You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
85 lines
3.1 KiB
85 lines
3.1 KiB
package technology.zim
|
|
|
|
import technology.zim.data.Directions
|
|
import technology.zim.data.Tile
|
|
import technology.zim.data.TileHeap
|
|
|
|
//A* to be upgraded with hierarchies
|
|
|
|
//Needs https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/PriorityQueue.html
|
|
//and https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Comparator.html
|
|
|
|
object PathFinder {
|
|
//TODO: Replace with array for coordinate lookups for speed - maybe abstract it?
|
|
val gVals = HashMap<Tile, Int>()
|
|
//work along the path, marking tiles with VISITED along the way
|
|
//if marking with visited is too expensive, just make the path and finalize it
|
|
fun generatePath(start: Tile, end: Tile) {
|
|
if(!start.isInBounds() || !end.isInBounds()) {
|
|
throw IndexOutOfBoundsException("Cannot generate a path to or from an out of bounds tile")
|
|
}
|
|
|
|
if(start == end) {
|
|
println("Ouroboros detected")
|
|
return
|
|
}
|
|
|
|
val frontier = TileHeap(end, gVals)
|
|
|
|
//Prime the things
|
|
gVals.put(start, 0)
|
|
frontier.insert(start)
|
|
|
|
var current: Tile
|
|
var currentG: Int
|
|
|
|
do {
|
|
current = frontier.popMin()
|
|
currentG = gVals.get(current) ?: 0.also { println("Failed to get gVal that must exist")}
|
|
|
|
|
|
current.getConnections().forEach { candidateTile ->
|
|
val candidateG = gVals.get(candidateTile)?:-1
|
|
//Ensure that the tile is within bounds
|
|
if(candidateTile.isInBounds())
|
|
{
|
|
if(candidateG != -1) {
|
|
//Then the candidateG already has a path leading to it, so check if the current path is better
|
|
if(currentG + 1 < candidateG) {
|
|
gVals.replace(candidateTile, candidateG)
|
|
frontier.insert(candidateTile)
|
|
|
|
}
|
|
|
|
} else {
|
|
//Otherwise, the tile has been reached and this path is not better, so carry on
|
|
gVals.put(candidateTile, currentG + 1)
|
|
frontier.insert(candidateTile)
|
|
World.update(candidateTile, candidateTile.getProperties() +Directions.FRONTIER)
|
|
}
|
|
}
|
|
}
|
|
} while( current != end)
|
|
|
|
//At this point, a path is found
|
|
println("Path found!")
|
|
|
|
//Step through the path from end until start
|
|
current = end
|
|
var lowestG = Int.MAX_VALUE
|
|
var lowestCost = end
|
|
while(current != start) {
|
|
World.update(current, current.getProperties() + Directions.INPATH)
|
|
current.getConnections().forEach { candidateTile ->
|
|
val candidateG = gVals.get(candidateTile) ?: -1
|
|
if(candidateTile.isInBounds() && candidateG != -1 && candidateG < lowestG ) {
|
|
lowestG = candidateG
|
|
lowestCost = candidateTile
|
|
}
|
|
}
|
|
current = lowestCost
|
|
}
|
|
World.update(start, start.getProperties() + Directions.INPATH)
|
|
|
|
}
|
|
} |