--- a/src/newgrf_airport.cpp
+++ b/src/newgrf_airport.cpp
@@ -217,7 +217,7 @@
 	res->GetTriggers   = AirportGetTriggers;
 	res->SetTriggers   = AirportSetTriggers;
 	res->GetVariable   = AirportGetVariable;
-	res->ResolveReal   = AirportResolveReal;
+	res->ResolveRealMethod = AirportResolveReal;
 	res->StorePSA      = AirportStorePSA;
 
 	res->u.airport.st         = st;

--- a/src/newgrf_airporttiles.cpp
+++ b/src/newgrf_airporttiles.cpp
@@ -226,7 +226,7 @@
 	res->GetTriggers   = NULL;
 	res->SetTriggers   = NULL;
 	res->GetVariable   = AirportTileGetVariable;
-	res->ResolveReal   = AirportTileResolveReal;
+	res->ResolveRealMethod = AirportTileResolveReal;
 	res->StorePSA      = NULL;
 
 	assert(st != NULL);

--- a/src/newgrf_canal.cpp
+++ b/src/newgrf_canal.cpp
@@ -82,7 +82,7 @@
 	res->GetTriggers   = &CanalGetTriggers;
 	res->SetTriggers   = &CanalSetTriggers;
 	res->GetVariable   = &CanalGetVariable;
-	res->ResolveReal   = &CanalResolveReal;
+	res->ResolveRealMethod = &CanalResolveReal;
 
 	res->u.canal.tile = tile;
 

--- a/src/newgrf_cargo.cpp
+++ b/src/newgrf_cargo.cpp
@@ -57,7 +57,7 @@
 	res->GetTriggers   = &CargoGetTriggers;
 	res->SetTriggers   = &CargoSetTriggers;
 	res->GetVariable   = &CargoGetVariable;
-	res->ResolveReal   = &CargoResolveReal;
+	res->ResolveRealMethod = &CargoResolveReal;
 
 	res->u.cargo.cs = cs;
 

--- a/src/newgrf_debug_gui.cpp
+++ b/src/newgrf_debug_gui.cpp
@@ -162,7 +162,7 @@
 		ResolverObject ro;
 		memset(&ro, 0, sizeof(ro));
 		this->Resolve(&ro, index);
-		return ro.GetVariable(&ro, var, param, avail);
+		return ro.GetScope(ro.scope)->GetVariable(var, param, avail);
 	}
 
 	/**

--- a/src/newgrf_engine.cpp
+++ b/src/newgrf_engine.cpp
@@ -938,7 +938,7 @@
 	res->GetTriggers   = &VehicleGetTriggers;
 	res->SetTriggers   = &VehicleSetTriggers;
 	res->GetVariable   = &VehicleGetVariable;
-	res->ResolveReal   = &VehicleResolveReal;
+	res->ResolveRealMethod = &VehicleResolveReal;
 
 	res->u.vehicle.self   = v;
 	res->u.vehicle.parent = (v != NULL) ? v->First() : v;
@@ -1330,7 +1330,7 @@
 		/* Only resolve when the cache isn't valid. */
 		if (HasBit(v->grf_cache.cache_valid, cache_entries[i][1])) continue;
 		bool stub;
-		ro.GetVariable(&ro, cache_entries[i][0], 0, &stub);
+		ro.GetScope(ro.scope)->GetVariable(cache_entries[i][0], 0, &stub);
 	}
 
 	/* Make sure really all bits are set. */

--- a/src/newgrf_generic.cpp
+++ b/src/newgrf_generic.cpp
@@ -130,7 +130,7 @@
 	res->GetTriggers   = &GenericCallbackGetTriggers;
 	res->SetTriggers   = &GenericCallbackSetTriggers;
 	res->GetVariable   = ai_callback ? &GenericAiCallbackGetVariable : &GenericCallbackGetVariable;
-	res->ResolveReal   = &GenericCallbackResolveReal;
+	res->ResolveRealMethod = &GenericCallbackResolveReal;
 
 	res->callback        = CBID_NO_CALLBACK;
 	res->callback_param1 = 0;

--- a/src/newgrf_house.cpp
+++ b/src/newgrf_house.cpp
@@ -423,7 +423,7 @@
 	res->GetTriggers   = HouseGetTriggers;
 	res->SetTriggers   = HouseSetTriggers;
 	res->GetVariable   = HouseGetVariable;
-	res->ResolveReal   = HouseResolveReal;
+	res->ResolveRealMethod = HouseResolveReal;
 	res->StorePSA      = HouseStorePSA;
 
 	res->u.house.tile     = tile;

--- a/src/newgrf_industries.cpp
+++ b/src/newgrf_industries.cpp
@@ -410,7 +410,7 @@
 	res->GetTriggers   = IndustryGetTriggers;
 	res->SetTriggers   = IndustrySetTriggers;
 	res->GetVariable   = IndustryGetVariable;
-	res->ResolveReal   = IndustryResolveReal;
+	res->ResolveRealMethod = IndustryResolveReal;
 	res->StorePSA      = IndustryStorePSA;
 
 	res->u.industry.tile = tile;

--- a/src/newgrf_industrytiles.cpp
+++ b/src/newgrf_industrytiles.cpp
@@ -176,7 +176,7 @@
 	res->GetTriggers   = IndustryTileGetTriggers;
 	res->SetTriggers   = IndustryTileSetTriggers;
 	res->GetVariable   = IndustryTileGetVariable;
-	res->ResolveReal   = IndustryTileResolveReal;
+	res->ResolveRealMethod = IndustryTileResolveReal;
 	res->StorePSA      = IndustryTileStorePSA;
 
 	res->u.industry.tile = tile;

--- a/src/newgrf_object.cpp
+++ b/src/newgrf_object.cpp
@@ -398,7 +398,7 @@
 	res->GetTriggers   = ObjectGetTriggers;
 	res->SetTriggers   = ObjectSetTriggers;
 	res->GetVariable   = ObjectGetVariable;
-	res->ResolveReal   = ObjectResolveReal;
+	res->ResolveRealMethod = ObjectResolveReal;
 	res->StorePSA      = ObjectStorePSA;
 
 	res->u.object.o    = o;

--- a/src/newgrf_railtype.cpp
+++ b/src/newgrf_railtype.cpp
@@ -83,7 +83,7 @@
 	res->GetTriggers   = &RailTypeGetTriggers;
 	res->SetTriggers   = &RailTypeSetTriggers;
 	res->GetVariable   = &RailTypeGetVariable;
-	res->ResolveReal   = &RailTypeResolveReal;
+	res->ResolveRealMethod = &RailTypeResolveReal;
 
 	res->u.routes.tile = tile;
 	res->u.routes.context = context;

--- a/src/newgrf_spritegroup.cpp
+++ b/src/newgrf_spritegroup.cpp
@@ -10,6 +10,7 @@
 /** @file newgrf_spritegroup.cpp Handling of primarily NewGRF action 2. */
 
 #include "stdafx.h"
+#include "debug.h"
 #include "newgrf_spritegroup.h"
 #include "core/pool_func.hpp"
 
@@ -36,7 +37,7 @@
 TemporaryStorageArray<int32, 0x110> _temp_store;
 
 
-static inline uint32 GetVariable(const ResolverObject *object, byte variable, uint32 parameter, bool *available)
+static inline uint32 GetVariable(const ResolverObject *object, ScopeResolver *scope, byte variable, uint32 parameter, bool *available)
 {
 	/* First handle variables common with Action7/9/D */
 	uint32 value;
@@ -49,7 +50,7 @@
 		case 0x18: return object->callback_param2;
 		case 0x1C: return object->last_value;
 
-		case 0x5F: return (object->GetRandomBits(object) << 8) | object->GetTriggers(object);
+		case 0x5F: return (scope->GetRandomBits() << 8) | scope->GetTriggers();
 
 		case 0x7D: return _temp_store.GetValue(parameter);
 
@@ -58,10 +59,119 @@
 			return object->grffile->GetParam(parameter);
 
 		/* Not a common variable, so evalute the feature specific variables */
-		default: return object->GetVariable(object, variable, parameter, available);
+		default: return scope->GetVariable(variable, parameter, available);
 	}
 }
 
+ScopeResolver::ScopeResolver(ResolverObject *ro)
+{
+	this->ro = ro;
+}
+
+ScopeResolver::~ScopeResolver() {}
+
+/**
+ * Get a few random bits. Default implementation has no random bits.
+ * @return Random bits.
+ */
+/* virtual */ uint32 ScopeResolver::GetRandomBits() const
+{
+	return 0;
+}
+
+/**
+ * Get the triggers. Base class returns \c 0 to prevent trouble.
+ * @return The triggers.
+ */
+/* virtual */ uint32 ScopeResolver::GetTriggers() const
+{
+	return 0;
+}
+
+/**
+ * Set the triggers. Base class implementation does nothing.
+ * @param triggers Triggers to set.
+ */
+/* virtual */ void ScopeResolver::SetTriggers(int triggers) const {}
+
+/**
+ * Get a variable value. Default implementation has no available variables.
+ * @param variable Variable to read
+ * @param parameter Parameter for 60+x variables
+ * @param[out] available Set to false, in case the variable does not exist.
+ * @return Value
+ */
+/* virtual */ uint32 ScopeResolver::GetVariable(byte variable, uint32 parameter, bool *available) const
+{
+	DEBUG(grf, 1, "Unhandled scope variable 0x%X", variable);
+	*available = false;
+	return UINT_MAX;
+}
+
+/**
+ * Store a value into the persistent storage area (PSA). Default implementation does nothing (for newgrf classes without storage).
+ * @param pos Position to store into.
+ * @param value Value to store.
+ */
+/* virtual */ void ScopeResolver::StorePSA(uint reg, int32 value) {}
+
+
+TempScopeResolver::TempScopeResolver(ResolverObject *ro) : ScopeResolver(ro) {}
+
+/* virtual */ uint32 TempScopeResolver::GetRandomBits() const
+{
+	return this->ro->GetRandomBits(this->ro);
+}
+
+/* virtual */ uint32 TempScopeResolver::GetTriggers() const
+{
+	return this->ro->GetTriggers(this->ro);
+}
+
+/* virtual */ void TempScopeResolver::SetTriggers(int triggers) const
+{
+	this->ro->SetTriggers(this->ro, triggers);
+}
+
+/* virtual */ uint32 TempScopeResolver::GetVariable(byte variable, uint32 parameter, bool *available) const
+{
+	return this->ro->GetVariable(this->ro, variable, parameter, available);
+}
+
+/* virtual */ void TempScopeResolver::StorePSA(uint reg, int32 value)
+{
+	if (this->ro->StorePSA != NULL) this->ro->StorePSA(this->ro, reg, value);
+}
+
+ResolverObject::ResolverObject() : temp_scope(this) {} // XXX Temporary
+
+ResolverObject::ResolverObject(const GRFFile *grffile, CallbackID callback, uint32 callback_param1, uint32 callback_param2) : temp_scope(this)
+{
+	this->callback = callback;
+	this->callback_param1 = callback_param1;
+	this->callback_param2 = callback_param2;
+	this->ResetState();
+
+	this->grffile = grffile;
+}
+
+ResolverObject::~ResolverObject() {}
+
+/* virtual */ const SpriteGroup *ResolverObject::ResolveReal(const RealSpriteGroup *group) const
+{
+	return this->ResolveRealMethod(this, group);
+}
+
+/**
+ * Get a specific ScopeResolver.
+ * @param scope Scope to return.
+ * @param relative Additional parameter for #VSG_SCOPE_RELATIVE.
+ * @return ScopeResolver.
+ */
+/* virtual */ ScopeResolver *ResolverObject::GetScope(VarSpriteGroupScope scope, byte relative)
+{
+	return &this->temp_scope;
+}
 
 /**
  * Rotate val rot times to the right
@@ -111,7 +221,7 @@
 		case DSGA_OP_XOR:  return last_value ^ value;
 		case DSGA_OP_STO:  _temp_store.StoreValue((U)value, (S)last_value); return last_value;
 		case DSGA_OP_RST:  return value;
-		case DSGA_OP_STOP: if (object->StorePSA != NULL) object->StorePSA(object, (U)value, (S)last_value); return last_value;
+		case DSGA_OP_STOP: object->GetScope(object->scope)->StorePSA((U)value, (S)last_value); return last_value;
 		case DSGA_OP_ROR:  return RotateRight(last_value, value);
 		case DSGA_OP_SCMP: return ((S)last_value == (S)value) ? 1 : ((S)last_value < (S)value ? 0 : 2);
 		case DSGA_OP_UCMP: return ((U)last_value == (U)value) ? 1 : ((U)last_value < (U)value ? 0 : 2);
@@ -148,9 +258,9 @@
 			 * Note: 'last_value' and 'reseed' are shared between the main chain and the procedure */
 			object->scope = this->var_scope;
 		} else if (adjust->variable == 0x7B) {
-			value = GetVariable(object, adjust->parameter, last_value, &available);
+			value = GetVariable(object, object->GetScope(this->var_scope), adjust->parameter, last_value, &available);
 		} else {
-			value = GetVariable(object, adjust->variable, adjust->parameter, &available);
+			value = GetVariable(object, object->GetScope(this->var_scope), adjust->variable, adjust->parameter, &available);
 		}
 
 		if (!available) {
@@ -190,16 +300,14 @@
 
 const SpriteGroup *RandomizedSpriteGroup::Resolve(ResolverObject *object) const
 {
-	uint32 mask;
-	byte index;
-
 	object->scope = this->var_scope;
 	object->count = this->count;
 
+	ScopeResolver *scope = object->GetScope(this->var_scope, this->count);
 	if (object->trigger != 0) {
 		/* Handle triggers */
 		/* Magic code that may or may not do the right things... */
-		byte waiting_triggers = object->GetTriggers(object);
+		byte waiting_triggers = scope->GetTriggers();
 		byte match = this->triggers & (waiting_triggers | object->trigger);
 		bool res = (this->cmp_mode == RSG_CMP_ANY) ? (match != 0) : (match == this->triggers);
 
@@ -210,11 +318,11 @@
 			waiting_triggers |= object->trigger;
 		}
 
-		object->SetTriggers(object, waiting_triggers);
+		scope->SetTriggers(waiting_triggers);
 	}
 
-	mask  = (this->num_groups - 1) << this->lowest_randbit;
-	index = (object->GetRandomBits(object) & mask) >> this->lowest_randbit;
+	uint32 mask  = (this->num_groups - 1) << this->lowest_randbit;
+	byte index = (scope->GetRandomBits() & mask) >> this->lowest_randbit;
 
 	return SpriteGroup::Resolve(this->groups[index], object);
 }
@@ -222,7 +330,7 @@
 
 const SpriteGroup *RealSpriteGroup::Resolve(ResolverObject *object) const
 {
-	return object->ResolveReal(object, this);
+	return object->ResolveReal(this);
 }
 
 /**

--- a/src/newgrf_spritegroup.h
+++ b/src/newgrf_spritegroup.h
@@ -301,8 +301,40 @@
 	uint8 again;
 };
 
+struct ResolverObject;
+
+struct ScopeResolver {
+	ResolverObject *ro;
+
+	ScopeResolver(ResolverObject *ro);
+	virtual ~ScopeResolver();
+
+	virtual uint32 GetRandomBits() const;
+	virtual uint32 GetTriggers() const;
+	virtual void SetTriggers(int triggers) const;
+
+	virtual uint32 GetVariable(byte variable, uint32 parameter, bool *available) const;
+	virtual void StorePSA(uint reg, int32 value);
+};
+
+struct TempScopeResolver : public ScopeResolver {
+	TempScopeResolver(ResolverObject *ro);
+
+	virtual uint32 GetRandomBits() const;
+	virtual uint32 GetTriggers() const;
+	virtual void SetTriggers(int triggers) const;
+
+	virtual uint32 GetVariable(byte variable, uint32 parameter, bool *available) const;
+	virtual void StorePSA(uint reg, int32 value);
+};
 
 struct ResolverObject {
+	ResolverObject();
+	ResolverObject(const GRFFile *grffile, CallbackID callback = CBID_NO_CALLBACK, uint32 callback_param1 = 0, uint32 callback_param2 = 0);
+	virtual ~ResolverObject();
+
+	TempScopeResolver temp_scope; ///< Temporary scope resolver to refer back to the methods of #ResolverObject.
+
 	CallbackID callback;
 	uint32 callback_param1;
 	uint32 callback_param2;
@@ -382,9 +414,13 @@
 	uint32 (*GetTriggers)(const struct ResolverObject*);
 	void (*SetTriggers)(const struct ResolverObject*, int);
 	uint32 (*GetVariable)(const struct ResolverObject *object, byte variable, uint32 parameter, bool *available);
-	const SpriteGroup *(*ResolveReal)(const struct ResolverObject*, const RealSpriteGroup*);
+	const SpriteGroup *(*ResolveRealMethod)(const struct ResolverObject*, const RealSpriteGroup*);
 	void (*StorePSA)(struct ResolverObject*, uint, int32);
 
+	virtual const SpriteGroup *ResolveReal(const RealSpriteGroup *group) const;
+
+	virtual ScopeResolver *GetScope(VarSpriteGroupScope scope = VSG_SCOPE_SELF, byte relative = 0);
+
 	/**
 	 * Returns the OR-sum of all bits that need reseeding
 	 * independent of the scope they were accessed with.

--- a/src/newgrf_station.cpp
+++ b/src/newgrf_station.cpp
@@ -550,7 +550,7 @@
 	res->GetTriggers   = StationGetTriggers;
 	res->SetTriggers   = StationSetTriggers;
 	res->GetVariable   = StationGetVariable;
-	res->ResolveReal   = StationResolveReal;
+	res->ResolveRealMethod = StationResolveReal;
 	res->StorePSA      = StationStorePSA;
 
 	res->u.station.st       = st;