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55 lines
2.0 KiB
C++
55 lines
2.0 KiB
C++
/* Python-rgbcx Texture Compression Library
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Copyright (C) 2021 Andrew Cassidy <drewcassidy@me.com>
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Partially derived from rgbcx.h written by Richard Geldreich <richgel99@gmail.com>
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and licenced under the public domain
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "BC1Decoder.h"
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#include <array>
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#include <cassert>
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#include <cstdint>
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#include "../../Block.h"
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#include "../../Color.h"
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#include "BC1Block.h"
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namespace quicktex::s3tc {
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ColorBlock<4, 4> BC1Decoder::DecodeBlock(const BC1Block &block) const { return DecodeBlock(block, false); }
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ColorBlock<4, 4> BC1Decoder::DecodeBlock(const BC1Block &block, bool use_3color) const {
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auto output = ColorBlock<4, 4>();
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const auto l = block.GetLowColor();
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const auto h = block.GetHighColor();
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const auto selectors = block.UnpackSelectors();
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const auto colors = _interpolator->InterpolateBC1(l, h, use_3color);
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for (unsigned y = 0; y < 4; y++) {
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for (unsigned x = 0; x < 4; x++) {
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const auto selector = selectors[y][x];
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auto color = colors[selector];
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assert(selector < 4);
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assert((color.a == 0 && selector == 3 && l <= h) || color.a == UINT8_MAX);
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if (!write_alpha) { color.a = output.Get(x, y).a; }
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output.Set(x, y, color);
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}
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}
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return output;
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}
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} // namespace quicktex::s3tc
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