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This article provides an '''overview''' on the implementation of ''The Legend of Zelda: Breath of the Wild''. | This article provides an '''overview''' on the implementation of ''The Legend of Zelda: Breath of the Wild''. | ||
''Breath of the Wild'''s internal project name is U-King<ref>The [[executable]] binary is called U-King, and numerous other assets refer to the game as U-King.</ref>. | |||
== Framework and engine == | == Framework and engine == | ||
''Breath of the Wild'' is a modern Nintendo game which was released in March 2017 for the Wii U and the Switch. It shares a lot of code with contemporary first-party Nintendo games such as ''Splatoon 2'' and ''Super Mario Odyssey'', notably the '''sead''' (Nintendo's in-house framework and utilities for first-party titles) and '''NintendoWare''' (GFX, audio, effects, and UI) [[Software libraries|libraries]]. | |||
''BotW'' is the first major Nintendo game to use '''XLink''' (EffectLink and SoundLink) as a system to make bridging code and graphics or sound effects easier, and also marks the first significant use of event flows (via the EventFlow or '''evfl''' library) to implement in-game events such as cutscenes and NPC interactions. | |||
=== Engine === | |||
A completely custom engine – which Nintendo seemingly calls [[KingSystem]] – is used for ''Breath of the Wild''. It appears to have been written from scratch as nothing significant is shared with previous Zelda games or even older Nintendo games. In particular, ''Breath of the Wild'' does '''not''' use LunchPack or ''SMO''<nowiki/>'s engine, even though games using the former appear to use a ''BotW''-inspired ROM structure. | |||
=== Physics === | |||
The game relies on the [[Havok]] physics engine for [[wikipedia:Ragdoll physics|ragdoll physics]], [[wikipedia:Collision detection|collision]] (Physics2012), navigation (NavMesh), and [[wikipedia:Cloth modeling|cloth modeling]]. ''Breath of the Wild'' does not use Nintendo's KCL library. | |||
== Architecture == | |||
Just like any other Switch game, executable code is stored in the ExeFS – with the game code in the main [[executable]] – and [[content]] files or assets are stored in the RomFS. In the context of ''Breath of the Wild'', the latter is referred to as the game ROM. | |||
''BotW'' is the | === Code === | ||
''BotW'' is written in C++ with almost no hand-written assembly code and with no usage of the C++ standard library. Standard structures such as strings and associative maps are implemented in the '''sead''' library. Standard RTTI is not used; instead the game relies on Nintendo's own implementation of RTTI in '''sead''', which does not leak symbols at all. | |||
The codebase appears to be compiled with high levels of optimisation enabled for both Wii U and Switch releases, with code on the latter platform being better optimised. Since 1.6.0 (Switch only), the game is additionally built with [[wikipedia:LTO|LTO]] enabled, which results in massive amounts of code bloat. All known public releases are stripped, i.e. don't contain any debugging symbol. | |||
The game | The game is divided into several components and makes heavy use of '''managers''', which are singletons that are usually responsible for one specific task (e.g. PlacementMgr for actor placement, EventMgr for in-game events, etc.). Unlike older Zelda games, most managers are dynamically allocated, not stored in BSS. In general, ''Breath of the Wild'' makes use of the heap and virtual functions a lot more. | ||
In total, there are 130+ '''[[subsystems]]'''. | |||
=== ROM === | |||
'''Resources''' are organised by type into a [[Content|directory tree]] with nested directories. | |||
Each resource type often has its own distinct file extension even when the file format is exactly the same. For example, [[Bgparamlist|Bgparamlist (GeneralParamList)]] and [[Blifecondition|Blifecondition (LifeCondition)]] are both [[AAMP]] files, but they have different file extensions because their types and purposes are different. | |||
==== Archives ==== | |||
Because the game tends to load several resources at the same time, related files are grouped and packed into '''archives''' to improve performance. Resources are packed [[Actor pack|at the actor level]], or [[Beventpack|at the event level]], or based on the moment they are loaded by the game, which is the case for [[Dungeon pack|dungeon packs]] and top-level [[Pack|packs]] for instance. | |||
This archive system does result in content duplication, but it is a fair space-time tradeoff. | |||
==== Resource auto-generation ==== | |||
Many resources in the ROM are automatically generated during the build process from source files that are not shipped with the game. Examples include Havok source collision data, UI map tiles or terrain statistics files. Some assets are generated by combining information from parameter files; this is done for performance issues as it allows the game to query information without loading any additional file. For example, [[ActorInfo.product.sbyml]] exists to avoid having to load entire actors or multiple [[ActorParam]] files at the very least. | |||
There is ample evidence implying that resources are packed into archives in a completely automated way. | |||
== Concepts == | == Concepts == | ||
While ''Breath of the Wild'' shares core concepts such as actors, scenes and flags with most (all?) Zelda games since ''Ocarina of Time'', most of them are implemented in radically different ways. New concepts have also been introduced. | |||
=== Actors === | |||
{{Link to article|link=Actor|include=true}} | |||
=== AI system === | |||
{{empty section}} | |||
=== Event flows === | |||
{{empty section}} | |||
=== Demos and cutscenes === | |||
{{empty section}} | |||
=== GameData flags === | |||
{{empty section}} | |||
=== Maps === | |||
{{Link to article|link=Map|include=true}} | |||
=== Stages and stage binders === | |||
{{Link to article|link=Stage|include=}} | |||
Maps which share characteristics with each other and use the same set of [[subsystems]] usually require very similar initialisation and main loop code. In order to avoid code duplication, ''Breath of the Wild'' moves such shared code into '''stages'''. As an example, all Hyrule and Trial of the Sword maps are handled by OpenWorldStage. | |||
'''Stage binders''' are among other things responsible for creating stage instances. | |||
=== Scenes === | |||
{{Link to article|link=Scene|include=true}} | |||
=== Map units === | |||
{{Link to article|link=Map unit|include=true}} | |||
=== AutoPlacement === | |||
{{empty section}} | |||
=== Resource system === | |||
{{empty section}} | |||
== File formats == | |||
[[AAMP]] and [[BYML]] are extremely common file formats, as they are most notably used for actor parameter ([[ActorParam]]) files, map units and more generally configuration files. They can be found in the ROM with various file extensions. | |||
[[SARC]] (along with the [[Yaz0]] compression format) is also omnipresent as it is used for all data archives which BotW heavily relies on. SARC archives have several file extensions. | |||
Large numbers of [[BFEVFL]] (binary event flows) files are stored in [[Content/EventFlow]]. | |||
Other commonly seen file formats include [[BFRES]] (models), [[BFSTM]] (sound streams), [[BFLYT]] (layouts) and various other standard NintendoWare formats. | |||
< | <references /> | ||