mirror of
https://github.com/neocturne/MinedMap.git
synced 2025-04-19 11:05:08 +02:00
Matthias Schiffer
457e993c92
Newtypes are cumbersome in C++, so this is mostly documentation for now. Also replace lots of questionable uses of size_t with int or types with explicit width and add a few comments for constants.
128 lines
4 KiB
C++
128 lines
4 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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/*
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Copyright (c) 2015-2021, Matthias Schiffer <mschiffer@universe-factory.net>
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All rights reserved.
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*/
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#include "Section.hpp"
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#include "../NBT/ByteTag.hpp"
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#include "../NBT/StringTag.hpp"
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#include <cstdio>
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namespace MinedMap {
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namespace World {
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Section::Section(const std::shared_ptr<const NBT::CompoundTag> §ion) {
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Y = assertValue(section->get<NBT::ByteTag>("Y"))->getValue();
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blockLight = section->get<NBT::ByteArrayTag>("BlockLight");
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}
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const Resource::BlockType * Section::getBlockStateAt(block_idx_t, block_idx_t, block_idx_t) const {
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return nullptr;
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}
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std::unique_ptr<Section> Section::makeSection(const std::shared_ptr<const NBT::CompoundTag> §ion, uint32_t dataVersion) {
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std::shared_ptr<const NBT::LongArrayTag> blockStates = section->get<NBT::LongArrayTag>("BlockStates");
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if (blockStates) {
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const std::shared_ptr<const NBT::ListTag> palette = assertValue(section->get<NBT::ListTag>("Palette"));
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return std::unique_ptr<Section>(new PaletteSection(section, std::move(blockStates), palette, dataVersion));
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}
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std::shared_ptr<const NBT::ByteArrayTag> blocks = section->get<NBT::ByteArrayTag>("Blocks");
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if (blocks) {
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std::shared_ptr<const NBT::ByteArrayTag> data = assertValue(section->get<NBT::ByteArrayTag>("Data"));
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return std::unique_ptr<Section>(new LegacySection(section, std::move(blocks), std::move(data)));
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}
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return std::unique_ptr<Section>(new Section(section));
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}
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const Resource::BlockType * LegacySection::getBlockStateAt(block_idx_t x, block_idx_t y, block_idx_t z) const {
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uint8_t type = getBlockAt(x, y, z);
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uint8_t data = getDataAt(x, y, z);
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return Resource::LEGACY_BLOCK_TYPES.types[type][data];
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}
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const Resource::BlockType * PaletteSection::lookup(const std::string &name, uint32_t dataVersion) {
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if (dataVersion < 1900 && name == "minecraft:stone_slab")
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return Resource::BlockType::lookup("minecraft:smooth_stone_slab");
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return Resource::BlockType::lookup(name);
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}
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PaletteSection::PaletteSection(
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const std::shared_ptr<const NBT::CompoundTag> §ion,
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std::shared_ptr<const NBT::LongArrayTag> &&blockStates0,
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const std::shared_ptr<const NBT::ListTag> &paletteData,
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uint32_t dataVersion0
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) : Section(section), blockStates(blockStates0), dataVersion(dataVersion0) {
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bits = 4;
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while ((1u << bits) < paletteData->size()) {
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bits++;
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if (bits > 12)
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throw std::invalid_argument("unsupported block palette size");
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}
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unsigned expectedLength;
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if (dataVersion < 2529) {
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expectedLength = 64 * bits;
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} else {
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unsigned blocksPerWord = (64 / bits);
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expectedLength = (4096 + blocksPerWord - 1) / blocksPerWord;
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}
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if (blockStates->getLength() != expectedLength)
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throw std::invalid_argument("corrupt section data");
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for (const auto &entry : *paletteData) {
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const NBT::CompoundTag &paletteEntry = *assertValue(dynamic_cast<const NBT::CompoundTag *>(entry.get()));
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std::string name = assertValue(paletteEntry.get<NBT::StringTag>("Name"))->getValue();
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const Resource::BlockType *type = lookup(name, dataVersion);
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if (!type)
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std::fprintf(stderr, "Warning: unknown block type: %s\n", name.c_str());
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palette.push_back(type);
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}
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}
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const Resource::BlockType * PaletteSection::getBlockStateAt(block_idx_t x, block_idx_t y, block_idx_t z) const {
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size_t index = getIndex(x, y, z);
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size_t bitIndex;
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if (dataVersion < 2529) {
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bitIndex = bits * index;
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} else {
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unsigned blocksPerWord = (64 / bits);
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size_t word = index / blocksPerWord;
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bitIndex = 64 * word + bits * (index % blocksPerWord);
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}
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size_t pos = bitIndex >> 3;
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unsigned shift = bitIndex & 7;
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uint16_t mask = (1u << bits) - 1;
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uint32_t v = blockStates->getPointer()[mangleByteIndex(pos)];
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if (shift + bits > 8)
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v |= blockStates->getPointer()[mangleByteIndex(pos + 1)] << 8;
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if (shift + bits > 16)
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v |= blockStates->getPointer()[mangleByteIndex(pos + 2)] << 16;
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/* We do not need to check for shift+bits > 24: bits should never
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be greater than 12, so our value will never span more than 3 bytes */
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return palette.at((v >> shift) & mask);
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}
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}
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}
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