raze-gles/source/common/textures/imagehelpers.cpp
2019-10-14 23:11:01 +02:00

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3.3 KiB
C++

/*
** imagehelpers.cpp
** Utilities for image conversion - mostly 8 bit paletted baggage
**
**---------------------------------------------------------------------------
** Copyright 2004-2007 Randy Heit
** Copyright 2006-2018 Christoph Oelckers
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
** derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
**
*/
#include "imagehelpers.h"
namespace ImageHelpers
{
uint8_t GrayMap[256];
PalEntry BaseColors[256];
PalEntry BasePalette[256]; // same as above, but with a being a proper alpha channel.
int WhiteIndex, BlackIndex;
int alphaThreshold;
ColorTable256k RGB256k;
int BestColor(int r, int g, int b, int first, int num)
{
const PalEntry* pal = BaseColors;
int bestcolor = first;
int bestdist = 257 * 257 + 257 * 257 + 257 * 257;
for (int color = first; color < num; color++)
{
if (pal[color].a > 0) continue; // marks a fullbright color which we should not pick here
int x = r - pal[color].r;
int y = g - pal[color].g;
int z = b - pal[color].b;
int dist = x * x + y * y + z * z;
if (dist < bestdist)
{
if (dist == 0)
return color;
bestdist = dist;
bestcolor = color;
}
}
return bestcolor;
}
void SetPalette(const PalEntry* colors)
{
for (int i = 0; i < 255; i++)
{
BasePalette[i] = BaseColors[i] = colors[i];
BasePalette[i].a = 255;
}
BasePalette[255] = BaseColors[255] = 0; // 255 is always translucent black - whatever color the original data has here
// Find white and black from the original palette so that they can be
// used to make an educated guess of the translucency % for a
// translucency map.
WhiteIndex = BestColor(255, 255, 255);
BlackIndex = BestColor(0, 0, 0);
// create the RGB666 lookup table
for (int r = 0; r < 64; r++)
for (int g = 0; g < 64; g++)
for (int b = 0; b < 64; b++)
RGB256k.RGB[r][g][b] = BestColor((r<<2)|(r>>4), (g<<2)|(g>>4), (b<<2)|(b>>4));
}
}