mirror of
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93 lines
3.5 KiB
C++
93 lines
3.5 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 2020 <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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#pragma once
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#include <climits>
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#include <cstdint>
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#include <memory>
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#include <string>
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#include "BlockView.h"
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namespace quicktex {
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class BlockEncoder {
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public:
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using EncoderPtr = std::shared_ptr<BlockEncoder>;
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virtual ~BlockEncoder() = default;
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virtual void EncodeImage(uint8_t *encoded, Color *decoded, unsigned image_width, unsigned image_height) const = 0;
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virtual size_t BlockSize() const = 0;
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virtual size_t BlockWidth() const = 0;
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virtual size_t BlockHeight() const = 0;
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};
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template <class B, size_t M, size_t N> class BlockEncoderTemplate : public BlockEncoder {
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public:
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using DecodedBlock = ColorBlockView<M, N>;
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using EncodedBlock = B;
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BlockEncoderTemplate() noexcept = default;
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virtual ~BlockEncoderTemplate() noexcept = default;
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virtual void EncodeBlock(DecodedBlock pixels, EncodedBlock *dest) const = 0;
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virtual void EncodeImage(uint8_t *encoded, Color *decoded, unsigned image_width, unsigned image_height) const override {
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assert(image_width % N == 0);
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assert(image_width % M == 0);
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unsigned block_width = image_width / N;
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unsigned block_height = image_height / M;
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auto blocks = reinterpret_cast<B *>(encoded);
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// from experimentation, multithreading this using OpenMP sometimes actually makes decoding slower
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// due to thread creation/teardown taking longer than the decoding process itself.
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// As a result, this is sometimes left as a serial operation despite being embarassingly parallelizable
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// threshold for number of blocks before multithreading is set by overriding MTThreshold()
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#pragma omp parallel for if (block_width * block_height >= MTThreshold())
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for (int y = 0; y < (int)block_height; y++) {
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for (int x = 0; x < (int)block_width; x++) {
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unsigned pixel_x = (unsigned)x * N;
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unsigned pixel_y = (unsigned)y * M;
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assert(pixel_x >= 0);
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assert(pixel_y >= 0);
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assert(pixel_y + M <= image_height);
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assert(pixel_x + N <= image_width);
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unsigned top_left = pixel_x + (pixel_y * image_width);
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unsigned block_index = (unsigned)x + (block_width * (unsigned)y);
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auto src = DecodedBlock(&decoded[top_left], (int)image_width);
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EncodeBlock(src, &blocks[block_index]);
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}
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}
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}
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virtual size_t BlockSize() const override { return sizeof(B); }
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virtual size_t BlockWidth() const override { return N; }
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virtual size_t BlockHeight() const override { return M; }
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virtual size_t MTThreshold() const { return SIZE_MAX; };
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};
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} // namespace quicktex
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