Some Thoughts on the pathfinding algorithm (1): A * algorithm introduces some Mens Nike Free 3.0 V2 Shoes Black Gold thoughts about pathfinding Ladies Nike Blazers High Tops Leopard Print YellowB algorithm (2): Heuristics Function Overview stripped the code, A * algorithm is very simple. The algorithm maintains two sets: OPEN and CLOSED set set. OPEN set contains nodes to be detected. The initial state, OPEN set contains only one element: the start position. CLOSED set contains detection node. The initial state, CLOSED set is empty. From the graphical point of view, OPEN set is visited border areas, CLOSED set is visited interior areas. Each node also contains a pointer to the parent node to determine the trace relationship. There is a main loop algorithm, repeatedly taking the optimal centralized LeBron James Shoes node n (ie, the minimum value of the node f) from OPEN to detect. If n is the target node, then the algorithm terminates; otherwise, will be removed from the OPEN set of n nodes, and add to the CLOSED concentrated, and then view all the neighbors n n '. If the neighbor set in CLOSED, it has been tested, it does not need re-testing (*); if the neighbor in the Nike Basketball OPEN set, it will be detected, there is no need at this time is detected (*); otherwise, the neighbor added OPEN set, set the parent node n, to n 'path cost g (n') = g (n) + Nike Air Jordan 6 Women movementcost (n, n '). There is a more detailed description, which includes interaction diagram. (*) Where I skipped over a small detail. You should check the value of the node g, and if the new path cost is lower than the calculated value of g, then to reopen the node (ie reinsert OPEN set). OPEN = priority queue containing STARTCLOSED = empty setwhile lowest rank in OPEN is not the GOAL: current = remove lowest rank item from OPEN add current to CLOSED for neighbors of current: cost = g (current) + movementcost (current, Mens Nike Free 3.0 V2 Shoes Grey Orange neighbor) if neighbor in OPEN and cost less than g (neighbor): remove neighbor from OPEN, because new path is better if neighbor in CLOSED and cost less than g (neighbor): ** remove 2015 Nike Free 5.0 neighbor Nike Blazers from CLOSED if neighbor not in OPEN and neighbor not in CLOSED : set g (neighbor) to cost add neighbor to OPEN set priority queue rank to g (neighbor) + h (neighbor) set neighbor's parent to currentreconstruct reverse path from goal to startby following parent pointers (**) If the heuristic function is always is credible, this situation should not arise. However, in the game, often get credible heuristic. Please click here for Python and C ++ implementation. Connectivity if the game did not start and end in communication in the chart, this time A * algorithm takes a long time, because from the start, it needs to identify the all nodes, until it We realize that there is no viable path. Mens Nike Free 3.0 V2 Shoes Black Gold Therefore, we can first determine the connected components, start and end only when a communication on the same branch, just use the A * algorithm. Performance A * main loop algorithm read from a priority queue node, the node analysis, and then to the priority queue insert a new node. Algorithm also tracks which nodes are visited. To improve the performance of the Air Jordan Outlet algorithm, consider the following aspects: to reduce the size of the graph it? This can reduce the number of nodes to be addressed, including the node on the final path and not on the final path. Can be considered instead of the grid (grids) navigation mesh (navigation meshes), you can consider the hierarchical map representation (hierarchical map representations). You can improve the accuracy of the heuristic function of it? This can reduce the number of nodes on the path is not final. Heuristic value, the more close to the real path length (not the distance), A * algorithm requires fewer nodes examined. Heuristic may be Mens Nike Free 3.0 V2 Shoes Black Blue considered for the grid to be considered for general graphics (including grid) ALT (A *, landmark Landmarks, triangle inequality Triangle Inequality). Let the priority queue faster? Consider a priority queue to build other data structures. You can also search the reference edge approach to batch nodes. You can also consider approximation sorting algorithms. Let heuristic faster? Each node must open call heuristic, consider caching function calculations, inline call can also be used. About grid map, I have some suggestions. Source code and demo presentations (demos) These demos run in the browser: I wrote an article with an interactive presentation, it is an introduction to the A *. I square mesh, hexagonal mesh, triangular mesh have compiled a flash demo. These demos written using Actionscript 3, click here to view the source code (which, Pathfinder.as be regarded as the main algorithm, Graph.as is abstract interface graphics). There are demos on the road map (not mesh) to run for the following algorithm: A *, breadth-first search, Dijkstra algorithm, greedy best-first search. Use Javascript to write A * demo can change the way the weights, the source code in github, using the MIT open source license. Demo can interrupt calculations, so you can run several iterations of each frame. James Macgill write java applet. You can select the A * algorithm or Dijkstra interactive demo. This demo is very good, and contains the source code of the demo javascript well, source code is visible. Another Nike Zoom Hyperdunk javascript demo This page Nike Air Max describes hops search, LeBron James Shoes which has an online demo. The A * using Actionscript tutorials, near the end where there is a demo. This demo is written in javascript code readable, but I do not know what its source code license is. The 541100-300 Black Green White Style Nike Lebron X 10 Outlet A * demo and hops search demo written with Unity. Code If you use C ++, be sure to check Mikko Mononen of Recast. If you plan to implement your own graph search, here are my Python and C ++ implementation guide. I collected some source code links, but I have not carefully look at these projects, so there is no more specific recommendations: C ++: