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Add (extremely bad) BC1 encoding support

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Andrew Cassidy 2021-02-18 02:43:57 -08:00
parent 628ad558d8
commit c879061e4e
5 changed files with 388 additions and 29 deletions
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175
src/BC1/BC1Encoder.cpp Normal file
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@ -0,0 +1,175 @@
/* 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 "BC1Encoder.h"
#include <cstdint>
#include <memory>
#include "../BlockView.h"
#include "../Color.h"
#include "../bitwiseEnums.h"
namespace rgbcx {
using MatchList = std::array<BC1MatchEntry, 256>;
using MatchListPtr = std::shared_ptr<MatchList>;
using InterpolatorPtr = std::shared_ptr<Interpolator>;
// region Free Functions/Templates
inline void PrepSingleColorTableEntry(unsigned &error, MatchList &match_table, uint8_t v, unsigned i, uint8_t low, uint8_t high, uint8_t low8, uint8_t high8,
bool ideal) {
unsigned new_error = iabs(v - (int)i);
// We only need to factor in 3% error in BC1 ideal mode.
if (ideal) new_error += (iabs(high8 - (int)low8) * 3) / 100;
// Favor equal endpoints, for lower error on actual GPU's which approximate the interpolation.
if ((new_error < error) || (new_error == error && low == high)) {
assert(new_error <= UINT8_MAX);
match_table[i].low = (uint8_t)low;
match_table[i].high = (uint8_t)high;
match_table[i].error = (uint8_t)new_error;
error = new_error;
}
}
template <size_t S> void PrepSingleColorTable(MatchList &match_table, MatchList &match_table_half, Interpolator &interpolator) {
unsigned size = 1 << S;
assert((S == 5 && size == 32) || (S == 6 && size == 64));
bool ideal = interpolator.IsIdeal();
bool use_8bit = interpolator.CanInterpolate8Bit();
for (unsigned i = 0; i < 256; i++) {
unsigned error = 256;
unsigned error_half = 256;
// TODO: Can probably avoid testing for values that definitely wont yield good results,
// e.g. low8 and high8 both much smaller or larger than index
for (uint8_t low = 0; low < size; low++) {
uint8_t low8 = (S == 5) ? scale5To8(low) : scale6To8(low);
for (uint8_t high = 0; high < size; high++) {
uint8_t high8 = (S == 5) ? scale5To8(high) : scale6To8(low);
uint8_t value, value_half;
if (use_8bit) {
value = interpolator.Interpolate8(high8, low8);
value_half = interpolator.InterpolateHalf8(high8, low8);
} else {
value = (S == 5) ? interpolator.Interpolate5(high, low) : interpolator.Interpolate6(high, low);
value_half = (S == 5) ? interpolator.InterpolateHalf5(high, low) : interpolator.InterpolateHalf6(high, low);
}
PrepSingleColorTableEntry(error, match_table, value, i, low, high, low8, high8, ideal);
PrepSingleColorTableEntry(error_half, match_table_half, value_half, i, low, high, low8, high8, ideal);
}
}
}
}
// endregion
BC1Encoder::BC1Encoder(InterpolatorPtr interpolator) : _interpolator(interpolator) {
PrepSingleColorTable<5>(*_single_match5, *_single_match5_half, *_interpolator);
PrepSingleColorTable<6>(*_single_match6, *_single_match6_half, *_interpolator);
}
void BC1Encoder::EncodeBlock(Color4x4 pixels, BC1Block *dest) const {
auto r_view = pixels.GetChannel(0);
auto g_view = pixels.GetChannel(1);
auto b_view = pixels.GetChannel(2);
if (pixels.IsSingleColor() || true) { // for now assume (wrongly) everything is a single-color block
// single-color pixel block, do it the fast way
EncodeBlockSingleColor(pixels.Get(0, 0), dest);
return;
}
Color min, max, avg;
pixels.GetMinMaxAvgRGB(min, max, avg);
}
void BC1Encoder::EncodeBlockSingleColor(Color color, BC1Block *dest) const {
uint8_t mask = 0xAA; // 2222
uint16_t min16, max16;
bool using_3color = false;
// why is there no subscript operator for shared_ptr<array>
MatchList &match5 = *_single_match5;
MatchList &match6 = *_single_match6;
MatchList &match5_half = *_single_match5_half;
MatchList &match6_half = *_single_match6_half;
BC1MatchEntry match_r = match5[color.r];
BC1MatchEntry match_g = match6[color.g];
BC1MatchEntry match_b = match5[color.b];
if ((_flags & (Flags::Use3ColorBlocks | Flags::Use3ColorBlocksForBlackPixels)) != Flags::None) {
BC1MatchEntry match_r_half = match5_half[color.r];
BC1MatchEntry match_g_half = match6_half[color.g];
BC1MatchEntry match_b_half = match5_half[color.b];
const unsigned err4 = match_r.error + match_g.error + match_b.error;
const unsigned err3 = match_r_half.error + match_g_half.error + match_b_half.error;
if (err3 < err4) {
min16 = Color::Pack565Unscaled(match_r_half.low, match_g_half.low, match_b_half.low);
max16 = Color::Pack565Unscaled(match_r_half.high, match_g_half.high, match_b_half.high);
if (max16 > min16) std::swap(min16, max16);
using_3color = true;
}
}
if (!using_3color) {
min16 = Color::Pack565Unscaled(match_r.low, match_g.low, match_b.low);
max16 = Color::Pack565Unscaled(match_r.high, match_g.high, match_b.high);
if (min16 == max16) {
// make sure this isnt accidentally a 3-color block
// so make max16 > min16 (l > h)
if (min16 > 0) {
min16--;
mask = 0; // endpoints are equal so mask doesnt matter
} else {
assert(min16 == 0 && max16 == 0);
max16 = 1;
min16 = 0;
mask = 0x55; // 1111 (min value only, max is ignored)
}
} else if (max16 < min16) {
std::swap(min16, max16);
mask = 0xFF; // invert mask to 3333
}
assert(max16 > min16);
}
dest->SetLowColor(max16);
dest->SetHighColor(min16);
dest->selectors[0] = mask;
dest->selectors[1] = mask;
dest->selectors[2] = mask;
dest->selectors[3] = mask;
}
} // namespace rgbcx

145
src/BC1/BC1Encoder.h Normal file
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@ -0,0 +1,145 @@
/* 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/>.
*/
#pragma once
#include <array>
#include <cassert>
#include <cstdint>
#include <mutex>
#include "../BlockEncoder.h"
#include "../BlockView.h"
#include "../Interpolator.h"
#include "../bitwiseEnums.h"
#include "../ndebug.h"
#include "../tables.h"
#include "BC1Block.h"
namespace rgbcx {
struct BC1MatchEntry {
uint8_t high;
uint8_t low;
uint8_t error;
};
class BC1Encoder : public BlockEncoder<BC1Block, 4, 4> {
public:
using InterpolatorPtr = std::shared_ptr<Interpolator>;
enum class Flags : uint32_t {
None = 0,
// Try to improve quality using the most likely total orderings.
// The total_orderings_to_try parameter will then control the number of total orderings to try for 4 color blocks, and the
// total_orderings_to_try3 parameter will control the number of total orderings to try for 3 color blocks (if they are enabled).
UseLikelyTotalOrderings = 2,
// Use 2 least squares pass, instead of one (same as stb_dxt's HIGHQUAL option).
// Recommended if you're enabling UseLikelyTotalOrderings.
TwoLeastSquaresPasses = 4,
// Use3ColorBlocksForBlackPixels allows the BC1 encoder to use 3-color blocks for blocks containing black or very dark pixels.
// You shader/engine MUST ignore the alpha channel on textures encoded with this flag.
// Average quality goes up substantially for my 100 texture corpus (~.5 dB), so it's worth using if you can.
// Note the BC1 encoder does not actually support transparency in 3-color mode.
// Don't set when encoding to BC3.
Use3ColorBlocksForBlackPixels = 8,
// If Use3ColorBlocks is set, the encoder can use 3-color mode for a small but noticeable gain in average quality, but lower perf.
// If you also specify the UseLikelyTotalOrderings flag, set the total_orderings_to_try3 paramter to the number of total orderings to try.
// Don't set when encoding to BC3.
Use3ColorBlocks = 16,
// Iterative will greatly increase encode time, but is very slightly higher quality.
// 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.
Iterative = 32,
// BoundingBox enables a fast all-integer PCA approximation on 4-color blocks.
// At level 0 options (no other flags), this is ~15% faster, and higher *average* quality.
BoundingBox = 64,
// Use a slightly lower quality, but ~30% faster MSE evaluation function for 4-color blocks.
UseFasterMSEEval = 128,
// Examine all colors to compute selectors/MSE (slower than default)
UseFullMSEEval = 256,
// Use 2D least squares+inset+optimal rounding (the method used in Humus's GPU texture encoding demo), instead of PCA.
// Around 18% faster, very slightly lower average quality to better (depends on the content).
Use2DLS = 512,
// Use 6 power iterations vs. 4 for PCA.
Use6PowerIters = 2048,
// Check all total orderings - *very* slow. The encoder is not designed to be used in this way.
Exhaustive = 8192,
// Try 2 different ways of choosing the initial endpoints.
TryAllInitialEndponts = 16384,
// Same as BoundingBox, but implemented using integer math (faster, slightly less quality)
BoundingBoxInt = 32768,
// Try refining the final endpoints by examining nearby colors.
EndpointSearchRoundsShift = 22,
EndpointSearchRoundsMask = 1023U << EndpointSearchRoundsShift,
};
BC1Encoder(InterpolatorPtr interpolator);
void EncodeBlock(Color4x4 pixels, BC1Block *dest) const override;
private:
const InterpolatorPtr _interpolator;
Flags _flags;
unsigned _search_rounds;
unsigned _orderings4;
unsigned _orderings3;
void EncodeBlockSingleColor(Color color, BC1Block *dest) const;
// match tables used for single-color blocks
// Each entry includes a high and low pair that best reproduces the 8-bit index as well as possible,
// with an included error value
// these depend on the interpolator
using MatchList = std::array<BC1MatchEntry, 256>;
using MatchListPtr = std::shared_ptr<MatchList>;
const MatchListPtr _single_match5 = std::make_shared<MatchList>();
const MatchListPtr _single_match6 = std::make_shared<MatchList>();
const MatchListPtr _single_match5_half = std::make_shared<MatchList>();
const MatchListPtr _single_match6_half = std::make_shared<MatchList>();
// static lookup tables, generated the first time an encoder is created
// the mutex prevents race conditions if two encoders are created on different threads
static std::mutex _luts_mutex;
static bool _luts_initialized;
// lookup table for hash values
static uint16_t g_total_ordering4_hash[4096];
static uint16_t g_total_ordering3_hash[256];
static float g_selector_factors4[NUM_UNIQUE_TOTAL_ORDERINGS4][3];
static float g_selector_factors3[NUM_UNIQUE_TOTAL_ORDERINGS3][3];
};
} // namespace rgbcx

31
src/BlockView.h
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@ -81,6 +81,9 @@ template <typename S, size_t M, size_t N> class BlockView {
start[(row_stride * (int)y) + (pixel_stride * (int)x)] = value;
}
constexpr S &Get(unsigned i) noexcept(ndebug) { return Get(i % N, i / N); }
constexpr S Get(unsigned i) const noexcept(ndebug) { return Get(i % N, i / N); }
constexpr std::array<S, M * N> Flatten() noexcept {
std::array<S, M * N> result;
for (unsigned x = 0; x < N; x++) {
@ -108,6 +111,34 @@ template <size_t M, size_t N> class ColorBlockView : public BlockView<Color, M,
}
void SetRGB(unsigned x, unsigned y, Color value) noexcept(ndebug) { Base::Get(x, y).SetRGB(value); }
bool IsSingleColor() {
auto first = Base::Get(0, 0);
for (unsigned j = 1; j < M * N; j++) {
if (Base::Get(j) != first) return false;
}
return true;
}
void GetMinMaxAvgRGB(Color &min, Color &max, Color &avg) {
min = Base::Get(0, 0);
max = Base::Get(0, 0);
std::array<unsigned, 3> sums;
for (unsigned i = 1; i < M * N; i++) {
auto val = Base::Get(i);
for (unsigned c = 0; c < 3; c++) {
if (val[c] < min[c]) {
min[c] = val[c];
} else {
max[c] = val[c];
}
sums[c] += val[c];
}
}
for (unsigned c = 0; c < 3; c++) { avg[c] = (uint8_t)(sums[c] / (M * N)); }
}
};
using Color4x4 = ColorBlockView<4, 4>;

61
src/Interpolator.h
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@ -52,6 +52,16 @@ class Interpolator {
*/
virtual uint8_t Interpolate6(uint8_t v0, uint8_t v1) const;
/**
* Performs a 2/3 interpolation of a pair of 8-bit values to produce an 8-bit value
* Output is approximately (2v0 + v1)/3.
* Output is not guranteed to be accurate for the given interpolator if CanInterpolate8Bit() is false
* @param v0 The first 8-bit value
* @param v1 The second 8-bit value
* @return The interpolated value
*/
virtual uint8_t Interpolate8(uint8_t v0, uint8_t v1) const;
/**
* Performs a 1/2 interpolation of a pair of 5-bit values to produce an 8-bit value
* Output is approximately (v0 + v1)/2, with v0 and v1 first extended to 8 bits.
@ -70,6 +80,16 @@ class Interpolator {
*/
virtual uint8_t InterpolateHalf6(uint8_t v0, uint8_t v1) const;
/**
* Performs a 1/2 interpolation of a pair of 8-bit values to produce an 8-bit value
* Output is approximately (v0 + v1)/2.
* Output is not guranteed to be accurate for the given interpolator if CanInterpolate8Bit() is false
* @param v0 The first 8-bit value
* @param v1 The second 8-bit value
* @return The interpolated value
*/
virtual uint8_t InterpolateHalf8(uint8_t v0, uint8_t v1) const;
/**
* Generates the 4 colors for a BC1 block from the given 5:6:5-packed colors
* @param low first 5:6:5 color for the block
@ -84,6 +104,8 @@ class Interpolator {
*/
virtual Type GetType() const noexcept { return Type::Ideal; }
virtual bool CanInterpolate8Bit() const noexcept { return true; }
/**
* Checks if the interpolator uses an ideal algorithm
* @return true if the interpolator is ideal, false otherwise.
@ -94,21 +116,6 @@ class Interpolator {
}
private:
virtual uint8_t Interpolate8(uint8_t v0, uint8_t v1) const;
virtual uint8_t InterpolateHalf8(uint8_t v0, uint8_t v1) const;
// constexpr static auto Expand5 = ExpandArray<Size5, scale5To8>();
// constexpr static auto Expand6 = ExpandArray<size6, scale6To8>();
//
// // match tables used for single-color blocks
// using MatchList = std::array<MatchEntry, match_count>;
// using MatchListPtr = std::shared_ptr<MatchList>;
//
// const MatchListPtr _single_match5 = {std::make_shared<MatchList>()};
// const MatchListPtr _single_match6 = {std::make_shared<MatchList>()};
// const MatchListPtr _single_match5_half = {std::make_shared<MatchList>()};
// const MatchListPtr _single_match6_half = {std::make_shared<MatchList>()};
Color InterpolateColor24(const Color &c0, const Color &c1) const {
return Color(Interpolate8(c0.r, c1.r), Interpolate8(c0.g, c1.g), Interpolate8(c0.b, c1.b));
}
@ -116,33 +123,29 @@ class Interpolator {
Color InterpolateHalfColor24(const Color &c0, const Color &c1) const {
return Color(InterpolateHalf8(c0.r, c1.r), InterpolateHalf8(c0.g, c1.g), InterpolateHalf8(c0.b, c1.b));
}
// virtual constexpr bool useExpandedInMatch() noexcept { return true; }
//
// void PrepSingleColorTables(const MatchListPtr &matchTable, const MatchListPtr &matchTableHalf, int len);
//
// int PrepSingleColorTableEntry(const MatchListPtr &matchTable, int v, int i, int low, int high, int low_e, int high_e, int lowest_error, bool half,
// bool ideal);
};
class InterpolatorRound : public Interpolator {
public:
uint8_t Interpolate5(uint8_t v0, uint8_t v1) const override;
uint8_t Interpolate6(uint8_t v0, uint8_t v1) const override;
Type GetType() const noexcept override { return Type::IdealRound; }
private:
uint8_t Interpolate8(uint8_t v0, uint8_t v1) const override;
Type GetType() const noexcept override { return Type::IdealRound; }
};
class InterpolatorNvidia : public Interpolator {
public:
uint8_t Interpolate5(uint8_t v0, uint8_t v1) const override;
uint8_t Interpolate6(uint8_t v0, uint8_t v1) const override;
uint8_t InterpolateHalf5(uint8_t v0, uint8_t v1) const override;
uint8_t InterpolateHalf6(uint8_t v0, uint8_t v1) const override;
std::array<Color, 4> InterpolateBC1(uint16_t low, uint16_t high) const override;
Type GetType() const noexcept override { return Type::Nvidia; }
bool CanInterpolate8Bit() const noexcept override { return false; }
private:
Color InterpolateColor565(const Color &c0, const Color &c1) const {
@ -158,12 +161,12 @@ class InterpolatorAMD : public Interpolator {
public:
uint8_t Interpolate5(uint8_t v0, uint8_t v1) const override;
uint8_t Interpolate6(uint8_t v0, uint8_t v1) const override;
uint8_t Interpolate8(uint8_t v0, uint8_t v1) const override;
uint8_t InterpolateHalf5(uint8_t v0, uint8_t v1) const override;
uint8_t InterpolateHalf6(uint8_t v0, uint8_t v1) const override;
Type GetType() const noexcept override { return Type::AMD; }
private:
uint8_t Interpolate8(uint8_t v0, uint8_t v1) const override;
uint8_t InterpolateHalf8(uint8_t v0, uint8_t v1) const override;
Type GetType() const noexcept override { return Type::AMD; }
};
} // namespace rgbcx

5
src/test/test.cpp
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@ -18,6 +18,7 @@
#include <vector>
#include "../BC4/BC4Encoder.h"
#include "../BC1/BC1Encoder.h"
#include "../rgbcx.h"
#include "../rgbcxDecoders.h"
#include "../util.h"
@ -671,7 +672,11 @@ int main(int argc, char *argv[]) {
for (int i = 0; i < test_count; i++)
bc4_encoder.EncodeImage(reinterpret_cast<uint8_t *>(&packed_image8[0]), src, source_image.width(), source_image.height());
} else if (dxgi_format == DXGI_FORMAT_BC1_UNORM) {
auto bc1_encoder = BC1Encoder(Interpolator::MakeInterpolator());
Color *src = &source_image.get_pixels()[0];
bc1_encoder.EncodeImage(reinterpret_cast<uint8_t *>(&packed_image8[0]), src, source_image.width(), source_image.height());
} else {
for (uint32_t by = 0; by < blocks_y; by++) {
for (uint32_t bx = 0; bx < blocks_x; bx++) {