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Add cluster fitting for 4-color blocks

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hotfix/mipmap-alpha-fix
Andrew Cassidy 3 years ago
parent ab752e51b6
commit ed89203510
4 changed files with 197 additions and 129 deletions
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288
src/BC1/BC1Encoder.cpp
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@ -43,8 +43,90 @@ namespace rgbcx {
using InterpolatorPtr = std::shared_ptr<Interpolator>;
using Hist3 = OrderTable<3>::Histogram;
using Hist4 = OrderTable<4>::Histogram;
using Hash = uint16_t;
using BlockMetrics = Color4x4::BlockMetrics;
using EncodeResults = BC1Encoder::EncodeResults;
using ColorMode = BC1Encoder::BlockColorMode;
// region Free Functions/Templates
template <ColorMode M> bool ComputeEndpoints(Color4x4 pixels, EncodeResults &block, BlockMetrics metrics) {
const int N = (M == ColorMode::FourColor) ? 4 : 3;
const bool is_3color = N == 3;
static_assert(M == ColorMode::FourColor || M == ColorMode::ThreeColor || M == ColorMode::ThreeColorBlack);
static_assert(N == 3 || N == 4);
Vector4 q00 = {0, 0, 0};
unsigned weight_accum = 0;
for (unsigned i = 0; i < 16; i++) {
const Color color = pixels.Get(i);
const uint8_t sel = block.selectors[i];
if (M == ColorMode::ThreeColorBlack && color.IsBlack()) continue;
if (is_3color && sel == 3U) continue; // NOTE: selectors for 3-color are in linear order here, but not in original
assert(sel < N);
const Vector4Int color_vector = Vector4Int::FromColorRGB(color);
q00 += color_vector * sel;
weight_accum += (N == 3) ? g_weight_vals3[sel] : g_weight_vals4[sel];
}
int denominator = N - 1;
Vector4 q10 = (metrics.sums * denominator) - q00;
float z00 = (float)((weight_accum >> 16) & 0xFF);
float z10 = (float)((weight_accum >> 8) & 0xFF);
float z11 = (float)(weight_accum & 0xFF);
float z01 = z10;
// invert matrix
float det = z00 * z11 - z01 * z10;
if (fabs(det) < 1e-8f) {
block.color_mode = ColorMode::Solid;
return false;
}
det = ((float)denominator / 255.0f) / det;
float iz00, iz01, iz10, iz11;
iz00 = z11 * det;
iz01 = -z01 * det;
iz10 = -z10 * det;
iz11 = z00 * det;
Vector4 low = (q00 * iz00) + (q10 * iz01);
Vector4 high = (q00 * iz10) + (q10 * iz11);
block.color_mode = M;
block.low = Color::PreciseRound565(low);
block.high = Color::PreciseRound565(high);
return true;
}
template <ColorMode M> void ComputeEndpoints(std::array<Vector4, 17> &sums, EncodeResults &block, Vector4 &matrix, Hash hash) {
const int N = (M == ColorMode::FourColor) ? 4 : 3;
const bool is_3color = N == 3;
static_assert(M != ColorMode::Solid);
static_assert(N == 3 || N == 4);
Vector4 q10 = {0, 0, 0};
unsigned level = 0;
for (unsigned i = 0; i < (N - 1); i++) {
level += OrderTable<N>::GetUniqueOrdering(hash, i);
q10 += sums[level];
}
Vector4 q00 = (sums[16] * (N - 1)) - q10;
Vector4 low = (matrix[0] * q00) + (matrix[1] * q10);
Vector4 high = (matrix[2] * q00) + (matrix[3] * q10);
block.color_mode = M;
block.low = Color::PreciseRound565(low);
block.high = Color::PreciseRound565(high);
}
// endregion
// Static Fields
@ -54,7 +136,8 @@ std::mutex BC1Encoder::order_table_mutex = std::mutex();
bool BC1Encoder::order_tables_generated = false;
BC1Encoder::BC1Encoder(InterpolatorPtr interpolator) : _interpolator(interpolator) {
_flags = Flags::UseFasterMSEEval | Flags::TwoLeastSquaresPasses;
_flags = Flags::UseFullMSEEval | Flags::TwoLeastSquaresPasses | Flags::UseLikelyTotalOrderings;
_orderings4 = 8;
// generate lookup tables
order_table_mutex.lock();
@ -103,19 +186,22 @@ void BC1Encoder::EncodeBlock(Color4x4 pixels, BC1Block *dest) const {
}
EncodeResults round_result;
FindEndpoints(pixels, modified_flags, metrics, round_result.low, round_result.high);
FindEndpoints(round_result, pixels, modified_flags, metrics);
FindSelectors4(pixels, round_result, needs_block_error);
for (unsigned pass = 0; pass < total_ls_passes; pass++) {
EncodeResults trial_result = round_result;
Vector4 low, high;
bool multicolor = ComputeEndpointsLS(pixels, trial_result, metrics, false, false);
bool multicolor = ComputeEndpoints<ColorMode::FourColor>(pixels, trial_result, metrics);
if (multicolor) {
FindSelectors4(pixels, trial_result, needs_block_error);
} else {
FindEndpointsSingleColor(trial_result, pixels, metrics.avg, false);
}
if (trial_result.low == round_result.low && trial_result.high == round_result.high) break;
FindSelectors4(pixels, trial_result, needs_block_error);
if (!needs_block_error || trial_result.error < round_result.error) {
round_result = trial_result;
} else {
@ -125,6 +211,7 @@ void BC1Encoder::EncodeBlock(Color4x4 pixels, BC1Block *dest) const {
if (!needs_block_error || round_result.error < result.error) { result = round_result; }
}
bool usedCF = false;
// First refinement pass using ordered cluster fit
if (result.error > 0 && (_flags & Flags::UseLikelyTotalOrderings) != Flags::None) {
const unsigned total_iters = (_flags & Flags::Iterative) != Flags::None ? 2 : 1;
@ -132,18 +219,15 @@ void BC1Encoder::EncodeBlock(Color4x4 pixels, BC1Block *dest) const {
EncodeResults orig = result;
Hist4 h(orig.selectors);
const Hash order_index = order_table4->GetHash(h);
Color low = orig.low.ScaleFrom565();
Color high = orig.high.ScaleFrom565();
const Hash start_hash = order_table4->GetHash(h);
Vector4Int axis = high - low;
Vector4 axis = orig.high.ScaleFrom565() - orig.low.ScaleFrom565();
std::array<Vector4, 16> color_vectors;
std::array<uint32_t, 16> dots;
for (unsigned i = 0; i < 16; i++) {
color_vectors[i] = Vector4::FromColorRGB(pixels.Get(i));
int dot = 0x1000000 + color_vectors[i].Dot(axis);
int dot = 0x1000000 + (int)color_vectors[i].Dot(axis);
assert(dot >= 0);
dots[i] = (uint32_t)(dot << 4) | i;
}
@ -157,27 +241,36 @@ void BC1Encoder::EncodeBlock(Color4x4 pixels, BC1Block *dest) const {
sums[i + 1] = sums[i] + color_vectors[p];
}
const unsigned q_total = ((_flags & Flags::Exhaustive) != Flags::None) ? order_table4->UniqueOrderings
: (unsigned)clampi(_orderings4, MIN_TOTAL_ORDERINGS, MAX_TOTAL_ORDERINGS4);
for (unsigned q = 0; q < q_total; q++) {
Hash s = ((_flags & Flags::Exhaustive) != Flags::None) ? q : g_best_total_orderings4[order_index][q];
const Hash q_total = ((_flags & Flags::Exhaustive) != Flags::None) ? order_table4->UniqueOrderings
: (Hash)clamp(_orderings4, MIN_TOTAL_ORDERINGS, MAX_TOTAL_ORDERINGS4);
for (Hash q = 0; q < q_total; q++) {
Hash trial_hash = ((_flags & Flags::Exhaustive) != Flags::None) ? q : g_best_total_orderings4[start_hash][q];
Vector4 trial_matrix = order_table4->GetFactors(trial_hash);
EncodeResults trial = orig;
EncodeResults trial_result = orig;
Vector4 low, high;
if (order_table4->IsSingleColor(order_index)) {
trial.is_1_color = true;
trial.is_3_color = false;
if (order_table4->IsSingleColor(trial_hash)) {
FindEndpointsSingleColor(trial_result, pixels, metrics.avg, false);
} else {
ComputeEndpoints<ColorMode::FourColor>(sums, trial_result, trial_matrix, trial_hash);
}
FindSelectors4(pixels, trial_result, true);
if (trial_result.error < result.error) {
result = trial_result;
usedCF = true;
}
if (trial_result.error == 0) break;
}
}
}
EncodeBlock4Color(result, dest);
if (result.low == result.high) {
EncodeBlockSingleColor(metrics.avg, dest);
} else {
EncodeBlock4Color(result, dest);
}
// if (result.low == result.high) {
// EncodeBlockSingleColor(metrics.avg, dest);
// } else {
// EncodeBlock4Color(result, dest);
// }
}
void BC1Encoder::EncodeBlockSingleColor(Color color, BC1Block *dest) const {
@ -187,6 +280,7 @@ void BC1Encoder::EncodeBlockSingleColor(Color color, BC1Block *dest) const {
bool using_3color = false;
// why is there no subscript operator for shared_ptr<array>
// TODO use endpoint finder below
BC1MatchEntry match_r = _single_match5->at(color.r);
BC1MatchEntry match_g = _single_match6->at(color.g);
BC1MatchEntry match_b = _single_match5->at(color.b);
@ -268,22 +362,26 @@ void BC1Encoder::EncodeBlock4Color(EncodeResults &block, BC1Block *dest) const {
dest->PackSelectors(selectors, mask);
}
void BC1Encoder::FindEndpoints(Color4x4 pixels, BC1Encoder::Flags flags, const BC1Encoder::BlockMetrics metrics, Color &low, Color &high) const {
void BC1Encoder::FindEndpoints(EncodeResults &block, Color4x4 pixels, BC1Encoder::Flags flags, const BC1Encoder::BlockMetrics &metrics) const {
if (metrics.is_greyscale) {
// specialized greyscale case
const unsigned fr = pixels.Get(0).r;
if (metrics.max.r - metrics.min.r < 2) {
// single color block
low.r = high.r = (uint8_t)scale8To5(fr);
low.g = high.g = (uint8_t)scale8To6(fr);
low.b = high.b = low.r;
uint8_t fr5 = (uint8_t)scale8To5(fr);
uint8_t fr6 = (uint8_t)scale8To6(fr);
block.low = Color(fr5, fr6, fr5);
block.high = block.low;
} else {
low.r = low.b = scale8To5(metrics.min.r);
low.g = scale8To6(metrics.min.r);
uint8_t lr5 = scale8To5(metrics.min.r);
uint8_t lr6 = scale8To6(metrics.min.r);
high.r = high.b = scale8To5(metrics.max.r);
high.g = scale8To6(metrics.max.r);
uint8_t hr5 = scale8To5(metrics.max.r);
uint8_t hr6 = scale8To6(metrics.max.r);
block.low = Color(lr5, lr6, lr5);
}
} else if ((flags & Flags::Use2DLS) != Flags::None) {
// 2D Least Squares approach from Humus's example, with added inset and optimal rounding.
@ -342,8 +440,8 @@ void BC1Encoder::FindEndpoints(Color4x4 pixels, BC1Encoder::Flags flags, const B
h[c] = ((h[c] - inset) / 255.0f);
}
low = Color::PreciseRound565(l);
high = Color::PreciseRound565(h);
block.low = Color::PreciseRound565(l);
block.high = Color::PreciseRound565(h);
} else if ((flags & Flags::BoundingBox) != Flags::None) {
// Algorithm from icbc.h compress_dxt1_fast()
Vector4 l, h;
@ -370,8 +468,8 @@ void BC1Encoder::FindEndpoints(Color4x4 pixels, BC1Encoder::Flags flags, const B
if (icov_xz < 0) std::swap(l[0], h[0]);
if (icov_yz < 0) std::swap(l[1], h[1]);
low = Color::PreciseRound565(l);
high = Color::PreciseRound565(h);
block.low = Color::PreciseRound565(l);
block.high = Color::PreciseRound565(h);
} else if ((flags & Flags::BoundingBoxInt) != Flags::None) {
// Algorithm from icbc.h compress_dxt1_fast(), but converted to integer.
@ -395,8 +493,8 @@ void BC1Encoder::FindEndpoints(Color4x4 pixels, BC1Encoder::Flags flags, const B
if (icov_xz < 0) std::swap(min.r, max.r);
if (icov_yz < 0) std::swap(min.g, max.g);
low = min.ScaleTo565();
high = max.ScaleTo565();
block.low = min.ScaleTo565();
block.high = max.ScaleTo565();
} else {
// the slow way
// Select 2 colors along the principle axis. (There must be a faster/simpler way.)
@ -459,14 +557,53 @@ void BC1Encoder::FindEndpoints(Color4x4 pixels, BC1Encoder::Flags flags, const B
}
}
low = pixels.Get(min_index).ScaleTo565();
high = pixels.Get(max_index).ScaleTo565();
block.low = pixels.Get(min_index).ScaleTo565();
block.high = pixels.Get(max_index).ScaleTo565();
}
block.color_mode = ColorMode::Incomplete;
}
void BC1Encoder::FindEndpointsSingleColor(EncodeResults &block, Color color, bool is_3color) const {
auto &match5 = is_3color ? _single_match5_half : _single_match5;
auto &match6 = is_3color ? _single_match6_half : _single_match6;
BC1MatchEntry match_r = match5->at(color.r);
BC1MatchEntry match_g = match6->at(color.g);
BC1MatchEntry match_b = match5->at(color.b);
block.color_mode = is_3color ? ColorMode::SolidThreeColor : ColorMode::Solid;
block.error = match_r.error + match_g.error + match_b.error;
block.low = Color(match_r.low, match_g.low, match_b.low);
block.high = Color(match_r.high, match_g.high, match_b.high);
// selectors decided when writing, no point deciding them now
}
void BC1Encoder::FindEndpointsSingleColor(EncodeResults &block, Color4x4 &pixels, Color color, bool is_3color) const {
std::array<Color, 4> colors = _interpolator->InterpolateBC1(block.low, block.high, is_3color);
Vector4Int result_vector = (Vector4Int)colors[2];
auto &match5 = is_3color ? _single_match5_half : _single_match5;
auto &match6 = is_3color ? _single_match6_half : _single_match6;
BC1MatchEntry match_r = match5->at(color.r);
BC1MatchEntry match_g = match6->at(color.g);
BC1MatchEntry match_b = match5->at(color.b);
block.color_mode = is_3color ? ColorMode::SolidThreeColor : ColorMode::Solid;
block.error = 0;
block.low = Color(match_r.low, match_g.low, match_b.low);
block.high = Color(match_r.high, match_g.high, match_b.high);
for (unsigned i = 0; i < 16; i++) {
Vector4Int pixel_vector = (Vector4Int)pixels.Get(i);
auto diff = pixel_vector - result_vector;
block.error += diff.SqrMag();
block.selectors[i] = 1;
}
}
unsigned BC1Encoder::FindSelectors4(Color4x4 pixels, BC1Encoder::EncodeResults &block, bool use_err) const {
// colors in selector order, 0, 1, 2, 3
// 0 = low color, 1 = high color, 2/3 = interpolated
std::array<Color, 4> colors = _interpolator->InterpolateBC1(block.low, block.high, false);
std::array<Vector4Int, 4> color_vectors = {(Vector4Int)colors[0], (Vector4Int)colors[2], (Vector4Int)colors[3], (Vector4Int)colors[1]};
unsigned total_error = 0;
@ -546,71 +683,8 @@ unsigned BC1Encoder::FindSelectors4(Color4x4 pixels, BC1Encoder::EncodeResults &
block.selectors[i] = best_sel;
}
}
block.is_3_color = false;
block.is_1_color = false;
block.color_mode = ColorMode::FourColor;
block.error = total_error;
return total_error;
}
bool BC1Encoder::ComputeEndpointsLS(Color4x4 pixels, EncodeResults &block, BlockMetrics metrics, bool is_3color, bool use_black) const {
Vector4 low, high;
Vector4 q00 = {0, 0, 0};
unsigned weight_accum = 0;
for (unsigned i = 0; i < 16; i++) {
const Color color = pixels.Get(i);
const int sel = (int)block.selectors[i];
if (use_black && color.IsBlack()) continue;
if (is_3color && sel == 3) continue; // NOTE: selectors for 3-color are in linear order here, but not in original
assert(sel <= 3);
const Vector4Int color_vector = Vector4Int::FromColorRGB(color);
q00 += color_vector * sel;
weight_accum += g_weight_vals4[sel];
}
int denominator = is_3color ? 2 : 3;
Vector4 q10 = (metrics.sums * denominator) - q00;
float z00 = (float)((weight_accum >> 16) & 0xFF);
float z10 = (float)((weight_accum >> 8) & 0xFF);
float z11 = (float)(weight_accum & 0xFF);
float z01 = z10;
// invert matrix
float det = z00 * z11 - z01 * z10;
if (fabs(det) < 1e-8f) {
block.is_1_color = true;
return false;
}
det = ((float)denominator / 255.0f) / det;
float iz00, iz01, iz10, iz11;
iz00 = z11 * det;
iz01 = -z01 * det;
iz10 = -z10 * det;
iz11 = z00 * det;
low = (q00 * iz00) + (q10 * iz01);
high = (q00 * iz10) + (q10 * iz11);
block.is_1_color = false;
block.low = Color::PreciseRound565(low);
block.high = Color::PreciseRound565(high);
return true;
}
/*
bool BC1Encoder::ComputeEndpointsLS(Color4x4 pixels, EncodeResults &block, BlockMetrics metrics, Hash hash, Vector4 &matrix, std::array<Vector4, 17> &sums,
bool is_3color, bool use_black) const {
unsigned f1, f2, f3;
int denominator = is_3color ? 2 : 3;
if (is_3color) {
order_table3->GetUniqueOrderingSums(hash, f1, f2, f3);
} else {
order_table4->GetUniqueOrderingSums(hash, f1, f2, f3);
}
}*/
} // namespace rgbcx

13
src/BC1/BC1Encoder.h
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@ -99,13 +99,14 @@ class BC1Encoder final : public BlockEncoder<BC1Block, 4, 4> {
EndpointSearchRoundsMask = 1023U << EndpointSearchRoundsShift,
};
enum class BlockColorMode {FourColor, ThreeColor, ThreeColorBlack, Solid, SolidThreeColor, Incomplete };
// Unpacked BC1 block with metadata
struct EncodeResults {
Color low;
Color high;
std::array<uint8_t, 16> selectors;
bool is_3_color;
bool is_1_color;
BlockColorMode color_mode;
unsigned error = UINT_MAX;
};
@ -141,11 +142,9 @@ class BC1Encoder final : public BlockEncoder<BC1Block, 4, 4> {
void EncodeBlockSingleColor(Color color, BC1Block *dest) const;
void EncodeBlock4Color(EncodeResults &block, BC1Block *dest) const;
void FindEndpoints(Color4x4 pixels, Flags flags, BlockMetrics const metrics, Color &low, Color &high) const;
void FindEndpoints(EncodeResults &block, Color4x4 pixels, Flags flags, BlockMetrics const &metrics) const;
void FindEndpointsSingleColor(EncodeResults &block, Color color, bool is_3color = false) const;
void FindEndpointsSingleColor(EncodeResults &block, Color4x4 &pixels, Color color, bool is_3color) const;
unsigned FindSelectors4(Color4x4 pixels, BC1Encoder::EncodeResults &block, bool use_err) const;
bool ComputeEndpointsLS(Color4x4 pixels, EncodeResults &block, BlockMetrics metrics, bool is_3color, bool use_black) const;
/* bool ComputeEndpointsLS(Color4x4 pixels, EncodeResults &block, BlockMetrics metrics, Hash hash, Vector4 &matrix, std::array<Vector4, 17> &sums,
bool is_3color, bool use_black) const;*/
};
} // namespace rgbcx

6
src/BC1/OrderTable.h
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@ -82,12 +82,6 @@ template <size_t N> class OrderTable {
return g_unique_total_orders3[hash][selector];
}
static inline constexpr void GetUniqueOrderingSums(Hash hash, unsigned &f1, unsigned &f2, unsigned &f3) {
f1 = GetUniqueOrdering(hash, 0);
f2 = f1 + GetUniqueOrdering(hash, 1);
f3 = f2 + GetUniqueOrdering(hash, 2);
}
OrderTable<N>() {
static_assert(N == 4 || N == 3);

19
src/BC1/SingleColorTable.h
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@ -28,11 +28,6 @@
namespace rgbcx {
/**
* Lookup table for single-color blocks
* @tparam B Number of bits (5 or 6)
* @tparam N Number of colors (3 or 4)
*/
struct BC1MatchEntry {
uint8_t high;
uint8_t low;
@ -43,9 +38,14 @@ using MatchList = std::array<BC1MatchEntry, 256>;
using MatchListPtr = std::shared_ptr<MatchList>;
using InterpolatorPtr = std::shared_ptr<Interpolator>;
/**
* Lookup table for single-color blocks
* @tparam B Number of bits (5 or 6)
* @tparam N Number of colors (3 or 4)
*/
template <size_t B, size_t N> MatchListPtr SingleColorTable(InterpolatorPtr interpolator) {
constexpr size_t Size = 1 << B;
MatchListPtr _matches = std::make_shared<MatchList>();
MatchListPtr matches = std::make_shared<MatchList>();
static_assert((B == 5 && Size == 32) || (B == 6 && Size == 64));
static_assert(N == 4 || N == 3);
@ -79,14 +79,15 @@ template <size_t B, size_t N> MatchListPtr SingleColorTable(InterpolatorPtr inte
if ((new_error < error) || (new_error == error && low == high)) {
assert(new_error <= UINT8_MAX);
(*_matches)[i].low = (uint8_t)low;
(*_matches)[i].high = (uint8_t)high;
(*_matches)[i].error = (uint8_t)new_error;
(*matches)[i].low = (uint8_t)low;
(*matches)[i].high = (uint8_t)high;
(*matches)[i].error = (uint8_t)new_error;
error = new_error;
}
}
}
}
return matches;
}
} // namespace rgbcx
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