Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
//
//===========================================================================//
#include <tier0/platform.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include "bitmap/float_bm.h"
static float ScaleValue(float f, float overbright)
{
// map a value between 0..255 to the scale factor
int ival=f;
return ival*(overbright/255.0);
}
static float IScaleValue(float f, float overbright)
{
f*=(1.0/overbright);
int ival=min(255,(int)ceil(f*255.0));
return ival;
}
void MaybeSetScaleVaue(FloatBitMap_t const &orig, FloatBitMap_t &newbm, int x, int y,
float newscale, float overbright)
{
// clamp the given scale value to the legal range for that pixel and regnerate the rgb
// components.
float maxc=max(max(orig.Pixel(x,y,0),orig.Pixel(x,y,1)),orig.Pixel(x,y,2));
if (maxc==0.0)
{
// pixel is black. any scale value is fine.
newbm.Pixel(x,y,3)=newscale;
for(int c=0;c<3;c++)
newbm.Pixel(x,y,c)=0;
}
else
{
// float desired_floatscale=maxc;
float scale_we_will_get=ScaleValue(newscale,overbright);
// if (scale_we_will_get >= desired_floatscale )
{
newbm.Pixel(x,y,3)=newscale;
for(int c=0;c<3;c++)
newbm.Pixel(x,y,c)=orig.Pixel(x,y,c)/(scale_we_will_get);
}
}
}
void FloatBitMap_t::Uncompress(float overbright)
{
for(int y=0;y<Height;y++)
for(int x=0;x<Width;x++)
{
int iactual_alpha_value=255.0*Pixel(x,y,3);
float actual_alpha_value=iactual_alpha_value*(1.0/255.0);
for(int c=0;c<3;c++)
{
int iactual_color_value=255.0*Pixel(x,y,c);
float actual_color_value=iactual_color_value*(1.0/255.0);
Pixel(x,y,c)=actual_alpha_value*actual_color_value*overbright;
}
}
}
#define GAUSSIAN_WIDTH 5
#define SQ(x) ((x)*(x))
void FloatBitMap_t::CompressTo8Bits(float overbright)
{
FloatBitMap_t TmpFBM(Width,Height);
// first, saturate to max overbright
for(int y=0;y<Height;y++)
for(int x=0;x<Width;x++)
for(int c=0;c<3;c++)
Pixel(x,y,c)=min(overbright,Pixel(x,y,c));
// first pass - choose nominal scale values to convert to rgb,scale
for(int y=0;y<Height;y++)
for(int x=0;x<Width;x++)
{
// determine maximum component
float maxc=max(max(Pixel(x,y,0),Pixel(x,y,1)),Pixel(x,y,2));
if (maxc==0)
{
for(int c=0;c<4;c++)
TmpFBM.Pixel(x,y,c)=0;
}
else
{
float desired_floatscale=maxc;
float closest_iscale=IScaleValue(desired_floatscale, overbright);
float scale_value_we_got=ScaleValue(closest_iscale, overbright );
TmpFBM.Pixel(x,y,3)=closest_iscale;
for(int c=0;c<3;c++)
TmpFBM.Pixel(x,y,c)=Pixel(x,y,c)/scale_value_we_got;
}
}
// now, refine scale values
#ifdef FILTER_TO_REDUCE_LERP_ARTIFACTS
// I haven't been able to come up with a filter which eleiminates objectionable artifacts on all
// source textures. So, I've gone to doing the lerping in the shader.
int pass=0;
while(pass<1)
{
FloatBitMap_t temp_filtered(&TmpFBM);
for(int y=0;y<Height;y++)
{
for(int x=0;x<Width;x++)
{
float sum_scales=0.0;
float sum_weights=0.0;
for(int yofs=-GAUSSIAN_WIDTH;yofs<=GAUSSIAN_WIDTH;yofs++)
for(int xofs=-GAUSSIAN_WIDTH;xofs<=GAUSSIAN_WIDTH;xofs++)
{
float r=0.456*GAUSSIAN_WIDTH;
r=0.26*GAUSSIAN_WIDTH;
float x1=xofs/r;
float y1=yofs/r;
float a=(SQ(x1)+SQ(y1))/(2.0*SQ(r));
float w=exp(-a);
sum_scales+=w*TmpFBM.PixelClamped(x+xofs,y+yofs,3);
sum_weights+=w;
}
int new_trial_scale=sum_scales*(1.0/sum_weights);
MaybeSetScaleVaue(*this,temp_filtered,x,y,new_trial_scale,overbright);
}
}
pass++;
memcpy(TmpFBM.RGBAData,temp_filtered.RGBAData,Width*Height*4*sizeof(float));
}
#endif
memcpy(RGBAData,TmpFBM.RGBAData,Width*Height*4*sizeof(float));
// now, map scale to real value
for(int y=0;y<Height;y++)
for(int x=0;x<Width;x++)
Pixel(x,y,3)*=(1.0/255.0);
}