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172 lines
7.4 KiB
C++
172 lines
7.4 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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#pragma once
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#include <array>
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#include <cassert>
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#include <cstdint>
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#include <mutex>
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#include "../BlockEncoder.h"
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#include "../BlockView.h"
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#include "../Interpolator.h"
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#include "../bitwiseEnums.h"
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#include "../ndebug.h"
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#include "BC1Block.h"
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#include "OrderTable.h"
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#include "SingleColorTable.h"
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#include "tables.h"
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namespace rgbcx {
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class BC1Encoder final : public BlockEncoder<BC1Block, 4, 4> {
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public:
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using InterpolatorPtr = std::shared_ptr<Interpolator>;
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enum class Flags : uint32_t {
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None = 0,
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// Try to improve quality using the most likely total orderings.
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// The total_orderings_to_try parameter will then control the number of total orderings to try for 4 color blocks, and the
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// total_orderings_to_try3 parameter will control the number of total orderings to try for 3 color blocks (if they are enabled).
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UseLikelyTotalOrderings = 2,
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// Use 2 least squares pass, instead of one (same as stb_dxt's HIGHQUAL option).
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// Recommended if you're enabling UseLikelyTotalOrderings.
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TwoLeastSquaresPasses = 4,
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// Use3ColorBlocksForBlackPixels allows the BC1 encoder to use 3-color blocks for blocks containing black or very dark pixels.
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// You shader/engine MUST ignore the alpha channel on textures encoded with this flag.
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// Average quality goes up substantially for my 100 texture corpus (~.5 dB), so it's worth using if you can.
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// Note the BC1 encoder does not actually support transparency in 3-color mode.
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// Don't set when encoding to BC3.
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Use3ColorBlocksForBlackPixels = 8,
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// If Use3ColorBlocks is set, the encoder can use 3-color mode for a small but noticeable gain in average quality, but lower perf.
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// If you also specify the UseLikelyTotalOrderings flag, set the total_orderings_to_try3 paramter to the number of total orderings to try.
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// Don't set when encoding to BC3.
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Use3ColorBlocks = 16,
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// Iterative will greatly increase encode time, but is very slightly higher quality.
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// Same as squish's iterative cluster fit option. Not really worth the tiny boost in quality, unless you just don't care about perf. at all.
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Iterative = 32,
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// BoundingBox enables a fast all-integer PCA approximation on 4-color blocks.
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// At level 0 options (no other flags), this is ~15% faster, and higher *average* quality.
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BoundingBox = 64,
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// Use a slightly lower quality, but ~30% faster MSE evaluation function for 4-color blocks.
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UseFasterMSEEval = 128,
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// Examine all colors to compute selectors/MSE (slower than default)
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UseFullMSEEval = 256,
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// Use 2D least squares+inset+optimal rounding (the method used in Humus's GPU texture encoding demo), instead of PCA.
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// Around 18% faster, very slightly lower average quality to better (depends on the content).
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Use2DLS = 512,
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// Use 6 power iterations vs. 4 for PCA.
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Use6PowerIters = 2048,
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// Check all total orderings - *very* slow. The encoder is not designed to be used in this way.
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Exhaustive = 8192,
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// Try 2 different ways of choosing the initial endpoints.
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TryAllInitialEndpoints = 16384,
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// Same as BoundingBox, but implemented using integer math (faster, slightly less quality)
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BoundingBoxInt = 32768,
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// Try refining the final endpoints by examining nearby colors.
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EndpointSearchRoundsShift = 22,
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EndpointSearchRoundsMask = 1023U << EndpointSearchRoundsShift,
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};
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enum class ColorMode {
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Incomplete = 0x00,
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ThreeColor = 0x03,
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FourColor = 0x04,
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UseBlack = 0x10,
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Solid = 0x20,
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ThreeColorBlack = ThreeColor | UseBlack,
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ThreeColorSolid = ThreeColor | Solid,
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FourColorSolid = FourColor | Solid,
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};
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enum class ErrorMode { None, Faster, Check2, Full };
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enum class EndpointMode { LeastSquares, BoundingBox, BoundingBoxInt, PCA };
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// Unpacked BC1 block with metadata
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struct EncodeResults {
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Color low;
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Color high;
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std::array<uint8_t, 16> selectors;
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ColorMode color_mode;
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unsigned error = UINT_MAX;
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};
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BC1Encoder(InterpolatorPtr interpolator);
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void EncodeBlock(Color4x4 pixels, BC1Block *dest) const override;
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private:
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using Hash = uint16_t;
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using BlockMetrics = Color4x4::BlockMetrics;
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const InterpolatorPtr _interpolator;
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// match tables used for single-color blocks
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// Each entry includes a high and low pair that best reproduces the 8-bit index as well as possible,
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// with an included error value
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// these depend on the interpolator
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const MatchListPtr _single_match5 = SingleColorTable<5, 4>(_interpolator);
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const MatchListPtr _single_match6 = SingleColorTable<6, 4>(_interpolator);
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const MatchListPtr _single_match5_half = SingleColorTable<5, 3>(_interpolator);
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const MatchListPtr _single_match6_half = SingleColorTable<6, 3>(_interpolator);
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Flags _flags;
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ErrorMode _error_mode;
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EndpointMode _endpoint_mode;
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unsigned _search_rounds;
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unsigned _orderings4;
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unsigned _orderings3;
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static OrderTable<4> *order_table4; // order table for 3-color blocks
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static OrderTable<3> *order_table3; // order table for 4-color blocks
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static std::mutex order_table_mutex; // prevent race condition with multiple BC1Encoders constructed at once
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static bool order_tables_generated; // have the order tables been generated by a previous instance?
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void EncodeBlockSingleColor(Color color, BC1Block *dest) const;
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void EncodeBlock4Color(EncodeResults &block, BC1Block *dest) const;
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void FindEndpoints(Color4x4 pixels, EncodeResults &block, const BlockMetrics &metrics, EndpointMode endpoint_mode) const;
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void FindEndpointsSingleColor(EncodeResults &block, Color color, bool is_3color = false) const;
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void FindEndpointsSingleColor(EncodeResults &block, Color4x4 &pixels, Color color, bool is_3color) const;
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template <ColorMode M> void FindSelectors(Color4x4 &pixels, EncodeResults &block, ErrorMode error_mode) const;
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template <ColorMode M> bool RefineEndpointsLS(Color4x4 pixels, EncodeResults &block, BlockMetrics metrics) const;
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template <ColorMode M> void RefineEndpointsLS(std::array<Vector4, 17> &sums, EncodeResults &block, Vector4 &matrix, Hash hash) const;
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template <ColorMode M> void RefineBlockLS(Color4x4 &pixels, EncodeResults &block, BlockMetrics &metrics, ErrorMode error_mode, unsigned passes) const;
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};
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} // namespace rgbcx
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