# direction_func.h File Reference

Different functions related to conversions between directions. More...

`#include "direction_type.h"`

Go to the source code of this file.

## Functions
static Direction | ReverseDir (Direction d)
| Return the reverse of a direction.
static DirDiff | DirDifference (Direction d0, Direction d1)
| Calculate the difference between to directions.
static DirDiff | ChangeDirDiff (DirDiff d, DirDiff delta)
| Applies two differences together.
static Direction | ChangeDir (Direction d, DirDiff delta)
| Change a direction by a given difference.
static DiagDirection | ReverseDiagDir (DiagDirection d)
| Returns the reverse direction of the given DiagDirection.
static DiagDirection | ChangeDiagDir (DiagDirection d, DiagDirDiff delta)
| Applies a difference on a DiagDirection.
static DiagDirection | DirToDiagDir (Direction dir)
| Convert a Direction to a DiagDirection.
static Direction | DiagDirToDir (DiagDirection dir)
| Convert a DiagDirection to a Direction.
static Axis | OtherAxis (Axis a)
| Select the other axis as provided.
static Axis | DiagDirToAxis (DiagDirection d)
| Convert a DiagDirection to the axis.
static DiagDirection | AxisToDiagDir (Axis a)
| Converts an Axis to a DiagDirection.
static DiagDirection | XYNSToDiagDir (Axis xy, uint ns)
| Convert an axis and a flag for north/south into a DiagDirection.
static bool | IsValidDiagDirection (DiagDirection d)
| Checks if an interger value is a valid DiagDirection.
static bool | IsValidDirection (Direction d)
| Checks if an integer value is a valid Direction.
static bool | IsValidAxis (Axis d)
| Checks if an integer value is a valid Axis.

## Detailed Description

Different functions related to conversions between directions.

Definition in file direction_func.h.

## Function Documentation

static DiagDirection AxisToDiagDir | ( | Axis | a | ) | `[inline, static]`

Converts an Axis to a DiagDirection.

This function returns the DiagDirection which belongs to the axis. As 2 directions are mapped to an axis this function returns the one which points to south, either south-west (on X axis) or south-east (on Y axis)

Parameters:

  | a | The axis

Returns:
  The direction pointed to south

Definition at line 165 of file direction_func.h.

Referenced by CmdBuildBridge(), DrawBridgePillars(), GetNorthernBridgeEnd(), GetSouthernBridgeEnd(), and TrainApproachingCrossing().

static DiagDirection ChangeDiagDir | ( | DiagDirection | d,
|  | DiagDirDiff | delta |
| ) |  |  | `[inline, static]`

Applies a difference on a DiagDirection.

This function applies a difference on a DiagDirection and returns the new DiagDirection.

Parameters:

  | d | The DiagDirection
  | delta | The difference to applie on

Returns:
  The new direction which was calculated

Definition at line 88 of file direction_func.h.

Referenced by GrowTownInTile(), IsNeighborRoadTile(), and TrainExitDir().

static Direction ChangeDir | ( | Direction | d,
|  | DirDiff | delta |
| ) |  |  | `[inline, static]`

Change a direction by a given difference.

This functions returns a new direction of the given direction which is rotated by the given difference.

Parameters:

  | d | The direction to get a new direction from
  | delta | The offset/drift applied to the direction

Returns:
  The new direction

Definition at line 60 of file direction_func.h.

Referenced by AircraftController(), and DisasterTick_Submarine().

static DirDiff ChangeDirDiff | ( | DirDiff | d,
|  | DirDiff | delta |
| ) |  |  | `[inline, static]`

Applies two differences together.

This function adds two differences together and return the resulting difference. So adding two DIRDIFF_REVERSE together results in the DIRDIFF_SAME difference.

Parameters:

  | d | The first difference
  | delta | The second difference to add on

Returns:
  The resulting difference

Definition at line 45 of file direction_func.h.

static Axis DiagDirToAxis | ( | DiagDirection | d | ) | `[inline, static]`

Convert a DiagDirection to the axis.

This function returns the axis which belongs to the given DiagDirection. The axis X belongs to the DiagDirection north-east and south-west.

Parameters:

  | d | The DiagDirection

Returns:
  The axis which belongs to the direction

Definition at line 148 of file direction_func.h.

Referenced by AdvanceWagonsAfterSwap(), CanEnterTileOwnerCheck(), CleanUpRoadBits(), CmdBuildBridge(), CmdBuildRoad(), CmdBuildTunnel(), CmdConvertRail(), DrawCatenaryRailway(), DrawTile_TunnelBridge(), ExploreSegment(), GetAnyRoadBits(), GetBridgeHeight(), GetRailTrackBitsUniversal(), and TrainApproachingCrossingTile().

static Direction DiagDirToDir | ( | DiagDirection | dir | ) | `[inline, static]`

Convert a DiagDirection to a Direction.

This function can be used to convert the 4-way DiagDirection to the 8-way Direction. As 4-way are less than 8-way not all possible directions can be calculated.

Parameters:

  | dir | The direction to convert

Returns:
  The resulting Direction

Definition at line 118 of file direction_func.h.

Referenced by CmdBuildRailVehicle(), CmdBuildRailWagon(), CmdBuildRoadVeh(), and TrainCanLeaveTile().

static DirDiff DirDifference | ( | Direction | d0,
|  | Direction | d1 |
| ) |  |  | `[inline, static]`

Calculate the difference between to directions.

Parameters:

  | d0 | The first direction as the base
  | d1 | The second direction as the offset from the base

Returns:
  The difference how the second directions drifts of the first one.

Definition at line 29 of file direction_func.h.

Referenced by AffectSpeedByDirChange(), AircraftController(), and GetTrainAcceleration().

static DiagDirection DirToDiagDir | ( | Direction | dir | ) | `[inline, static]`

Convert a Direction to a DiagDirection.

This function can be used to convert the 8-way Direction to the 4-way DiagDirection. If the direction cannot be mapped its "rounded clockwise". So DIR_N becomes DIAGDIR_NE.

Parameters:

  | dir | The direction to convert

Returns:
  The resulting DiagDirection, maybe "rounded clockwise".

Definition at line 103 of file direction_func.h.

Referenced by CmdTurnRoadVeh(), DisasterTick_Submarine(), GetTrainAcceleration(), GetVehicleTrackdir(), and TrainExitDir().

static bool IsValidAxis | ( | Axis | d | ) | `[inline, static]`

Checks if an integer value is a valid Axis.

Parameters:

  | d | The value to check

Returns:
  True if the value belongs to an Axis, else false

Definition at line 209 of file direction_func.h.

References AXIS_END.

Referenced by CmdBuildRoadStop().

static bool IsValidDiagDirection | ( | DiagDirection | d | ) | `[inline, static]`

Checks if an interger value is a valid DiagDirection.

Parameters:

  | d | The value to check

Returns:
  True if the value belongs to a DiagDirection, else false

Definition at line 187 of file direction_func.h.

References DIAGDIR_END.

Referenced by ChooseShipTrack(), CmdBuildRoadStop(), TileIndexDiffCByDiagDir(), and TileOffsByDiagDir().

static bool IsValidDirection | ( | Direction | d | ) | `[inline, static]`

Checks if an integer value is a valid Direction.

Parameters:

  | d | The value to check

Returns:
  True if the value belongs to a Direction, else false

Definition at line 198 of file direction_func.h.

References DIR_END.

Referenced by TileIndexDiffCByDir(), and TileOffsByDir().

static Axis OtherAxis | ( | Axis | a | ) | `[inline, static]`

Select the other axis as provided.

This is basically the not-operator for the axis.

Parameters:

  | a | The given axis

Returns:
  The other axis

Definition at line 132 of file direction_func.h.

Referenced by CmdBuildTunnel().

static DiagDirection ReverseDiagDir | ( | DiagDirection | d | ) | `[inline, static]`

Returns the reverse direction of the given DiagDirection.

Parameters:

  | d | The DiagDirection to get the reverse from

Returns:
  The reverse direction

Definition at line 72 of file direction_func.h.

Referenced by CFollowTrackT< Ttr_type_, T90deg_turns_allowed_ >::CanEnterNewTile(), CanEnterTile(), CheckTownBuild2House(), CheckTownBuild2x2House(), ChooseShipTrack(), CmdBuildBridge(), CmdBuildDock(), CmdBuildTunnel(), DrawBridgePillars(), DrawCatenaryRailway(), ExploreSegment(), CFollowTrackT< Ttr_type_, T90deg_turns_allowed_ >::FollowTileExit(), CFollowTrackT< Ttr_type_, T90deg_turns_allowed_ >::ForcedReverse(), GetAnyRoadBits(), GetBridgeEnd(), GetNorthernBridgeEnd(), GetOtherTunnelEnd(), GetTownRoadGridElement(), GrowTownAtRoad(), GrowTownInTile(), GrowTownWithBridge(), IsNeighborRoadTile(), TrainApproachingCrossing(), TrainCanLeaveTile(), TrainCheckIfLineEnds(), CFollowTrackT< Ttr_type_, T90deg_turns_allowed_ >::TryReverse(), and UpdateSignalsInBuffer().

static Direction ReverseDir | ( | Direction | d | ) | `[inline, static]`

Return the reverse of a direction.

Parameters:

  | d | The direction to get the reverse from

Returns:
  The reverse Direction

Definition at line 16 of file direction_func.h.

Referenced by FindClosestTrainDepot(), and TileLoop_Water().

static DiagDirection XYNSToDiagDir | ( | Axis | xy,
|  | uint | ns |
| ) |  |  | `[inline, static]`

Convert an axis and a flag for north/south into a DiagDirection.

Parameters:

  | xy | axis to convert
  | ns | north -> 0, south -> 1

Returns:
  the desired DiagDirection

Definition at line 176 of file direction_func.h.