OASIS Learn/Case Studies/ODOOM
Advanced ⏱ 60 min WEB4 WEB5 C/C++

💀 Case Study: ODOOM

ODOOM is a fork of UZDoom — the popular Doom source port — extended with full OASIS WEB4 and WEB5 integration via OGLib (shared C helper layer) and the OGEngine Client C ABI. Players authenticate as OASIS Avatars, earn karma for kills and completions, carry cross-game inventory shared with OQuake and Our World, and advance quest objectives that persist across all three games. ODOOM is the reference game for how to integrate any C/C++ title with the OASIS Omniverse in minutes.

Tech stack

  • Base engine: UZDoom (C/C++) extended with OGEngine OASIS layer
  • OGLib: shared C helper library — config loading, beamin/beamout, session forwarders, cross-game mapping (oglib.h)
  • OASIS integration: OGEngine Client — a C ABI (ogengine_* functions) wrapping WEB4 + WEB5
  • OASIS WEB4: Avatar auth, Karma (kills/completions), cross-game Inventory, HyperDrive save data
  • OASIS WEB5: Missions, Quests, Inventory Items (keys/weapons), Cross-game quest chains
  • Shared with: OQuake (same quest chain), Our World (same inventory)

What is OGEngine?

OGEngine is the full OASIS game integration stack: OGEngine Client (the C# NativeAOT DLL), WEB4, WEB5, and the optional OGLib C helper layer that sits on top. OGLib handles the boilerplate every game needs — config loading, session management, beamin/beamout workflow, and cross-game asset mapping — so game-specific code stays lean and only contains engine hooks.

OGEngine stack
uzdoom_star_integration.cpp  (ODOOM engine hooks only)
         ↓  #include "oglib.h"
    OGLib  (shared C library — config, beamin, session shims, cross-game)
         ↓  star_api_* calls
  OGEngine Client  (C# NativeAOT → star_api.dll)
         ↓  HTTPS
  WEB4 / WEB5 OASIS APIs

Step 1 — Initialise OASIS at Startup

c
// uzdoom_star_integration.cpp — OGLib handles config + session boilerplate
#define OGLIB_SESSION_IMPL
#define OGLIB_CONFIG_IMPL
#define OGLIB_BEAMIN_IMPL
#include "oglib.h"   // config, beamin, session forwarders, cross-game, JSON/str utils
#include "star_api.h"

void I_OASISInit(void)
{
    // OGLib loads oasisstar.json, sets the API URL, and restores saved JWT
    oglib_config_load(&g_star_config, "oasisstar.json", NULL, NULL);
    star_api_init(g_star_config.star_api_url);
    oglib_beamin_restore_session(&g_star_config);
}

Step 2 — Avatar Login Screen

c
// Called from the ODOOM login menu
void M_OASISLogin(const char *email, const char *password)
{
    star_api_login_async(email, password, on_login_result);
}

static void on_login_result(star_api_result_t *r)
{
    if (r->is_error) {
        M_ShowError(r->message);
        return;
    }
    config_set_string("oasis_token", r->token);
    G_StartGame();   // proceed to game
}

Step 3 — Karma for Kills & Level Completion

c
// p_interaction.c — called when monster dies
void P_KillMobj(mobj_t *source, mobj_t *target)
{
    // ... existing Doom kill logic ...

    // Award karma for the kill
    int karma = monster_karma_value(target->type);   // e.g. Cacodemon = 5, CyberDemon = 100
    star_api_award_karma(karma, "Kill");
}

// g_game.c — called when level exits
void G_WorldDone(void)
{
    star_api_complete_mission_objective(current_mission_id, current_objective, avatar_id);
    star_api_award_karma(500, "LevelComplete");
}

Step 4 — Cross-Game Inventory (Keys)

The Crimson Key found in ODOOM's E1M1 is stored in the OASIS cross-game inventory. In Our World, a secret AR door only opens if the player holds this key.

c
// p_map.c — when player picks up a key
void P_TouchSpecialThing(mobj_t *special, mobj_t *toucher)
{
    switch (special->sprite) {
    case SPR_RKEY:   // Red (Crimson) Key
        star_api_add_inventory_item("crimson_key",
                                    "Crimson Key",
                                    "Key discovered in Doom E1M1 — opens the citadel gate.");
        break;
    case SPR_BKEY:   // Blue Key
        star_api_add_inventory_item("blue_key", "Blue Key", "...");
        break;
    }
}

// Check if player already has a key (e.g. carried over from Our World)
if (star_api_has_item("golden_key")) {
    door_open(GOLDEN_DOOR);   // a door that only OQuake players can find the key for
}

Step 5 — Quest Chain (ODOOM → OQuake → Our World)

c
// Complete quest objective 0 of the Key Hunters Trilogy
// (collecting the Crimson Key advances the cross-game quest)
star_api_complete_quest_objective(KEY_HUNTERS_QUEST_ID, 0, avatar_id);

// Query quest progress for HUD display
star_api_quest_progress_t prog;
star_api_get_quest_progress(KEY_HUNTERS_QUEST_ID, avatar_id, &prog);
HU_DrawQuestProgress(prog.completed_missions, prog.total_missions);
💡
Source code

ODOOM game code: UZDoom fork ↗ · OASIS ODOOM integration: OASIS Omniverse/ODOOM ↗ · OGLib: OASIS Omniverse/OGLib ↗ · OGEngine Client: OGEngine Client ↗

Related case studies