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  • Finding the shortest path through a digraph that visits all nodes

    - by Boluc Papuccuoglu
    I am trying to find the shortest possible path that visits every node through a graph (a node may be visited more than once, the solution may pick any node as the starting node.). The graph is directed, meaning that being able to travel from node A to node B does not mean one can travel from node B to node A. All distances between nodes are equal. I was able to code a brute force search that found a path of only 27 nodes when I had 27 nodes and each node had a connection to 2 or 1 other node. However, the actual problem that I am trying to solve consists of 256 nodes, with each node connecting to either 4 or 3 other nodes. The brute force algorithm that solved the 27 node graph can produce a 415 node solution (not optimal) within a few seconds, but using the processing power I have at my disposal takes about 6 hours to arrive at a 402 node solution. What approach should I use to arrive at a solution that I can be certain is the optimal one? For example, use an optimizer algorithm to shorten a non-optimal solution? Or somehow adopt a brute force search that discards paths that are not optimal? EDIT: (Copying a comment to an answer here to better clarify the question) To clarify, I am not saying that there is a Hamiltonian path and I need to find it, I am trying to find the shortest path in the 256 node graph that visits each node AT LEAST once. With the 27 node run, I was able to find a Hamiltonian path, which assured me that it was an optimal solution. I want to find a solution for the 256 node graph which is the shortest.

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  • Creating movement path displays in a top-down 2d RTS

    - by nihohit
    My game is a top-down 2d RTS coded in C# using SFML's libraries. I want that during unit selection, a unit will display it's movement path on the map. Currently, after the path is computed as a list of directions ({left, up,down, down, down, left}, as an example), it's sent to the graphical component to create it's UI equivalent, and here I'm having some problems. current, these I've checked three ways to do it: compute the size of the image (in the example above it'll be a 3*2 rectangle) and create an invisible rectangle, and then go over the directions list and mark each spot with a visible point, so as to get a continous line. This system is slightly problematic because of the amount of large images that I need to save, but mostly because I have a lot of fine detail onscreen, and a continous line obstructs the view. again, compute the size of the image, but now create several (let's say 4) invisible images of that size, and then instead of a single continous line I'll switch between the four images, in each will appear only a fourth of the spots, in a way which creates a path animation. This is nicer on the eye, but here the memory demands, and the amount of time needed to compute each such image-loop is significant. Just create a list of single markers, each on a different spot on the path. This is very quick & easy on memory, but too sparse. Is there a simple or resource-light system to create path-animations?

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  • What is the best way to return two values from a method?

    - by Edward Tanguay
    When I have to write methods which return two values, I usually go about it as in the following code which returns a List<string>. Or if I have to return e.g. a id and string, then I return a List<object> and then pick them out with index number and recast the values. This recasting and referencing by index seems inelegant so I want to develop a new habit for methods that return two values. What is the best pattern for this? using System; using System.Collections.Generic; using System.Linq; namespace MultipleReturns { class Program { static void Main(string[] args) { string extension = "txt"; { List<string> entries = GetIdCodeAndFileName("first.txt", extension); Console.WriteLine("{0}, {1}", entries[0], entries[1]); } { List<string> entries = GetIdCodeAndFileName("first", extension); Console.WriteLine("{0}, {1}", entries[0], entries[1]); } Console.ReadLine(); } /// <summary> /// gets "first.txt", "txt" and returns "first", "first.txt" /// gets "first", "txt" and returns "first", "first.txt" /// it is assumed that extensions will always match /// </summary> /// <param name="line"></param> public static List<string> GetIdCodeAndFileName(string line, string extension) { if (line.Contains(".")) { List<string> parts = line.BreakIntoParts("."); List<string> returnItems = new List<string>(); returnItems.Add(parts[0]); returnItems.Add(line); return returnItems; } else { List<string> returnItems = new List<string>(); returnItems.Add(line); returnItems.Add(line + "." + extension); return returnItems; } } } public static class StringHelpers { public static List<string> BreakIntoParts(this string line, string separator) { if (String.IsNullOrEmpty(line)) return null; else { return line.Split(new string[] { separator }, StringSplitOptions.None).Select(p => p.Trim()).ToList(); } } } }

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  • Multiple returns: Which one sets the final return value?

    - by DR
    Given this code: String test() { try { return "1"; } finally { return "2"; } } Do the language specifications define the return value of a call to test()? In other words: Is it always the same in every JVM? In the Sun JVM the return value is 2, but I want to be sure, that this is not VM-dependant.

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  • Group arrival steering

    - by ltjax
    I've got group movement implemented pretty much like this: http://www.red3d.com/cwr/steer/CrowdPath.html Basically, that's combining path following and separation. It works nicely as long as units are in transit, but arrival does not work very well at all. Right now, units just cease to use the path following component once the "exit" the path, i.e. when their closest point on the path is on or past the end. This leads to those units bumping into each other and also overshooting the point the player clicked. Ideally, I'd have the units arrive scattered around the finish point (and reasonable close to each other), not all clumped up past the finish line. I'd imagine that some kind of arrival steering might work here, but based on other units and a "fuzzy" classification of the end of the path. Is there any proven way to do this?

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  • When does a const return type interfere with template instantiation?

    - by Rimo
    From Herb Sutter's GotW #6 Return-by-value should normally be const for non-builtin return types. ... Note: Lakos (pg. 618) argues against returning const value, and notes that it is redundant for builtins anyway (for example, returning "const int"), which he notes may interfere with template instantiation. While Sutter seems to disagree on whether to return a const value or non-const value when returning an object of a non-built type by value with Lakos, he generally agrees that returning a const value of a built-in type (e.g const int) is not a good idea. While I understand why that is useless because the return value cannot be modified as it is an rvalue, I cannot find an example of how that might interfere with template instantiation. Please give me an example of how having a const qualifier for a return type might interfere with template instantiation.

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  • Is it advisable to have an interface as the return type?

    - by wb
    I have a set of classes with the same functions but with different logic. However, each class function can return a number of objects. It is safe to set the return type as the interface? Each class (all using the same interface) is doing this with different business logic. protected IMessage validateReturnType; <-- This is in an abstract class public bool IsValid() <-- This is in an abstract class { return (validateReturnType.GetType() == typeof(Success)); } public IMessage Validate() { if (name.Length < 5) { validateReturnType = new Error("Name must be 5 characters or greater."); } else { validateReturnType = new Success("Name is valid."); } return validateReturnType; } Are there any pitfalls with unit testing the return type of an function? Also, is it considered bad design to have functions needing to be run in order for them to succeed? In this example, Validate() would have to be run before IsValid() or else IsValid() would always return false. Thank you.

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  • When should one use "out" parameters?

    - by qegal
    In Objective-C, there are several methods like initWithContentsOfFile:encoding:error: where one passes in a reference to an NSError object for the error: parameter. In this example, the value of the NSError object passed in can change based on what goes on at runtime when the method is being called and whether the body of the method was executed in a certain way successfully. In a way I think of this NSError object as sort of like a second return value from the method, and only differs from an object anObject in the statement return anObject; in that when this statement is called, execution leaves the method. So my question is, not only in the context of error handling in Objective-C, but in general, when should one use an "out" parameter in place of returning said value in a return statement?

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  • How to know the full path of a file using SSH?

    - by Roy
    Hi I am beginner for SSH stuff but i want to dump a big sql file and for that i need to be able to navigate to the appropriate path in my hosting account. I managed to login to SSH and i typed pwdbut it gave me a shared hosting pathway like /home/content/r/o/s/roshanjonah How Can i go to the path where i upload my files to...i use FTP but in FTP path it just shows / so i cannot go any further back than that...so using SSH how can i come to this path in ftp... Thanks Roshan

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  • SVG animation along path with Raphael

    - by Toby Hede
    I have a rather interesting issue with SVG animation. I am animating along a circular path using Raphael obj = canvas.circle(x, y, size); path = canvas.circlePath(x, y, radius); path = canvas.path(path); //generate path from path value string obj.animateAlong(path, rate, false); The circlePath method is one I have created myself to generate the circle path in SVG path notation: Raphael.fn.circlePath = function(x , y, r) { var s = "M" + x + "," + (y-r) + "A"+r+","+r+",0,1,1,"+(x-0.1)+","+(y-r)+" z"; return s; } So far, so good. This all works. I have my object (obj) animating along the circular path. BUT: The animation only works if I create the object at the same X, Y coords as the path itself. If I start the animation from any other coordinates (say, half-way along the path) the object animates in a circle of the correct radius, however it starts the animation from the object X,Y coordinates, rather than along the path as it is displayed visually. Ideally I would like to be able to stop/start the animation - the same problem occurs on restart. When I stop then restart the animation, it animates in a circle starting from the stopped X,Y.

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  • How to modify PATH variable for X11 during log-in?

    - by user1028435
    I originally posted this over at StackOverflow, but someone said it might fit better here. Original question is here: http://stackoverflow.com/questions/10096327/overwriting-print-screen-actions-in-linux-without-administrative-rights. Decided to revise my question, based on what I learned there: Essentially, my problem is that I am working on some lab computers (read: no administrative rights) that, if I log in, I need to change the PATH variable as X11 starts. The reason is that I need to change the PATH variable at this time, as opposed to later, is that the Print Screen command seems to "bind" during login (forgive my bad explanation of this). You can see in the work-around I listed in the previous question, that I can make it work by starting a new X, but I was wondering if it is possible to change upon login. If this seems a poor explanation, you can check out the original link for my context and reasoning behind what I'm doing. Any ideas? Details about Distribution: cat /etc/redhat-release tells me: Red Hat Enterprise Linux Client release 5.8 (Tikanga)

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  • Supervisord: how to append to $PATH

    - by Prody
    I can't seem to figure out how to append to the default path in a supervisord program config. I can reset the path: environment=PATH="/home/site/environments/master/bin" But when I try: environment=PATH="/home/site/environments/master/bin:$PATH" I see that supervisord doesn't evaluate $PATH. Google wasn't a big help on this for some reason, I cannot believe I'm the first person to need this. Supervisord must have support for this, any idea what it is?

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  • where.exe does not find OpenSSL libs when %ProgramFiles% variable is used in the PATH environment variable

    - by Piotr Dobrogost
    I installed both 32bit and 64bit version of OpenSSL libs on Vista x64. The 32bit version was installed in c:\Program Files (x86)\OpenSSL and the 64bit version was installed in c:\Program Files\OpenSSL. Then I added the entry %ProgramFiles%\OpenSSL to the PATH environment variable. %ProgramFiles%\OpenSSL is expanded to c:\Program Files (x86)\OpenSSL for 32bit programs and it's expanded to c:\Program Files\OpenSSL for 64bit programs. The idea is to have 32bit programs use 32bit version of OpenSSL libs and 64bit programs use 64bit version. I wanted to check if this works by running 32bit cmd.exe and issuing where ssleay32.dll and then by running 64bit cmd.exe and issuing the same. However in both cases I get the error INFO: Could not find files for the given pattern(s). What's wrong? This is a follow up to Different PATH environment variable for 32bit and 64bit Windows - is it possible?

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  • Count the Number of Characters in a Full FIle Path?

    - by Richie086
    I need to be able to count the number of characters in a full path to a file in windows. How I am currently accomplishing this task is as follows: Open a command prompt cd to the directory in question (for example c:\CruiseControl\ProjectArtifacts\ProjectName) type the following command dir /s /b output.csv Open the resulting output.csv file in excel. use the =LEN() function in excel to count the number of characters per row as listed in the output.csv file. Does anyone know of an explorer shell extension, or some 3rd party tool that could preform this function without me having to manipulate the output from dir in excel? Is there some easier way to go about doing this? The root of the issue I am having is the ~260 character file path limit in Windows. I am trying to analyze which paths are approx ~260 characters so I can shorten them to avoid getting this error.

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  • Mac OS X: Change $PATH from within python script

    - by Eye of Hell
    I have a bunch of python scripts. One of them installs software (subversion) that requires it's path to be added to $PATH. After it is installed, I want the next script to use the software. If I run export PATH=/opt/subversion/bin:$PATH in bash between the first and second script, all is ok. But if I add os.system( 'export PATH=/opt/subversion/bin:$PATH' ) as the last command of the first script (that installs subversion), $PATH remains unaltered after it exits. Is it any way to change $PATH from within python script so it will remain changed after the script finishes (inside single bash session, of course, I know about /etc/profile).

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  • Does -localizedDescription of NSError return the actual localized string, or does it return a key fo

    - by mystify
    Must I do something like this? NSString *errorDescription = [error localizedDescription]; NSString *errorInfoStr = NSLocalizedString(errorDescription, nil); Or do I use NSLocalizedString already when populating the userInfo dictionary with the NSLocalizedDescriptionKey key and value? So the value for that is not actually a key for NSLocalizedString, but it is the actual localized string ready to show up on screen?

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  • .Net in HTML tp return true if reader object not null, otherwise return false

    - by Phill Healey
    I'm using a DataList to show some data from the database and populating the fields on the html side. I now have a requirement to change the visibility of a panel based on whether or not a db field has data or not. I need to be able to show the panel if the relevant data field has content, and hide it if it doesn't. Eg: <asp:Panel ID="pnlNew" runat="server" Style="margin:0; padding:0; width:42px; height:18px; bottom:5px; right:10px; float:right; position:relative; background:url(../_imgVideoBadge.png) no-repeat;" Visible='<%# Eval("cheese") != null %>' ToolTip="available"></asp:Panel> Obviously this doesn't work in terms of the visible property. But hopefully it gives an idea of what I'm trying to achieve. Any help would be greatly appreciated. I've seen examples previously of doing something along the lines of: a ?? b:c How could this be applied to the above requirement?? Thanks in advance.

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  • A star algorithm implementation problems

    - by bryan226
    I’m having some trouble implementing the A* algorithm in a 2D tile based game. The problem is basically that the algorithm gets stuck when something gets in its direct way (e.g. walls) Note that it only allows Horizontal and Vertical movement. Here's a picture as it works fine across the map without something in its direct way: (Green tile = destination, Blue = In closed list, Green = in open list) This is what happens if I try to walk 'around' a wall: I calculate costs with the F = G + H formula: G = 1 Cost per Step H = 10 Cost per Step //Count how many tiles are between current-tile & destination-tile The functions: short c_astar::GuessH(short Startx,short Starty,short Destinationx,short Destinationy) { hgeVector Start, Destination; Start.x = Startx; Start.y = Starty; Destination.x = Destinationx; Destination.y = Destinationy; short a = 0; short b = 0; if(Start.x > Destination.x) a = Start.x - Destination.x; else a = Destination.x - Start.x; if(Start.y > Destination.y) b = Start.y - Destination.y; else b = Destination.y - Start.y; return (a+b)*10; } short c_astar::GuessG(short Startx,short Starty,short Currentx,short Currenty) { hgeVector Start, Destination; Start.x = Startx; Start.y = Starty; Destination.x = Currentx; Destination.y = Currenty; short a = 0; short b = 0; if(Start.x > Destination.x) a = Start.x - Destination.x; else a = Destination.x - Start.x; if(Start.y > Destination.y) b = Start.y - Destination.y; else b = Destination.y - Start.y; return (a+b); } At the end of the loop I check which tile is the cheapest to go according to its F value: Then some quick checks are done for each tile (UP,DOWN,LEFT,RIGHT): //...CX are holding the F value of the TILE specified // Info: C0 = Center (Current) // C1 = UP // C2 = DOWN // C3 = LEFT // C4 = RIGHT //Quick checks if(((C1 < C2) && (C1 < C3) && (C1 < C4))) { Current.y -= 1; bSimilar = false; if(DEBUG) hge->System_Log("C1 < ALL"); } //.. same for C2,C3 & C4 If there are multiple tiles with the same F value: It’s actually a switch for DOWNLEFT,UPRIGHT.. etc. Here’s one of it: case UPRIGHT: { //UP Temporary = Current; Temporary.y -= 1; bTileStatus[0] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[0]) { //Proceed normal we are OK & walkable Tilex.Tile = map.at(Temporary.y).at(Temporary.x); //Search in lists if(SearchInClosedList(Tilex.Tile.ID,C0)) bFoundInClosedList[0] = true; if(SearchInOpenList(Tilex.Tile.ID,C0)) bFoundInOpenList[0] = true; //RIGHT Temporary = Current; Temporary.x += 1; bTileStatus[1] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[1]) { //Proceed normal we are OK & walkable Tilex.Tile = map.at(Temporary.y).at(Temporary.x); //Search in lists if(SearchInClosedList(Tilex.Tile.ID,C0)) bFoundInClosedList[1] = true; if(SearchInOpenList(Tilex.Tile.ID,C0)) bFoundInOpenList[1] = true; //************************************************* // Purpose: ClosedList behavior //************************************************* if(bFoundInClosedList[0] && !bFoundInClosedList[1]) { //UP found in ClosedList. Go RIGHT return RIGHT; } if(!bFoundInClosedList[0] && bFoundInClosedList[1]) { //RIGHT found in ClosedList. Go UP return UP; } if(bFoundInClosedList[0] && bFoundInClosedList[1]) { //Both found in ClosedList. Random value switch(hge->Random_Int(8,9)) { case 8: return UP; break; case 9: return RIGHT; break; } } //************************************************* // Purpose: OpenList behavior //************************************************* if(bFoundInOpenList[0] && !bFoundInOpenList[1]) { //UP found in OpenList. Go RIGHT return RIGHT; } if(!bFoundInOpenList[0] && bFoundInOpenList[1]) { //RIGHT found in OpenList. Go UP return UP; } if(bFoundInOpenList[0] && bFoundInOpenList[1]) { //Both found in OpenList. Random value switch(hge->Random_Int(8,9)) { case 8: return UP; break; case 9: return RIGHT; break; } } } else if(!bTileStatus[1]) { //RIGHT is not walkable OR out of range //Choose UP return UP; } } else if(!bTileStatus[0]) { //UP is not walkable OR out of range //Fast check RIGHT Temporary = Current; Temporary.x += 1; bTileStatus[1] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[1]) { return RIGHT; } else return FAILED; //Failed, no valid path found! } } break; A log for the second picture: (Cut down to ten passes, because it’s just repeating itself) ----------------------------------------------------- PASS: 1 | C1: 211 | C2: 191 | C3: 211 | C4: 191 DOWN + RIGHT SIMILAR Going DOWN ----------------------------------------------------- PASS: 2 | C1: 200 | C2: 182 | C3: 202 | C4: 182 DOWN + RIGHT SIMILAR Going DOWN ----------------------------------------------------- PASS: 3 | C1: 191 | C2: 193 | C3: 193 | C4: 173 C4 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 4 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going UP Tile(12.000000,5.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 5 | C1: 191 | C2: 173 | C3: 191 | C4: 999 C2 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 6 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going UP Tile(12.000000,5.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 7 | C1: 191 | C2: 173 | C3: 191 | C4: 999 C2 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 8 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going LEFT ----------------------------------------------------- PASS: 9 | C1: 191 | C2: 193 | C3: 193 | C4: 173 C4 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 10 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going LEFT ----------------------------------------------------- Its always going after the cheapest F value, which seems to be wrong. If someone could point me to the right direction I'd be thankful. Regards, bryan226

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  • A* algorithm very slow

    - by Amaranth
    I have an programming a RTS game (I use XNA with C#). The pathfinding is working fine, except that when it has a lot of node to search in, there is a lag period of one or two seconds, it happens mainly when there is no path to the target destination, since it that situation there is more nodes to explore. I have the same problem when the path is shorter but selected more than 3 units (can't take the same path since the selected units can be in different part of the map). private List<NodeInfo> FindPath(Unit u, NodeInfo start, NodeInfo end) { Map map = GameInfo.GetInstance().GameMap; _nearestToTarget = start; start.MoveCost = 0; Vector2 endPosition = map.getTileByPos(end.X, end.Y).Position; //getTileByPos simply gets the tile in a 2D array with the X and Y indexes start.EstimatedRemainingCost = (int)(endPosition - map.getTileByPos(start.X, start.Y).Position).Length(); start.Parent = null; List<NodeInfo> openedNodes = new List<NodeInfo>(); ; List<NodeInfo> closedNodes = new List<NodeInfo>(); Point[] movements = GetMovements(u.UnitType); openedNodes.Add(start); while (!closedNodes.Contains(end) && openedNodes.Count > 0) { //Loop in nodes to find lowest cost NodeInfo currentNode = FindLowestCostOpenedNode(openedNodes); openedNodes.Remove(currentNode); closedNodes.Add(currentNode); Vector2 previousMouvement; if (currentNode.Parent == null) { previousMouvement = ConvertRotationToDirectionVector(u.Rotation); } else { previousMouvement = map.getTileByPos(currentNode.X, currentNode.Y).Position - map.getTileByPos(currentNode.Parent.X, currentNode.Parent.Y).Position; previousMouvement.Normalize(); } //For each neighbor foreach (Point movement in movements) { Point exploredGridPos = new Point(currentNode.X + movement.X, currentNode.Y + movement.Y); //Checks if valid move and checks if not if closed nodes list if (ValidNavigableNode(u.UnitType, new Point(currentNode.X, currentNode.Y), exploredGridPos) && !closedNodes.Contains(_gridMap[exploredGridPos.Y, exploredGridPos.X])) { NodeInfo exploredNode = _gridMap[exploredGridPos.Y, exploredGridPos.X]; Tile.TileType exploredTerrain = map.getTileByPos(exploredGridPos.X, exploredGridPos.Y).TerrainType; if(openedNodes.Contains(exploredNode)) { int newCost = currentNode.MoveCost + GetMoveCost(previousMouvement, movement, exploredTerrain); if (newCost < exploredNode.MoveCost) { exploredNode.Parent = currentNode; exploredNode.MoveCost = newCost; //Find nearest tile to the target (in case doesn't find path to target) //Only compares the node to the current nearest FindNearest(exploredNode); } } else { exploredNode.Parent = currentNode; exploredNode.MoveCost = currentNode.MoveCost + GetMoveCost(previousMouvement, movement, exploredTerrain); Vector2 exploredNodeWorldPos = map.getTileByPos(exploredGridPos.X, exploredGridPos.Y).Position; exploredNode.EstimatedRemainingCost = (int)(endPosition - exploredNodeWorldPos).Length(); //Find nearest tile to the target (in case doesn't find path to target) //Only compares the node to the current nearest FindNearest(exploredNode); openedNodes.Add(exploredNode); } } } } return closedNodes; } After that, I simply check if the end node is contained in the returned nodes. If so, I add the end node and each parent until I reach the start. If not, I add the nearestToTarget and each parent until I reach the start. I added a condition before calling FindPath so that only one unit can call a find path each frame (60 frame per second), but it makes no difference. I thought maybe I could solve this by allowing the find path to run in background while the game continues to run correctly, even if it takes a few frame (it is currently sequential sonce it is called in the update() of the unit if there's a target location but no path), but I don't really know how... I also though about sorting my opened nodes list by cost so I don't have to loop them, but I don't know if that would have an effect on the performance... Would there be other solutions? P.S. In the code, when I get the Move Cost, I check if the unit has to turn to perform the move, and the terrain type, nothing hard to do.

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  • Objective-C Moving UIView along a curved path

    - by PruitIgoe
    I'm not sure if I am approaching this the correct way. In my app, when a user touches the screen I capture the point and create an arc from a fixed point to that touch point. I then want to move a UIView along that arc. Here's my code: ViewController.m //method to "shoot" object - KIP_Projectile creates the arc, KIP_Character creates the object I want to move along the arc ... //get arc for trajectory KIP_Projectile* vThisProjectile = [[KIP_Projectile alloc] initWithFrame:CGRectMake(51.0, fatElvisCenterPoint-30.0, touchPoint.x, 60.0)]; vThisProjectile.backgroundColor = [UIColor clearColor]; [self.view addSubview:vThisProjectile]; ... KIP_Character* thisChar = [[KIP_Character alloc] initWithFrame:CGRectMake(51, objCenterPoint-5, imgThisChar.size.width, imgThisChar.size.height)]; thisChar.backgroundColor = [UIColor clearColor]; thisChar.charID = charID; thisChar.charType = 2; thisChar.strCharType = @"Projectile"; thisChar.imgMyImage = imgThisChar; thisChar.myArc = vThisProjectile; [thisChar buildImage]; [thisChar traceArc]; in KIP_Projectile I build the arc using this code: - (CGMutablePathRef) createArcPathFromBottomOfRect : (CGRect) rect : (CGFloat) arcHeight { CGRect arcRect = CGRectMake(rect.origin.x, rect.origin.y + rect.size.height - arcHeight, rect.size.width, arcHeight); CGFloat arcRadius = (arcRect.size.height/2) + (pow(arcRect.size.width, 2) / (8*arcRect.size.height)); CGPoint arcCenter = CGPointMake(arcRect.origin.x + arcRect.size.width/2, arcRect.origin.y + arcRadius); CGFloat angle = acos(arcRect.size.width / (2*arcRadius)); CGFloat startAngle = radians(180) + angle; CGFloat endAngle = radians(360) - angle; CGMutablePathRef path = CGPathCreateMutable(); CGPathAddArc(path, NULL, arcCenter.x, arcCenter.y, arcRadius, startAngle, endAngle, 0); return path; } - (void)drawRect:(CGRect)rect { CGContextRef currentContext = UIGraphicsGetCurrentContext(); _myArcPath = [self createArcPathFromBottomOfRect:self.bounds:30.0]; CGContextSetLineWidth(currentContext, 1); CGFloat red[4] = {1.0f, 0.0f, 0.0f, 1.0f}; CGContextSetStrokeColor(currentContext, red); CGContextAddPath(currentContext, _myArcPath); CGContextStrokePath(currentContext); } Works fine. The arc is displayed with a red stroke on the screen. In KIP_Character, which has been passed it's relevant arc, I am using this code but getting no results. - (void) traceArc { CGMutablePathRef myArc = _myArc.myArcPath; // Set up path movement CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"]; pathAnimation.calculationMode = kCAAnimationPaced; pathAnimation.fillMode = kCAFillModeForwards; pathAnimation.removedOnCompletion = NO; pathAnimation.path = myArc; CGPathRelease(myArc); [self.layer addAnimation:pathAnimation forKey:@"savingAnimation"]; } Any help here would be appreciated.

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  • returning a heap block by reference in c++

    - by basicR
    I was trying to brush up my c++ skills. I got 2 functions: concat_HeapVal() returns the output heap variable by value concat_HeapRef() returns the output heap variable by reference When main() runs it will be on stack,s1 and s2 will be on stack, I pass the value by ref only and in each of the below functions, I create a variable on heap and concat them. When concat_HeapVal() is called it returns me the correct output. When concat_HeapRef() is called it returns me some memory address (wrong output). Why? I use new operator in both the functions. Hence it allocates on heap. So when I return by reference, heap will still be VALID even when my main() stack memory goes out of scope. So it's left to OS to cleanup the memory. Right? string& concat_HeapRef(const string& s1, const string& s2) { string *temp = new string(); temp->append(s1); temp->append(s2); return *temp; } string* concat_HeapVal(const string& s1, const string& s2) { string *temp = new string(); temp->append(s1); temp->append(s2); return temp; } int main() { string s1,s2; string heapOPRef; string *heapOPVal; cout<<"String Conact Experimentations\n"; cout<<"Enter s-1 : "; cin>>s1; cout<<"Enter s-2 : "; cin>>s2; heapOPRef = concat_HeapRef(s1,s2); heapOPVal = concat_HeapVal(s1,s2); cout<<heapOPRef<<" "<<heapOPVal<<" "<<endl; return -9; }

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  • How to create a JAX-RS service where the sub-resource @Path doesn't have a leading slash

    - by Matt
    I've created a JAX-RS service (MyService) that has a number of sub resources, each of which is a subclass of MySubResource. The sub resource class being chosen is picked based on the parameters given in the MyService path, for example: @Path("/") @Provides({"text/html", "text/xml"}) public class MyResource { @Path("people/{id}") public MySubResource getPeople(@PathParam("id") String id) { return new MyPeopleSubResource(id); } @Path("places/{id}") public MySubResource getPlaces(@PathParam("id") String id) { return new MyPlacesSubResource(id); } } where MyPlacesSubResource and MyPeopleSubResource are both sub-classes of MySubResource. MySubResource is defined as: public abstract class MySubResource { protected abstract Results getResults(); @GET public Results get() { return getResults(); } @GET @Path("xml") public Response getXml() { return Response.ok(getResults(), MediaType.TEXT_XML_TYPE).build(); } @GET @Path("html") public Response getHtml() { return Response.ok(getResults(), MediaType.TEXT_HTML_TYPE).build(); } } Results is processed by corresponding MessageBodyWriters depending on the mimetype of the response. While this works it results in paths like /people/Bob/html or /people/Bob/xml where what I really want is /people/Bob.html or /people/Bob.xml Does anybody know how to accomplish what I want to do?

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