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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
/*
* This code is based on Broken Sword 2.5 engine
*
* Copyright (c) Malte Thiesen, Daniel Queteschiner and Michael Elsdoerfer
*
* Licensed under GNU GPL v2
*
*/
#include "sword25/kernel/kernel.h"
#include "sword25/kernel/inputpersistenceblock.h"
#include "sword25/kernel/outputpersistenceblock.h"
#include "sword25/math/walkregion.h"
#include "sword25/math/line.h"
#define BS_LOG_PREFIX "WALKREGION"
namespace Sword25 {
static const int Infinity = 0x7fffffff;
WalkRegion::WalkRegion() {
_type = RT_WALKREGION;
}
WalkRegion::WalkRegion(InputPersistenceBlock &reader, uint handle) :
Region(reader, handle) {
_type = RT_WALKREGION;
unpersist(reader);
}
WalkRegion::~WalkRegion() {
}
bool WalkRegion::init(const Polygon &contour, const Common::Array<Polygon> *pHoles) {
// Default initialisation of the region
if (!Region::init(contour, pHoles)) return false;
// Prepare structures for pathfinding
initNodeVector();
computeVisibilityMatrix();
// Signal success
return true;
}
bool WalkRegion::queryPath(Vertex startPoint, Vertex endPoint, BS_Path &path) {
BS_ASSERT(path.empty());
// If the start and finish are identical, no path can be found trivially
if (startPoint == endPoint)
return true;
// Ensure that the start and finish are valid and find new start points if either
// are outside the polygon
if (!checkAndPrepareStartAndEnd(startPoint, endPoint)) return false;
// If between the start and point a line of sight exists, then it can be returned.
if (isLineOfSight(startPoint, endPoint)) {
path.push_back(startPoint);
path.push_back(endPoint);
return true;
}
return findPath(startPoint, endPoint, path);
}
struct DijkstraNode {
typedef Common::Array<DijkstraNode> Container;
typedef Container::iterator Iter;
typedef Container::const_iterator ConstIter;
DijkstraNode() : cost(Infinity), chosen(false) {}
ConstIter parentIter;
int cost;
bool chosen;
};
static void initDijkstraNodes(DijkstraNode::Container &dijkstraNodes, const Region ®ion,
const Vertex &start, const Common::Array<Vertex> &nodes) {
// Allocate sufficient space in the array
dijkstraNodes.resize(nodes.size());
// Initialise all the nodes which are visible from the starting node
DijkstraNode::Iter dijkstraIter = dijkstraNodes.begin();
for (Common::Array<Vertex>::const_iterator nodesIter = nodes.begin();
nodesIter != nodes.end(); nodesIter++, dijkstraIter++) {
(*dijkstraIter).parentIter = dijkstraNodes.end();
if (region.isLineOfSight(*nodesIter, start))(*dijkstraIter).cost = (*nodesIter).distance(start);
}
BS_ASSERT(dijkstraIter == dijkstraNodes.end());
}
static DijkstraNode::Iter chooseClosestNode(DijkstraNode::Container &nodes) {
DijkstraNode::Iter closestNodeInter = nodes.end();
int minCost = Infinity;
for (DijkstraNode::Iter iter = nodes.begin(); iter != nodes.end(); iter++) {
if (!(*iter).chosen && (*iter).cost < minCost) {
minCost = (*iter).cost;
closestNodeInter = iter;
}
}
return closestNodeInter;
}
static void relaxNodes(DijkstraNode::Container &nodes,
const Common::Array< Common::Array<int> > &visibilityMatrix,
const DijkstraNode::ConstIter &curNodeIter) {
// All the successors of the current node that have not been chosen will be
// inserted into the boundary node list, and the cost will be updated if
// a shorter path has been found to them.
int curNodeIndex = curNodeIter - nodes.begin();
for (uint i = 0; i < nodes.size(); i++) {
int cost = visibilityMatrix[curNodeIndex][i];
if (!nodes[i].chosen && cost != Infinity) {
int totalCost = (*curNodeIter).cost + cost;
if (totalCost < nodes[i].cost) {
nodes[i].parentIter = curNodeIter;
nodes[i].cost = totalCost;
}
}
}
}
static void relaxEndPoint(const Vertex &curNodePos,
const DijkstraNode::ConstIter &curNodeIter,
const Vertex &endPointPos,
DijkstraNode &endPoint,
const Region ®ion) {
if (region.isLineOfSight(curNodePos, endPointPos)) {
int totalCost = (*curNodeIter).cost + curNodePos.distance(endPointPos);
if (totalCost < endPoint.cost) {
endPoint.parentIter = curNodeIter;
endPoint.cost = totalCost;
}
}
}
template<class T>
void reverseArray(Common::Array<T> &arr) {
const uint size = arr.size();
if (size < 2)
return;
for (uint i = 0; i <= (size / 2 - 1); ++i) {
SWAP(arr[i], arr[size - i - 1]);
}
}
bool WalkRegion::findPath(const Vertex &start, const Vertex &end, BS_Path &path) const {
// This is an implementation of Dijkstra's algorithm
// Initialise edge node list
DijkstraNode::Container dijkstraNodes;
initDijkstraNodes(dijkstraNodes, *this, start, _nodes);
// The end point is treated separately, since it does not exist in the visibility graph
DijkstraNode endPoint;
// Since a node is selected each round from the node list, and can never be selected again
// after that, the maximum number of loop iterations is limited by the number of nodes
for (uint i = 0; i < _nodes.size(); i++) {
// Determine the nearest edge node in the node list
DijkstraNode::Iter nodeInter = chooseClosestNode(dijkstraNodes);
// If no free nodes are absent from the edge node list, there is no path from start
// to end node. This case should never occur, since the number of loop passes is
// limited, but etter safe than sorry
if (nodeInter == dijkstraNodes.end())
return false;
// If the destination point is closer than the point cost, scan can stop
(*nodeInter).chosen = true;
if (endPoint.cost <= (*nodeInter).cost) {
// Insert the end point in the list
path.push_back(end);
// The list is done in reverse order and inserted into the path
DijkstraNode::ConstIter curNode = endPoint.parentIter;
while (curNode != dijkstraNodes.end()) {
BS_ASSERT((*curNode).chosen);
path.push_back(_nodes[curNode - dijkstraNodes.begin()]);
curNode = (*curNode).parentIter;
}
// The starting point is inserted into the path
path.push_back(start);
// The nodes of the path must be untwisted, as they were extracted in reverse order.
// This step could be saved if the path from end to the beginning was desired
reverseArray<Vertex>(path);
return true;
}
// Relaxation step for nodes of the graph, and perform the end nodes
relaxNodes(dijkstraNodes, _visibilityMatrix, nodeInter);
relaxEndPoint(_nodes[nodeInter - dijkstraNodes.begin()], nodeInter, end, endPoint, *this);
}
// If the loop has been completely run through, all the nodes have been chosen, and still
// no path was found. There is therefore no path available
return false;
}
void WalkRegion::initNodeVector() {
// Empty the Node list
_nodes.clear();
// Determine the number of nodes
int nodeCount = 0;
{
for (uint i = 0; i < _polygons.size(); i++)
nodeCount += _polygons[i].vertexCount;
}
// Knoten-Vector f�llen
_nodes.reserve(nodeCount);
{
for (uint j = 0; j < _polygons.size(); j++)
for (int i = 0; i < _polygons[j].vertexCount; i++)
_nodes.push_back(_polygons[j].vertices[i]);
}
}
void WalkRegion::computeVisibilityMatrix() {
// Initialise visibility matrix
_visibilityMatrix = Common::Array< Common::Array <int> >();
for (uint idx = 0; idx < _nodes.size(); ++idx) {
Common::Array<int> arr;
for (uint idx2 = 0; idx2 < _nodes.size(); ++idx2)
arr.push_back(Infinity);
_visibilityMatrix.push_back(arr);
}
// Calculate visibility been vertecies
for (uint j = 0; j < _nodes.size(); ++j) {
for (uint i = j; i < _nodes.size(); ++i) {
if (isLineOfSight(_nodes[i], _nodes[j])) {
// There is a line of sight, so save the distance between the two
int distance = _nodes[i].distance(_nodes[j]);
_visibilityMatrix[i][j] = distance;
_visibilityMatrix[j][i] = distance;
} else {
// There is no line of sight, so save Infinity as the distance
_visibilityMatrix[i][j] = Infinity;
_visibilityMatrix[j][i] = Infinity;
}
}
}
}
bool WalkRegion::checkAndPrepareStartAndEnd(Vertex &start, Vertex &end) const {
if (!isPointInRegion(start)) {
Vertex newStart = findClosestRegionPoint(start);
// Check to make sure the point is really in the region. If not, stop with an error
if (!isPointInRegion(newStart)) {
BS_LOG_ERRORLN("Constructed startpoint ((%d,%d) from (%d,%d)) is not inside the region.",
newStart.x, newStart.y,
start.x, start.y);
return false;
}
start = newStart;
}
// If the destination is outside the region, a point is determined that is within the region,
// and that is used as an endpoint instead
if (!isPointInRegion(end)) {
Vertex newEnd = findClosestRegionPoint(end);
// Make sure that the determined point is really within the region
if (!isPointInRegion(newEnd)) {
BS_LOG_ERRORLN("Constructed endpoint ((%d,%d) from (%d,%d)) is not inside the region.",
newEnd.x, newEnd.y,
end.x, end.y);
return false;
}
end = newEnd;
}
// Signal success
return true;
}
void WalkRegion::setPos(int x, int y) {
// Calculate the difference between old and new position
Vertex Delta(x - _position.x, y - _position.y);
// Move all the nodes
for (uint i = 0; i < _nodes.size(); i++)
_nodes[i] += Delta;
// Move regions
Region::setPos(x, y);
}
bool WalkRegion::persist(OutputPersistenceBlock &writer) {
bool result = true;
// Persist the parent region
result &= Region::persist(writer);
// Persist the nodes
writer.write(_nodes.size());
Common::Array<Vertex>::const_iterator it = _nodes.begin();
while (it != _nodes.end()) {
writer.write(it->x);
writer.write(it->y);
++it;
}
// Persist the visibility matrix
writer.write(_visibilityMatrix.size());
Common::Array< Common::Array<int> >::const_iterator rowIter = _visibilityMatrix.begin();
while (rowIter != _visibilityMatrix.end()) {
writer.write(rowIter->size());
Common::Array<int>::const_iterator colIter = rowIter->begin();
while (colIter != rowIter->end()) {
writer.write(*colIter);
++colIter;
}
++rowIter;
}
return result;
}
bool WalkRegion::unpersist(InputPersistenceBlock &reader) {
bool result = true;
// The parent object was already loaded in the constructor of BS_Region, so at
// this point only the additional data from BS_WalkRegion needs to be loaded
// Node load
uint nodeCount;
reader.read(nodeCount);
_nodes.clear();
_nodes.resize(nodeCount);
Common::Array<Vertex>::iterator it = _nodes.begin();
while (it != _nodes.end()) {
reader.read(it->x);
reader.read(it->y);
++it;
}
// Visibility matrix load
uint rowCount;
reader.read(rowCount);
_visibilityMatrix.clear();
_visibilityMatrix.resize(rowCount);
Common::Array< Common::Array<int> >::iterator rowIter = _visibilityMatrix.begin();
while (rowIter != _visibilityMatrix.end()) {
uint colCount;
reader.read(colCount);
rowIter->resize(colCount);
Common::Array<int>::iterator colIter = rowIter->begin();
while (colIter != rowIter->end()) {
reader.read(*colIter);
++colIter;
}
++rowIter;
}
return result && reader.isGood();
}
} // End of namespace Sword25
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