Package megamek.common.board

Class BridgeConstruction

java.lang.Object

megamek.common.board.BridgeConstruction

public final class BridgeConstruction
extends Object

Validates sites for and places single-hex bridges that are constructed during a game, as opposed to bridges that are part of the board file. Used by Bridge-Building Engineer infantry (TO:AUE p.152) and intended for reuse by vehicle Bridge-Layer equipment (TM p.242). Placement rules (TO:AUE p.152): a bridge may be placed in any water hex that connects to at least one land hex or another bridge, or across a dry canyon of any depth (a hex below its rims). A single-hex span changes at most one level (the multi-level bridge rule of at most 1 level per hex), so its two mount banks must be within one level; a deeper canyon-floor or deep-water far side is exempt and continued by a further span. A building hex cannot be bridged. Note: ramping multi-hex bridges (a sloped deck) are not modelled - each bridge hex has a single flat deck level.

The Construction Factor of the new bridge is supplied by the caller, since it differs by source: engineers raise bridges with CF 15/40 (doubled over water), while Bridge-Layer equipment deploys bridges with its own CF values and no water doubling.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	BridgeConstruction.BridgeRepairIssue	The reason a hex is or is not a valid bridge-repair site, so callers can explain a rejection to the player.
static enum	BridgeConstruction.BridgeSiteIssue	The reason a bridge site is or is not buildable, so callers can explain a rejection to the player.

Method Summary

Modifier and Type	Method	Description
static BridgeConstruction.BridgeRepairIssue	bridgeRepairIssue(Board board, Coords target, int exits)	Checks whether a single destroyed bridge section may be rebuilt in the target hex (unofficial bridge-repair option).
static BridgeConstruction.BridgeSiteIssue	bridgeSiteIssue(Board board, Coords target, int exits)
static int	exitsFor(int firstDirection, int secondDirection)
static boolean	isAnchoringBank(Hex bank, Hex targetHex)
static boolean	isBridgeRepairSite(Board board, Coords target, int exits)
static boolean	isOverWater(Hex hex)
static boolean	isValidBridgeExits(int exits)
static boolean	isValidBridgeSite(Board board, Coords target, int exits)	Checks whether a single-hex bridge with the given orientation may be constructed in the target hex (TO:AUE p.152): the hex exists and holds no structure, both banks are on the board, and at least one bank anchors the span (land/rim over a canyon, or a bridge).
static IBuilding	placeBridge(Board board, Coords target, int exits, int bridgeType, int cf)	Places a finished single-hex bridge in the target hex: adds the bridge terrain, registers the bridge as a board structure so it can take damage and collapse, and recomputes terrain exits around the hex.
static IBuilding	placeRepairedBridge(Board board, Coords target, int exits, int bridgeType, int cf)	Rebuilds a single destroyed bridge section in the gap hex (unofficial repair option): adds the bridge terrain at the surviving span's deck height so the section reconnects, registers it as a board structure, and recomputes terrain exits.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

isValidBridgeExits

public static boolean isValidBridgeExits(int exits)

Parameters:

exits - the exits bitmask to check

Returns:

true if the bitmask describes a legal single-hex bridge orientation: exactly two distinct connected hexsides. Opposite sides give a straight bridge; non-opposite sides give a curved bridge. The finished bridge uses the tileset image matching this exits value.

exitsFor

public static int exitsFor(int firstDirection,
 int secondDirection)

Parameters:

firstDirection - one connected hexside direction (0-5)

secondDirection - the other connected hexside direction (0-5)

Returns:

The exits bitmask connecting the two given hexsides.

isValidBridgeSite

public static boolean isValidBridgeSite(Board board,
 @Nullable
 Coords target,
 int exits)

Checks whether a single-hex bridge with the given orientation may be constructed in the target hex (TO:AUE p.152): the hex exists and holds no structure, both banks are on the board, and at least one bank anchors the span (land/rim over a canyon, or a bridge). If both banks are mount points they must be within one level (a single-hex span changes at most one level); a deeper canyon-floor or deep-water far side is exempt (chaining).

Parameters:

board - the board to build on

target - the hex the bridge would be placed in, or null (returns false)

exits - exits bitmask of the two hexsides the bridge would connect

Returns:

true if the bridge may be constructed there.

bridgeSiteIssue

public static BridgeConstruction.BridgeSiteIssue bridgeSiteIssue(Board board,
 @Nullable
 Coords target,
 int exits)

Parameters:

board - the board to build on

target - the hex the bridge would be placed in, or null

exits - exits bitmask of the two hexsides the bridge would connect

Returns:

Why the site is or is not buildable (see BridgeConstruction.BridgeSiteIssue). The single source of truth for bridge placement validity; isValidBridgeSite(megamek.common.board.Board, megamek.common.board.Coords, int) returns whether this is VALID.

isAnchoringBank

public static boolean isAnchoringBank(Hex bank,
 Hex targetHex)

Parameters:

bank - a hex adjacent to a bridge site (e.g. the bridgelayer's own hex)

targetHex - the hex a bridge would be placed in

Returns:

whether the bank can anchor a bridge in the target hex: over water it must be land/shallow (or already hold a bridge); over a dry gap it must be a rim higher than the target floor (or hold a bridge). Exposes the internal anchor test for callers that must require a specific bank to anchor - e.g. the AVLB bridgelayer's own hex, which must be a rim/land rather than the canyon floor. TM p.242 / TW.

isOverWater

public static boolean isOverWater(Hex hex)

Parameters:

hex - the hex to check

Returns:

true if the hex is a water hex for bridge purposes. A water hex (Total Warfare p.32) is one covered by a stream, river, swamp, pond or lake, so this is any hex holding water of any depth (streams/rivers/ponds/lakes), a swamp, or rapids. A bridge may be placed in any water hex (when adjacent to a land hex or another bridge), and a bridge over water gains double CF from its flotation devices. Shared by Bridge-Building Engineers (TO:AUE p.152) and the Bridge-Layer / AVLB (TM p.242 / TW) so both use the same water-hex definition.

placeBridge

public static IBuilding placeBridge(Board board,
 Coords target,
 int exits,
 int bridgeType,
 int cf)

Places a finished single-hex bridge in the target hex: adds the bridge terrain, registers the bridge as a board structure so it can take damage and collapse, and recomputes terrain exits around the hex. The deck sits at the lower anchoring rim (the two rims are within one level) so units cross at grade and a chain of spans stays level. The caller is responsible for validating the site with isValidBridgeSite(Board, Coords, int) and for sending the changed hex and the new building to the clients.

Parameters:

board - the board to build on

target - the hex the bridge is placed in

exits - exits bitmask of the two hexsides the bridge connects

bridgeType - the bridge type as a BuildingType value (1 = light, 2 = medium)

cf - the Construction Factor of the new bridge

Returns:

The newly registered bridge structure, for sending to the clients.

isBridgeRepairSite

public static boolean isBridgeRepairSite(Board board,
 @Nullable
 Coords target,
 int exits)

Parameters:

board - the board to repair on

target - the gap hex the section would be rebuilt in, or null

exits - exits bitmask of the two hexsides the repaired section would connect

Returns:

true if a destroyed bridge section may be rebuilt in the target hex (unofficial). See bridgeRepairIssue(Board, Coords, int) for the full set of conditions.

bridgeRepairIssue

public static BridgeConstruction.BridgeRepairIssue bridgeRepairIssue(Board board,
 @Nullable
 Coords target,
 int exits)

Checks whether a single destroyed bridge section may be rebuilt in the target hex (unofficial bridge-repair option). A repair fills a gap - a hex that currently holds no structure - and must reconnect the broken run: at least one connected neighbor is a surviving span of a bridge pointing back into the hex (that span also fixes the repaired deck height, so the section lines up with the rest of the bridge), and the far side either continues the bridge with another surviving span or reaches a bank a unit can step on/off of. A gap flanked only by banks is a fresh build, not a repair, and a span whose far side is open water or deep canyon with no bank cannot be repaired (the run is rebuilt inward from a span or bank). Any underlying rubble or water left by the collapse is preserved.

Parameters:

board - the board to repair on

target - the gap hex the section would be rebuilt in, or null

exits - exits bitmask of the two hexsides the repaired section would connect

Returns:

Why the site is or is not a repairable gap (see BridgeConstruction.BridgeRepairIssue).

placeRepairedBridge

public static IBuilding placeRepairedBridge(Board board,
 Coords target,
 int exits,
 int bridgeType,
 int cf)

Rebuilds a single destroyed bridge section in the gap hex (unofficial repair option): adds the bridge terrain at the surviving span's deck height so the section reconnects, registers it as a board structure, and recomputes terrain exits. Underlying rubble or water left by the collapse is preserved (only bridge terrain is added). The caller is responsible for validating the site with isBridgeRepairSite(Board, Coords, int) and for sending the changed hex and the new structure to the clients.

Parameters:

board - the board to repair on

target - the gap hex the section is rebuilt in

exits - exits bitmask of the two hexsides the repaired section connects

bridgeType - the bridge type as a BuildingType value (1 = light, 2 = medium)

cf - the Construction Factor of the rebuilt section

Returns:

The newly registered bridge structure, for sending to the clients.