Codechange: When checking industry placement conditions, perform cheap checks first. (#9987)

1. Built-in checks on industry level.
2. Built-in checks on industry tiles.
3. NewGRF-defined checks on industry level.
4. NewGRF-defined checks on industry tiles.

src/industry_cmd.cpp

@@ -1429,18 +1429,12 @@ bool IsSlopeRefused(Slope current, Slope refused)
  * Are the tiles of the industry free?
  * @param tile                    Position to check.
  * @param layout                  Industry tiles table.
- * @param layout_index            The index of the layout to build/fund
  * @param type                    Type of the industry.
- * @param initial_random_bits     The random bits the industry is going to have after construction.
- * @param founder                 Industry founder
- * @param creation_type           The circumstances the industry is created under.
- * @param[out] custom_shape_check Perform custom check for the site.
  * @return Failed or succeeded command.
  */
-static CommandCost CheckIfIndustryTilesAreFree(TileIndex tile, const IndustryTileLayout &layout, size_t layout_index, int type, uint16 initial_random_bits, Owner founder, IndustryAvailabilityCallType creation_type, bool *custom_shape_check = nullptr)
+static CommandCost CheckIfIndustryTilesAreFree(TileIndex tile, const IndustryTileLayout &layout, IndustryType type)
 {
-	bool refused_slope = false;
+	IndustryBehaviour ind_behav = GetIndustrySpec(type)->behaviour;
-	bool custom_shape = false;
 
 	for (const IndustryTileLayoutTile &it : layout) {
 		IndustryGfx gfx = GetTranslatedIndustryTileID(it.gfx);
@@ -1462,20 +1456,9 @@ static CommandCost CheckIfIndustryTilesAreFree(TileIndex tile, const IndustryTil
 
 			const IndustryTileSpec *its = GetIndustryTileSpec(gfx);
 
-			IndustryBehaviour ind_behav = GetIndustrySpec(type)->behaviour;
-
 			/* Perform land/water check if not disabled */
 			if (!HasBit(its->slopes_refused, 5) && ((HasTileWaterClass(cur_tile) && IsTileOnWater(cur_tile)) == !(ind_behav & INDUSTRYBEH_BUILT_ONWATER))) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
 
-			if (HasBit(its->callback_mask, CBM_INDT_SHAPE_CHECK)) {
-				custom_shape = true;
-				CommandCost ret = PerformIndustryTileSlopeCheck(tile, cur_tile, its, type, gfx, layout_index, initial_random_bits, founder, creation_type);
-				if (ret.Failed()) return ret;
-			} else {
-				Slope tileh = GetTileSlope(cur_tile);
-				refused_slope |= IsSlopeRefused(tileh, its->slopes_refused);
-			}
-
 			if ((ind_behav & (INDUSTRYBEH_ONLY_INTOWN | INDUSTRYBEH_TOWN1200_MORE)) || // Tile must be a house
 					((ind_behav & INDUSTRYBEH_ONLY_NEARTOWN) && IsTileType(cur_tile, MP_HOUSE))) { // Tile is allowed to be a house (and it is a house)
 				if (!IsTileType(cur_tile, MP_HOUSE)) {
@@ -1491,12 +1474,50 @@ static CommandCost CheckIfIndustryTilesAreFree(TileIndex tile, const IndustryTil
 			} else {
 				/* Clear the tiles, but do not affect town ratings */
 				CommandCost ret = Command<CMD_LANDSCAPE_CLEAR>::Do(DC_AUTO | DC_NO_TEST_TOWN_RATING | DC_NO_MODIFY_TOWN_RATING, cur_tile);
-
 				if (ret.Failed()) return ret;
 			}
 		}
 	}
 
+	return CommandCost();
+}
+
+/**
+ * Check slope requirements for industry tiles.
+ * @param tile                    Position to check.
+ * @param layout                  Industry tiles table.
+ * @param layout_index            The index of the layout to build/fund
+ * @param type                    Type of the industry.
+ * @param initial_random_bits     The random bits the industry is going to have after construction.
+ * @param founder                 Industry founder
+ * @param creation_type           The circumstances the industry is created under.
+ * @param[out] custom_shape_check Perform custom check for the site.
+ * @return Failed or succeeded command.
+ */
+static CommandCost CheckIfIndustryTileSlopes(TileIndex tile, const IndustryTileLayout &layout, size_t layout_index, int type, uint16 initial_random_bits, Owner founder, IndustryAvailabilityCallType creation_type, bool *custom_shape_check = nullptr)
+{
+	bool refused_slope = false;
+	bool custom_shape = false;
+
+	for (const IndustryTileLayoutTile &it : layout) {
+		IndustryGfx gfx = GetTranslatedIndustryTileID(it.gfx);
+		TileIndex cur_tile = TileAddWrap(tile, it.ti.x, it.ti.y);
+		assert(IsValidTile(cur_tile)); // checked before in CheckIfIndustryTilesAreFree
+
+		if (gfx != GFX_WATERTILE_SPECIALCHECK) {
+			const IndustryTileSpec *its = GetIndustryTileSpec(gfx);
+
+			if (HasBit(its->callback_mask, CBM_INDT_SHAPE_CHECK)) {
+				custom_shape = true;
+				CommandCost ret = PerformIndustryTileSlopeCheck(tile, cur_tile, its, type, gfx, layout_index, initial_random_bits, founder, creation_type);
+				if (ret.Failed()) return ret;
+			} else {
+				Slope tileh = GetTileSlope(cur_tile);
+				refused_slope |= IsSlopeRefused(tileh, its->slopes_refused);
+			}
+		}
+	}
+
 	if (custom_shape_check != nullptr) *custom_shape_check = custom_shape;
 
 	/* It is almost impossible to have a fully flat land in TG, so what we
@@ -1929,28 +1950,11 @@ static CommandCost CreateNewIndustryHelper(TileIndex tile, IndustryType type, Do
 {
 	assert(layout_index < indspec->layouts.size());
 	const IndustryTileLayout &layout = indspec->layouts[layout_index];
-	bool custom_shape_check = false;
 
 	*ip = nullptr;
 
-	std::vector<ClearedObjectArea> object_areas(_cleared_object_areas);
+	/* 1. Cheap: Built-in checks on industry level. */
-	CommandCost ret = CheckIfIndustryTilesAreFree(tile, layout, layout_index, type, random_initial_bits, founder, creation_type, &custom_shape_check);
+	CommandCost ret = CheckIfFarEnoughFromConflictingIndustry(tile, type);
-	_cleared_object_areas = object_areas;
-	if (ret.Failed()) return ret;
-
-	if (HasBit(GetIndustrySpec(type)->callback_mask, CBM_IND_LOCATION)) {
-		ret = CheckIfCallBackAllowsCreation(tile, type, layout_index, random_var8f, random_initial_bits, founder, creation_type);
-	} else {
-		ret = _check_new_industry_procs[indspec->check_proc](tile);
-	}
-	if (ret.Failed()) return ret;
-
-	if (!custom_shape_check && _settings_game.game_creation.land_generator == LG_TERRAGENESIS && _generating_world &&
-			!_ignore_restrictions && !CheckIfCanLevelIndustryPlatform(tile, DC_NO_WATER, layout, type)) {
-		return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
-	}
-
-	ret = CheckIfFarEnoughFromConflictingIndustry(tile, type);
 	if (ret.Failed()) return ret;
 
 	Town *t = nullptr;
@@ -1961,6 +1965,30 @@ static CommandCost CreateNewIndustryHelper(TileIndex tile, IndustryType type, Do
 	ret = CheckIfIndustryIsAllowed(tile, type, t);
 	if (ret.Failed()) return ret;
 
+	/* 2. Built-in checks on industry tiles. */
+	std::vector<ClearedObjectArea> object_areas(_cleared_object_areas);
+	ret = CheckIfIndustryTilesAreFree(tile, layout, type);
+	_cleared_object_areas = object_areas;
+	if (ret.Failed()) return ret;
+
+	/* 3. NewGRF-defined checks on industry level. */
+	if (HasBit(GetIndustrySpec(type)->callback_mask, CBM_IND_LOCATION)) {
+		ret = CheckIfCallBackAllowsCreation(tile, type, layout_index, random_var8f, random_initial_bits, founder, creation_type);
+	} else {
+		ret = _check_new_industry_procs[indspec->check_proc](tile);
+	}
+	if (ret.Failed()) return ret;
+
+	/* 4. Expensive: NewGRF-defined checks on industry tiles. */
+	bool custom_shape_check = false;
+	ret = CheckIfIndustryTileSlopes(tile, layout, layout_index, type, random_initial_bits, founder, creation_type, &custom_shape_check);
+	if (ret.Failed()) return ret;
+
+	if (!custom_shape_check && _settings_game.game_creation.land_generator == LG_TERRAGENESIS && _generating_world &&
+			!_ignore_restrictions && !CheckIfCanLevelIndustryPlatform(tile, DC_NO_WATER, layout, type)) {
+		return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
+	}
+
 	if (!Industry::CanAllocateItem()) return_cmd_error(STR_ERROR_TOO_MANY_INDUSTRIES);
 
 	if (flags & DC_EXEC) {