Dn2GameGrid

Unreal Engine 4 plug-in for square and hex grids and simple A*(Star) pathfinding. An instance of a grid is managed by an Actor that holds an array of the cells (points/nodes) on the grid. There are helper functions in both C++ and Blueprints for you to manipulate the grid, it's cells and your gameplay actors. Made and tested in Unreal Engine 4.27.

Features

• Async grid generation
• Async A* pathfinding
• Non iterative cell validation
• World Location <-> Grid coordinates conversion
• GameplayTag based filtering for cell retrieval
• Cell and Cell Vertex location data
• Grid Movement Component

Not Implemented (Yet)

• Hexagon version
• Common helper cell selection operations (think trace and overlap but for cells, sorta)
• WFC (Wave Function Collapse) base class
• Map importing

Setup

1. Install plugin to your project's plugin folder and enable it by going to Edit > Plugins. e.g: MyProject\Plugins\Dn2GameGrids
2. Add a BoxGridActor to your level or create a blueprint with BoxGridActor as its parent class.
3. In the details panel of your placed BoxGridActor or class defaults panel of your blueprint, under the Grid category, check bAutoGenerate, and set the extents or your grid.
4. Alternately, you can skip step 3 and use the blueprint node Update Grid Async to build your base grid at runtime. Update Grid Async overwrites the current grid if there is one.
5. Additionally Update Grid Async, on completion fires off Blueprint and C++ events with the resulting grid array, grid extents and cell size.

Terminology

• Cell: A point or node on the grid with associated 2D coordinates (e.g 4,20). See Cell Info.

• Cell Address or Address: the 2D coordinates (e.g 7,11) that represent a position on the grid.

• Cell Info: FCellInfo Struct that holds the info for the cells on a grid. UpdateGridAsync() populates TArray<FCellInfo> GridArray with these. You can find FCellAdress, FGameplayTagContainer, etc held within.

• Cell Tags: FGameplayTagContainer that holds the FGameTags that are associated with a Cell Info.

• Grid Extents: The extents of the grid. A FIntPoint, X being how many cells wide and Y being how many cells 'tall'.

• Neighbors: Any cells directly next to a given cell. e.g. GetCellNeighbors() returns cells next to a given cell.

• Cell Size: The size of a cell when calculating its dimensions & location in world space in relation to the AGridActorBase that owns it.

Types

Name	Members	Description
FCellAddress	int32 X in32 Y	Coordinates for a cell, X and Y
FCellInfo	FCellAddress Address FGameplayTagContainer CellTags	Used for grid array. Holds info for each cell in the grid array
FAStarCellInfo	float H float G float F FCellAddress Address FCellAddress CameFrom	Used for the A-Star algo
FAStarSearchResults	bool bFoundGoal TArray<FCellAddress> Path	Struct holding the results of AStar search algorithm

AGridActorBase Members

Name	Type	Description
bAutoGenerate	bool	Show a grid preview in editor & generate on BeginPlay
CellSize	float	Size of cells
DefaultCellTags	FGameplayTagContainer	If bAutoGenerate, generate a grid on BeginPlay using these Tags
GridArray	TArray<FCellInfo>	Array holding our grid cells
GridMeshComp	UStaticMeshComponent*	Visual of the grid and trace collisions for world locations <-> grid address conversions
GridMat	UMaterial*	The material we'll make and instance of and use for visual debugging

AGridActorBase C++ Functions & Blueprint Nodes

Name	CPP	BP	Description
UpdateGridAsync	Yes	Yes	Create default grid for this grid actor. Populates TArray<FCellInfo> GridArray. On completion calls C++ event ABoxGridActor::OnUpdateGrid_Internal and blueprint event ABoxGridActor::OnUpdateGrid with the results of the grid creation.
GetPathToGoalAsync	Yes	Yes	Create default grid for this grid actor. Populates TArray<FCellInfo> GridArray. On completion calls C++ event ABoxGridActor::OnUpdateGrid_Internal and blueprint event ABoxGridActor::OnUpdateGrid with the results of the grid creation
CreateEmptyGrid	Yes	Yes	Create a grid array that you can do what you want with. Not Async. No sort of setups of anything. Just returns an array of FCellInfo
AStarSearchToGoal	Yes	Yes	Not Async. Try to find a path to the goal given addresses and optional filters, using an AStar pathfinding algorithm
GetCellLocationFromAddress	Yes	Yes	Given the address of a cell (e.g 12,24) return the cell's world location. Uses the Actor's GridArray
GetCellAddressFromLocation	Yes	Yes	Given a world location (e.g FVector(123,456,10)) return a cell address IF the address is valid. Return value of FCellAddress(-1,-1) means there is no cell associated with given location. Uses the Actor's GridArray
GetIndexFromAddress	Yes	Yes	Given the address of a cell, return the Index for that cell's FCellInfo in AGridActorBase::GridArray. Avoids iterating arrays by just calculation its index
DoesCellExist	Yes	Yes	Returns true if the given address is valid and the FCellInfo in the assumed index of AGridActorBase::GridArray matches
GetCellInfoByAddress	Yes	Yes	Given and address returns the associated FCellInfo from AGridActorBase::GridArray. Make sure the returned FCellInfo::Address is valid. i.e. not FCellAddress(-1,-1)
GetCellNeighbors	Yes	Yes	Given an address, an array of neighbouring cells are returned. Optionally filtered using GameplayTags. ToDo: maybe return addresses instead of cell infos
GetGridExtents	Yes	Yes	Returns the extents of the grid.