--- a/Makefile	Fri Feb 03 07:45:58 2006 +0000
+++ b/Makefile	Fri Feb 03 12:55:21 2006 +0000
@@ -653,6 +653,7 @@
 SRCS += network_server.c
 SRCS += network_udp.c
 SRCS += newgrf.c
+SRCS += newgrf_engine.c
 SRCS += news_gui.c
 SRCS += npf.c
 SRCS += oldloader.c

--- a/aircraft_cmd.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/aircraft_cmd.c	Fri Feb 03 12:55:21 2006 +0000
@@ -18,6 +18,7 @@
 #include "airport.h"
 #include "vehicle_gui.h"
 #include "table/sprites.h"
+#include "newgrf_engine.h"
 
 static bool AirportMove(Vehicle *v, const AirportFTAClass *Airport);
 static bool AirportSetBlocks(Vehicle *v, AirportFTA *current_pos, const AirportFTAClass *Airport);

--- a/aircraft_gui.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/aircraft_gui.c	Fri Feb 03 12:55:21 2006 +0000
@@ -19,6 +19,7 @@
 #include "player.h"
 #include "depot.h"
 #include "vehicle_gui.h"
+#include "newgrf_engine.h"
 
 /**
  * Draw the purchase info details of an aircraft at a given location.

--- a/economy.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/economy.c	Fri Feb 03 12:55:21 2006 +0000
@@ -27,6 +27,7 @@
 #include "vehicle_gui.h"
 #include "ai/ai.h"
 #include "train.h"
+#include "newgrf_engine.h"
 
 // Score info
 const ScoreInfo _score_info[] = {

--- a/engine.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/engine.c	Fri Feb 03 12:55:21 2006 +0000
@@ -4,8 +4,6 @@
 #include "openttd.h"
 #include "debug.h"
 #include "functions.h"
-#include "string.h"
-#include "strings.h"
 #include "table/strings.h"
 #include "engine.h"
 #include "table/engines.h"
@@ -18,6 +16,7 @@
 #include "sprite.h"
 #include "variables.h"
 #include "train.h"
+#include "newgrf_engine.h"
 
 EngineInfo _engine_info[TOTAL_NUM_ENGINES];
 RailVehicleInfo _rail_vehicle_info[NUM_TRAIN_ENGINES];
@@ -257,586 +256,6 @@
 	AdjustAvailAircraft();
 }
 
-// TODO: We don't support cargo-specific wagon overrides. Pretty exotic... ;-) --pasky
-
-typedef struct WagonOverride {
-	byte *train_id;
-	int trains;
-	SpriteGroup *group;
-} WagonOverride;
-
-typedef struct WagonOverrides {
-	int overrides_count;
-	WagonOverride *overrides;
-} WagonOverrides;
-
-static WagonOverrides _engine_wagon_overrides[TOTAL_NUM_ENGINES];
-
-void SetWagonOverrideSprites(EngineID engine, SpriteGroup *group, byte *train_id,
-	int trains)
-{
-	WagonOverrides *wos;
-	WagonOverride *wo;
-
-	wos = &_engine_wagon_overrides[engine];
-	wos->overrides_count++;
-	wos->overrides = realloc(wos->overrides,
-		wos->overrides_count * sizeof(*wos->overrides));
-
-	wo = &wos->overrides[wos->overrides_count - 1];
-	/* FIXME: If we are replacing an override, release original SpriteGroup
-	 * to prevent leaks. But first we need to refcount the SpriteGroup.
-	 * --pasky */
-	wo->group = group;
-	group->ref_count++;
-	wo->trains = trains;
-	wo->train_id = malloc(trains);
-	memcpy(wo->train_id, train_id, trains);
-}
-
-static const SpriteGroup *GetWagonOverrideSpriteSet(EngineID engine, byte overriding_engine)
-{
-	const WagonOverrides *wos = &_engine_wagon_overrides[engine];
-	int i;
-
-	// XXX: This could turn out to be a timesink on profiles. We could
-	// always just dedicate 65535 bytes for an [engine][train] trampoline
-	// for O(1). Or O(logMlogN) and searching binary tree or smt. like
-	// that. --pasky
-
-	for (i = 0; i < wos->overrides_count; i++) {
-		const WagonOverride *wo = &wos->overrides[i];
-		int j;
-
-		for (j = 0; j < wo->trains; j++) {
-			if (wo->train_id[j] == overriding_engine)
-				return wo->group;
-		}
-	}
-	return NULL;
-}
-
-/**
- * Unload all wagon override sprite groups.
- */
-void UnloadWagonOverrides(void)
-{
-	WagonOverrides *wos;
-	WagonOverride *wo;
-	EngineID engine;
-	int i;
-
-	for (engine = 0; engine < TOTAL_NUM_ENGINES; engine++) {
-		wos = &_engine_wagon_overrides[engine];
-		for (i = 0; i < wos->overrides_count; i++) {
-			wo = &wos->overrides[i];
-			UnloadSpriteGroup(&wo->group);
-			free(wo->train_id);
-		}
-		free(wos->overrides);
-		wos->overrides_count = 0;
-		wos->overrides = NULL;
-	}
-}
-
-// 0 - 28 are cargos, 29 is default, 30 is the advert (purchase list)
-// (It isn't and shouldn't be like this in the GRF files since new cargo types
-// may appear in future - however it's more convenient to store it like this in
-// memory. --pasky)
-static SpriteGroup *engine_custom_sprites[TOTAL_NUM_ENGINES][NUM_GLOBAL_CID];
-
-void SetCustomEngineSprites(EngineID engine, byte cargo, SpriteGroup *group)
-{
-	if (engine_custom_sprites[engine][cargo] != NULL) {
-		DEBUG(grf, 6)("SetCustomEngineSprites: engine `%d' cargo `%d' already has group -- removing.", engine, cargo);
-		UnloadSpriteGroup(&engine_custom_sprites[engine][cargo]);
-	}
-	engine_custom_sprites[engine][cargo] = group;
-	group->ref_count++;
-}
-
-/**
- * Unload all engine sprite groups.
- */
-void UnloadCustomEngineSprites(void)
-{
-	EngineID engine;
-	CargoID cargo;
-
-	for (engine = 0; engine < TOTAL_NUM_ENGINES; engine++) {
-		for (cargo = 0; cargo < NUM_GLOBAL_CID; cargo++) {
-			if (engine_custom_sprites[engine][cargo] != NULL) {
-				DEBUG(grf, 6)("UnloadCustomEngineSprites: Unloading group for engine `%d' cargo `%d'.", engine, cargo);
-				UnloadSpriteGroup(&engine_custom_sprites[engine][cargo]);
-			}
-		}
-	}
-}
-
-static int MapOldSubType(const Vehicle *v)
-{
-	if (v->type != VEH_Train) return v->subtype;
-	if (IsTrainEngine(v)) return 0;
-	if (IsFreeWagon(v)) return 4;
-	return 2;
-}
-
-typedef SpriteGroup *(*resolve_callback)(const SpriteGroup *spritegroup,
-	const Vehicle *veh, uint16 callback_info, void *resolve_func); /* XXX data pointer used as function pointer */
-
-static const SpriteGroup* ResolveVehicleSpriteGroup(const SpriteGroup *spritegroup,
-	const Vehicle *veh, uint16 callback_info, resolve_callback resolve_func)
-{
-	if (spritegroup == NULL)
-		return NULL;
-
-	//debug("spgt %d", spritegroup->type);
-	switch (spritegroup->type) {
-		case SGT_REAL:
-		case SGT_CALLBACK:
-			return spritegroup;
-
-		case SGT_DETERMINISTIC: {
-			const DeterministicSpriteGroup *dsg = &spritegroup->g.determ;
-			const SpriteGroup *target;
-			int value = -1;
-
-			//debug("[%p] Having fun resolving variable %x", veh, dsg->variable);
-			if (dsg->variable == 0x0C) {
-				/* Callback ID */
-				value = callback_info & 0xFF;
-			} else if (dsg->variable == 0x10) {
-				value = (callback_info >> 8) & 0xFF;
-			} else if ((dsg->variable >> 6) == 0) {
-				/* General property */
-				value = GetDeterministicSpriteValue(dsg->variable);
-			} else {
-				/* Vehicle-specific property. */
-
-				if (veh == NULL) {
-					/* We are in a purchase list of something,
-					 * and we are checking for something undefined.
-					 * That means we should get the first target
-					 * (NOT the default one). */
-					if (dsg->num_ranges > 0) {
-						target = dsg->ranges[0].group;
-					} else {
-						target = dsg->default_group;
-					}
-					return resolve_func(target, NULL, callback_info, resolve_func);
-				}
-
-				if (dsg->var_scope == VSG_SCOPE_PARENT) {
-					/* First engine in the vehicle chain */
-					if (veh->type == VEH_Train)
-						veh = GetFirstVehicleInChain(veh);
-				}
-
-				if (dsg->variable == 0x40 || dsg->variable == 0x41) {
-					if (veh->type == VEH_Train) {
-						const Vehicle *u = GetFirstVehicleInChain(veh);
-						byte chain_before = 0, chain_after = 0;
-
-						while (u != veh) {
-							chain_before++;
-							if (dsg->variable == 0x41 && u->engine_type != veh->engine_type)
-								chain_before = 0;
-							u = u->next;
-						}
-						while (u->next != NULL && (dsg->variable == 0x40 || u->next->engine_type == veh->engine_type)) {
-							chain_after++;
-							u = u->next;
-						};
-
-						value = chain_before | chain_after << 8
-						        | (chain_before + chain_after) << 16;
-					} else {
-						value = 1; /* 1 vehicle in the chain */
-					}
-
-				} else {
-					// TTDPatch runs on little-endian arch;
-					// Variable is 0x80 + offset in TTD's vehicle structure
-					switch (dsg->variable - 0x80) {
-#define veh_prop(id_, value_) case (id_): value = (value_); break
-						veh_prop(0x00, veh->type);
-						veh_prop(0x01, MapOldSubType(veh));
-						veh_prop(0x04, veh->index);
-						veh_prop(0x05, veh->index & 0xFF);
-						/* XXX? Is THIS right? */
-						veh_prop(0x0A, PackOrder(&veh->current_order));
-						veh_prop(0x0B, PackOrder(&veh->current_order) & 0xff);
-						veh_prop(0x0C, veh->num_orders);
-						veh_prop(0x0D, veh->cur_order_index);
-						veh_prop(0x10, veh->load_unload_time_rem);
-						veh_prop(0x11, veh->load_unload_time_rem & 0xFF);
-						veh_prop(0x12, veh->date_of_last_service);
-						veh_prop(0x13, veh->date_of_last_service & 0xFF);
-						veh_prop(0x14, veh->service_interval);
-						veh_prop(0x15, veh->service_interval & 0xFF);
-						veh_prop(0x16, veh->last_station_visited);
-						veh_prop(0x17, veh->tick_counter);
-						veh_prop(0x18, veh->max_speed);
-						veh_prop(0x19, veh->max_speed & 0xFF);
-						veh_prop(0x1F, veh->direction);
-						veh_prop(0x28, veh->cur_image);
-						veh_prop(0x29, veh->cur_image & 0xFF);
-						veh_prop(0x32, veh->vehstatus);
-						veh_prop(0x33, veh->vehstatus);
-						veh_prop(0x34, veh->cur_speed);
-						veh_prop(0x35, veh->cur_speed & 0xFF);
-						veh_prop(0x36, veh->subspeed);
-						veh_prop(0x37, veh->acceleration);
-						veh_prop(0x39, veh->cargo_type);
-						veh_prop(0x3A, veh->cargo_cap);
-						veh_prop(0x3B, veh->cargo_cap & 0xFF);
-						veh_prop(0x3C, veh->cargo_count);
-						veh_prop(0x3D, veh->cargo_count & 0xFF);
-						veh_prop(0x3E, veh->cargo_source); // Probably useless; so what
-						veh_prop(0x3F, veh->cargo_days);
-						veh_prop(0x40, veh->age);
-						veh_prop(0x41, veh->age & 0xFF);
-						veh_prop(0x42, veh->max_age);
-						veh_prop(0x43, veh->max_age & 0xFF);
-						veh_prop(0x44, veh->build_year);
-						veh_prop(0x45, veh->unitnumber);
-						veh_prop(0x46, veh->engine_type);
-						veh_prop(0x47, veh->engine_type & 0xFF);
-						veh_prop(0x48, veh->spritenum);
-						veh_prop(0x49, veh->day_counter);
-						veh_prop(0x4A, veh->breakdowns_since_last_service);
-						veh_prop(0x4B, veh->breakdown_ctr);
-						veh_prop(0x4C, veh->breakdown_delay);
-						veh_prop(0x4D, veh->breakdown_chance);
-						veh_prop(0x4E, veh->reliability);
-						veh_prop(0x4F, veh->reliability & 0xFF);
-						veh_prop(0x50, veh->reliability_spd_dec);
-						veh_prop(0x51, veh->reliability_spd_dec & 0xFF);
-						veh_prop(0x52, veh->profit_this_year);
-						veh_prop(0x53, veh->profit_this_year & 0xFFFFFF);
-						veh_prop(0x54, veh->profit_this_year & 0xFFFF);
-						veh_prop(0x55, veh->profit_this_year & 0xFF);
-						veh_prop(0x56, veh->profit_last_year);
-						veh_prop(0x57, veh->profit_last_year & 0xFF);
-						veh_prop(0x58, veh->profit_last_year);
-						veh_prop(0x59, veh->profit_last_year & 0xFF);
-						veh_prop(0x5A, veh->next == NULL ? INVALID_VEHICLE : veh->next->index);
-						veh_prop(0x5C, veh->value);
-						veh_prop(0x5D, veh->value & 0xFFFFFF);
-						veh_prop(0x5E, veh->value & 0xFFFF);
-						veh_prop(0x5F, veh->value & 0xFF);
-						veh_prop(0x60, veh->string_id);
-						veh_prop(0x61, veh->string_id & 0xFF);
-						/* 00h..07h=sub image? 40h=in tunnel; actually some kind of status
-						 * aircraft: >=13h when in flight
-						 * train, ship: 80h=in depot
-						 * rv: 0feh=in depot */
-						/* TODO veh_prop(0x62, veh->???); */
-
-						/* TODO: The rest is per-vehicle, I hope no GRF file looks so far.
-						 * But they won't let us have an easy ride so surely *some* GRF
-						 * file does. So someone needs to do this too. --pasky */
-
-#undef veh_prop
-					}
-				}
-			}
-
-			target = value != -1 ? EvalDeterministicSpriteGroup(dsg, value) : dsg->default_group;
-			//debug("Resolved variable %x: %d, %p", dsg->variable, value, callback);
-			return resolve_func(target, veh, callback_info, resolve_func);
-		}
-
-		case SGT_RANDOMIZED: {
-			const RandomizedSpriteGroup *rsg = &spritegroup->g.random;
-
-			if (veh == NULL) {
-				/* Purchase list of something. Show the first one. */
-				assert(rsg->num_groups > 0);
-				//debug("going for %p: %d", rsg->groups[0], rsg->groups[0].type);
-				return resolve_func(rsg->groups[0], NULL, callback_info, resolve_func);
-			}
-
-			if (rsg->var_scope == VSG_SCOPE_PARENT) {
-				/* First engine in the vehicle chain */
-				if (veh->type == VEH_Train)
-					veh = GetFirstVehicleInChain(veh);
-			}
-
-			return resolve_func(EvalRandomizedSpriteGroup(rsg, veh->random_bits), veh, callback_info, resolve_func);
-		}
-
-		default:
-			error("I don't know how to handle such a spritegroup %d!", spritegroup->type);
-			return NULL;
-	}
-}
-
-static const SpriteGroup *GetVehicleSpriteGroup(EngineID engine, const Vehicle *v)
-{
-	const SpriteGroup *group;
-	byte cargo = GC_PURCHASE;
-
-	if (v != NULL) {
-		cargo = _global_cargo_id[_opt.landscape][v->cargo_type];
-		assert(cargo != GC_INVALID);
-	}
-
-	group = engine_custom_sprites[engine][cargo];
-
-	if (v != NULL && v->type == VEH_Train) {
-		const SpriteGroup *overset = GetWagonOverrideSpriteSet(engine, v->u.rail.first_engine);
-
-		if (overset != NULL) group = overset;
-	}
-
-	return group;
-}
-
-int GetCustomEngineSprite(EngineID engine, const Vehicle *v, byte direction)
-{
-	const SpriteGroup *group;
-	const RealSpriteGroup *rsg;
-	byte cargo = GC_PURCHASE;
-	byte loaded = 0;
-	bool in_motion = 0;
-	int totalsets, spriteset;
-	int r;
-
-	if (v != NULL) {
-		int capacity = v->cargo_cap;
-
-		cargo = _global_cargo_id[_opt.landscape][v->cargo_type];
-		assert(cargo != GC_INVALID);
-
-		if (capacity == 0) capacity = 1;
-		loaded = (v->cargo_count * 100) / capacity;
-
-		if (v->type == VEH_Train) {
-			in_motion = GetFirstVehicleInChain(v)->current_order.type != OT_LOADING;
-		} else {
-			in_motion = v->current_order.type != OT_LOADING;
-		}
-	}
-
-	group = GetVehicleSpriteGroup(engine, v);
-	group = ResolveVehicleSpriteGroup(group, v, 0, (resolve_callback) ResolveVehicleSpriteGroup);
-
-	if (group == NULL && cargo != GC_DEFAULT) {
-		// This group is empty but perhaps there'll be a default one.
-		group = ResolveVehicleSpriteGroup(engine_custom_sprites[engine][GC_DEFAULT], v, 0,
-		                                (resolve_callback) ResolveVehicleSpriteGroup);
-	}
-
-	if (group == NULL)
-		return 0;
-
-	assert(group->type == SGT_REAL);
-	rsg = &group->g.real;
-
-	if (!rsg->sprites_per_set) {
-		// This group is empty. This function users should therefore
-		// look up the sprite number in _engine_original_sprites.
-		return 0;
-	}
-
-	assert(rsg->sprites_per_set <= 8);
-	direction %= rsg->sprites_per_set;
-
-	totalsets = in_motion ? rsg->loaded_count : rsg->loading_count;
-
-	// My aim here is to make it possible to visually determine absolutely
-	// empty and totally full vehicles. --pasky
-	if (loaded == 100 || totalsets == 1) { // full
-		spriteset = totalsets - 1;
-	} else if (loaded == 0 || totalsets == 2) { // empty
-		spriteset = 0;
-	} else { // something inbetween
-		spriteset = loaded * (totalsets - 2) / 100 + 1;
-		// correct possible rounding errors
-		if (!spriteset)
-			spriteset = 1;
-		else if (spriteset == totalsets - 1)
-			spriteset--;
-	}
-
-	r = (in_motion ? rsg->loaded[spriteset]->g.result.result : rsg->loading[spriteset]->g.result.result) + direction;
-	return r;
-}
-
-/**
- * Check if a wagon is currently using a wagon override
- * @param v The wagon to check
- * @return true if it is using an override, false otherwise
- */
-bool UsesWagonOverride(const Vehicle* v)
-{
-	assert(v->type == VEH_Train);
-	return GetWagonOverrideSpriteSet(v->engine_type, v->u.rail.first_engine) != NULL;
-}
-
-/**
- * Evaluates a newgrf callback
- * @param callback_info info about which callback to evaluate
- *  (bit 0-7)  = CallBack id of the callback to use, see CallBackId enum
- *  (bit 8-15) = Other info some callbacks need to have, callback specific, see CallBackId enum, not used yet
- * @param engine Engine type of the vehicle to evaluate the callback for
- * @param vehicle The vehicle to evaluate the callback for, NULL if it doesnt exist (yet)
- * @return The value the callback returned, or CALLBACK_FAILED if it failed
- */
-uint16 GetCallBackResult(uint16 callback_info, EngineID engine, const Vehicle *v)
-{
-	const SpriteGroup *group;
-	byte cargo = GC_DEFAULT;
-
-	if (v != NULL)
-		cargo = _global_cargo_id[_opt.landscape][v->cargo_type];
-
-	group = engine_custom_sprites[engine][cargo];
-
-	if (v != NULL && v->type == VEH_Train) {
-		const SpriteGroup *overset = GetWagonOverrideSpriteSet(engine, v->u.rail.first_engine);
-
-		if (overset != NULL) group = overset;
-	}
-
-	group = ResolveVehicleSpriteGroup(group, v, callback_info, (resolve_callback) ResolveVehicleSpriteGroup);
-
-	if (group == NULL && cargo != GC_DEFAULT) {
-		// This group is empty but perhaps there'll be a default one.
-		group = ResolveVehicleSpriteGroup(engine_custom_sprites[engine][GC_DEFAULT], v, callback_info,
-		                                (resolve_callback) ResolveVehicleSpriteGroup);
-	}
-
-	if (group == NULL || group->type != SGT_CALLBACK)
-		return CALLBACK_FAILED;
-
-	return group->g.callback.result;
-}
-
-
-
-// Global variables are evil, yes, but we would end up with horribly overblown
-// calling convention otherwise and this should be 100% reentrant.
-static byte _vsg_random_triggers;
-static byte _vsg_bits_to_reseed;
-
-static const SpriteGroup *TriggerVehicleSpriteGroup(const SpriteGroup *spritegroup,
-	Vehicle *veh, uint16 callback_info, resolve_callback resolve_func)
-{
-	if (spritegroup == NULL)
-		return NULL;
-
-	if (spritegroup->type == SGT_RANDOMIZED) {
-		_vsg_bits_to_reseed |= RandomizedSpriteGroupTriggeredBits(
-			&spritegroup->g.random,
-			_vsg_random_triggers,
-			&veh->waiting_triggers
-		);
-	}
-
-	return ResolveVehicleSpriteGroup(spritegroup, veh, callback_info, resolve_func);
-}
-
-static void DoTriggerVehicle(Vehicle *veh, VehicleTrigger trigger, byte base_random_bits, bool first)
-{
-	const SpriteGroup *group;
-	const RealSpriteGroup *rsg;
-	byte new_random_bits;
-
-	_vsg_random_triggers = trigger;
-	_vsg_bits_to_reseed = 0;
-	group = TriggerVehicleSpriteGroup(GetVehicleSpriteGroup(veh->engine_type, veh), veh, 0,
-	                                  (resolve_callback) TriggerVehicleSpriteGroup);
-
-	if (group == NULL && veh->cargo_type != GC_DEFAULT) {
-		// This group turned out to be empty but perhaps there'll be a default one.
-		group = TriggerVehicleSpriteGroup(engine_custom_sprites[veh->engine_type][GC_DEFAULT], veh, 0,
-		                                  (resolve_callback) TriggerVehicleSpriteGroup);
-	}
-
-	if (group == NULL)
-		return;
-
-	assert(group->type == SGT_REAL);
-	rsg = &group->g.real;
-
-	new_random_bits = Random();
-	veh->random_bits &= ~_vsg_bits_to_reseed;
-	veh->random_bits |= (first ? new_random_bits : base_random_bits) & _vsg_bits_to_reseed;
-
-	switch (trigger) {
-		case VEHICLE_TRIGGER_NEW_CARGO:
-			/* All vehicles in chain get ANY_NEW_CARGO trigger now.
-			 * So we call it for the first one and they will recurse. */
-			/* Indexing part of vehicle random bits needs to be
-			 * same for all triggered vehicles in the chain (to get
-			 * all the random-cargo wagons carry the same cargo,
-			 * i.e.), so we give them all the NEW_CARGO triggered
-			 * vehicle's portion of random bits. */
-			assert(first);
-			DoTriggerVehicle(GetFirstVehicleInChain(veh), VEHICLE_TRIGGER_ANY_NEW_CARGO, new_random_bits, false);
-			break;
-		case VEHICLE_TRIGGER_DEPOT:
-			/* We now trigger the next vehicle in chain recursively.
-			 * The random bits portions may be different for each
-			 * vehicle in chain. */
-			if (veh->next != NULL)
-				DoTriggerVehicle(veh->next, trigger, 0, true);
-			break;
-		case VEHICLE_TRIGGER_EMPTY:
-			/* We now trigger the next vehicle in chain
-			 * recursively.  The random bits portions must be same
-			 * for each vehicle in chain, so we give them all
-			 * first chained vehicle's portion of random bits. */
-			if (veh->next != NULL)
-				DoTriggerVehicle(veh->next, trigger, first ? new_random_bits : base_random_bits, false);
-			break;
-		case VEHICLE_TRIGGER_ANY_NEW_CARGO:
-			/* Now pass the trigger recursively to the next vehicle
-			 * in chain. */
-			assert(!first);
-			if (veh->next != NULL)
-				DoTriggerVehicle(veh->next, VEHICLE_TRIGGER_ANY_NEW_CARGO, base_random_bits, false);
-			break;
-	}
-}
-
-void TriggerVehicle(Vehicle *veh, VehicleTrigger trigger)
-{
-	if (trigger == VEHICLE_TRIGGER_DEPOT) {
-		// store that the vehicle entered a depot this tick
-		VehicleEnteredDepotThisTick(veh);
-	}
-
-	DoTriggerVehicle(veh, trigger, 0, true);
-}
-
-static char *_engine_custom_names[TOTAL_NUM_ENGINES];
-
-void SetCustomEngineName(EngineID engine, const char *name)
-{
-	_engine_custom_names[engine] = strdup(name);
-}
-
-void UnloadCustomEngineNames(void)
-{
-	char **i;
-	for (i = _engine_custom_names; i != endof(_engine_custom_names); i++) {
-		free(*i);
-		*i = NULL;
-	}
-}
-
-StringID GetCustomEngineName(EngineID engine)
-{
-	if (!_engine_custom_names[engine])
-		return _engine_name_strings[engine];
-	ttd_strlcpy(_userstring, _engine_custom_names[engine], lengthof(_userstring));
-	return STR_SPEC_USERSTRING;
-}
-
-
 static void AcceptEnginePreview(Engine *e, PlayerID player)
 {
 	Player *p = GetPlayer(player);

--- a/engine.h	Fri Feb 03 07:45:58 2006 +0000
+++ b/engine.h	Fri Feb 03 12:55:21 2006 +0000
@@ -146,67 +146,12 @@
 	NUM_GLOBAL_CID  =  31
 };
 
-// This enum lists the implemented callbacks
-// Use as argument for the GetCallBackResult function (see comments there)
-enum CallbackID {
-	// Powered wagons, if the result is lower as 0x40 then the wagon is powered
-	// TODO: interpret the rest of the result, aka "visual effects"
-	CBID_WAGON_POWER = 0x10,
-
-	// Vehicle length, returns the amount of 1/8's the vehicle is shorter
-	// only for train vehicles
-	CBID_VEH_LENGTH = 0x11,
-
-	// Refit capacity, the passed vehicle needs to have its ->cargo_type set to
-	// the cargo we are refitting to, returns the new cargo capacity
-	CBID_REFIT_CAP = 0x15,
-
-	CBID_ARTIC_ENGINE = 0x16,
-};
-
-// bit positions for rvi->callbackmask, indicates which callbacks are used by an engine
-// (some callbacks are always used, and dont appear here)
-enum CallbackMask {
-	CBM_WAGON_POWER = 0,
-	CBM_VEH_LENGTH = 1,
-	CBM_REFIT_CAP = 3,
-	CBM_ARTIC_ENGINE = 4,
-};
-
-enum {
-	CALLBACK_FAILED = 0xFFFF
-};
-
 VARDEF const uint32 _default_refitmasks[NUM_VEHICLE_TYPES];
 VARDEF const CargoID _global_cargo_id[NUM_LANDSCAPE][NUM_CARGO];
 VARDEF const uint32 _landscape_global_cargo_mask[NUM_LANDSCAPE];
 VARDEF const CargoID _local_cargo_id_ctype[NUM_GLOBAL_CID];
 VARDEF const uint32 cargo_classes[16];
 
-void SetWagonOverrideSprites(EngineID engine, struct SpriteGroup *group, byte *train_id, int trains);
-void SetCustomEngineSprites(EngineID engine, byte cargo, struct SpriteGroup *group);
-// loaded is in percents, overriding_engine 0xffff is none
-int GetCustomEngineSprite(EngineID engine, const Vehicle *v, byte direction);
-uint16 GetCallBackResult(uint16 callback_info, EngineID engine, const Vehicle *v);
-bool UsesWagonOverride(const Vehicle *v);
-#define GetCustomVehicleSprite(v, direction) GetCustomEngineSprite(v->engine_type, v, direction)
-#define GetCustomVehicleIcon(et, direction) GetCustomEngineSprite(et, NULL, direction)
-
-typedef enum VehicleTrigger {
-	VEHICLE_TRIGGER_NEW_CARGO = 1,
-	// Externally triggered only for the first vehicle in chain
-	VEHICLE_TRIGGER_DEPOT = 2,
-	// Externally triggered only for the first vehicle in chain, only if whole chain is empty
-	VEHICLE_TRIGGER_EMPTY = 4,
-	// Not triggered externally (called for the whole chain if we got NEW_CARGO)
-	VEHICLE_TRIGGER_ANY_NEW_CARGO = 8,
-} VehicleTrigger;
-void TriggerVehicle(Vehicle *veh, VehicleTrigger trigger);
-
-void SetCustomEngineName(EngineID engine, const char *name);
-StringID GetCustomEngineName(EngineID engine);
-
-
 void DrawTrainEngine(int x, int y, EngineID engine, uint32 image_ormod);
 void DrawRoadVehEngine(int x, int y, EngineID engine, uint32 image_ormod);
 void DrawShipEngine(int x, int y, EngineID engine, uint32 image_ormod);
@@ -284,10 +229,6 @@
 	return &_road_vehicle_info[e - ROAD_ENGINES_INDEX];
 }
 
-void UnloadWagonOverrides(void);
-void UnloadCustomEngineSprites(void);
-void UnloadCustomEngineNames(void);
-
 /************************************************************************
  * Engine Replacement stuff
  ************************************************************************/

--- a/engine_gui.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/engine_gui.c	Fri Feb 03 12:55:21 2006 +0000
@@ -13,6 +13,7 @@
 #include "command.h"
 #include "news.h"
 #include "variables.h"
+#include "newgrf_engine.h"
 
 
 static StringID GetEngineCategoryName(EngineID engine)

--- a/newgrf.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/newgrf.c	Fri Feb 03 12:55:21 2006 +0000
@@ -17,6 +17,7 @@
 #include "variables.h"
 #include "bridge.h"
 #include "economy.h"
+#include "newgrf_engine.h"
 
 /* TTDPatch extended GRF format codec
  * (c) Petr Baudis 2004 (GPL'd)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/newgrf_engine.c	Fri Feb 03 12:55:21 2006 +0000
@@ -0,0 +1,593 @@
+/* $Id$ */
+
+#include "stdafx.h"
+#include "openttd.h"
+#include "debug.h"
+#include "functions.h"
+#include "string.h"
+#include "strings.h"
+#include "engine.h"
+#include "newgrf_engine.h"
+#include "sprite.h"
+#include "variables.h"
+#include "train.h"
+
+// TODO: We don't support cargo-specific wagon overrides. Pretty exotic... ;-) --pasky
+
+typedef struct WagonOverride {
+	byte *train_id;
+	int trains;
+	SpriteGroup *group;
+} WagonOverride;
+
+typedef struct WagonOverrides {
+	int overrides_count;
+	WagonOverride *overrides;
+} WagonOverrides;
+
+static WagonOverrides _engine_wagon_overrides[TOTAL_NUM_ENGINES];
+
+void SetWagonOverrideSprites(EngineID engine, SpriteGroup *group, byte *train_id,
+	int trains)
+{
+	WagonOverrides *wos;
+	WagonOverride *wo;
+
+	wos = &_engine_wagon_overrides[engine];
+	wos->overrides_count++;
+	wos->overrides = realloc(wos->overrides,
+		wos->overrides_count * sizeof(*wos->overrides));
+
+	wo = &wos->overrides[wos->overrides_count - 1];
+	/* FIXME: If we are replacing an override, release original SpriteGroup
+	 * to prevent leaks. But first we need to refcount the SpriteGroup.
+	 * --pasky */
+	wo->group = group;
+	group->ref_count++;
+	wo->trains = trains;
+	wo->train_id = malloc(trains);
+	memcpy(wo->train_id, train_id, trains);
+}
+
+static const SpriteGroup *GetWagonOverrideSpriteSet(EngineID engine, byte overriding_engine)
+{
+	const WagonOverrides *wos = &_engine_wagon_overrides[engine];
+	int i;
+
+	// XXX: This could turn out to be a timesink on profiles. We could
+	// always just dedicate 65535 bytes for an [engine][train] trampoline
+	// for O(1). Or O(logMlogN) and searching binary tree or smt. like
+	// that. --pasky
+
+	for (i = 0; i < wos->overrides_count; i++) {
+		const WagonOverride *wo = &wos->overrides[i];
+		int j;
+
+		for (j = 0; j < wo->trains; j++) {
+			if (wo->train_id[j] == overriding_engine)
+				return wo->group;
+		}
+	}
+	return NULL;
+}
+
+/**
+ * Unload all wagon override sprite groups.
+ */
+void UnloadWagonOverrides(void)
+{
+	WagonOverrides *wos;
+	WagonOverride *wo;
+	EngineID engine;
+	int i;
+
+	for (engine = 0; engine < TOTAL_NUM_ENGINES; engine++) {
+		wos = &_engine_wagon_overrides[engine];
+		for (i = 0; i < wos->overrides_count; i++) {
+			wo = &wos->overrides[i];
+			UnloadSpriteGroup(&wo->group);
+			free(wo->train_id);
+		}
+		free(wos->overrides);
+		wos->overrides_count = 0;
+		wos->overrides = NULL;
+	}
+}
+
+// 0 - 28 are cargos, 29 is default, 30 is the advert (purchase list)
+// (It isn't and shouldn't be like this in the GRF files since new cargo types
+// may appear in future - however it's more convenient to store it like this in
+// memory. --pasky)
+static SpriteGroup *engine_custom_sprites[TOTAL_NUM_ENGINES][NUM_GLOBAL_CID];
+
+void SetCustomEngineSprites(EngineID engine, byte cargo, SpriteGroup *group)
+{
+	if (engine_custom_sprites[engine][cargo] != NULL) {
+		DEBUG(grf, 6)("SetCustomEngineSprites: engine `%d' cargo `%d' already has group -- removing.", engine, cargo);
+		UnloadSpriteGroup(&engine_custom_sprites[engine][cargo]);
+	}
+	engine_custom_sprites[engine][cargo] = group;
+	group->ref_count++;
+}
+
+/**
+ * Unload all engine sprite groups.
+ */
+void UnloadCustomEngineSprites(void)
+{
+	EngineID engine;
+	CargoID cargo;
+
+	for (engine = 0; engine < TOTAL_NUM_ENGINES; engine++) {
+		for (cargo = 0; cargo < NUM_GLOBAL_CID; cargo++) {
+			if (engine_custom_sprites[engine][cargo] != NULL) {
+				DEBUG(grf, 6)("UnloadCustomEngineSprites: Unloading group for engine `%d' cargo `%d'.", engine, cargo);
+				UnloadSpriteGroup(&engine_custom_sprites[engine][cargo]);
+			}
+		}
+	}
+}
+
+static int MapOldSubType(const Vehicle *v)
+{
+	if (v->type != VEH_Train) return v->subtype;
+	if (IsTrainEngine(v)) return 0;
+	if (IsFreeWagon(v)) return 4;
+	return 2;
+}
+
+typedef SpriteGroup *(*resolve_callback)(const SpriteGroup *spritegroup,
+	const Vehicle *veh, uint16 callback_info, void *resolve_func); /* XXX data pointer used as function pointer */
+
+static const SpriteGroup* ResolveVehicleSpriteGroup(const SpriteGroup *spritegroup,
+	const Vehicle *veh, uint16 callback_info, resolve_callback resolve_func)
+{
+	if (spritegroup == NULL)
+		return NULL;
+
+	//debug("spgt %d", spritegroup->type);
+	switch (spritegroup->type) {
+		case SGT_REAL:
+		case SGT_CALLBACK:
+			return spritegroup;
+
+		case SGT_DETERMINISTIC: {
+			const DeterministicSpriteGroup *dsg = &spritegroup->g.determ;
+			const SpriteGroup *target;
+			int value = -1;
+
+			//debug("[%p] Having fun resolving variable %x", veh, dsg->variable);
+			if (dsg->variable == 0x0C) {
+				/* Callback ID */
+				value = callback_info & 0xFF;
+			} else if (dsg->variable == 0x10) {
+				value = (callback_info >> 8) & 0xFF;
+			} else if ((dsg->variable >> 6) == 0) {
+				/* General property */
+				value = GetDeterministicSpriteValue(dsg->variable);
+			} else {
+				/* Vehicle-specific property. */
+
+				if (veh == NULL) {
+					/* We are in a purchase list of something,
+					 * and we are checking for something undefined.
+					 * That means we should get the first target
+					 * (NOT the default one). */
+					if (dsg->num_ranges > 0) {
+						target = dsg->ranges[0].group;
+					} else {
+						target = dsg->default_group;
+					}
+					return resolve_func(target, NULL, callback_info, resolve_func);
+				}
+
+				if (dsg->var_scope == VSG_SCOPE_PARENT) {
+					/* First engine in the vehicle chain */
+					if (veh->type == VEH_Train)
+						veh = GetFirstVehicleInChain(veh);
+				}
+
+				if (dsg->variable == 0x40 || dsg->variable == 0x41) {
+					if (veh->type == VEH_Train) {
+						const Vehicle *u = GetFirstVehicleInChain(veh);
+						byte chain_before = 0, chain_after = 0;
+
+						while (u != veh) {
+							chain_before++;
+							if (dsg->variable == 0x41 && u->engine_type != veh->engine_type)
+								chain_before = 0;
+							u = u->next;
+						}
+						while (u->next != NULL && (dsg->variable == 0x40 || u->next->engine_type == veh->engine_type)) {
+							chain_after++;
+							u = u->next;
+						};
+
+						value = chain_before | chain_after << 8
+						        | (chain_before + chain_after) << 16;
+					} else {
+						value = 1; /* 1 vehicle in the chain */
+					}
+
+				} else {
+					// TTDPatch runs on little-endian arch;
+					// Variable is 0x80 + offset in TTD's vehicle structure
+					switch (dsg->variable - 0x80) {
+#define veh_prop(id_, value_) case (id_): value = (value_); break
+						veh_prop(0x00, veh->type);
+						veh_prop(0x01, MapOldSubType(veh));
+						veh_prop(0x04, veh->index);
+						veh_prop(0x05, veh->index & 0xFF);
+						/* XXX? Is THIS right? */
+						veh_prop(0x0A, PackOrder(&veh->current_order));
+						veh_prop(0x0B, PackOrder(&veh->current_order) & 0xff);
+						veh_prop(0x0C, veh->num_orders);
+						veh_prop(0x0D, veh->cur_order_index);
+						veh_prop(0x10, veh->load_unload_time_rem);
+						veh_prop(0x11, veh->load_unload_time_rem & 0xFF);
+						veh_prop(0x12, veh->date_of_last_service);
+						veh_prop(0x13, veh->date_of_last_service & 0xFF);
+						veh_prop(0x14, veh->service_interval);
+						veh_prop(0x15, veh->service_interval & 0xFF);
+						veh_prop(0x16, veh->last_station_visited);
+						veh_prop(0x17, veh->tick_counter);
+						veh_prop(0x18, veh->max_speed);
+						veh_prop(0x19, veh->max_speed & 0xFF);
+						veh_prop(0x1F, veh->direction);
+						veh_prop(0x28, veh->cur_image);
+						veh_prop(0x29, veh->cur_image & 0xFF);
+						veh_prop(0x32, veh->vehstatus);
+						veh_prop(0x33, veh->vehstatus);
+						veh_prop(0x34, veh->cur_speed);
+						veh_prop(0x35, veh->cur_speed & 0xFF);
+						veh_prop(0x36, veh->subspeed);
+						veh_prop(0x37, veh->acceleration);
+						veh_prop(0x39, veh->cargo_type);
+						veh_prop(0x3A, veh->cargo_cap);
+						veh_prop(0x3B, veh->cargo_cap & 0xFF);
+						veh_prop(0x3C, veh->cargo_count);
+						veh_prop(0x3D, veh->cargo_count & 0xFF);
+						veh_prop(0x3E, veh->cargo_source); // Probably useless; so what
+						veh_prop(0x3F, veh->cargo_days);
+						veh_prop(0x40, veh->age);
+						veh_prop(0x41, veh->age & 0xFF);
+						veh_prop(0x42, veh->max_age);
+						veh_prop(0x43, veh->max_age & 0xFF);
+						veh_prop(0x44, veh->build_year);
+						veh_prop(0x45, veh->unitnumber);
+						veh_prop(0x46, veh->engine_type);
+						veh_prop(0x47, veh->engine_type & 0xFF);
+						veh_prop(0x48, veh->spritenum);
+						veh_prop(0x49, veh->day_counter);
+						veh_prop(0x4A, veh->breakdowns_since_last_service);
+						veh_prop(0x4B, veh->breakdown_ctr);
+						veh_prop(0x4C, veh->breakdown_delay);
+						veh_prop(0x4D, veh->breakdown_chance);
+						veh_prop(0x4E, veh->reliability);
+						veh_prop(0x4F, veh->reliability & 0xFF);
+						veh_prop(0x50, veh->reliability_spd_dec);
+						veh_prop(0x51, veh->reliability_spd_dec & 0xFF);
+						veh_prop(0x52, veh->profit_this_year);
+						veh_prop(0x53, veh->profit_this_year & 0xFFFFFF);
+						veh_prop(0x54, veh->profit_this_year & 0xFFFF);
+						veh_prop(0x55, veh->profit_this_year & 0xFF);
+						veh_prop(0x56, veh->profit_last_year);
+						veh_prop(0x57, veh->profit_last_year & 0xFF);
+						veh_prop(0x58, veh->profit_last_year);
+						veh_prop(0x59, veh->profit_last_year & 0xFF);
+						veh_prop(0x5A, veh->next == NULL ? INVALID_VEHICLE : veh->next->index);
+						veh_prop(0x5C, veh->value);
+						veh_prop(0x5D, veh->value & 0xFFFFFF);
+						veh_prop(0x5E, veh->value & 0xFFFF);
+						veh_prop(0x5F, veh->value & 0xFF);
+						veh_prop(0x60, veh->string_id);
+						veh_prop(0x61, veh->string_id & 0xFF);
+						/* 00h..07h=sub image? 40h=in tunnel; actually some kind of status
+						 * aircraft: >=13h when in flight
+						 * train, ship: 80h=in depot
+						 * rv: 0feh=in depot */
+						/* TODO veh_prop(0x62, veh->???); */
+
+						/* TODO: The rest is per-vehicle, I hope no GRF file looks so far.
+						 * But they won't let us have an easy ride so surely *some* GRF
+						 * file does. So someone needs to do this too. --pasky */
+
+#undef veh_prop
+					}
+				}
+			}
+
+			target = value != -1 ? EvalDeterministicSpriteGroup(dsg, value) : dsg->default_group;
+			//debug("Resolved variable %x: %d, %p", dsg->variable, value, callback);
+			return resolve_func(target, veh, callback_info, resolve_func);
+		}
+
+		case SGT_RANDOMIZED: {
+			const RandomizedSpriteGroup *rsg = &spritegroup->g.random;
+
+			if (veh == NULL) {
+				/* Purchase list of something. Show the first one. */
+				assert(rsg->num_groups > 0);
+				//debug("going for %p: %d", rsg->groups[0], rsg->groups[0].type);
+				return resolve_func(rsg->groups[0], NULL, callback_info, resolve_func);
+			}
+
+			if (rsg->var_scope == VSG_SCOPE_PARENT) {
+				/* First engine in the vehicle chain */
+				if (veh->type == VEH_Train)
+					veh = GetFirstVehicleInChain(veh);
+			}
+
+			return resolve_func(EvalRandomizedSpriteGroup(rsg, veh->random_bits), veh, callback_info, resolve_func);
+		}
+
+		default:
+			error("I don't know how to handle such a spritegroup %d!", spritegroup->type);
+			return NULL;
+	}
+}
+
+static const SpriteGroup *GetVehicleSpriteGroup(EngineID engine, const Vehicle *v)
+{
+	const SpriteGroup *group;
+	byte cargo = GC_PURCHASE;
+
+	if (v != NULL) {
+		cargo = _global_cargo_id[_opt.landscape][v->cargo_type];
+		assert(cargo != GC_INVALID);
+	}
+
+	group = engine_custom_sprites[engine][cargo];
+
+	if (v != NULL && v->type == VEH_Train) {
+		const SpriteGroup *overset = GetWagonOverrideSpriteSet(engine, v->u.rail.first_engine);
+
+		if (overset != NULL) group = overset;
+	}
+
+	return group;
+}
+
+int GetCustomEngineSprite(EngineID engine, const Vehicle *v, byte direction)
+{
+	const SpriteGroup *group;
+	const RealSpriteGroup *rsg;
+	byte cargo = GC_PURCHASE;
+	byte loaded = 0;
+	bool in_motion = 0;
+	int totalsets, spriteset;
+	int r;
+
+	if (v != NULL) {
+		int capacity = v->cargo_cap;
+
+		cargo = _global_cargo_id[_opt.landscape][v->cargo_type];
+		assert(cargo != GC_INVALID);
+
+		if (capacity == 0) capacity = 1;
+		loaded = (v->cargo_count * 100) / capacity;
+
+		if (v->type == VEH_Train) {
+			in_motion = GetFirstVehicleInChain(v)->current_order.type != OT_LOADING;
+		} else {
+			in_motion = v->current_order.type != OT_LOADING;
+		}
+	}
+
+	group = GetVehicleSpriteGroup(engine, v);
+	group = ResolveVehicleSpriteGroup(group, v, 0, (resolve_callback) ResolveVehicleSpriteGroup);
+
+	if (group == NULL && cargo != GC_DEFAULT) {
+		// This group is empty but perhaps there'll be a default one.
+		group = ResolveVehicleSpriteGroup(engine_custom_sprites[engine][GC_DEFAULT], v, 0,
+		                                (resolve_callback) ResolveVehicleSpriteGroup);
+	}
+
+	if (group == NULL)
+		return 0;
+
+	assert(group->type == SGT_REAL);
+	rsg = &group->g.real;
+
+	if (!rsg->sprites_per_set) {
+		// This group is empty. This function users should therefore
+		// look up the sprite number in _engine_original_sprites.
+		return 0;
+	}
+
+	assert(rsg->sprites_per_set <= 8);
+	direction %= rsg->sprites_per_set;
+
+	totalsets = in_motion ? rsg->loaded_count : rsg->loading_count;
+
+	// My aim here is to make it possible to visually determine absolutely
+	// empty and totally full vehicles. --pasky
+	if (loaded == 100 || totalsets == 1) { // full
+		spriteset = totalsets - 1;
+	} else if (loaded == 0 || totalsets == 2) { // empty
+		spriteset = 0;
+	} else { // something inbetween
+		spriteset = loaded * (totalsets - 2) / 100 + 1;
+		// correct possible rounding errors
+		if (!spriteset)
+			spriteset = 1;
+		else if (spriteset == totalsets - 1)
+			spriteset--;
+	}
+
+	r = (in_motion ? rsg->loaded[spriteset]->g.result.result : rsg->loading[spriteset]->g.result.result) + direction;
+	return r;
+}
+
+/**
+ * Check if a wagon is currently using a wagon override
+ * @param v The wagon to check
+ * @return true if it is using an override, false otherwise
+ */
+bool UsesWagonOverride(const Vehicle* v)
+{
+	assert(v->type == VEH_Train);
+	return GetWagonOverrideSpriteSet(v->engine_type, v->u.rail.first_engine) != NULL;
+}
+
+/**
+ * Evaluates a newgrf callback
+ * @param callback_info info about which callback to evaluate
+ *  (bit 0-7)  = CallBack id of the callback to use, see CallBackId enum
+ *  (bit 8-15) = Other info some callbacks need to have, callback specific, see CallBackId enum, not used yet
+ * @param engine Engine type of the vehicle to evaluate the callback for
+ * @param vehicle The vehicle to evaluate the callback for, NULL if it doesnt exist (yet)
+ * @return The value the callback returned, or CALLBACK_FAILED if it failed
+ */
+uint16 GetCallBackResult(uint16 callback_info, EngineID engine, const Vehicle *v)
+{
+	const SpriteGroup *group;
+	byte cargo = GC_DEFAULT;
+
+	if (v != NULL)
+		cargo = _global_cargo_id[_opt.landscape][v->cargo_type];
+
+	group = engine_custom_sprites[engine][cargo];
+
+	if (v != NULL && v->type == VEH_Train) {
+		const SpriteGroup *overset = GetWagonOverrideSpriteSet(engine, v->u.rail.first_engine);
+
+		if (overset != NULL) group = overset;
+	}
+
+	group = ResolveVehicleSpriteGroup(group, v, callback_info, (resolve_callback) ResolveVehicleSpriteGroup);
+
+	if (group == NULL && cargo != GC_DEFAULT) {
+		// This group is empty but perhaps there'll be a default one.
+		group = ResolveVehicleSpriteGroup(engine_custom_sprites[engine][GC_DEFAULT], v, callback_info,
+		                                (resolve_callback) ResolveVehicleSpriteGroup);
+	}
+
+	if (group == NULL || group->type != SGT_CALLBACK)
+		return CALLBACK_FAILED;
+
+	return group->g.callback.result;
+}
+
+
+
+// Global variables are evil, yes, but we would end up with horribly overblown
+// calling convention otherwise and this should be 100% reentrant.
+static byte _vsg_random_triggers;
+static byte _vsg_bits_to_reseed;
+
+static const SpriteGroup *TriggerVehicleSpriteGroup(const SpriteGroup *spritegroup,
+	Vehicle *veh, uint16 callback_info, resolve_callback resolve_func)
+{
+	if (spritegroup == NULL)
+		return NULL;
+
+	if (spritegroup->type == SGT_RANDOMIZED) {
+		_vsg_bits_to_reseed |= RandomizedSpriteGroupTriggeredBits(
+			&spritegroup->g.random,
+			_vsg_random_triggers,
+			&veh->waiting_triggers
+		);
+	}
+
+	return ResolveVehicleSpriteGroup(spritegroup, veh, callback_info, resolve_func);
+}
+
+static void DoTriggerVehicle(Vehicle *veh, VehicleTrigger trigger, byte base_random_bits, bool first)
+{
+	const SpriteGroup *group;
+	const RealSpriteGroup *rsg;
+	byte new_random_bits;
+
+	_vsg_random_triggers = trigger;
+	_vsg_bits_to_reseed = 0;
+	group = TriggerVehicleSpriteGroup(GetVehicleSpriteGroup(veh->engine_type, veh), veh, 0,
+	                                  (resolve_callback) TriggerVehicleSpriteGroup);
+
+	if (group == NULL && veh->cargo_type != GC_DEFAULT) {
+		// This group turned out to be empty but perhaps there'll be a default one.
+		group = TriggerVehicleSpriteGroup(engine_custom_sprites[veh->engine_type][GC_DEFAULT], veh, 0,
+		                                  (resolve_callback) TriggerVehicleSpriteGroup);
+	}
+
+	if (group == NULL)
+		return;
+
+	assert(group->type == SGT_REAL);
+	rsg = &group->g.real;
+
+	new_random_bits = Random();
+	veh->random_bits &= ~_vsg_bits_to_reseed;
+	veh->random_bits |= (first ? new_random_bits : base_random_bits) & _vsg_bits_to_reseed;
+
+	switch (trigger) {
+		case VEHICLE_TRIGGER_NEW_CARGO:
+			/* All vehicles in chain get ANY_NEW_CARGO trigger now.
+			 * So we call it for the first one and they will recurse. */
+			/* Indexing part of vehicle random bits needs to be
+			 * same for all triggered vehicles in the chain (to get
+			 * all the random-cargo wagons carry the same cargo,
+			 * i.e.), so we give them all the NEW_CARGO triggered
+			 * vehicle's portion of random bits. */
+			assert(first);
+			DoTriggerVehicle(GetFirstVehicleInChain(veh), VEHICLE_TRIGGER_ANY_NEW_CARGO, new_random_bits, false);
+			break;
+		case VEHICLE_TRIGGER_DEPOT:
+			/* We now trigger the next vehicle in chain recursively.
+			 * The random bits portions may be different for each
+			 * vehicle in chain. */
+			if (veh->next != NULL)
+				DoTriggerVehicle(veh->next, trigger, 0, true);
+			break;
+		case VEHICLE_TRIGGER_EMPTY:
+			/* We now trigger the next vehicle in chain
+			 * recursively.  The random bits portions must be same
+			 * for each vehicle in chain, so we give them all
+			 * first chained vehicle's portion of random bits. */
+			if (veh->next != NULL)
+				DoTriggerVehicle(veh->next, trigger, first ? new_random_bits : base_random_bits, false);
+			break;
+		case VEHICLE_TRIGGER_ANY_NEW_CARGO:
+			/* Now pass the trigger recursively to the next vehicle
+			 * in chain. */
+			assert(!first);
+			if (veh->next != NULL)
+				DoTriggerVehicle(veh->next, VEHICLE_TRIGGER_ANY_NEW_CARGO, base_random_bits, false);
+			break;
+	}
+}
+
+void TriggerVehicle(Vehicle *veh, VehicleTrigger trigger)
+{
+	if (trigger == VEHICLE_TRIGGER_DEPOT) {
+		// store that the vehicle entered a depot this tick
+		VehicleEnteredDepotThisTick(veh);
+	}
+
+	DoTriggerVehicle(veh, trigger, 0, true);
+}
+
+static char *_engine_custom_names[TOTAL_NUM_ENGINES];
+
+void SetCustomEngineName(EngineID engine, const char *name)
+{
+	_engine_custom_names[engine] = strdup(name);
+}
+
+void UnloadCustomEngineNames(void)
+{
+	char **i;
+	for (i = _engine_custom_names; i != endof(_engine_custom_names); i++) {
+		free(*i);
+		*i = NULL;
+	}
+}
+
+StringID GetCustomEngineName(EngineID engine)
+{
+	if (!_engine_custom_names[engine])
+		return _engine_name_strings[engine];
+	ttd_strlcpy(_userstring, _engine_custom_names[engine], lengthof(_userstring));
+	return STR_SPEC_USERSTRING;
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/newgrf_engine.h	Fri Feb 03 12:55:21 2006 +0000
@@ -0,0 +1,73 @@
+/* $Id$ */
+
+#ifndef NEWGRF_ENGINE_H
+#define NEWGRF_ENGINE_H
+
+/** @file newgrf_engine.h
+ */
+
+// This enum lists the implemented callbacks
+// Use as argument for the GetCallBackResult function (see comments there)
+enum CallbackID {
+	// Powered wagons, if the result is lower as 0x40 then the wagon is powered
+	// TODO: interpret the rest of the result, aka "visual effects"
+	CBID_WAGON_POWER = 0x10,
+
+	// Vehicle length, returns the amount of 1/8's the vehicle is shorter
+	// only for train vehicles
+	CBID_VEH_LENGTH = 0x11,
+
+	// Refit capacity, the passed vehicle needs to have its ->cargo_type set to
+	// the cargo we are refitting to, returns the new cargo capacity
+	CBID_REFIT_CAP = 0x15,
+
+	CBID_ARTIC_ENGINE = 0x16,
+};
+
+// bit positions for rvi->callbackmask, indicates which callbacks are used by an engine
+// (some callbacks are always used, and dont appear here)
+enum CallbackMask {
+	CBM_WAGON_POWER = 0,
+	CBM_VEH_LENGTH = 1,
+	CBM_REFIT_CAP = 3,
+	CBM_ARTIC_ENGINE = 4,
+};
+
+enum {
+	CALLBACK_FAILED = 0xFFFF
+};
+
+VARDEF const uint32 _default_refitmasks[NUM_VEHICLE_TYPES];
+VARDEF const CargoID _global_cargo_id[NUM_LANDSCAPE][NUM_CARGO];
+VARDEF const uint32 _landscape_global_cargo_mask[NUM_LANDSCAPE];
+VARDEF const CargoID _local_cargo_id_ctype[NUM_GLOBAL_CID];
+VARDEF const uint32 cargo_classes[16];
+
+void SetWagonOverrideSprites(EngineID engine, struct SpriteGroup *group, byte *train_id, int trains);
+void SetCustomEngineSprites(EngineID engine, byte cargo, struct SpriteGroup *group);
+// loaded is in percents, overriding_engine 0xffff is none
+int GetCustomEngineSprite(EngineID engine, const Vehicle *v, byte direction);
+uint16 GetCallBackResult(uint16 callback_info, EngineID engine, const Vehicle *v);
+bool UsesWagonOverride(const Vehicle *v);
+#define GetCustomVehicleSprite(v, direction) GetCustomEngineSprite(v->engine_type, v, direction)
+#define GetCustomVehicleIcon(et, direction) GetCustomEngineSprite(et, NULL, direction)
+
+typedef enum VehicleTrigger {
+	VEHICLE_TRIGGER_NEW_CARGO = 1,
+	// Externally triggered only for the first vehicle in chain
+	VEHICLE_TRIGGER_DEPOT = 2,
+	// Externally triggered only for the first vehicle in chain, only if whole chain is empty
+	VEHICLE_TRIGGER_EMPTY = 4,
+	// Not triggered externally (called for the whole chain if we got NEW_CARGO)
+	VEHICLE_TRIGGER_ANY_NEW_CARGO = 8,
+} VehicleTrigger;
+void TriggerVehicle(Vehicle *veh, VehicleTrigger trigger);
+
+void SetCustomEngineName(EngineID engine, const char *name);
+StringID GetCustomEngineName(EngineID engine);
+
+void UnloadWagonOverrides(void);
+void UnloadCustomEngineSprites(void);
+void UnloadCustomEngineNames(void);
+
+#endif /* NEWGRF_ENGINE_H */

--- a/openttd.dsp	Fri Feb 03 07:45:58 2006 +0000
+++ b/openttd.dsp	Fri Feb 03 12:55:21 2006 +0000
@@ -276,6 +276,10 @@
 # End Source File
 # Begin Source File
 
+SOURCE=.\newgrf_engine.c
+# End Source File
+# Begin Source File
+
 SOURCE=.\npf.c
 # End Source File
 # Begin Source File
@@ -618,6 +622,14 @@
 # End Source File
 # Begin Source File
 
+SOURCE=.\newgrf.h
+# End Source File
+# Begin Source File
+
+SOURCE=.\newgrf_engine.h
+# End Source File
+# Begin Source File
+
 SOURCE=.\news.h
 # End Source File
 # Begin Source File

--- a/openttd.vcproj	Fri Feb 03 07:45:58 2006 +0000
+++ b/openttd.vcproj	Fri Feb 03 12:55:21 2006 +0000
@@ -273,6 +273,9 @@
 				RelativePath=".\newgrf.c">
 			</File>
 			<File
+				RelativePath=".\newgrf_engine.c">
+			</File>
+			<File
 				RelativePath=".\npf.c">
 			</File>
 			<File
@@ -487,6 +490,9 @@
 				RelativePath=".\newgrf.h">
 			</File>
 			<File
+				RelativePath=".\newgrf_engine.h">
+			</File>
+			<File
 				RelativePath=".\news.h">
 			</File>
 			<File

--- a/roadveh_cmd.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/roadveh_cmd.c	Fri Feb 03 12:55:21 2006 +0000
@@ -18,6 +18,7 @@
 #include "sound.h"
 #include "depot.h"
 #include "vehicle_gui.h"
+#include "newgrf_engine.h"
 
 static const uint16 _roadveh_images[63] = {
 	0xCD4, 0xCDC, 0xCE4, 0xCEC, 0xCF4, 0xCFC, 0xD0C, 0xD14,

--- a/roadveh_gui.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/roadveh_gui.c	Fri Feb 03 12:55:21 2006 +0000
@@ -18,6 +18,7 @@
 #include "engine.h"
 #include "depot.h"
 #include "vehicle_gui.h"
+#include "newgrf_engine.h"
 
 /**
  * Draw the purchase info details of road vehicle at a given location.

--- a/ship_cmd.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/ship_cmd.c	Fri Feb 03 12:55:21 2006 +0000
@@ -17,6 +17,7 @@
 #include "npf.h"
 #include "depot.h"
 #include "vehicle_gui.h"
+#include "newgrf_engine.h"
 
 static const uint16 _ship_sprites[] = {0x0E5D, 0x0E55, 0x0E65, 0x0E6D};
 static const byte _ship_sometracks[4] = {0x19, 0x16, 0x25, 0x2A};

--- a/ship_gui.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/ship_gui.c	Fri Feb 03 12:55:21 2006 +0000
@@ -18,6 +18,7 @@
 #include "engine.h"
 #include "depot.h"
 #include "vehicle_gui.h"
+#include "newgrf_engine.h"
 
 /**
  * Draw the purchase info details of a ship at a given location.

--- a/train_cmd.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/train_cmd.c	Fri Feb 03 12:55:21 2006 +0000
@@ -22,6 +22,7 @@
 #include "waypoint.h"
 #include "vehicle_gui.h"
 #include "train.h"
+#include "newgrf_engine.h"
 
 static bool TrainCheckIfLineEnds(Vehicle *v);
 static void TrainController(Vehicle *v);

--- a/train_gui.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/train_gui.c	Fri Feb 03 12:55:21 2006 +0000
@@ -19,6 +19,7 @@
 #include "vehicle_gui.h"
 #include "depot.h"
 #include "train.h"
+#include "newgrf_engine.h"
 
 int _traininfo_vehicle_pitch = 0;
 

--- a/vehicle_gui.c	Fri Feb 03 07:45:58 2006 +0000
+++ b/vehicle_gui.c	Fri Feb 03 12:55:21 2006 +0000
@@ -19,6 +19,7 @@
 #include "vehicle_gui.h"
 #include "viewport.h"
 #include "train.h"
+#include "newgrf_engine.h"
 
 Sorting _sorting;