worked on disjkstra and a*

nav/a-star/AStar.h

@@ -0,0 +1,119 @@
+#ifndef ASTAR_H
+#define ASTAR_H
+
+#include <iostream>
+#include <vector>
+#include <algorithm>
+#include <limits>
+#include <queue>
+#include <unordered_map>
+#include <cassert>
+
+#include "../../grid/Grid.h"
+
+
+template <typename T> class AStar {
+
+public:
+
+
+
+	//dijkstra with priority queue O(E log V)
+	template <typename Access> static std::vector<const T*> get(const T* source, const T* destination, Access acc) {
+
+		// track distances from the source to each other node
+		std::unordered_map<const T*, float> distance;
+
+		// track the previous node for each node along the path
+		std::unordered_map<const T*, const T*> parent;
+
+		// all nodes
+		const std::vector<T>& nodes = acc.getAllNodes();
+
+		// priority queue to check which node is to-be-processed next
+		std::priority_queue<std::pair<T*,float>, std::vector<std::pair<const T*,float>>, Comparator2> Q;
+
+		// start with infinite distance
+		for(const auto& node : nodes){
+			distance[&node] = std::numeric_limits<float>::max();
+		}
+
+
+		// start at the source
+		distance[source] = 0.0f;
+		Q.push(std::make_pair(source,distance[source]));
+
+		// proceed until there are now new nodes to follow
+		while(!Q.empty()) {
+
+			// fetch the next-nearest node from the queue
+			const T* u = Q.top().first;
+
+			// and check whether we reached the destination
+			if (u == destination) {break;}
+
+			// remove from the Queue
+			Q.pop();
+
+			// process all neighbors for the current element
+			for( const T& v : acc.getNeighbors(*u)) {
+
+				// weight (distance) between the current node and its neighbor
+				//const float w = ((Point3)v - (Point3)*u).length();
+				const float w = acc.getWeightBetween(v, *u);
+
+				// found a better route?
+				if (distance[&v] > distance[u] + w) {
+					distance[&v] = distance[u] + w;
+					parent[&v] = u;
+					Q.push(std::make_pair(&v, distance[&v] + acc.getHeuristic(v, *source)));
+				}
+
+			}
+		}
+
+
+		// construct the path
+		std::vector<const T*> path;
+		const T* p = destination;
+		path.push_back(destination);
+
+		// until we reached the source-node
+		while (p!=source) {
+			if (p) {
+				p = parent[p];
+				path.push_back(p);
+			} else {
+				return std::vector<const T*>(); //if no path could be found, just return an empty vector.
+			}
+		}
+
+		// done
+		return path;
+
+	}
+
+
+//	template <typename Access> static std::vector<const T*> getShortestPathAStar(const T* src, const T* dst, Access acc){
+
+//		std::vector<const T*> shortestPath;
+
+//		//here we could do some preprocessing. e.g. area of interest of nodes
+
+
+//		// call aStar
+//		shortestPath = aStar(src, dst, acc);
+
+//		return shortestPath;
+//	}
+
+	class Comparator2 {
+	public:
+		int operator() ( const std::pair<const T*,float>& p1, const std::pair<const T*,float>& p2){
+			return p1.second > p2.second;
+		}
+	};
+
+};
+
+#endif // ASTAR_H