355 lines
7.5 KiB
Java
355 lines
7.5 KiB
Java
/*
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* Pixel Dungeon
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* Copyright (C) 2012-2015 Oleg Dolya
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*
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* Shattered Pixel Dungeon
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* Copyright (C) 2014-2016 Evan Debenham
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>
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*/
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package com.watabou.utils;
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import java.util.Arrays;
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import java.util.LinkedList;
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public class PathFinder {
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public static int[] distance;
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private static int[] maxVal;
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private static boolean[] goals;
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private static int[] queue;
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private static int size = 0;
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private static int[] dir;
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//performance-light shortcuts for some common pathfinder cases
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public static int[] NEIGHBOURS4;
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public static int[] NEIGHBOURS8;
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public static int[] NEIGHBOURS9;
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public static void setMapSize( int width, int height ) {
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int size = width * height;
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PathFinder.size = size;
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distance = new int[size];
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goals = new boolean[size];
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queue = new int[size];
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maxVal = new int[size];
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Arrays.fill(maxVal, Integer.MAX_VALUE);
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dir = new int[]{-1, +1, -width, +width, -width-1, -width+1, +width-1, +width+1};
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NEIGHBOURS4 = new int[]{-width, +1, +width, -1};
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NEIGHBOURS8 = new int[]{-width, +1-width, +1, +1+width, +width, -1+width, -1, -1-width};
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NEIGHBOURS9 = new int[]{0, -width, +1-width, +1, +1+width, +width, -1+width, -1, -1-width};
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}
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//TODO currently this isn't used, and all pathfinding is recomputed each step.
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// Computing each step is performance expensive, but pre-computing a path leads to incorrect
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// pathing in cases where passable changes. Need to look into a compromise, something that's
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// correct but is less costly
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public static Path find( int from, int to, boolean[] passable ) {
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if (!buildDistanceMap( from, to, passable )) {
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return null;
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}
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Path result = new Path();
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int s = from;
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// From the starting position we are moving downwards,
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// until we reach the ending point
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do {
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int minD = distance[s];
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int mins = s;
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for (int i=0; i < dir.length; i++) {
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int n = s + dir[i];
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int thisD = distance[n];
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if (thisD < minD) {
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minD = thisD;
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mins = n;
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}
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}
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s = mins;
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result.add( s );
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} while (s != to);
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return result;
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}
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public static int getStep( int from, int to, boolean[] passable ) {
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if (!buildDistanceMap( from, to, passable )) {
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return -1;
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}
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// From the starting position we are making one step downwards
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int minD = distance[from];
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int best = from;
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int step, stepD;
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for (int i=0; i < dir.length; i++) {
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if ((stepD = distance[step = from + dir[i]]) < minD) {
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minD = stepD;
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best = step;
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}
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}
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return best;
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}
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public static int getStepBack( int cur, int from, boolean[] passable ) {
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int d = buildEscapeDistanceMap( cur, from, 2f, passable );
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for (int i=0; i < size; i++) {
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goals[i] = distance[i] == d;
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}
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if (!buildDistanceMap( cur, goals, passable )) {
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return -1;
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}
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int s = cur;
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// From the starting position we are making one step downwards
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int minD = distance[s];
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int mins = s;
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for (int i=0; i < dir.length; i++) {
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int n = s + dir[i];
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int thisD = distance[n];
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if (thisD < minD) {
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minD = thisD;
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mins = n;
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}
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}
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return mins;
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}
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private static boolean buildDistanceMap( int from, int to, boolean[] passable ) {
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if (from == to) {
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return false;
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}
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System.arraycopy(maxVal, 0, distance, 0, maxVal.length);
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boolean pathFound = false;
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int head = 0;
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int tail = 0;
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// Add to queue
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queue[tail++] = to;
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distance[to] = 0;
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while (head < tail) {
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// Remove from queue
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int step = queue[head++];
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if (step == from) {
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pathFound = true;
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break;
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}
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int nextDistance = distance[step] + 1;
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for (int i=0; i < dir.length; i++) {
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int n = step + dir[i];
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if (n == from || (n >= 0 && n < size && passable[n] && (distance[n] > nextDistance))) {
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// Add to queue
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queue[tail++] = n;
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distance[n] = nextDistance;
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}
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}
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}
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return pathFound;
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}
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public static void buildDistanceMap( int to, boolean[] passable, int limit ) {
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System.arraycopy(maxVal, 0, distance, 0, maxVal.length);
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int head = 0;
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int tail = 0;
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// Add to queue
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queue[tail++] = to;
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distance[to] = 0;
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while (head < tail) {
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// Remove from queue
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int step = queue[head++];
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int nextDistance = distance[step] + 1;
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if (nextDistance > limit) {
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return;
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}
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for (int i=0; i < dir.length; i++) {
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int n = step + dir[i];
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if (n >= 0 && n < size && passable[n] && (distance[n] > nextDistance)) {
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// Add to queue
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queue[tail++] = n;
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distance[n] = nextDistance;
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}
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}
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}
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}
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private static boolean buildDistanceMap( int from, boolean[] to, boolean[] passable ) {
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if (to[from]) {
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return false;
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}
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System.arraycopy(maxVal, 0, distance, 0, maxVal.length);
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boolean pathFound = false;
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int head = 0;
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int tail = 0;
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// Add to queue
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for (int i=0; i < size; i++) {
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if (to[i]) {
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queue[tail++] = i;
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distance[i] = 0;
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}
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}
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while (head < tail) {
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// Remove from queue
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int step = queue[head++];
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if (step == from) {
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pathFound = true;
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break;
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}
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int nextDistance = distance[step] + 1;
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for (int i=0; i < dir.length; i++) {
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int n = step + dir[i];
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if (n == from || (n >= 0 && n < size && passable[n] && (distance[n] > nextDistance))) {
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// Add to queue
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queue[tail++] = n;
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distance[n] = nextDistance;
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}
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}
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}
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return pathFound;
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}
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private static int buildEscapeDistanceMap( int cur, int from, float factor, boolean[] passable ) {
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System.arraycopy(maxVal, 0, distance, 0, maxVal.length);
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int destDist = Integer.MAX_VALUE;
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int head = 0;
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int tail = 0;
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// Add to queue
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queue[tail++] = from;
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distance[from] = 0;
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int dist = 0;
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while (head < tail) {
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// Remove from queue
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int step = queue[head++];
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dist = distance[step];
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if (dist > destDist) {
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return destDist;
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}
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if (step == cur) {
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destDist = (int)(dist * factor) + 1;
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}
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int nextDistance = dist + 1;
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for (int i=0; i < dir.length; i++) {
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int n = step + dir[i];
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if (n >= 0 && n < size && passable[n] && distance[n] > nextDistance) {
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// Add to queue
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queue[tail++] = n;
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distance[n] = nextDistance;
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}
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}
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}
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return dist;
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}
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@SuppressWarnings("unused")
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private static void buildDistanceMap( int to, boolean[] passable ) {
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System.arraycopy(maxVal, 0, distance, 0, maxVal.length);
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int head = 0;
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int tail = 0;
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// Add to queue
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queue[tail++] = to;
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distance[to] = 0;
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while (head < tail) {
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// Remove from queue
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int step = queue[head++];
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int nextDistance = distance[step] + 1;
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for (int i=0; i < dir.length; i++) {
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int n = step + dir[i];
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if (n >= 0 && n < size && passable[n] && (distance[n] > nextDistance)) {
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// Add to queue
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queue[tail++] = n;
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distance[n] = nextDistance;
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}
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}
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}
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}
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@SuppressWarnings("serial")
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public static class Path extends LinkedList<Integer> {
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}
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}
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