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