Give your mod its own settings

Let a player configure your mod by editing a plain text file, with no help from the API — T3SdkApi has no settings calls, so a mod reads its own configuration the same way any other Win32 program would.

The recipe

1. Ship <id>.ini next to your DLL. Packaging already supports this: any file placed next to your DLL in the package is installed alongside it (see Packaging), so the finished layout is System/mods/<id>/<id>.ini, right next to System/mods/<id>/<id>.dll.
2. Find your own DLL's folder at runtime. A DLL is not handed a path the way an executable is, but Windows does pass your module's handle to DllMain; save it there.
3. Read values with GetPrivateProfileStringW/GetPrivateProfileIntW, the same calls T3SDK itself uses to read T3SDK.ini (sdk/loader/sdk.cpp).

#include <t3sdk/t3sdk.h>

#include <windows.h>
#include <wchar.h>

static const T3SdkApi* api;
static HMODULE selfModule;
static int verbosity = 1; /* default, used if the key or the file is missing */

static void LoadSettings(void) {
    wchar_t path[MAX_PATH];
    wchar_t* slash;

    GetModuleFileNameW(selfModule, path, MAX_PATH);
    slash = wcsrchr(path, L'\\');
    if (slash) {
        slash[1] = L'\0';
    }
    wcscat_s(path, MAX_PATH, L"my-mod.ini");

    verbosity = (int)GetPrivateProfileIntW(L"MyMod", L"Verbosity", verbosity, path);
}

T3SDK_EXPORT int T3SDK_CALL T3Mod_Init(const T3SdkApi* sdk) {
    if (sdk->version < T3SDK_API_VERSION) {
        return 1;
    }
    api = sdk;
    LoadSettings();
    api->Log("verbosity=%d", verbosity);
    return 0;
}

BOOL WINAPI DllMain(HINSTANCE instance, DWORD reason, LPVOID reserved) {
    (void)reserved;
    if (reason == DLL_PROCESS_ATTACH) {
        selfModule = instance;
    }
    return TRUE;
}

with my-mod.ini:

[MyMod]
Verbosity=2

Watch out for

• GetPrivateProfileInt/String return your default when the file, the section or the key is missing — there is no error to handle. Ship a default <id>.ini in your package anyway, so a player has something to find and edit.
• T3SDK does not provide a DllMain for you, and mods are not required to define one; add your own only if you need it, as above. It runs before T3Mod_Init and is a normal Windows DLL entry point, so keep it simple: do only what you would do in any DLL's DLL_PROCESS_ATTACH.
• Settings read this way are static for the run: nothing calls LoadSettings again on its own. Re-read the file yourself (for example from a frame callback, occasionally) if you want a player's edits to take effect without restarting the game.
• This is your mod's own file, in your own package folder — it has nothing to do with T3SDK.ini or the game's own .ini files, and nothing here lets you add a page to the launcher's settings UI.

Reference

• Packaging: how extra files next to your DLL are installed.
• Mod packages: the installed layout, System/mods/<id>/....