# Modding A mod is a special plugin that can do things that alter the experience of the game. ## Making your own Any mods that need to be compiled for a 32 bit WASM freestanding environment. ### Mod exported functions A mod **MUST** provide atleast 2 functions: `init` and `deinit` The signatures are: - `uint64_t init(uint32_t modID)` - `uint64_t deinit()` The return values of `init` and `deinit` are results. Any non zero result will abort `sideros` and have the exit code of the result This `modID` parameter in `init` is used in some engine functions. (See [engine functions](#engine-functions) for more) #### init The `init` function is the first function called in a mod and is used for setting up variables, initializing a memory manager and defining [systems](#systems). #### update There's no formal definition of an `update` function but you can emulate an update function by hooking on `render` (See [hooking](#hooking) for more info on how to do this) #### deinit The `deinit` function is the last function called in a mod and is used for deleting the defined memory managers and deleting the defined systems ### Engine functions There are a couple of functions you can use. (All of them have to be defined with the IA32 Cdecl + [system-V (Subsection 3.2.3)](https://refspecs.linuxbase.org/elf/x86_64-abi-0.99.pdf) calling convention): #### Logging - `void logDebug(const uint8_t* string, uint64_t length)` - `void logInfo(const uint8_t* string, uint64_t length)` - `void logWarn(const uint8_t* string, uint64_t length)` - `void logErr(const uint8_t* string, uint64_t length)` The `logDebug` function is only executed if the `sideros` binary **AND** the mod itself are compiled in debug mode. Each of these logging functions will print either until a null character has been found, or the length is exhausted. They will also print a special identifier in front of them with their logging level (So [DEBUG] for logDebug, [INFO] for logInfo, ...) #### Hooking functions - `void hook(uint32_t modID, uint32_t functionID)` ### Systems TODO ### Hooks Hooks are special in a way that they can latch on to a function in the engine and be executed when that function is called. See [this](#hooking-functions) for function signatures. #### Special information All hooks have a special parameter refered to internally as `deltatime` this is just the time how long it took between the previous call and this call ## Installing mods Installing mods can be done by copying the produced and/or downloaded .wasm file and copying it to the $SIDEROS_PATH/assets/mods directory. All .wasm files in that directory will be loaded and ran.