dllmain.cpp

#define NOMINMAX
#include <Windows.h>
#include <cstdlib>

#include <libhat/scanner.hpp>
#include <libhat/signature.hpp>

#include <MinHook.h>

// MinHook will redirect Dimension::getTimeOfDay to this function, replacing its behavior with our own code.
static float hk_getTimeOfDay(void* _this, int32_t time, float alpha) {
    static float value = 0.f;
    value += 0.00001f;
    value = std::fmodf(value, 1.f);

    return value;
}

static DWORD WINAPI startup(LPVOID dll) {
    constexpr auto signature = hat::compile_signature<"44 8B C2 B8 F1 19 76 05 F7 EA">();

    hat::scan_result scanResult = hat::find_pattern(signature, ".text");
    std::byte* getTimeOfDay = scanResult.get();

    // Initialize MinHook.
    MH_Initialize();

    // Hook getTimeOfDay.
    LPVOID original;
    MH_CreateHook(getTimeOfDay, &hk_getTimeOfDay, &original);
    MH_EnableHook(getTimeOfDay);

    // Exiting this thread without calling FreeLibraryAndExitThread on `dll` will cause the DLL to remain injected forever.
    return 0;
}

// `DllMain` is the function that will be called by Windows when your mod is injected into the game's process.
BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved) {
    switch (fdwReason) {
    case DLL_PROCESS_ATTACH:
        // DLL_PROCESS_ATTACH means the DLL is being initialized.

        // We create a new thread to call `startup`.
        // This is necessary since we can't use most Windows APIs inside DllMain.
        CreateThread(nullptr, 0, &startup, hinstDLL, 0, nullptr);
        break;

    case DLL_PROCESS_DETACH:
        // DLL_PROCESS_DETACH means that the DLL is being ejected,
        // or that the game is shutting down.

    default:
        break;
    }

    return TRUE;
}