Avoid unnecessary viewport redraws for unused tile loop house triggers

src/genworld.cpp

@@ -320,6 +320,8 @@ void GenerateWorld(GenWorldMode mode, uint size_x, uint size_y, bool reset_setti
 	LoadStringWidthTable();
 	AnalyseEngineCallbacks();
 	AnalyseIndustryTileSpriteGroups();
+	extern void AnalyseHouseSpriteGroups();
+	AnalyseHouseSpriteGroups();
 
 	/* Re-init the windowing system */
 	ResetWindowSystem();

src/house.h

@@ -95,6 +95,13 @@ enum HouseExtraFlags {
 
 DECLARE_ENUM_AS_BIT_SET(HouseExtraFlags)
 
+enum HouseCtrlFlags {
+	HCF_NONE                 =       0,
+	HCF_NO_TRIGGERS          = 1U << 0,  ///< this house does not use random triggers
+};
+
+DECLARE_ENUM_AS_BIT_SET(HouseCtrlFlags)
+
 struct HouseSpec {
 	/* Standard properties */
 	Year min_year;                            ///< introduction year of the house
@@ -116,6 +123,7 @@ struct HouseSpec {
 	byte random_colour[4];                    ///< 4 "random" colours
 	byte probability;                         ///< Relative probability of appearing (16 is the standard value)
 	HouseExtraFlags extra_flags;              ///< some more flags
+	HouseCtrlFlags ctrl_flags;                ///< control flags
 	HouseClassID class_id;                    ///< defines the class this house has (not grf file based)
 	AnimationInfo animation;                  ///< information about the animation.
 	byte processing_time;                     ///< Periodic refresh multiplier

src/newgrf_analysis.cpp

@@ -299,7 +299,9 @@ void RandomizedSpriteGroup::AnalyseCallbacks(AnalyseCallbackOperation &op) const
 {
 	op.result_flags |= ACORF_CB_REFIT_CAP_NON_WHITELIST_FOUND;
 
-	if (op.mode == ACOM_CB_VAR) op.callbacks_used |= SGCU_RANDOM_TRIGGER;
+	if ((op.mode == ACOM_CB_VAR || op.mode == ACOM_FIND_RANDOM_TRIGGER) && (this->triggers != 0 || this->cmp_mode == RSG_CMP_ALL)) {
+		op.callbacks_used |= SGCU_RANDOM_TRIGGER;
+	}
 
 	for (const SpriteGroup *group: this->groups) {
 		if (group != nullptr) group->AnalyseCallbacks(op);

src/newgrf_analysis.h

@@ -23,6 +23,7 @@ enum AnalyseCallbackOperationMode : uint8 {
 	ACOM_CB36_SPEED,
 	ACOM_INDUSTRY_TILE,
 	ACOM_CB_REFIT_CAPACITY,
+	ACOM_FIND_RANDOM_TRIGGER,
 };
 
 struct AnalyseCallbackOperationIndustryTileData;

src/newgrf_house.cpp

@@ -22,6 +22,7 @@
 #include "newgrf_animation_base.h"
 #include "newgrf_cargo.h"
 #include "station_base.h"
+#include "newgrf_analysis.h"
 
 #include "safeguards.h"
 
@@ -727,8 +728,12 @@ bool NewHouseTileLoop(TileIndex tile)
 		return true;
 	}
 
-	TriggerHouse(tile, HOUSE_TRIGGER_TILE_LOOP);
-	if (hs->building_flags & BUILDING_HAS_1_TILE) TriggerHouse(tile, HOUSE_TRIGGER_TILE_LOOP_TOP);
+	bool do_triggers = !(hs->ctrl_flags & HCF_NO_TRIGGERS);
+
+	if (do_triggers) {
+		TriggerHouse(tile, HOUSE_TRIGGER_TILE_LOOP);
+		if (hs->building_flags & BUILDING_HAS_1_TILE) TriggerHouse(tile, HOUSE_TRIGGER_TILE_LOOP_TOP);
+	}
 
 	if (HasBit(hs->callback_mask, CBM_HOUSE_ANIMATION_START_STOP)) {
 		/* If this house is marked as having a synchronised callback, all the
@@ -758,7 +763,7 @@ bool NewHouseTileLoop(TileIndex tile)
 	}
 
 	SetHouseProcessingTime(tile, hs->processing_time);
-	MarkTileDirtyByTile(tile, VMDF_NOT_MAP_MODE);
+	if (do_triggers) MarkTileDirtyByTile(tile, VMDF_NOT_MAP_MODE);
 	return true;
 }
 
@@ -857,3 +862,21 @@ void WatchedCargoCallback(TileIndex tile, CargoTypes trigger_cargoes)
 	if (hs->building_flags & BUILDING_HAS_4_TILES) DoWatchedCargoCallback(TILE_ADDXY(north, 1, 1), tile, trigger_cargoes, r);
 }
 
+void AnalyseHouseSpriteGroups()
+{
+	for (uint i = 0; i < NUM_HOUSES; i++) {
+		HouseSpec *spec = HouseSpec::Get(i);
+		spec->ctrl_flags = HCF_NONE;
+
+		if (spec->grf_prop.spritegroup[0] == nullptr) {
+			spec->ctrl_flags |= HCF_NO_TRIGGERS;
+			continue;
+		}
+
+		AnalyseCallbackOperation find_triggers_op(ACOM_FIND_RANDOM_TRIGGER);
+		spec->grf_prop.spritegroup[0]->AnalyseCallbacks(find_triggers_op);
+		if ((find_triggers_op.callbacks_used & SGCU_RANDOM_TRIGGER) == 0) {
+			spec->ctrl_flags |= HCF_NO_TRIGGERS;
+		}
+	}
+}

src/newgrf_house.h

@@ -166,4 +166,6 @@ enum HouseTrigger {
 };
 void TriggerHouse(TileIndex t, HouseTrigger trigger);
 
+void AnalyseHouseSpriteGroups();
+
 #endif /* NEWGRF_HOUSE_H */

src/saveload/afterload.cpp

@@ -952,6 +952,8 @@ bool AfterLoadGame()
 
 	AfterLoadEngines();
 	AnalyseIndustryTileSpriteGroups();
+	extern void AnalyseHouseSpriteGroups();
+	AnalyseHouseSpriteGroups();
 
 	/* Update all vehicles */
 	AfterLoadVehicles(true);
@@ -4211,6 +4213,8 @@ void ReloadNewGRFData()
 	ResetVehicleHash();
 	AfterLoadEngines();
 	AnalyseIndustryTileSpriteGroups();
+	extern void AnalyseHouseSpriteGroups();
+	AnalyseHouseSpriteGroups();
 	AfterLoadVehicles(false);
 	StartupEngines();
 	GroupStatistics::UpdateAfterLoad();

src/table/newgrf_debug_data.h

@@ -592,7 +592,7 @@ class NIHHouse : public NIHelper {
 		const HouseSpec *hs = HouseSpec::Get(GetHouseType(index));
 		seprintf(buffer, lastof(buffer), "  building_flags: 0x%X", hs->building_flags);
 		output.print(buffer);
-		seprintf(buffer, lastof(buffer), "  extra_flags: 0x%X", hs->extra_flags);
+		seprintf(buffer, lastof(buffer), "  extra_flags: 0x%X, ctrl_flags: 0x%X", hs->extra_flags, hs->ctrl_flags);
 		output.print(buffer);
 		seprintf(buffer, lastof(buffer), "  remove_rating_decrease: %u, minimum_life: %u", hs->remove_rating_decrease, hs->minimum_life);
 		output.print(buffer);

src/table/town_land.h

@@ -1814,7 +1814,7 @@ static_assert(lengthof(_town_draw_tile_data) == (NEW_HOUSE_OFFSET) * 4 * 4);
 	{ca1, ca2, ca3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, \
 	{cg1, cg2, cg3, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID, CT_INVALID}, \
 	bf, ba, true, GRFFileProps(INVALID_HOUSE_ID), 0, {0, 0, 0, 0}, \
-	16, NO_EXTRA_FLAG, HOUSE_NO_CLASS, {0, 2, 0, 0}, 0, 0, 0}
+	16, NO_EXTRA_FLAG, HCF_NONE, HOUSE_NO_CLASS, {0, 2, 0, 0}, 0, 0, 0}
 /** House specifications from original data */
 static const HouseSpec _original_house_specs[] = {
 	/**