From 1f107077333b17993eede7a0bb1d1d7be9458c9f Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Wed, 11 Dec 2019 21:37:00 +0100
Subject: [PATCH] Chunk: add support for Minecraft 1.15 biome map

---
 src/World/Chunk.cpp | 29 ++++++++++++++++++++++-------
 src/World/Chunk.hpp | 14 +++++++-------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/src/World/Chunk.cpp b/src/World/Chunk.cpp
index dfc46db..1e4872f 100644
--- a/src/World/Chunk.cpp
+++ b/src/World/Chunk.cpp
@@ -43,13 +43,16 @@ Chunk::Chunk(const ChunkData *data) {
 	if (!sectionsTag || sectionsTag->empty())
 		return;
 
-	biomeBytes = level->get<NBT::ByteArrayTag>("Biomes");
-	biomeInts = level->get<NBT::IntArrayTag>("Biomes");
-	assertValue(biomeBytes || biomeInts);
+	auto biomesIntArray = level->get<NBT::IntArrayTag>("Biomes");
+	auto biomesByteArray = level->get<NBT::ByteArrayTag>("Biomes");
 
-	if (biomeBytes && biomeBytes->getLength() != SIZE*SIZE)
-		throw std::invalid_argument("corrupt biome data");
-	else if (biomeInts && biomeInts->getLength() != SIZE*SIZE)
+	if (biomesIntArray && biomesIntArray->getLength() == BSIZE*BSIZE*BMAXY)
+		biomeInts = std::move(biomesIntArray);
+	else if (biomesIntArray && biomesIntArray->getLength() == SIZE*SIZE)
+		biomeIntsPre115 = std::move(biomesIntArray);
+	else if (biomesByteArray && biomesByteArray->getLength() == SIZE*SIZE)
+		biomeBytes = std::move(biomesByteArray);
+	else
 		throw std::invalid_argument("corrupt biome data");
 
 	auto dataVersionTag = data->getRoot().get<NBT::IntTag>("DataVersion");
@@ -64,6 +67,18 @@ Chunk::Chunk(const ChunkData *data) {
 	}
 }
 
+uint8_t Chunk::getBiome(size_t x, size_t y, size_t z) const {
+	if (x > SIZE || y > MAXY || z > SIZE)
+		throw std::invalid_argument("corrupt chunk data");
+
+	if (biomeInts)
+		return biomeInts->getValue((y/BGROUP)*BSIZE*BSIZE + (z/BGROUP)*BSIZE + (x/BGROUP));
+	else if (biomeIntsPre115)
+		return biomeIntsPre115->getValue(z*SIZE + x);
+	else
+		return biomeBytes->getValue(z*SIZE + x);
+}
+
 bool Chunk::getBlock(Block *block, const Section *section, size_t x, size_t y, size_t z, uint8_t prev_light) const {
 	if (block->height > 0)
 		return false;
@@ -75,7 +90,7 @@ bool Chunk::getBlock(Block *block, const Section *section, size_t x, size_t y, s
 	if (!block->type) {
 		block->type = type;
 		block->blockLight = prev_light;
-		block->biome = getBiomeAt(x, z);
+		block->biome = getBiome(x, y, z);
 	}
 
 	if (type->blue)
diff --git a/src/World/Chunk.hpp b/src/World/Chunk.hpp
index 77299ec..1a40635 100644
--- a/src/World/Chunk.hpp
+++ b/src/World/Chunk.hpp
@@ -44,6 +44,11 @@ namespace World {
 class Chunk {
 public:
 	static const size_t SIZE = Section::SIZE;
+	static const size_t MAXY = 256;
+
+	static const size_t BGROUP = 4;
+	static const size_t BSIZE = SIZE / BGROUP;
+	static const size_t BMAXY = MAXY / BGROUP;
 
 	struct Blocks {
 		Block blocks[SIZE][SIZE];
@@ -54,15 +59,10 @@ private:
 	std::vector<std::unique_ptr<Section>> sections;
 
 	std::shared_ptr<const NBT::ByteArrayTag> biomeBytes;
+	std::shared_ptr<const NBT::IntArrayTag> biomeIntsPre115;
 	std::shared_ptr<const NBT::IntArrayTag> biomeInts;
 
-	uint8_t getBiomeAt(size_t x, size_t z) const {
-		if (biomeBytes)
-			return biomeBytes->getValue(z*SIZE + x);
-		else
-			return biomeInts->getValue(z*SIZE + x);
-	}
-
+	uint8_t getBiome(size_t x, size_t y, size_t z) const;
 	bool getBlock(Block *block, const Section *section, size_t x, size_t y, size_t z, uint8_t prev_light) const;
 
 public: