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quicktex/src/BC1/BC1Decoder.cpp

47 lines
1.7 KiB
C++

/* Python-rgbcx Texture Compression Library
Copyright (C) 2021 Andrew Cassidy <drewcassidy@me.com>
Partially derived from rgbcx.h written by Richard Geldreich <richgel99@gmail.com>
and licenced under the public domain
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "BC1Decoder.h"
#include "../ColorBlock.h"
#include "../blocks.h"
namespace rgbcx {
void BC1Decoder::DecodeBlock(Color4x4 dest, BC1Block *const block) const {
const auto l = block->GetLowColor();
const auto h = block->GetHighColor();
const auto selectors = block->UnpackSelectors();
const auto colors = _interpolator.InterpolateBC1(l, h);
for (unsigned y = 0; y < 4; y++) {
for (unsigned x = 0; x < 4; x++) {
const auto selector = selectors[y][x];
const auto color = colors[selector];
assert(selector < 4);
assert((color.a == 0 && selector == 3 && l <= h) || color.a == UINT8_MAX);
if (_write_alpha) {
dest[y][x].SetRGBA(color);
} else {
dest[y][x].SetRGB(color);
}
}
}
}
} // namespace rgbcx