219 lines
7.4 KiB
C++
219 lines
7.4 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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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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*/
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#include "ultima/shared/std/containers.h"
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#include "ultima/nuvie/core/nuvie_defs.h"
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#include "ultima/nuvie/pathfinder/dir_finder.h"
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#include "ultima/nuvie/pathfinder/astar_path.h"
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namespace Ultima {
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namespace Nuvie {
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AStarPath::AStarPath() : final_node(0) {
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}
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void AStarPath::create_path() {
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astar_node *i = final_node; // iterator through steps, from back
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delete_path();
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Std::vector<astar_node *> reverse_list;
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while (i) {
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reverse_list.push_back(i);
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i = i->parent;
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}
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while (!reverse_list.empty()) {
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i = reverse_list.back();
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add_step(i->loc);
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reverse_list.pop_back();
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}
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set_path_size(step_count);
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}/* Get a new neighbor to nnode and score it, returning true if it's usable. */
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bool AStarPath::score_to_neighbor(sint8 dir, astar_node *nnode, astar_node *neighbor,
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sint32 &nnode_to_neighbor) {
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sint8 sx = -1, sy = -1;
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DirFinder::get_adjacent_dir(sx, sy, dir); // sx,sy = neighbor -1,-1 + dir
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// get neighbor of nnode towards sx,sy, and cost to that neighbor
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neighbor->loc = nnode->loc.abs_coords(sx, sy);
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nnode_to_neighbor = step_cost(nnode->loc, neighbor->loc);
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if (nnode_to_neighbor == -1) {
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delete neighbor; // this neighbor is blocked
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return false;
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}
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return true;
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}/* Compare a node's score to the start node to already scored neighbors. */
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bool AStarPath::compare_neighbors(astar_node *nnode, astar_node *neighbor,
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sint32 nnode_to_neighbor, astar_node *in_open,
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astar_node *in_closed) {
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neighbor->to_start = nnode->to_start + nnode_to_neighbor;
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// ignore this neighbor if already checked and closer to start
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if ((in_open && in_open->to_start <= neighbor->to_start)
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|| (in_closed && in_closed->to_start <= neighbor->to_start)) {
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delete neighbor;
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return false;
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}
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return true;
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}/* Check all neighbors of a node (location) and save them to the "seen" list. */
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bool AStarPath::search_node_neighbors(astar_node *nnode, const MapCoord &goal,
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const uint32 max_score) {
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for (uint32 dir = 1; dir < 8; dir += 2) {
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astar_node *neighbor = new astar_node;
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sint32 nnode_to_neighbor = -1;
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if (!score_to_neighbor(dir, nnode, neighbor, nnode_to_neighbor))
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continue; // this neighbor is blocked
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astar_node *in_open = find_open_node(neighbor),
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*in_closed = find_closed_node(neighbor);
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if (!compare_neighbors(nnode, neighbor, nnode_to_neighbor, in_open, in_closed))
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continue;
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neighbor->parent = nnode;
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neighbor->to_goal = path_cost_est(neighbor->loc, goal);
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neighbor->score = neighbor->to_start + neighbor->to_goal;
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neighbor->len = nnode->len + 1;
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if (neighbor->score > max_score) {
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delete neighbor; // too far away
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continue;
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}
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// take neighbor out of closed list and put into open list
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if (in_closed)
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remove_closed_node(in_closed);
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if (!in_open)
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push_open_node(neighbor);
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}
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return true;
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}
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/* Do A* search of tiles to create a path from `start' to `goal'.
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* Don't search past nodes with a score over the max. score.
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* Create a partial path to low-score nodes with a distance-to-start over the
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* max_steps count, defined here. Actor may perform another search when needed.
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* Returns true if a path is created
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*/
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bool AStarPath::path_search(const MapCoord &start, const MapCoord &goal) {
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//DEBUG(0,LEVEL_DEBUGGING,"SEARCH: %d: %d,%d -> %d,%d\n",actor->get_actor_num(),start.x,start.y,goal.x,goal.y);
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astar_node *start_node = new astar_node;
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start_node->loc = start;
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start_node->to_start = 0;
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start_node->to_goal = path_cost_est(start, goal);
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start_node->score = start_node->to_start + start_node->to_goal;
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start_node->len = 0;
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push_open_node(start_node);
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const uint32 max_score = get_max_score(start_node->to_goal);
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const uint32 max_steps = 8 * 2 * 4; // walk up to four screen lengths before searching again
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while (!open_nodes.empty()) {
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astar_node *nnode = pop_open_node(); // next closest
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if (nnode->loc == goal || nnode->len >= max_steps) {
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if (nnode->loc != goal)
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DEBUG(0, LEVEL_DEBUGGING, "out of steps, making partial path (nnode->len=%d)\n", nnode->len);
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//DEBUG(0,LEVEL_DEBUGGING,"GOAL\n");
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final_node = nnode;
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create_path();
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delete_nodes();
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return true; // reached goal - success
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}
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// check cardinal neighbors (starting at top going clockwise)
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search_node_neighbors(nnode, goal, max_score);
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// node and neighbors checked, put into closed
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closed_nodes.push_back(nnode);
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}
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//DEBUG(0,LEVEL_DEBUGGING,"FAIL\n");
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delete_nodes();
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return false; // out of open nodes - failure
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}
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/* Return the cost of moving one step from `c1' to `c2', which is always 1. This
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* isn't very helpful, so subclasses should provide their own function.
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* Returns -1 if c2 is blocked. */
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sint32 AStarPath::step_cost(const MapCoord &c1, const MapCoord &c2) {
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if (!pf->check_loc(c2.x, c2.y, c2.z)
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|| c2.distance(c1) > 1)
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return -1;
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return 1;
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}
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/* Return an item in the list of closed nodes whose location matches `ncmp'.
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*/
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astar_node *AStarPath::find_closed_node(astar_node *ncmp) {
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for (astar_node *n : closed_nodes)
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if (n->loc == ncmp->loc)
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return n;
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return nullptr;
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}
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/* Return an item in the list of open nodes whose location matches `ncmp'.
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*/
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astar_node *AStarPath::find_open_node(astar_node *ncmp) {
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for (astar_node *n : open_nodes)
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if (n->loc == ncmp->loc)
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return n;
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return nullptr;
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}
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/* Add new node pointer to the list of open nodes (sorting by score).
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*/
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void AStarPath::push_open_node(astar_node *node) {
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if (open_nodes.empty()) {
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open_nodes.push_front(node);
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return;
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}
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Std::list<astar_node *>::iterator n = open_nodes.begin();
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// get to end of list or to a node with equal or greater score
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while (n != open_nodes.end() && (*n++)->score < node->score);
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open_nodes.insert(n, node); // and add before that location
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}
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/* Return pointer to the highest priority node from the list of open nodes, and
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* remove it.
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*/
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astar_node *AStarPath::pop_open_node() {
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astar_node *best = open_nodes.front();
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open_nodes.pop_front(); // remove it
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return best;
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}
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/* Find item in the list of closed nodes whose location matched `ncmp', and
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* remove it from the list.
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*/
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void AStarPath::remove_closed_node(astar_node *ncmp) {
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Std::list<astar_node *>::iterator n;
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for (n = closed_nodes.begin(); n != closed_nodes.end(); n++)
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if ((*n)->loc == ncmp->loc) {
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closed_nodes.erase(n);
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return;
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}
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}
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/* Delete nodes dereferenced from pointers in the lists.
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*/
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void AStarPath::delete_nodes() {
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while (!open_nodes.empty()) {
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astar_node *delnode = open_nodes.front();
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open_nodes.pop_front();
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delete delnode;
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}
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while (!closed_nodes.empty()) {
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astar_node *delnode = closed_nodes.front();
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closed_nodes.pop_front();
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delete delnode;
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}
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}
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} // End of namespace Nuvie
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} // End of namespace Ultima
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