/// <summary>
/// The heuristic function for doing A* pathfinding for this unit.
/// Note that to reduce garbage, this heuristic may reuse global variables,
/// which means only one Unit can have a heuristic at any time.
/// </summary>
protected void AStarEdgeCalc(Pathfinding.Goal <Vector2i> goal,
Pathfinding.Edge <Vector2i> edge,
out float edgeLength, out float heuristic)
{
Graph.AStarEdgeCalc(goal, edge, out edgeLength, out heuristic);
//Subtract enemy distances squared from the heuristic.
foreach (Unit enemy in _temp_enemies)
{
float distSqr = enemy.Pos.Value.DistanceSqr(Pos);
float distT = distSqr * One_Over_MaxEnemyDistance;
distT = Math.Max(0.0f, Math.Min(1.0f, distT));
heuristic += Units.Consts.EnemyDistanceHeuristicMax * distT;
}
}
/// <summary>
/// Does the basic edge length/heuristic calculation
/// that all units will likely use for their pathing.
/// </summary>
public static void AStarEdgeCalc(Pathfinding.Goal <Vector2i> goal,
Pathfinding.Edge <Vector2i> edge,
out float edgeLength, out float heuristic)
{
//For performance (and because they'll generally be adjacent),
// use manhattan distance between nodes.
edgeLength = Math.Abs(edge.Start.x - edge.End.x) + Math.Abs(edge.Start.y - edge.End.y);
heuristic = 0.0f;
//Manhattan distance to the goal.
if (goal.SpecificGoal.HasValue)
{
Vector2i specificGoal = goal.SpecificGoal.Value;
float dist = Math.Abs(edge.End.x - specificGoal.x) +
Math.Abs(edge.End.y - specificGoal.y);
//Square it to make it more important.
heuristic += dist * dist;
}
}