Package com.tenio.engine.physic.utility

Class CellSpacePartition<E extends BaseGameEntity>

  • Type Parameters:
    E - the game entity template
    All Implemented Interfaces:
    IRender
    public class CellSpacePartition<E extends BaseGameEntity>
extends java.lang.Object
implements IRender
    This class is used to divide a 2D space into a grid of cells each of which may contain a number of entities. Once created and initialized with entities, fast proximity queries can be made by calling the CalculateNeighbors method with a position and proximity radius. If an entity is capable of moving, and therefore capable of moving between cells, the Update method should be called each update-cycle to synchronize the entity and the cell space it occupies
    Author:
    sallyx (https://www.sallyx.org/sally/en/game-ai/)

    • Constructor Summary

      Constructors 
      Constructor Description
      CellSpacePartition​(float width, float height, int cellsX, int cellsY, int maxEntities)
      Create a new instance

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addEntity​(E entity)
      Used to add the entities to the data structure adds entities to the class by allocating them to the appropriate cell
      void calculateNeighbors​(Vector2 targetPos, float queryRadius)
      This must be called to create the vector of neighbors.This method examines each cell within range of the target, If the cells contain entities then they are tested to see if they are situated within the target's neighborhood region.
      void clearCells()
      Clears the cells of all entities
      E getFrontOfNeighbor()  
      E getNextOfNeighbor()  
      boolean isEndOfNeighbors()  
      void render​(Paint paint)
      To render objects to screen
      void updateEntity​(E entity, Vector2 oldPosition)
      Update an entity's cell by calling this from your entity's Update method Checks to see if an entity has moved cells.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • CellSpacePartition

        public CellSpacePartition​(float width,
                          float height,
                          int cellsX,
                          int cellsY,
                          int maxEntities)
        Create a new instance
        Parameters:
        width - width of 2D space
        height - height of 2D space
        cellsX - number of divisions horizontally
        cellsY - number of divisions vertically
        maxEntities - maximum number of entities to partition

    • Method Detail

      • addEntity

        public void addEntity​(E entity)
        Used to add the entities to the data structure adds entities to the class by allocating them to the appropriate cell
        Parameters:
        entity - an entity

      • updateEntity

        public void updateEntity​(E entity,
                         Vector2 oldPosition)
        Update an entity's cell by calling this from your entity's Update method Checks to see if an entity has moved cells. If so the data structure is updated accordingly
        Parameters:
        entity - an entity
        oldPosition - see Vector2

      • calculateNeighbors

        public void calculateNeighbors​(Vector2 targetPos,
                               float queryRadius)
        This must be called to create the vector of neighbors.This method examines each cell within range of the target, If the cells contain entities then they are tested to see if they are situated within the target's neighborhood region. If they are they are added to neighbor list this method stores a target's neighbors in the neighbor vector. After you have called this method use the begin, next and end methods to iterate through the vector.
        Parameters:
        targetPos - see Vector2
        queryRadius - radius value

      • getFrontOfNeighbor

        public E getFrontOfNeighbor()
        Returns:
        a reference to the entity at the front of the neighbor vector

      • getNextOfNeighbor

        public E getNextOfNeighbor()
        Returns:
        the next entity in the neighbor vector

      • isEndOfNeighbors

        public boolean isEndOfNeighbors()
        Returns:
        true if the end of the vector is found (a zero value marks the end)

      • clearCells

        public void clearCells()
        Clears the cells of all entities

      • render

        public void render​(Paint paint)
        Description copied from interface: IRender
        To render objects to screen
        Specified by:
        render in interface IRender
        Parameters:
        paint - see Paint