Fixing broken hashmaps on linux

Fixes #414

The issue is caused by Linux (and possibly other platforms) implementing the hash function as an identify function for data smaller than 64bit (including `int`).

Fixing only the TerrainGenerator is possible, but the issue could be generated again elsewhere and it would be quite difficult to identify and debug.

Therefore the proposed solution is to replace the `wi::unordered_map` on Linux with another implementation which is still quite fast and does account for the issue of the identify hash function.
The library is https://github.com/martinus/robin-hood-hashing (MIT License)

robin_hood.h:768
```
// return mixed of that, to be safe against identity hash
```

CMakeLists.txt

@@ -40,7 +40,7 @@ if (WICKED_TESTS)
     add_subdirectory(Tests)
 endif()
 
-if (WICKED_TESTS)
+if (WICKED_IMGUI_EXAMPLE)
     add_subdirectory(Example_ImGui)
     add_subdirectory(Example_ImGui_Docking)
 endif()

Editor/TerrainGenerator.h

@@ -62,12 +62,7 @@ struct TerrainGenerator : public wi::gui::Window
 	wi::scene::MaterialComponent material_HighAltitude;
 	wi::scene::MaterialComponent material_GrassParticle;
 	wi::HairParticleSystem grass_properties;
-#ifdef PLATFORM_LINUX
-	// TODO: investigate why wi::unordered_map is crashing terrain generator on Linux
-	std::unordered_map<Chunk, ChunkData> chunks;
-#else
 	wi::unordered_map<Chunk, ChunkData> chunks;
-#endif
 	wi::vector<uint32_t> indices;
 	struct LOD
 	{

WickedEngine/CMakeLists.txt

@@ -229,6 +229,10 @@ if (WIN32)
 
 	set(LIBDXCOMPILER "dxcompiler.dll")
 else ()
+	# `ska::flat_hash_map` has issues on linux because of the hash function being identity
+	# in same cases. Use `robin_hood::unordered_flat_map` instead
+	target_compile_definitions(${TARGET_NAME} PUBLIC WI_UNORDERED_MAP_TYPE=2)
+
 	target_link_libraries(${TARGET_NAME} PUBLIC
 		Threads::Threads
 		SDL2::SDL2

WickedEngine/offlineshadercompiler.cpp

@@ -556,7 +556,7 @@ int main(int argc, char* argv[])
 			std::string name_repl = name;
 			std::replace(name_repl.begin(), name_repl.end(), '/', '_');
 			std::replace(name_repl.begin(), name_repl.end(), '.', '_');
-			ss += "std::pair<std::string, ShaderDumpEntry>(\"" + name + "\", {" + name_repl + ",sizeof(" + name_repl + ")}),\n";
+			ss += "{\"" + name + "\", {" + name_repl + ",sizeof(" + name_repl + ")}},\n";
 		}
 		ss += "};\n"; // map end
 		ss += "}\n"; // namespace end

WickedEngine/wiResourceManager.cpp

@@ -100,17 +100,17 @@ namespace wi
 			SOUND,
 		};
 		static const wi::unordered_map<std::string, DataType> types = {
-			std::make_pair("BASIS", DataType::IMAGE),
-			std::make_pair("KTX2", DataType::IMAGE),
-			std::make_pair("JPG", DataType::IMAGE),
-			std::make_pair("JPEG", DataType::IMAGE),
-			std::make_pair("PNG", DataType::IMAGE),
-			std::make_pair("BMP", DataType::IMAGE),
-			std::make_pair("DDS", DataType::IMAGE),
-			std::make_pair("TGA", DataType::IMAGE),
-			std::make_pair("QOI", DataType::IMAGE),
-			std::make_pair("WAV", DataType::SOUND),
-			std::make_pair("OGG", DataType::SOUND),
+			{"BASIS", DataType::IMAGE},
+			{"KTX2", DataType::IMAGE},
+			{"JPG", DataType::IMAGE},
+			{"JPEG", DataType::IMAGE},
+			{"PNG", DataType::IMAGE},
+			{"BMP", DataType::IMAGE},
+			{"DDS", DataType::IMAGE},
+			{"TGA", DataType::IMAGE},
+			{"QOI", DataType::IMAGE},
+			{"WAV", DataType::SOUND},
+			{"OGG", DataType::SOUND},
 		};
 		wi::vector<std::string> GetSupportedImageExtensions()
 		{

WickedEngine/wiUnorderedMap.h

@@ -8,6 +8,8 @@
 
 #if WI_UNORDERED_MAP_TYPE == 1
 #include "Utility/flat_hash_map.hpp"
+#elif WI_UNORDERED_MAP_TYPE == 2
+#include "Utility/robin_hood.h"
 #else
 #include <unordered_map>
 #endif // WI_UNORDERED_MAP_TYPE
@@ -17,6 +19,8 @@ namespace wi
 	template<typename K, typename V, typename H = std::hash<K>, typename E = std::equal_to<K>, typename A = std::allocator<std::pair<const K, V> > >
 #if WI_UNORDERED_MAP_TYPE == 1
 	using unordered_map = ska::flat_hash_map<K, V, H, E, A>;
+#elif WI_UNORDERED_MAP_TYPE == 2
+	using unordered_map = robin_hood::unordered_flat_map<K, V, H, E>;
 #else
 	using unordered_map = std::unordered_map<K, V, H, E, A>;
 #endif // WI_UNORDERED_MAP_TYPE