);
	assert(m_boolDiff == true);

	unsigned int uiOriginRed = (unsigned int)m_frgbaColor1.IntRed(63.0f);
	unsigned int uiOriginGreen = (unsigned int)m_frgbaColor1.IntGreen(127.0f);
	unsigned int uiOriginBlue = (unsigned int)m_frgbaColor1.IntBlue(63.0f);

	unsigned int uiHorizRed = (unsigned int)m_frgbaColor2.IntRed(63.0f);
	unsigned int uiHorizGreen = (unsigned int)m_frgbaColor2.IntGreen(127.0f);
	unsigned int uiHorizBlue = (unsigned int)m_frgbaColor2.IntBlue(63.0f);

	unsigned int uiVertRed = (unsigned int)m_frgbaColor3.IntRed(63.0f);
	unsigned int uiVertGreen = (unsigned int)m_frgbaColor3.IntGreen(127.0f);
	unsigned int uiVertBlue = (unsigned int)m_frgbaColor3.IntBlue(63.0f);

	m_pencodingbitsRGB8->planar.originRed = uiOriginRed;
	m_pencodingbitsRGB8->planar.originGreen1 = uiOriginGreen >> 6;
	m_pencodingbitsRGB8->planar.originGreen2 = uiOriginGreen;
	m_pencodingbitsRGB8->planar.originBlue1 = uiOriginBlue >> 5;
	m_pencodingbitsRGB8->planar.originBlue2 = uiOriginBlue >> 3;
	m_pencodingbitsRGB8->planar.originBlue3 = uiOriginBlue >> 1;
	m_pencodingbitsRGB8->planar.originBlue4 = uiOriginBlue;

	m_pencodingbitsRGB8->planar.horizRed1 = uiHorizRed >> 1;
	m_pencodingbitsRGB8->planar.horizRed2 = uiHorizRed;
	m_pencodingbitsRGB8->planar.horizGreen = uiHorizGreen;
	m_pencodingbitsRGB8->planar.horizBlue1 = uiHorizBlue >> 5;
	m_pencodingbitsRGB8->planar.horizBlue2 = uiHorizBlue;

	m_pencodingbitsRGB8->planar.vertRed1 = uiVertRed >> 3;
	m_pencodingbitsRGB8->planar.vertRed2 = uiVertRed;
	m_pencodingbitsRGB8->planar.vertGreen1 = uiVertGreen >> 2;
	m_pencodingbitsRGB8->planar.vertGreen2 = uiVertGreen;
	m_pencodingbitsRGB8->planar.vertBlue = uiVertBlue;

	m_pencodingbitsRGB8->planar.diff = 1;

	// create valid RG differentials and an invalid B differential to trigger planar mode
	m_pencodingbitsRGB8->planar.detect1 = 0;
	m_pencodingbitsRGB8->planar.detect2 = 0;
	m_pencodingbitsRGB8->planar.detect3 = 0;
	m_pencodingbitsRGB8->planar.detect4 = 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;
	int iBlue2 = (int)m_pencodingbitsRGB8->differential.blue1 + (int)m_pencodingbitsRGB8->differential.dblue2;
	if (iRed2 < 0 || iRed2 > 31) {
		m_pencodingbitsRGB8->planar.detect1 = 1;
	}
	if (iGreen2 < 0 || iGreen2 > 31) {
		m_pencodingbitsRGB8->planar.detect2 = 1;
	}
	if (iBlue2 >= 4) {
		m_pencodingbitsRGB8->planar.detect3 = 7;
		m_pencodingbitsRGB8->planar.detect4 = 0;
	} else {
		m_pencodingbitsRGB8->planar.detect3 = 0;
		m_pencodingbitsRGB8->planar.detect4 = 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;
		iBlue2 = (int)m_pencodingbitsRGB8->differential.blue1 + (int)m_pencodingbitsRGB8->differential.dblue2;

		// make sure red and green don't overflow and blue does
		assert(iRed2 >= 0 && iRed2 <= 31);
		assert(iGreen2 >= 0 && iGreen2 <= 31);
		assert(iBlue2 < 0 || iBlue2 > 31);
	}
}

// ----------------------------------------------------------------------------------------------------
// set the decoded colors and decoded alpha based on the encoding state for T mode
//
void Block4x4Encoding_RGB8::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;
				break;

			case 1:
				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 + frgbaDistance).ClampRGB();
				break;

			case 2:
				m_afrgbaDecodedColors[uiPixel] = m_frgbaColor2;
				break;

			case 3:
				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 - frgbaDistance).ClampRGB();
				break;
		}
	}
}

// ----------------------------------------------------------------------------------------------------
// set the decoded colors and decoded alpha based on the encoding state for H mode
//
void Block4x4Encoding_RGB8::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();
				break;

			case 1:
				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor1 - frgbaDistance).ClampRGB();
				break;

			case 2:
				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 + frgbaDistance).ClampRGB();
				break;

			case 3:
				m_afrgbaDecodedColors[uiPixel] = (m_frgbaColor2 - frgbaDistance).ClampRGB();
				break;
		}
	}
}

// ----------------------------------------------------------------------------------------------------
// set the decoded colors and decoded alpha based on the encoding state for Planar mode
//
void Block4x4Encoding_RGB8::DecodePixels_Planar(void) {

	int iRO = (int)roundf(m_frgbaColor1.fR * 255.0f);
	int iGO = (int)roundf(m_frgbaColor1.fG * 255.0f);
	int iBO = (int)roundf(m_frgbaColor1.fB * 255.0f);

	int iRH = (int)roundf(m_frgbaColor2.fR * 255.0f);
	int iGH = (int)roundf(m_frgbaColor2.fG * 255.0f);
	int iBH = (int)roundf(m_frgbaColor2.fB * 255.0f);

	int iRV = (int)roundf(m_frgbaColor3.fR * 255.0f);
	int iGV = (int)roundf(m_frgbaColor3.fG * 255.0f);
	int iBV = (int)roundf(m_frgbaColor3.fB * 255.0f);

	for (unsigned int uiPixel = 0; uiPixel < PIXELS; uiPixel++) {
		int iX = (int)(uiPixel >> 2);
		int iY = (int)(uiPixel & 3);

		int iR = (iX * (iRH - iRO) + iY * (iRV - iRO) + 4 * iRO + 2) >> 2;
		int iG = (iX * (iGH - iGO) + iY * (iGV - iGO) + 4 * iGO + 2) >> 2;
		int iB = (iX * (iBH - iBO) + iY * (iBV - iBO) + 4 * iBO + 2) >> 2;

		ColorFloatRGBA frgba;
		frgba.fR = (float)iR / 255.0f;
		frgba.fG = (float)iG / 255.0f;
		frgba.fB = (float)iB / 255.0f;
		frgba.fA = 1.0f;

		m_afrgbaDecodedColors[uiPixel] = frgba.ClampRGB();
	}
}

// ----------------------------------------------------------------------------------------------------
// perform a linear regression for the a_uiPixels in a_pafrgbaPixels[]
//
// output the closest color line using a_pfrgbaSlope and a_pfrgbaOffset
//
void Block4x4Encoding_RGB8::ColorRegression(ColorFloatRGBA *a_pafrgbaPixels, unsigned int a_uiPixels,
		ColorFloatRGBA *a_pfrgbaSlope, ColorFloatRGBA *a_pfrgbaOffset) {
	typedef struct
	{
		float f[4];
	} Float4;

	Float4 *paf4Pixels = (Float4 *)(a_pafrgbaPixels);
	Float4 *pf4Slope = (Float4 *)(a_pfrgbaSlope);
	Float4 *pf4Offset = (Float4 *)(a_pfrgbaOffset);

	float afX[MAX_PLANAR_REGRESSION_SIZE];
	float afY[MAX_PLANAR_REGRESSION_SIZE];

	// handle r, g and b separately.  don't bother with a
	for (unsigned int uiComponent = 0; uiComponent < 3; uiComponent++) {
		for (unsigned int uiPixel = 0; uiPixel < a_uiPixels; uiPixel++) {
			afX[uiPixel] = (float)uiPixel;
			afY[uiPixel] = paf4Pixels[uiPixel].f[uiComponent];
		}
		Etc::Regression(afX, afY, a_uiPixels,
				&(pf4Slope->f[uiComponent]), &(pf4Offset->f[uiComponent]));
	}
}

// ----------------------------------------------------------------------------------------------------
//
}