From 3c92f581101b0352c97db6662b26012747614ae1 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sat, 25 May 2019 16:56:25 +0200
Subject: [PATCH] Section: allow empty sections

---
 src/World/Section.cpp | 15 +++++++++++----
 src/World/Section.hpp |  4 ++--
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/World/Section.cpp b/src/World/Section.cpp
index fbf1c33..aa13bc8 100644
--- a/src/World/Section.cpp
+++ b/src/World/Section.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright (c) 2015-2018, Matthias Schiffer <mschiffer@universe-factory.net>
+  Copyright (c) 2015-2019, Matthias Schiffer <mschiffer@universe-factory.net>
   All rights reserved.
 
   Redistribution and use in source and binary forms, with or without
@@ -40,6 +40,9 @@ Section::Section(const std::shared_ptr<const NBT::CompoundTag> &section) {
 	blockLight = section->get<NBT::ByteArrayTag>("BlockLight");
 }
 
+const Resource::BlockType * Section::getBlockStateAt(size_t, size_t, size_t) const {
+	return nullptr;
+}
 
 std::unique_ptr<Section> Section::makeSection(const std::shared_ptr<const NBT::CompoundTag> &section) {
 	std::shared_ptr<const NBT::LongArrayTag> blockStates = section->get<NBT::LongArrayTag>("BlockStates");
@@ -49,10 +52,14 @@ std::unique_ptr<Section> Section::makeSection(const std::shared_ptr<const NBT::C
 		return std::unique_ptr<Section>(new PaletteSection(section, std::move(blockStates), palette));
 	}
 
-	std::shared_ptr<const NBT::ByteArrayTag> blocks = assertValue(section->get<NBT::ByteArrayTag>("Blocks"));
-	std::shared_ptr<const NBT::ByteArrayTag> data = assertValue(section->get<NBT::ByteArrayTag>("Data"));
+	std::shared_ptr<const NBT::ByteArrayTag> blocks = section->get<NBT::ByteArrayTag>("Blocks");
+	if (blocks) {
+		std::shared_ptr<const NBT::ByteArrayTag> data = assertValue(section->get<NBT::ByteArrayTag>("Data"));
 
-	return std::unique_ptr<Section>(new LegacySection(section, std::move(blocks), std::move(data)));
+		return std::unique_ptr<Section>(new LegacySection(section, std::move(blocks), std::move(data)));
+	}
+
+	return std::unique_ptr<Section>(new Section(section));
 }
 
 
diff --git a/src/World/Section.hpp b/src/World/Section.hpp
index 3444bce..e5f71f4 100644
--- a/src/World/Section.hpp
+++ b/src/World/Section.hpp
@@ -1,5 +1,5 @@
 /*
-  Copyright (c) 2015-2018, Matthias Schiffer <mschiffer@universe-factory.net>
+  Copyright (c) 2015-2019, Matthias Schiffer <mschiffer@universe-factory.net>
   All rights reserved.
 
   Redistribution and use in source and binary forms, with or without
@@ -72,7 +72,7 @@ public:
 
 	size_t getY() const { return Y; };
 
-	virtual const Resource::BlockType * getBlockStateAt(size_t x, size_t y, size_t z) const = 0;
+	virtual const Resource::BlockType * getBlockStateAt(size_t x, size_t y, size_t z) const;
 
 	uint8_t getBlockLightAt(size_t x, size_t y, size_t z) const {
 		if (!blockLight)