saints row iv · systems

Saints Row IV Engine Systems

Every major system in one line each: what it does, how it works, where it lives.

Systems26 rows

Every major part of the engine. 'Key functions' gives the name and address to start from.

System	What it does	How it works	Key functions	Data files	Detail doc
Game flow	Decides which 'mode' the game is in.	A stack of 10 states (boot, menu, loading, in game, pause...). Changes are queued and applied once per frame.	gamestate_register `00865f20`, game_frame_tick `00724f40`	01_architecture.md
Threads & jobs	Runs work in parallel.	Named threads for rendering, file loading, audio, network, saves; a job scheduler with worker threads; Havok has its own physics threads.	thread_create `010c1a10`, job_submit `010c1050`	04_core_systems.md
Memory	Gives every system a fixed budget.	At start-up the game reserves named pools (e.g. 32 MB for Lua, 11 MB for objects). new/delete can be redirected per thread.	game_memory_budget_init `00726620`	04_core_systems.md
Files & packfiles	Finds and reads game data.	Search order: mods folder first, then packfiles (.vpp_pc), then memory, then loose files. Reads happen on background threads.	cf_find_file `010b7b00`, cf_open `010baf90`	04_core_systems.md
Streaming	Loads the city around you.	The world is split into zones; each is a 'stream2 container' loaded and unloaded as you move.	stream2_container_create `010dd670`	.asm_pc, .str2_pc	04_core_systems.md
Data tables	Holds nearly all tuning numbers.	282 XML tables (.xtbl) parsed at boot or on demand - weapons, vehicles, AI, cheats, weather...	xtbl_load_file `010a6690`	every .xtbl	07_xtbl_loaders.md
Scripting (Lua)	Runs missions and UI logic.	Two Lua 5.1 engines: 'game play' (missions) and 'interface' (menus/HUD). Scripts call ~1,900 native commands.	lua_gameplay_vm_init `00bbd970`	02_lua_api.md
Objects	Everything that exists in the world.	67 object types in a family tree (player is a human is a physical_object...). Objects find each other by 64-bit handles.	handle_table_lookup `004988d0`, object_is_a `0069d040`	06_gameplay.md
Humans & player	People, including you.	One 'human' class for player, NPCs and homies. Health, team, current vehicle, super power all live in the human object.	get_local_player `00b639c0`, human_take_damage `00adeb60`	character.xtbl	06_gameplay.md
AI	Makes NPCs act.	Every NPC checks 20 goals in priority order; for the first goal that applies, it tries that goal's actions in order until one works.	ai_select_action `00532300`	ai_goals, ai_behavior, ai_personalities	09_ai.md
Vehicles	Cars, bikes, boats, aircraft.	Driving physics is Havok's vehicle kit (engine, gears, wheels, suspension) fed from vehicles.xtbl. Flying vehicles have their own code.	handle_to_vehicle `004eb410`	vehicles.xtbl	06_gameplay.md
Weapons & combat	Guns, melee, explosions.	Each weapon is a weapon_info record from weapons.xtbl; upgrades patch its stats per level; all damage goes through human_take_damage.	weapon_info_parse `00d7cb90`, weapon_upgrade_apply_overrides `00d6d5c0`	weapons, weapon_upgrades	13_weapons.md
Superpowers	Telekinesis, stomp, blast, buff, sprint, jump...	8 power slots, 21 elements; unlock/select flags live in the player object and are synced in co-op.	superpower_select `006c6310`	super_power_levels	06_gameplay.md
Animation	Moves characters.	Volition's own animation system (not Havok): data-driven node graphs that blend clips and run state machines.	anim_system_init `004903c0`	anim_*.xtbl	10_animation.md
Physics	Collisions, ragdolls, vehicles.	Havok Physics 2011.3 with Volition glue code.	01_architecture.md
Rendering	Draws the frame.	D3D11 renderer using Volition's 'Inferred Lighting' (lights computed in a separate buffer), selectable shadow techniques, HDR, bloom, depth of field, motion blur.	render_thread_main `00729ce0`	dof_situations, refraction_situations	11_rendering.md
UI	Menus and HUD.	'vint' UI system: documents of elements animated by Lua scripts; ~110 screen classes; HUD meters are 'gsi' widgets.	vint_doc_parse `0112ccf0`	.vint_doc	12_ui.md
World	Time of day, weather, crowds, traffic.	Game clock drives lighting; weather stages; spawn tables decide who and what appears.	game_clock_advance `0085d430`	weather, spawn_info_*	14_world.md
Notoriety	Police heat.	One family ('police'), levels 0-5, decays over time; only the co-op host changes it.	notoriety_set_level `00766230`	notoriety*.xtbl	06_gameplay.md
Cheats	Phone cheat codes.	Loaded from cheats.xtbl; activating one flags the save unless the cheat is marked 'don't flag'.	cheat_set_active `00857f30`	cheats.xtbl	06_gameplay.md
Co-op networking	Two-player online.	Steam P2P + Steam lobbies; 98 message types; objects are replicated with per-type compressors.	net_register_msg `009a85d0`	06_gameplay.md
Saves	Your progress.	Only in Steam Cloud: numbered save files plus a checksummed directory file.	gamesave_cloud_write_file `00d93110`	06_gameplay.md
Audio	Sound and music.	Audiokinetic Wwise plus an engine audio thread; interactive music reacts to powers and action.	audio_thread_main `005a9560`	interactive_music.xtbl	06_gameplay.md
Missions & scripts	Story missions and activities.	Missions come from _objectives.xtbl; their logic is Lua run as threads resumed once per frame; only the co-op host ends a mission.	mission_end `00849760`, script_system_frame `011497b0`	_objectives, mission_checkpoints, activity_types	16_missions.md
Customization	Your look, your gang, your cars.	Slot/item/tattoo-layer/morph tables; the skin texture is rebuilt on the GPU; co-op sends your look to the partner.	player`+0x27DC`, pcr_/pcu_ commands	customization_*.xtbl	17_customization.md
Online services	Accounts and extras.	Koch Media DSU/Silverlink account services, Steam achievements/cloud, OpenSSL + libcurl for HTTPS.	silverlink_thread_main `00ba7a80`	00_overview.md

Built from SR4_Game_Explained.xlsx (650 KB), if you'd rather filter it in Excel. SaintsRowIV.exe v1.0.6.1 (Steam). Names are ours unless they're Volition's own Lua or C++ class names.