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  • Vectors with Circles Physics -java

    - by Joe Hearty
    This is a problem I've been having, When making a set number of filled circles at random locations on a JPanel and applying a gravity (a negative change in the y), each of the circles collide. I want them to have collision detection and push in the opposite direction using vectors but i don't know how to apply that to my scenario could someone help? public void drawballs(Graphics g){ g.setColor (Color.white); //displays circles for(int i = 0; i<xlocationofcircles.length-1; i++){ g.fillOval( (int) xlocationofcircles[i], (int) (ylocationofcircles[i]) ,16 ,16 ); ylocationofcircles[i]+=.2; //gravity if(ylocationofcircles[i] > 550) //stops gravity at bottom of screen ylocationofcircles[i]-=.2; //Check distance between circles(i think..) float distance =(xlocationofcircles[i+1]-xlocationofcircles[i]) + (ylocationofcircles[i+1]-xlocationofcircles[i]) ; if( Math.sqrt(distance) <16)

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  • Algorithm to Find the Aggregate Mass of "Granola Bar"-Like Structures?

    - by Stuart Robbins
    I'm a planetary science researcher and one project I'm working on is N-body simulations of Saturn's rings. The goal of this particular study is to watch as particles clump together under their own self-gravity and measure the aggregate mass of the clumps versus the mean velocity of all particles in the cell. We're trying to figure out if this can explain some observations made by the Cassini spacecraft during the Saturnian summer solstice when large structures were seen casting shadows on the nearly edge-on rings. Below is a screenshot of what any given timestep looks like. (Each particle is 2 m in diameter and the simulation cell itself is around 700 m across.) The code I'm using already spits out the mean velocity at every timestep. What I need to do is figure out a way to determine the mass of particles in the clumps and NOT the stray particles between them. I know every particle's position, mass, size, etc., but I don't know easily that, say, particles 30,000-40,000 along with 102,000-105,000 make up one strand that to the human eye is obvious. So, the algorithm I need to write would need to be a code with as few user-entered parameters as possible (for replicability and objectivity) that would go through all the particle positions, figure out what particles belong to clumps, and then calculate the mass. It would be great if it could do it for "each" clump/strand as opposed to everything over the cell, but I don't think I actually need it to separate them out. The only thing I was thinking of was doing some sort of N2 distance calculation where I'd calculate the distance between every particle and if, say, the closest 100 particles were within a certain distance, then that particle would be considered part of a cluster. But that seems pretty sloppy and I was hoping that you CS folks and programmers might know of a more elegant solution? Edited with My Solution: What I did was to take a sort of nearest-neighbor / cluster approach and do the quick-n-dirty N2 implementation first. So, take every particle, calculate distance to all other particles, and the threshold for in a cluster or not was whether there were N particles within d distance (two parameters that have to be set a priori, unfortunately, but as was said by some responses/comments, I wasn't going to get away with not having some of those). I then sped it up by not sorting distances but simply doing an order N search and increment a counter for the particles within d, and that sped stuff up by a factor of 6. Then I added a "stupid programmer's tree" (because I know next to nothing about tree codes). I divide up the simulation cell into a set number of grids (best results when grid size ˜7 d) where the main grid lines up with the cell, one grid is offset by half in x and y, and the other two are offset by 1/4 in ±x and ±y. The code then divides particles into the grids, then each particle N only has to have distances calculated to the other particles in that cell. Theoretically, if this were a real tree, I should get order N*log(N) as opposed to N2 speeds. I got somewhere between the two, where for a 50,000-particle sub-set I got a 17x increase in speed, and for a 150,000-particle cell, I got a 38x increase in speed. 12 seconds for the first, 53 seconds for the second, 460 seconds for a 500,000-particle cell. Those are comparable speeds to how long the code takes to run the simulation 1 timestep forward, so that's reasonable at this point. Oh -- and it's fully threaded, so it'll take as many processors as I can throw at it.

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  • Determining explosion radius damage - Circle to Rectangle 2D

    - by Paul Renton
    One of the Cocos2D games I am working on has circular explosion effects. These explosion effects need to deal a percentage of their set maximum damage to all game characters (represented by rectangular bounding boxes as the objects in question are tanks) within the explosion radius. So this boils down to circle to rectangle collision and how far away the circle's radius is from the closest rectangle edge. I took a stab at figuring this out last night, but I believe there may be a better way. In particular, I don't know the best way to determine what percentage of damage to apply based on the distance calculated. Note : All tank objects have an anchor point of (0,0) so position is according to bottom left corner of bounding box. Explosion point is the center point of the circular explosion. TankObject * tank = (TankObject*) gameSprite; float distanceFromExplosionCenter; // IMPORTANT :: All GameCharacter have an assumed (0,0) anchor if (explosionPoint.x < tank.position.x) { // Explosion to WEST of tank if (explosionPoint.y <= tank.position.y) { //Explosion SOUTHWEST distanceFromExplosionCenter = ccpDistance(explosionPoint, tank.position); } else if (explosionPoint.y >= (tank.position.y + tank.contentSize.height)) { // Explosion NORTHWEST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x, tank.position.y + tank.contentSize.height)); } else { // Exp center's y is between bottom and top corner of rect distanceFromExplosionCenter = tank.position.x - explosionPoint.x; } // end if } else if (explosionPoint.x > (tank.position.x + tank.contentSize.width)) { // Explosion to EAST of tank if (explosionPoint.y <= tank.position.y) { //Explosion SOUTHEAST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x + tank.contentSize.width, tank.position.y)); } else if (explosionPoint.y >= (tank.position.y + tank.contentSize.height)) { // Explosion NORTHEAST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x + tank.contentSize.width, tank.position.y + tank.contentSize.height)); } else { // Exp center's y is between bottom and top corner of rect distanceFromExplosionCenter = explosionPoint.x - (tank.position.x + tank.contentSize.width); } // end if } else { // Tank is either north or south and is inbetween left and right corner of rect if (explosionPoint.y < tank.position.y) { // Explosion is South distanceFromExplosionCenter = tank.position.y - explosionPoint.y; } else { // Explosion is North distanceFromExplosionCenter = explosionPoint.y - (tank.position.y + tank.contentSize.height); } // end if } // end outer if if (distanceFromExplosionCenter < explosionRadius) { /* Collision :: Smaller distance larger the damage */ int damageToApply; if (self.directHit) { damageToApply = self.explosionMaxDamage + self.directHitBonusDamage; [tank takeDamageAndAdjustHealthBar:damageToApply]; CCLOG(@"Explsoion-> DIRECT HIT with total damage %d", damageToApply); } else { // TODO adjust this... turning out negative for some reason... damageToApply = (1 - (distanceFromExplosionCenter/explosionRadius) * explosionMaxDamage); [tank takeDamageAndAdjustHealthBar:damageToApply]; CCLOG(@"Explosion-> Non direct hit collision with tank"); CCLOG(@"Damage to apply is %d", damageToApply); } // end if } else { CCLOG(@"Explosion-> Explosion distance is larger than explosion radius"); } // end if } // end if Questions: 1) Can this circle to rect collision algorithm be done better? Do I have too many checks? 2) How to calculate the percentage based damage? My current method generates negative numbers occasionally and I don't understand why (Maybe I need more sleep!). But, in my if statement, I ask if distance < explosion radius. When control goes through, distance/radius must be < 1 right? So 1 - that intermediate calculation should not be negative. Appreciate any help/advice!

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  • Multithreading 2D gravity calculations

    - by Postman
    I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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  • C#: Struct Constructor: "fields must be fully assigned before control is returned to the caller."

    - by Rosarch
    Here is a struct I am trying to write: public struct AttackTraits { public AttackTraits(double probability, int damage, float distance) { Probability = probability; Distance = distance; Damage = damage; } private double probability; public double Probability { get { return probability; } set { if (value > 1 || value < 0) { throw new ArgumentOutOfRangeException("Probability values must be in the range [0, 1]"); } probability = value; } } public int Damage { get; set; } public float Distance { get; set; } } This results in the following compilation errors: The 'this' object cannot be used before all of its fields are assigned to Field 'AttackTraits.probability' must be fully assigned before control is returned to the caller Backing field for automatically implemented property 'AttackTraits.Damage' must be fully assigned before control is returned to the caller. Consider calling the default constructor from a constructor initializer. Backing field for automatically implemented property 'AttackTraits.Distance' must be fully assigned before control is returned to the caller. Consider calling the default constructor from a constructor initializer. What am I doing wrong?

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  • Show certain InfoWindow in Google Map API V3

    - by pash
    Hello. I wrote the following code to display markers. There are 2 buttons which show Next or Previous Infowindow for markers. But problem is that InfoWindows are not shown using google.maps.event.trigger Can someone help me with this problem. Thank you. Here is code: <html> <head> <meta name="viewport" content="initial-scale=1.0, user-scalable=no" /> <meta http-equiv="content-type" content="text/html; charset=UTF-8"/> <title>Google Maps JavaScript API v3 Example: Common Loader</title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> <script type="text/javascript"> var infowindow; var map; var bounds; var markers = []; var markerIndex=0; function initialize() { var myLatlng = new google.maps.LatLng(41.051407, 28.991134); var myOptions = { zoom: 5, center: myLatlng, mapTypeId: google.maps.MapTypeId.ROADMAP } map = new google.maps.Map(document.getElementById("map_canvas"), myOptions); markers = document.getElementsByTagName("marker"); for (var i = 0; i < markers.length; i++) { var latlng = new google.maps.LatLng(parseFloat(markers[i].getAttribute("lat")), parseFloat(markers[i].getAttribute("lng"))); var marker = createMarker(markers[i].getAttribute("name"), latlng, markers[i].getAttribute("phone"), markers[i].getAttribute("distance")); } rebound(map); } function createMarker(name, latlng, phone, distance) { var marker = new google.maps.Marker({position: latlng, map: map}); var myHtml = "<table style='width:100%;'><tr><td><b>" + name + "</b></td></tr><tr><td>" + phone + "</td></tr><tr><td align='right'>" + distance + "</td></tr></table>"; google.maps.event.addListener(marker, "click", function() { if (infowindow) infowindow.close(); infowindow = new google.maps.InfoWindow({content: myHtml}); infowindow.open(map, marker); }); return marker; } function rebound(mymap){ bounds = new google.maps.LatLngBounds(); for (var i = 0; i < markers.length; i++) { bounds.extend(new google.maps.LatLng(parseFloat(markers[i].getAttribute("lat")),parseFloat(markers[i].getAttribute("lng")))); } mymap.fitBounds(bounds); } function showNextInfo() { if(markerIndex<markers.length-1) markerIndex++; else markerIndex = 0 ; alert(markers[markerIndex].getAttribute('name')); google.maps.event.trigger(markers[markerIndex],"click"); } function showPrevInfo() { if(markerIndex>0) markerIndex--; else markerIndex = markers.length-1 ; google.maps.event.trigger(markers[markerIndex],'click'); } </script> </head> <body onload="initialize()"> <div id="map_canvas" style="width:400px; height:300px"></div> <markers> <marker name='Name1' lat='41.051407' lng='28.991134' phone='+902121234561' distance=''/> <marker name='Name2' lat='40.858746' lng='29.121666' phone='+902121234562' distance=''/> <marker name='Name3' lat='41.014604' lng='28.972256' phone='+902121234562' distance=''/> <marker name='Name4' lat='41.012386' lng='26.978350' phone='+902121234562' distance=''/> </markers> <input type="button" onclick="showPrevInfo()" value="prev">&nbsp;<input type="button" onclick="showNextInfo()" value="next"> </body> </html>

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  • How can I include a .eps figure within a Tikz simple flow chart?

    - by Jan
    Hi, I would like to create a simple flow chart in latex with the TikZ package similar to the following example http://www.texample.net/tikz/examples/simple-flow-chart/ However I would like to include figures (a time series plot created in R, as eps or something else) within the flowchart (e.g. for example within a {block}? \documentclass{article} \usepackage[latin1]{inputenc} \usepackage{tikz} \usetikzlibrary{shapes,arrows} \begin{document} \pagestyle{empty} % Define block styles \tikzstyle{decision} = [diamond, draw, fill=blue!20, text width=4.5em, text badly centered, node distance=3cm, inner sep=0pt] \tikzstyle{block} = [rectangle, draw, fill=blue!20, text width=5em, text centered, rounded corners, minimum height=4em] \tikzstyle{line} = [draw, -latex'] \tikzstyle{cloud} = [draw, ellipse,fill=red!20, node distance=3cm, minimum height=2em] \begin{tikzpicture}[node distance = 2cm, auto] % Place nodes \node [block] (init) {initialize model}; \node [cloud, left of=init] (expert) {expert}; \node [cloud, right of=init] (system) {system}; \node [block, below of=init] (identify) {identify candidate models}; \node [block, below of=identify] (evaluate) {evaluate candidate models}; \node [block, left of=evaluate, node distance=3cm] (update) {update model}; \node [decision, below of=evaluate] (decide) {is best candidate better?}; \node [block, below of=decide, node distance=3cm] (stop) {stop}; % Draw edges \path [line] (init) -- (identify); \path [line] (identify) -- (evaluate); \path [line] (evaluate) -- (decide); \path [line] (decide) -| node [near start] {yes} (update); \path [line] (update) |- (identify); \path [line] (decide) -- node {no}(stop); \path [line,dashed] (expert) -- (init); \path [line,dashed] (system) -- (init); \path [line,dashed] (system) |- (evaluate); \end{tikzpicture} \end{document} Thanks, Jan

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  • Crash on replacing map annotations

    - by Alwin
    Solved it, see below code I'm trying to replace annotations on my MapView depending on the distance between user location and annotation. The annotations are getting replaced like they should, but when I touch te mapview my app crashes. This is de code I have so far: NSMutableArray *tempArray = [[NSMutableArray alloc] init]; for (id object in self.mapAnnotations) { if([object isKindOfClass:[ClosedAnnotation class]]) { ClosedAnnotation *ann = (ClosedAnnotation *)object; CLLocation *tempLocation = [[CLLocation alloc] initWithLatitude:ann.coordinate.latitude longitude:ann.coordinate.longitude]; double distance = [self.currentLocation getDistanceFrom: tempLocation] / 1000; [tempLocation release]; if(distance <= 1.0){ [mapView removeAnnotation:object]; OpenAnnotation *openAnnotation = [[OpenAnnotation alloc] initWithLatitude:ann.coordinate.latitude longitude:ann.coordinate.longitude imageSrc:[ann getImageSrcForAnnotation] title:ann.title tekst:[ann getTextForAnnotation] imageSize:[ann getSizeForImage] username:[ann getUserNameForAnnotation] usertext:[ann getUserTextForAnnotation]]; [mapView addAnnotation:openAnnotation]; [tempArray addObject:openAnnotation]; [openAnnotation release]; } else { [tempArray addObject:object]; } } else if([object isKindOfClass:[OpenAnnotation class]]){ OpenAnnotation *ann = (OpenAnnotation *)object; CLLocation *tempLocation = [[[CLLocation alloc] initWithLatitude:ann.coordinate.latitude longitude:ann.coordinate.longitude] autorelease]; double distance = [self.currentLocation getDistanceFrom: tempLocation] / 1000; [tempLocation release]; if(distance > 1.0){ [mapView removeAnnotation:object]; ClosedAnnotation *closedAnnotation = [[ClosedAnnotation alloc] initWithLatitude:ann.coordinate.latitude longitude:ann.coordinate.longitude imageSrc:[ann getImageSrcForAnnotation] title:ann.title tekst:[ann getTextForAnnotation] imageSize:[ann getSizeForImage] username:[ann getUserNameForAnnotation] usertext:[ann getUserTextForAnnotation]]; [mapView addAnnotation:closedAnnotation]; [tempArray addObject:closedAnnotation]; [closedAnnotation release]; } else { [tempArray addObject:object]; } } } [self.mapAnnotations removeAllObjects]; [self.mapAnnotations addObjectsFromArray:tempArray]; [tempArray release]; I solved it by getting rid of the complete "two-class"-structure and handling everything within one annotation class. Works like a charm now.

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  • Using Dijkstra's algorithm with negative edges?

    - by Riddler
    Most books explain the reason the algorithm doesn't work with negative edges as nodes are deleted from the priority queue after the node is arrived at since the algorithm assumes the shortest distance has been found. However since negative edges can reduce the distance, a future shorter distance might be found; but since the node is deleted it cannot be updated. Wouldn't an obvious solution to this be to not delete the node? Why not keep the node in the queue, so if a future shorter distance is found, it can be updated? If I am misunderstanding the problem, what is preventing the algorithm from being used with negative edges?

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  • Idiomatic STL: Iterating over a list and inserting elements

    - by mkilling
    I'm writing an algorithm that iterates over a list of points, calculates the distance between them and inserts additional points if the distance is too great. However I seem to be lacking the proper familiarity with STL to come up with an elegant solution. I'm hoping that I can learn something, so I'll just show you my code. You might have some hints for me. for (std::list<PathPoint>::iterator it = ++points_.begin(); it != points_.end(); it++) { Vector curPos = it->getPosition(); Vector prevPos = (--it)->getPosition(); Vector vecFromPrev = curPos - prevPos; float distance = vecFromPrev.abs(); it++; if (distance > MAX_DISTANCE_BETWEEN_POINTS) { int pointsToInsert = (int)(distance / MAX_DISTANCE_BETWEEN_POINTS); Vector curPos = prevPos; for (int i = 0; i < pointsToInsert; i++) { curPos += vecFromPrev / pointsToInsert; it = points_.insert(it, PathPoint(curPos, false)); it++; } } }

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  • transform longitude latitude into meters

    - by Sponge
    I need a function that maps gps positions to x/y values like this: getXYpos(GeoPoint relativeNullPoint, GeoPoint p){ deltaLatitude=p.latitude-relativeNullPoint.latitude; deltaLongitude=p.longitude-relativeNullPoint.longitude; ... resultX=latitude (or west to east) distance in meters from p to relativeNullPoint resultY=longitude (or south to north) distance in meters from p to relativeNullPoint } i have seen some implementations of "distance of two geoPoints" but they all just calculate the air-line distance. i think the deltaLongitude can be transformed into meters directly but the deltaLatitude depends in the Longitude. does anyone know how this problem can be solved?

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  • How to add additional data column in EF using ASP.Net MVC 2

    - by Picflight
    My Table: [LocationId] [Address] [ZipCode] When I show a list of Location's, I also want to show the distance from a given zip code. In Asp.Net Web Forms I had a stored procedure that would return the distance and I would call this SP on ItemDataBound on my GridView. Or, I also would have my SP that is returning the Location list add another column ([Distance]) which I could display in my GridView. How would you do this using Entity Framework and Asp.Net Mvc 2?

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  • [iPhone] How to order an array

    - by Fabrizio
    Hi all, I got an array in my app and I need to order by one of its key. Basically what the app does is taking latitude and longitude somewhere, calculate the distance from my actual position and create an array containing a key called "distance". I'm using myArray sortUsingDescriptors: [NSArray arrayWithObject:[[[NSSortDescriptor alloc] initWithKey:@"distance" ascending:YES] autorelease]]]; I'm not sure it's working, I mean the first results are ordered but then it shows distance closer to the previous, as example: 0.8 km 1.6 km 1.9 km 10053.9 km 1098.0 km 2372.0 km 470.5 km Any suggestion? I thank you in advance for any kind of help. Fabrizio

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  • Add kilometers to a map point

    - by proveyourselfthom
    Good morning. I would like to know how do I add kilometers to a map point (latitude / longitude). For example: The city Jaraguá do Sul is in latitude -26.462049, longitude -49.059448. I want to add 100 kilometers up, down, and on the sides. I want to do a square and get the new points. How do I do that? I tried it: <?php $distance = 100; $earthRadius = 6371; $lat1 = -26.4853239150483; $lon1 = -49.075927734375; $bearing = 0; $lat2 = asin(sin($lat1) * cos($distance / $earthRadius) + cos($lat1) * sin($distance / $earthRadius) * cos($bearing)); $lon2 = $lon1 + atan2(sin($bearing) * sin($distance / $earthRadius) * cos($lat1), cos($distance / $earthRadius) - sin($lat1) * sin($lat2)); echo 'LAT: ' . $lat2 . '<br >'; echo 'LNG: ' . $lon2; ?> But it's returning wrong cordinates. Thank you! Thank you very much.

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  • Simple calculation in SQL Server

    - by meep
    I got a distance field in my database that stores the distance traveled on a specific route. I need to select all the distance fields and plus them together, then returning the result from my stored procedure. How can this be done?

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  • Abstract Classes and ReadOnly Properties

    - by serhio
    Let's have three classes; Line PoliLine SuperPoliLine for all that three classes a Distance is defined. But only for the Line a Distance can be Set. Is there a possibility to build a common abstract (MustInherit) class Segment, having a Distance as (abstract +? ReadOnly) member? Question for VB.NET, but C# answers welcomed too. Business Background Imagine a Bus. It has a lot of Stations, MainStations, and 2 TerminalStations. So Line is between 2 Stations, PoliLine is between 2 MainStations, and SuperPoliLine is between 2 TerminalStations. All "lines" are "Segments", but only the distance A-B between 2 stations - Line can be defined.

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  • SQL database self interaction entity

    - by Ricardo Costa
    I've been working on a database, wich is referent to an Aeroport management. I'm having a problem that it's freaking me out.. What i'm trying to do is, assuming that a client wants to know the distance between 2 locations, in miles or kms. As an example, if the user wants to know the distance between London and Amsterdam, should that distance be calculated by a formule or should it be already stored on the database? (1,N) ____________ ____________|__ | | | | | City/Airport |<---------| |______________| How can i show to user the distance between his 2 choices? RicardoCosta

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  • More than one unique key for HashMap problem (Java)

    - by Alex Cheng
    This question is a continuation of this thread: In short: To solve my problem, I want to use Map<Set<String>, String>. However, after I sort my data entries in Excel, remove the unnecessary parameters, and the following came out: flow content ==> content content flow content ==> content depth distance flow content ==> content depth within flow content ==> content depth within distance flow content ==> content within flow content ==> content within distance I have more than one unique key for the hashmap if that is the case. How do I go around this... anyone have any idea? I was thinking of maybe Map<Set <String>, List <String>> so that I can do something like: Set <flow content>, List <'content content','content depth distance','content depth within ', ..., 'content within distance'> But because I am parsing the entries line by line I can't figure out the way how to store values of the same repeated keys (flow content) into the same list and add it to the map. Anyone have a rough logic on how can this be done in Java? Thanks in advance.

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  • Workaround with paths in vista

    - by Argiropoulos Stavros
    Not really a programming question but i think quite relative. I have a .exe running in my windows XP PC. This exe needs a file in the same directory to run and has no problem finding it in XP BUT in Vista(I tried this in several machines and works in some of them) fails to run. I'm guessing there is a problem finding the path.The program is written in basic(Yes i know..) I attach the code below. Can you think of any workarounds? Thank you The exe is located in c:\tools Also the program runs in windows console(It starts but then during the execution cannot find a custom file type .TOP made by the creator of the program) ' PROGRAMM TOP11.BAS DEFDBL A-Z CLS LOCATE 1, 1 COLOR 14, 1 FOR i = 1 TO 80 PRINT "±"; NEXT i LOCATE 1, 35: PRINT "?? TOP11 ??" PRINT " €€‚—‚„‘ ’— ‹„’†‘„— ‘’† „”€„€ ’†‘ ‡€€‘‘†‘ ‰€ † „.‚.‘.€. " COLOR 7, 0 PRINT "-------------------------------------------------------------------------------" PRINT INPUT "ƒ?©« «¦¤ ©¬¤«?©«? ¤???... : ", Factor# INPUT "¤¦£ ¨®e¦¬ [.TOP] : ", topfile$ VIEW PRINT 7 TO 25 file1$ = topfile$ + ".TOP" file2$ = topfile$ + ".T_P" file3$ = "Syntel" OPEN file3$ FOR OUTPUT AS #3 PRINT #3, " ‘¬¤«?©«?? ¤??? = " + STR$(Factor#) + " †‹„‹†€: " + DATE$ CLOSE #3 command1$ = "copy" + " " + file1$ + " " + file2$ SHELL command1$ '’¦ ¨®e¦ .TOP ¤« ¨a­«  £ «¤ ?«a?¥ .T_P OPEN file2$ FOR INPUT AS #1 OPEN file1$ FOR OUTPUT AS #2 bb$ = " \\\ \ , ###.#### ###.#### ####.### ##.### " DO LINE INPUT #1, Line$ Line$ = RTRIM$(LTRIM$(Line$)) icode$ = LEFT$(Line$, 1) IF icode$ = "1" THEN Line$ = " " + Line$ PRINT #2, Line$ PRINT Line$ ELSEIF icode$ = "2" THEN Line$ = " " + Line$ PRINT #2, Line$ PRINT Line$ ELSEIF icode$ = "3" THEN Number$ = MID$(Line$, 3, 6) Hangle = VAL(MID$(Line$, 14, 9)) Zangle = VAL(MID$(Line$, 25, 9)) Distance = VAL(MID$(Line$, 36, 9)) Distance = Distance * Factor# Height = VAL(MID$(Line$, 48, 6)) PRINT #2, USING bb$; icode$; Number$; Hangle; Zangle; Distance; Height PRINT USING bb$; icode$; Number$; Hangle; Zangle; Distance; Height ELSE END IF LOOP UNTIL EOF(1) VIEW PRINT CLS LOCATE 1, 1 PRINT " *** ’„‘ ’“ ‚€‹‹€’‘ *** " END

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  • Draw a never-ending line in XNA

    - by user2236165
    I am drawing a line in XNA which I want to never end. I also have a tool that moves forward in X-direction and a camera which is centered at this tool. However, when I reach the end of the viewport the lines are not drawn anymore. Here are some pictures to illustrate my problem: At the start the line goes across the whole screen, but as my tool moves forward, we reach the end of the line. Here are the method which draws the lines: private void DrawEvenlySpacedSprites (Texture2D texture, Vector2 point1, Vector2 point2, float increment) { var distance = Vector2.Distance (point1, point2); // the distance between two points var iterations = (int)(distance / increment); // how many sprites with be drawn var normalizedIncrement = 1.0f / iterations; // the Lerp method needs values between 0.0 and 1.0 var amount = 0.0f; if (iterations == 0) iterations = 1; for (int i = 0; i < iterations; i++) { var drawPoint = Vector2.Lerp (point1, point2, amount); spriteBatch.Draw (texture, drawPoint, Color.White); amount += normalizedIncrement; } } Here are the draw method in Game. The dots are my lines: protected override void Draw (GameTime gameTime) { graphics.GraphicsDevice.Clear(Color.Black); nyVector = nextVector (gammelVector); GraphicsDevice.SetRenderTarget (renderTarget); spriteBatch.Begin (); DrawEvenlySpacedSprites (dot, gammelVector, nyVector, 0.9F); spriteBatch.End (); GraphicsDevice.SetRenderTarget (null); spriteBatch.Begin (SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null, null, camera.transform); spriteBatch.Draw (renderTarget, new Vector2 (), Color.White); spriteBatch.Draw (tool, new Vector2(toolPos.X - (tool.Width/2), toolPos.Y - (tool.Height/2)), Color.White); spriteBatch.End (); gammelVector = new Vector2 (nyVector.X, nyVector.Y); base.Draw (gameTime); } Here's the next vector-method, It just finds me a new point where the line should be drawn with a new X-coordinate between 100 and 200 pixels and a random Y-coordinate between the old vector Y-coordinate and the height of the viewport: Vector2 nextVector (Vector2 vector) { return new Vector2 (vector.X + r.Next(100, 200), r.Next ((int)(vector.Y - 100), viewport.Height)); } Can anyone point me in the right direction here? I'm guessing it has to do with the viewport.width, but I'm not quite sure how to solve it. Thank you for reading!

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  • XNA - Moving Background Calculations

    - by Jesse Emond
    Hi, My question is relatively hard to explain(for me, at least), so I'll go one step at a time and just tell me in the comments if it's not clear enough. So I'm making a "Defend Your Castle" type 2D game, where two players own a castle and create units that will move horizontally to try to destroy the opponent's base. Here's a screenshot of the game: The distance between both castles is much bigger in a real game though, bigger than the screen's width actually. Because the distance is bigger than the screen's width, I had to implement a simple 2D camera: Camera2D, which only holds a Location Vector2 (and I always make sure this camera is within the field area). Then, I just move all the game elements(castles, units, health bars) by that location, so that if a unit is at (5, 0), and the camera's location is (5, 0), then the unit's position will be moved by 5 units to the left, making it (0, 0) on the screen. At first, I simply used a static background with mountains and clouds(yeah, those are supposed to be mountains and clouds). Obviously, this looked awful: when you moved the camera, the background would stay immobile. Instead, I'd like to make a moving background, kind of a "scrolling" one. But rather than making a background with the same width as the distance between the castles, I'd like to make one that is a little bit smaller(but still bigger than the screen's width). I thought this would create an effect of "distance" with the background(but it might just look awful, too). Here's the background I'm testing with: I tried different ways, but none of them seems to work. I tried this: float backgroundFieldRatio = BackgroundTexture.Width / fieldWidth;//find the ratio between the background and the field. float backgroundPositionX = -cam.Location.X * backgroundFieldRatio;//move the background to the left When I run this with fieldWith = 1600, BackgroundTexture.Width = 1500 and while looking at the rightmost area, the background is offset to the left by a too big amount, and we can see the black clear color in the back, as you can see here: I hope I explained properly what I'm trying to achieve. Thank you for your time. Note: I didn't know what to look for on Google, so I thought I'd ask here.

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  • Arrive steering behavior

    - by dbostream
    I bought a book called Programming game AI by example and I am trying to implement the arrive steering behavior. The problem I am having is that my objects oscillate around the target position; after oscillating less and less for awhile they finally come to a stop at the target position. Does anyone have any idea why this oscillating behavior occur? Since the examples accompanying the book are written in C++ I had to rewrite the code into C#. Below is the relevant parts of the steering behavior: private enum Deceleration { Fast = 1, Normal = 2, Slow = 3 } public MovingEntity Entity { get; private set; } public Vector2 SteeringForce { get; private set; } public Vector2 Target { get; set; } public Vector2 Calculate() { SteeringForce.Zero(); SteeringForce = SumForces(); SteeringForce.Truncate(Entity.MaxForce); return SteeringForce; } private Vector2 SumForces() { Vector2 force = new Vector2(); if (Activated(BehaviorTypes.Arrive)) { force += Arrive(Target, Deceleration.Slow); if (!AccumulateForce(force)) return SteeringForce; } return SteeringForce; } private Vector2 Arrive(Vector2 target, Deceleration deceleration) { Vector2 toTarget = target - Entity.Position; double distance = toTarget.Length(); if (distance > 0) { //because Deceleration is enumerated as an int, this value is required //to provide fine tweaking of the deceleration.. double decelerationTweaker = 0.3; double speed = distance / ((double)deceleration * decelerationTweaker); speed = Math.Min(speed, Entity.MaxSpeed); Vector2 desiredVelocity = toTarget * speed / distance; return desiredVelocity - Entity.Velocity; } return new Vector2(); } private bool AccumulateForce(Vector2 forceToAdd) { double magnitudeRemaining = Entity.MaxForce - SteeringForce.Length(); if (magnitudeRemaining <= 0) return false; double magnitudeToAdd = forceToAdd.Length(); if (magnitudeToAdd > magnitudeRemaining) magnitudeToAdd = magnitudeRemaining; SteeringForce += Vector2.NormalizeRet(forceToAdd) * magnitudeToAdd; return true; } This is the update method of my objects: public void Update(double deltaTime) { Vector2 steeringForce = Steering.Calculate(); Vector2 acceleration = steeringForce / Mass; Velocity = Velocity + acceleration * deltaTime; Velocity.Truncate(MaxSpeed); Position = Position + Velocity * deltaTime; } If you want to see the problem with your own eyes you can download a minimal example here. Thanks in advance.

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  • SQL SERVER – SSAS – Multidimensional Space Terms and Explanation

    - by pinaldave
    I was presenting on SQL Server session at one of the Tech Ed On Road event in India. I was asked very interesting question during ‘Stump the Speaker‘ session. I am sharing the same with all of you over here. Question: Can you tell me in simple words what is dimension, member and other terms of multidimensional space? There is no simple example for it. This is extreme fundamental question if you know Analysis Service. Those who have no exposure to the same and have not yet started on this subject, may find it a bit difficult. I really liked his question so I decided to answer him there as well blog about the same over here. Answer: Here are the most important terms of multidimensional space – dimension, member, value, attribute and size. Dimension – It describes the point of interests for analysis. Member – It is one of the point of interests in the dimension. Value – It uniquely describes the member. Attribute – It is collection of multiple members. Size – It is total numbers for any dimension. Let us understand this further detail taking example of any space. I am going to take example of distance as a space in our example. Dimension – Distance is a dimension for us. Member – Kilometer – We can measure distance in Kilometer. Value – 4 – We can measure distance in the kilometer unit and the value of the unit can be 4. Attribute – Kilometer, Miles, Meter – The complete set of members is called attribute. Size – 100 KM – The maximum size decided for the dimension is called size. The same example can be also defined by using time space. Here is the example using time space. Dimension – Time Member – Date Value – 25 Attribute – 1, 2, 3…31 Size – 31 I hope it is clear enough that what are various multidimensional space and its terms. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Business Intelligence, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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