Package de.bsommerfeld.pathetic.api.pathing.heuristic

Interface IHeuristicStrategy

All Known Implementing Classes:
LinearHeuristicStrategy, SquaredHeuristicStrategy
public interface IHeuristicStrategy
Defines the contract for heuristic strategies used in pathfinding algorithms.

A heuristic strategy provides two key functions:

  • Computing the heuristic value (estimated cost) from a position to the target
  • Calculating the actual transition cost between two adjacent positions

The heuristic function is crucial for guiding the A* algorithm towards the target efficiently. It must be admissible (never overestimate the actual cost) to guarantee optimal pathfinding results.

Since:
5.3.0
See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    double
    calculate(HeuristicContext heuristicContext)
    Calculates the heuristic value (estimated cost) from the current position to the target.
    double
    calculateTransitionCost(PathPosition from, PathPosition to)
    Calculates the actual transition cost between two adjacent positions.

  • Method Details

    • calculate

      double calculate(HeuristicContext heuristicContext)
      Calculates the heuristic value (estimated cost) from the current position to the target.

      This method computes an estimate of the remaining cost to reach the target from the current position. The heuristic should be admissible (never overestimate the actual cost) to ensure optimal pathfinding results.

      Common heuristic functions include:

      • Manhattan distance for grid-based movement
      • Euclidean distance for free movement
      • Octile distance for diagonal movement
      • Combined metrics considering elevation and terrain
      Parameters:
      heuristicContext - the context containing information about the current position, target position, and other relevant pathfinding data
      Returns:
      the estimated cost from the current position to the target, must be non-negative
      Throws:
      IllegalArgumentException - if the heuristic context is invalid
      See Also:

    • calculateTransitionCost

      double calculateTransitionCost(PathPosition from, PathPosition to)
      Calculates the actual transition cost between two adjacent positions.

      This method determines the cost of moving from one position to another. The cost should reflect the actual difficulty or expense of the movement, taking into account factors such as:

      • Distance between positions
      • Terrain difficulty
      • Elevation changes
      • Movement penalties

      The transition cost is used to calculate the G-cost (actual cost from start) in the A* algorithm.

      Parameters:
      from - the starting position of the movement
      to - the destination position of the movement
      Returns:
      the cost of moving from the 'from' position to the 'to' position, must be positive for valid movements
      Throws:
      IllegalArgumentException - if either position is null or invalid
      See Also: