godot/thirdparty/etc2comp/EtcFilter.cpp

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#include <stdlib.h>
#include <math.h>
#include "EtcFilter.h"
namespace Etc
{
static const double PiConst = 3.14159265358979323846;
inline double sinc(double x)
{
if ( x == 0.0 )
{
return 1.0;
}
return sin(PiConst * x) / (PiConst * x);
}
//inline float sincf( float x )
//{
// x *= F_PI;
// if (x < 0.01f && x > -0.01f)
// {
// return 1.0f + x*x*(-1.0f/6.0f + x*x*1.0f/120.0f);
// }
//
// return sinf(x)/x;
//}
//
//double bessel0(double x)
//{
// const double EPSILON_RATIO = 1E-16;
// double xh, sum, pow, ds;
// int k;
//
// xh = 0.5 * x;
// sum = 1.0;
// pow = 1.0;
// k = 0;
// ds = 1.0;
// while (ds > sum * EPSILON_RATIO)
// {
// ++k;
// pow = pow * (xh / k);
// ds = pow * pow;
// sum = sum + ds;
// }
//
// return sum;
//}
//**--------------------------------------------------------------------------
//** Name: kaiser(double alpha, double half_width, double x)
//** Returns:
//** Description: Alpha controls shape of filter. We are using 4.
//**--------------------------------------------------------------------------
//inline double kaiser(double alpha, double half_width, double x)
//{
// double ratio = (x / half_width);
// return bessel0(alpha * sqrt(1 - ratio * ratio)) / bessel0(alpha);
//}
//
//float Filter_Lanczos4Sinc(float x)
//{
// if (x <= -4.0f || x >= 4.0f) // half-width of 4
// {
// return 0.0;
// }
//
// return sinc(0.875f * x) * sinc(0.25f * x);
//}
//
//double Filter_Kaiser4( double t )
//{
// return kaiser( 4.0, 3.0, t);
//}
//
//double Filter_KaiserOptimal( double t )
//{
// return kaiser( 8.93, 3.0f, t);
//}
double FilterLanczos3( double t )
{
if ( t <= -3.0 || t >= 3.0 )
{
return 0.0;
}
return sinc( t ) * sinc( t / 3.0 );
}
double FilterBox( double t )
{
return ( t > -0.5 && t < 0.5) ? 1.0 : 0.0;
}
double FilterLinear( double t )
{
if (t < 0.0) t = -t;
return (t < 1.0) ? (1.0 - t) : 0.0;
}
//**--------------------------------------------------------------------------
//** Name: CalcContributions( int srcSize,
//** int destSize,
//** double filterSize,
//** bool wrap,
//** double (*FilterProc)(double),
//** FilterWeights contrib[] )
//** Returns: void
//** Description:
//**--------------------------------------------------------------------------
void CalcContributions( int srcSize, int destSize, double filterSize, bool wrap, double (*FilterProc)(double), FilterWeights contrib[] )
{
double scale;
double filterScale;
double center;
double totalWeight;
double weight;
int iRight;
int iLeft;
int iDest;
scale = (double)destSize / srcSize;
if ( scale < 1.0 )
{
filterSize = filterSize / scale;
filterScale = scale;
}
else
{
filterScale = 1.0;
}
if ( filterSize > (double)MaxFilterSize )
{
filterSize = (double)MaxFilterSize;
}
for ( iDest = 0; iDest < destSize; ++iDest )
{
center = (double)iDest / scale;
iLeft = (int)ceil(center - filterSize);
iRight = (int)floor(center + filterSize);
if ( !wrap )
{
if ( iLeft < 0 )
{
iLeft = 0;
}
if ( iRight >= srcSize )
{
iRight = srcSize - 1;
}
}
int numWeights = iRight - iLeft + 1;
contrib[iDest].first = iLeft;
contrib[iDest].numWeights = numWeights;
totalWeight = 0;
double t = ((double)iLeft - center) * filterScale;
for (int i = 0; i < numWeights; i++)
{
weight = (*FilterProc)(t) * filterScale;
totalWeight += weight;
contrib[iDest].weight[i] = weight;
t += filterScale;
}
//**--------------------------------------------------------
//** Normalize weights by dividing by the sum of the weights
//**--------------------------------------------------------
if ( totalWeight > 0.0 )
{
for ( int i = 0; i < numWeights; i++)
{
contrib[iDest].weight[i] /= totalWeight;
}
}
}
}
//**-------------------------------------------------------------------------
//** Name: Filter_TwoPass( RGBCOLOR *pSrcImage,
//** int srcWidth, int srcHeight,
//** RGBCOLOR *pDestImage,
//** int destWidth, int destHeight,
//** double (*FilterProc)(double) )
//** Returns: 0 on failure and 1 on success
//** Description: Filters a 2d image with a two pass filter by averaging the
//** weighted contributions of the pixels within the filter region. The
//** contributions are determined by a weighting function parameter.
//**-------------------------------------------------------------------------
int FilterTwoPass( RGBCOLOR *pSrcImage, int srcWidth, int srcHeight,
RGBCOLOR *pDestImage, int destWidth, int destHeight, unsigned int wrapFlags, double (*FilterProc)(double) )
{
FilterWeights *contrib;
RGBCOLOR *pPixel;
RGBCOLOR *pSrcPixel;
RGBCOLOR *pTempImage;
int iRow;
int iCol;
int iSrcCol;
int iSrcRow;
int iWeight;
double dRed;
double dGreen;
double dBlue;
double dAlpha;
double filterSize = 3.0;
int maxDim = (srcWidth>srcHeight)?srcWidth:srcHeight;
contrib = (FilterWeights*)malloc(maxDim * sizeof(FilterWeights));
//**------------------------------------------------------------------------
//** Need to create a temporary image to stuff the horizontally scaled image
//**------------------------------------------------------------------------
pTempImage = (RGBCOLOR *)malloc( destWidth * srcHeight * sizeof(RGBCOLOR) );
if ( pTempImage == NULL )
{
return 0;
}
//**-------------------------------------------------------
//** Horizontally filter the image into the temporary image
//**-------------------------------------------------------
bool bWrapHorizontal = !!(wrapFlags&FILTER_WRAP_X);
CalcContributions( srcWidth, destWidth, filterSize, bWrapHorizontal, FilterProc, contrib );
for ( iRow = 0; iRow < srcHeight; iRow++ )
{
for ( iCol = 0; iCol < destWidth; iCol++ )
{
dRed = 0;
dGreen = 0;
dBlue = 0;
dAlpha = 0;
for ( iWeight = 0; iWeight < contrib[iCol].numWeights; iWeight++ )
{
iSrcCol = iWeight + contrib[iCol].first;
if (bWrapHorizontal)
{
iSrcCol = (iSrcCol < 0) ? (srcWidth + iSrcCol) : (iSrcCol >= srcWidth) ? (iSrcCol - srcWidth) : iSrcCol;
}
pSrcPixel = pSrcImage + (iRow * srcWidth) + iSrcCol;
dRed += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[0];
dGreen += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[1];
dBlue += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[2];
dAlpha += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[3];
}
pPixel = pTempImage + (iRow * destWidth) + iCol;
pPixel->rgba[0] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dRed)));
pPixel->rgba[1] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dGreen)));
pPixel->rgba[2] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dBlue)));
pPixel->rgba[3] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dAlpha)));
}
}
//**-------------------------------------------------------
//** Vertically filter the image into the destination image
//**-------------------------------------------------------
bool bWrapVertical = !!(wrapFlags&FILTER_WRAP_Y);
CalcContributions(srcHeight, destHeight, filterSize, bWrapVertical, FilterProc, contrib);
for ( iCol = 0; iCol < destWidth; iCol++ )
{
for ( iRow = 0; iRow < destHeight; iRow++ )
{
dRed = 0;
dGreen = 0;
dBlue = 0;
dAlpha = 0;
for ( iWeight = 0; iWeight < contrib[iRow].numWeights; iWeight++ )
{
iSrcRow = iWeight + contrib[iRow].first;
if (bWrapVertical)
{
iSrcRow = (iSrcRow < 0) ? (srcHeight + iSrcRow) : (iSrcRow >= srcHeight) ? (iSrcRow - srcHeight) : iSrcRow;
}
pSrcPixel = pTempImage + (iSrcRow * destWidth) + iCol;
dRed += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[0];
dGreen += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[1];
dBlue += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[2];
dAlpha += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[3];
}
pPixel = pDestImage + (iRow * destWidth) + iCol;
pPixel->rgba[0] = (unsigned char)(std::max( 0.0, std::min( 255.0, dRed)));
pPixel->rgba[1] = (unsigned char)(std::max( 0.0, std::min( 255.0, dGreen)));
pPixel->rgba[2] = (unsigned char)(std::max( 0.0, std::min( 255.0, dBlue)));
pPixel->rgba[3] = (unsigned char)(std::max( 0.0, std::min( 255.0, dAlpha)));
}
}
free( pTempImage );
free( contrib );
return 1;
}
//**-------------------------------------------------------------------------
//** Name: FilterResample(RGBCOLOR *pSrcImage, int srcWidth, int srcHeight,
//** RGBCOLOR *pDstImage, int dstWidth, int dstHeight)
//** Returns: 1
//** Description: This function runs a 2d box filter over the srouce image
//** to produce the destination image.
//**-------------------------------------------------------------------------
void FilterResample( RGBCOLOR *pSrcImage, int srcWidth, int srcHeight,
RGBCOLOR *pDstImage, int dstWidth, int dstHeight )
{
int iRow;
int iCol;
int iSampleRow;
int iSampleCol;
int iFirstSampleRow;
int iFirstSampleCol;
int iLastSampleRow;
int iLastSampleCol;
int red;
int green;
int blue;
int alpha;
int samples;
float xScale;
float yScale;
RGBCOLOR *pSrcPixel;
RGBCOLOR *pDstPixel;
xScale = (float)srcWidth / dstWidth;
yScale = (float)srcHeight / dstHeight;
for ( iRow = 0; iRow < dstHeight; iRow++ )
{
for ( iCol = 0; iCol < dstWidth; iCol++ )
{
iFirstSampleRow = (int)(iRow * yScale);
iLastSampleRow = (int)ceil(iFirstSampleRow + yScale - 1);
if ( iLastSampleRow >= srcHeight )
{
iLastSampleRow = srcHeight - 1;
}
iFirstSampleCol = (int)(iCol * xScale);
iLastSampleCol = (int)ceil(iFirstSampleCol + xScale - 1);
if ( iLastSampleCol >= srcWidth )
{
iLastSampleCol = srcWidth - 1;
}
samples = 0;
red = 0;
green = 0;
blue = 0;
alpha = 0;
for ( iSampleRow = iFirstSampleRow; iSampleRow <= iLastSampleRow; iSampleRow++ )
{
for ( iSampleCol = iFirstSampleCol; iSampleCol <= iLastSampleCol; iSampleCol++ )
{
pSrcPixel = pSrcImage + iSampleRow * srcWidth + iSampleCol;
red += pSrcPixel->rgba[0];
green += pSrcPixel->rgba[1];
blue += pSrcPixel->rgba[2];
alpha += pSrcPixel->rgba[3];
samples++;
}
}
pDstPixel = pDstImage + iRow * dstWidth + iCol;
if ( samples > 0 )
{
pDstPixel->rgba[0] = static_cast<uint8_t>(red / samples);
pDstPixel->rgba[1] = static_cast<uint8_t>(green / samples);
pDstPixel->rgba[2] = static_cast<uint8_t>(blue / samples);
pDstPixel->rgba[3] = static_cast<uint8_t>(alpha / samples);
}
else
{
pDstPixel->rgba[0] = static_cast<uint8_t>(red);
pDstPixel->rgba[1] = static_cast<uint8_t>(green);
pDstPixel->rgba[2] = static_cast<uint8_t>(blue);
pDstPixel->rgba[3] = static_cast<uint8_t>(alpha);
}
}
}
}
}