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// Copyright 2017 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <array>
#include "common/bit_field.h"
#include "common/color.h"
#include "common/common_types.h"
#include "common/math_util.h"
#include "common/vector_math.h"
#include "video_core/texture/etc1.h"
namespace Pica {
namespace Texture {
namespace {
constexpr std::array<std::array<u8, 2>, 8> etc1_modifier_table = {{
{2, 8}, {5, 17}, {9, 29}, {13, 42}, {18, 60}, {24, 80}, {33, 106}, {47, 183},
}};
union ETC1Tile {
u64 raw;
// Each of these two is a collection of 16 bits (one per lookup value)
BitField<0, 16, u64> table_subindexes;
BitField<16, 16, u64> negation_flags;
unsigned GetTableSubIndex(unsigned index) const {
return (table_subindexes >> index) & 1;
}
bool GetNegationFlag(unsigned index) const {
return ((negation_flags >> index) & 1) == 1;
}
BitField<32, 1, u64> flip;
BitField<33, 1, u64> differential_mode;
BitField<34, 3, u64> table_index_2;
BitField<37, 3, u64> table_index_1;
union {
// delta value + base value
BitField<40, 3, s64> db;
BitField<43, 5, u64> b;
BitField<48, 3, s64> dg;
BitField<51, 5, u64> g;
BitField<56, 3, s64> dr;
BitField<59, 5, u64> r;
} differential;
union {
BitField<40, 4, u64> b2;
BitField<44, 4, u64> b1;
BitField<48, 4, u64> g2;
BitField<52, 4, u64> g1;
BitField<56, 4, u64> r2;
BitField<60, 4, u64> r1;
} separate;
const Math::Vec3<u8> GetRGB(unsigned int x, unsigned int y) const {
int texel = 4 * x + y;
if (flip)
std::swap(x, y);
// Lookup base value
Math::Vec3<int> ret;
if (differential_mode) {
ret.r() = static_cast<int>(differential.r);
ret.g() = static_cast<int>(differential.g);
ret.b() = static_cast<int>(differential.b);
if (x >= 2) {
ret.r() += static_cast<int>(differential.dr);
ret.g() += static_cast<int>(differential.dg);
ret.b() += static_cast<int>(differential.db);
}
ret.r() = Color::Convert5To8(ret.r());
ret.g() = Color::Convert5To8(ret.g());
ret.b() = Color::Convert5To8(ret.b());
} else {
if (x < 2) {
ret.r() = Color::Convert4To8(static_cast<u8>(separate.r1));
ret.g() = Color::Convert4To8(static_cast<u8>(separate.g1));
ret.b() = Color::Convert4To8(static_cast<u8>(separate.b1));
} else {
ret.r() = Color::Convert4To8(static_cast<u8>(separate.r2));
ret.g() = Color::Convert4To8(static_cast<u8>(separate.g2));
ret.b() = Color::Convert4To8(static_cast<u8>(separate.b2));
}
}
// Add modifier
unsigned table_index =
static_cast<int>((x < 2) ? table_index_1.Value() : table_index_2.Value());
int modifier = etc1_modifier_table[table_index][GetTableSubIndex(texel)];
if (GetNegationFlag(texel))
modifier *= -1;
ret.r() = MathUtil::Clamp(ret.r() + modifier, 0, 255);
ret.g() = MathUtil::Clamp(ret.g() + modifier, 0, 255);
ret.b() = MathUtil::Clamp(ret.b() + modifier, 0, 255);
return ret.Cast<u8>();
}
};
} // anonymous namespace
Math::Vec3<u8> SampleETC1Subtile(u64 value, unsigned int x, unsigned int y) {
ETC1Tile tile{value};
return tile.GetRGB(x, y);
}
} // namespace Texture
} // namespace Pica
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