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  • help in the Donalds B. Johnson's algorithm, i cannot understand the pseudo code (PART II)

    - by Pitelk
    Hi all , i cannot understand a certain part of the paper published by Donald Johnson about finding cycles (Circuits) in a graph. More specific i cannot understand what is the matrix Ak which is mentioned in the following line of the pseudo code : Ak:=adjacency structure of strong component K with least vertex in subgraph of G induced by {s,s+1,....n}; to make things worse some lines after is mentins " for i in Vk do " without declaring what the Vk is... As far i have understand we have the following: 1) in general, a strong component is a sub-graph of a graph, in which for every node of this sub-graph there is a path to any node of the sub-graph (in other words you can access any node of the sub-graph from any other node of the sub-graph) 2) a sub-graph induced by a list of nodes is a graph containing all these nodes plus all the edges connecting these nodes. in paper the mathematical definition is " F is a subgraph of G induced by W if W is subset of V and F = (W,{u,y)|u,y in W and (u,y) in E)}) where u,y are edges , E is the set of all the edges in the graph, W is a set of nodes. 3)in the code implementation the nodes are named by integer numbers 1 ... n. 4) I suspect that the Vk is the set of nodes of the strong component K. now to the question. Lets say we have a graph G= (V,E) with V = {1,2,3,4,5,6,7,8,9} which it can be divided into 3 strong components the SC1 = {1,4,7,8} SC2= {2,3,9} SC3 = {5,6} (and their edges) Can anybody give me an example for s =1, s= 2, s= 5 what if going to be the Vk and Ak according to the code? The pseudo code is in my previous question in http://stackoverflow.com/questions/2908575/help-in-the-donalds-b-johnsons-algorithm-i-cannot-understand-the-pseudo-code and the paper can be found at http://stackoverflow.com/questions/2908575/help-in-the-donalds-b-johnsons-algorithm-i-cannot-understand-the-pseudo-code thank you in advance

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  • why is my Bamboo pen always drawing and a yellow note pad appears?

    - by cboi
    I have had a Bamboo pen and touch tablet for a couple years but have not used it in a long time. Now that I'm trying to use it again it is behaving very strangely. It won't drag anything on my desktop, the minute I try there is this yellow pad that appears and the pen draws a line on it instead of dragging the file. The yellow pad and drawn line disappear the second I lift the pen from the tablet. The most frustrating is it does the same thing when I try to draw in Photoshop. It won't draw with the paintbrush on my canvas because the minute I try to this yellow pad appears and it draws a line on it instead of on the canvas, which disappears the second I lift the pen from the tablet. It also bizarrely automatically switches from the paintbrush to the automatic selection tool. Has anyone had this problem? Any suggestions on how to fix this? I operate with Mac OS X 10.5.8

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  • In Silverlight, what is the best way to convert between a System.Drawing.Color and a System.Windows.

    - by Gene
    I'm trying to convert from a System.Drawing.Color to a Silverlight System.Windows.Media.Color. I'm actually trying to pass this color through a service. The System.Drawing.Color, passed over the wire, does not serialize the argb value independently. I can convert the argb value to a 32-bit int [DataMember] public int MyColor { get { return Color.Red.ToArgb(); } set {} } But I don't see any corresponding method in System.Windows.Media.Color to convert that back. What is the best way to do this?

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  • Reading graph inputs for a programming puzzle and then solving it

    - by Vrashabh
    I just took a programming competition question and I absolutely bombed it. I had trouble right at the beginning itself from reading the input set. The question was basically a variant of this puzzle http://codercharts.com/puzzle/evacuation-plan but also had an hour component in the first line(say 3 hours after start of evacuation). It reads like this This puzzle is a tribute to all the people who suffered from the earthquake in Japan. The goal of this puzzle is, given a network of road and locations, to determine the maximum number of people that can be evacuated. The people must be evacuated from evacuation points to rescue points. The list of road and the number of people they can carry per hour is provided. Input Specifications Your program must accept one and only one command line argument: the input file. The input file is formatted as follows: the first line contains 4 integers n r s t n is the number of locations (each location is given by a number from 0 to n-1) r is the number of roads s is the number of locations to be evacuated from (evacuation points) t is the number of locations where people must be evacuated to (rescue points) the second line contains s integers giving the locations of the evacuation points the third line contains t integers giving the locations of the rescue points the r following lines contain to the road definitions. Each road is defined by 3 integers l1 l2 width where l1 and l2 are the locations connected by the road (roads are one-way) and width is the number of people per hour that can fit on the road Now look at the sample input set 5 5 1 2 3 0 3 4 0 1 10 0 2 5 1 2 4 1 3 5 2 4 10 The 3 in the first line is the additional component and is defined as the number of hours since the resuce has started which is 3 in this case. Now my solution was to use Dijisktras algorithm to find the shortest path between each of the rescue and evac nodes. Now my problem started with how to read the input set. I read the first line in python and stored the values in variables. But then I did not know how to store the values of the distance between the nodes and what DS to use and how to input it to say a standard implementation of dijikstras algorithm. So my question is two fold 1.) How do I take the input of such problems? - I have faced this problem in quite a few competitions recently and I hope I can get a simple code snippet or an explanation in java or python to read the data input set in such a way that I can input it as a graph to graph algorithms like dijikstra and floyd/warshall. Also a solution to the above problem would also help. 2.) How to solve this puzzle? My algorithm was: Find shortest path between evac points (in the above example it is 14 from 0 to 3) Multiply it by number of hours to get maximal number of saves Also the answer given for the variant for the input set was 24 which I dont understand. Can someone explain that also. UPDATE: I get how the answer is 14 in the given problem link - it seems to be just the shortest path between node 0 and 3. But with the 3 hour component how is the answer 24 UPDATE I get how it is 24 - its a complete graph traversal at every hour and this is how I solve it Hour 1 Node 0 to Node 1 - 10 people Node 0 to Node 2- 5 people TotalRescueCount=0 Node 1=10 Node 2= 5 Hour 2 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5(Rescued) Node 0 to Node 1 = 10 Node 0 to Node 2 = 5 Node 1 to Node 2 = 4 TotalRescueCount = 10 Node 1 = 10 Node 2= 5+4 = 9 Hour 3 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5+4 = 9(Rescued) TotalRescueCount = 9+5+10 = 24 It hard enough for this case , for multiple evac and rescue points how in the world would I write a pgm for this ?

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  • Problem with OOP Class Definitions

    - by oben
    Hi, this is Oben from Turkey. I work for my homework in C++ and i have some problems with multiply definitions. My graph class ; class Graph{ private: string name; //Graph name fstream* graphFile; //Graph's file protected: string opBuf; //Operations buffer int containsNode(string); //Query if a node is present Node* nodes; //Nodes in the graph int nofNodes; //Number of nodes in the graph public: static int nOfGraphs; //Number of graphs produced Graph(); //Constructors and destructor Graph(int); Graph(string); Graph(const Graph &); ~Graph(); string getGraphName(); //Get graph name bool addNode(string); //add a node to the graph bool deleteNode(string); //delete a node from the graph bool addEdge(string,string); //add an edge to the graph bool deleteEdge(string,string); //delete an edge from the graph void intersect(const Graph&); //intersect the graph with the <par> void unite(const Graph&); //intersect the graph with the <par> string toString(); //get string representation of the graph void acceptTraverse(BreadthFirst*); void acceptTraverse(DepthFirst *); }; and my traversal class; class Traversal { public: string *visitedNodes; virtual string traverse (const Graph & ); }; class BreadthFirst : public Traversal { public : BreadthFirst(); string traverse(); }; class DepthFirst : public Traversal { public : DepthFirst(); string traverse(); }; My problem is in traversal class , i need to declare Graph class at the same time , in graph class i need traversal class to declare. I have big problems with declerations :) Could you please help me ?

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  • Drawing text from update method in XNA

    - by Sigh-AniDe
    I am having a problem drawing the "Game Over!" text once the user is on the last tile. This is what I have: The Update and drawText methods are in a class named turtle: public void Update(float scalingFactor, int[,] map, SpriteBatch batch, SpriteFont font) { if (isMovable(mapX, mapY - 1, map)) { position.Y = position.Y - (int)scalingFactor; angle = 0.0f; Program.form.direction = ""; if (mapX == 17 && mapY == 1)// This is the last tile(Tested) { Program.form.BackColor = System.Drawing.Color.Red; drawText(batch, font); } } } public void drawText(SpriteBatch spritebatch, SpriteFont spriteFont) { textPosition.X = 200; // a vector2 textPosition.Y = 200; spritebatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend); spritebatch.DrawString(spriteFont, "Game Over!!!", textPosition, Color.Red); spritebatch.End(); } This update is in the Game1 class: protected override void Update(GameTime gameTime) { // Allows the game to exit if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); turtle.Update(scalingFactor, map, spriteBatch, font); base.Update(gameTime); } I have also added the font content to LoadContent: font = Content.Load<SpriteFont>("fontType"); What am I doing wrong? Why does the text not want to show on game completion? If I call the turtle.draw() in the main Draw method. The "Game Over" text stays on screen from the beggining. What am I missing? Thanks

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  • Drawing a sprite or text causes the OpenGl rendering to 'disappear' in SFML

    - by Ken
    I'm using some SFML built in functions to draw sprites and text as an overlay on top of some OpenGL rending in an SFML RenderWindow. The opengl rendering appears fine until I add the code to draw the sprites or text. The sprite or text drawing causes the OpenGL stuff to disappear. The follow code show what I'm trying to do sf::RenderWindow window(sf::VideoMode(viewport.width,viewport.height,32), "SFML Window"); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0,viewport.width,0,viewport.height,0,1); while (window.pollEvent(Event)) { //event handling... //begin drawing glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glBegin(GL_TRIANGLES); glColor3f(col.x,col.y,col.z); for(int i=0;i<3;i++) glVertex2f(pos.x+verts[i].x,pos.y+verts[i].y); glEnd(); // adding this line causes all the previous opengl triangles not to appear window.draw("Sometext"); window.display(); }

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  • Can't use SFML sprite drawing and OpenGL rendering at the same time

    - by Ken
    I'm using some SFML built in functions to draw sprites and text as an overlay on top of some OpenGL rending in an SFML RenderWindow. The opengl rendering appears fine until I add the code to draw the sprites or text. The sprite or text drawing causes the OpenGL stuff to disappear. The follow code show what I'm trying to do sf::RenderWindow window(sf::VideoMode(viewport.width,viewport.height,32), "SFML Window"); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0,viewport.width,0,viewport.height,0,1); while (window.pollEvent(Event)) { //event handling... //begin drawing glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glBegin(GL_TRIANGLES); glColor3f(col.x,col.y,col.z); for(int i=0;i<3;i++) glVertex2f(pos.x+verts[i].x,pos.y+verts[i].y); glEnd(); // adding this line causes all the previous opengl triangles not to appear window.draw("Sometext"); window.display(); }

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  • Seperation of drawing and logic in games

    - by BFree
    I'm a developer that's just now starting to mess around with game development. I'm a .Net guy, so I've messed with XNA and am now playing around with Cocos2d for the iPhone. My question really is more general though. Let's say I'm building a simple Pong game. I'd have a Ball class and a Paddle class. Coming from the business world development, my first instinct is to not have any drawing or input handling code in either of these classes. //pseudo code class Ball { Vector2D position; Vector2D velocity; Color color; void Move(){} } Nothing in the ball class handles input, or deals with drawing. I'd then have another class, my Game class, or my Scene.m (in Cocos2D) which would new up the Ball, and during the game loop, it would manipulate the ball as needed. The thing is though, in many tutorials for both XNA and Cocos2D, I see a pattern like this: //pseudo code class Ball : SomeUpdatableComponent { Vector2D position; Vector2D velocity; Color color; void Update(){} void Draw(){} void HandleInput(){} } My question is, is this right? Is this the pattern that people use in game development? It somehow goes against everything I'm used to, to have my Ball class do everything. Furthermore, in this second example, where my Ball knows how to move around, how would I handle collision detection with the Paddle? Would the Ball need to have knowledge of the Paddle? In my first example, the Game class would have references to both the Ball and the Paddle, and then ship both of those off to some CollisionDetection manager or something, but how do I deal with the complexity of various components, if each individual component does everything themselves? (I hope I'm making sense.....)

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  • Drawing chunks, and positioning the camera

    - by Troubleshoot
    I've seen many questions and answers regarding how to draw tiled maps but I can't really get my head around it. Many answers suggest either loading the visible part of the map, or loading and unloading chunks of the map. I've decided the best option would be to load chunks, but I'm slightly confused as to how this would be implemented. Currently I'm loading the full map to a 2D array of buffered images, then drawing it every time repaint is called. Q1: If I were to load chunks of the map, would I load the map as a whole then draw the necessary chunk(s), or load & unload the chunks as the player moves along, and if so, how? My second question regards the camera. I want the player to be in the centre of the X axis and the camera to follow it. I've thought of drawing everything in relation to the map and calculating the position of the camera in relation to the players coordinates on the map. So, to calculate the camera's X position I understand that I should use cameraX = playerX - (canvasWidth/2), but how should I calculate the Y position? I want the camera to only move up when the player reaches cameraHeight/2 but to move down when the player reaches 3/4(cameraHeight). Q2: Should I check for this in the same way I check for collision, and move the camera relative to the movement of the player until the player stops moving, or am I thinking about it in the wrong way?

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  • Reverse Bredth First Search in C#

    - by Ngu Soon Hui
    Anyone has a ready implementation of the Reverse Bredth First Search algorithm in C#? By Reverse Bredth First Search, I mean instead of searching a tree starting from a common node, I want to search the tree from the bottom and gradually converged to a common node. Let's see the below figure, this is the output of a Bredth First Search: In my reverse bredth first search, 9,10,11 and 12 will be the first few nodes found ( the order of them are not important as they are all first order). 5, 6, 7 and 8 are the second few nodes found, and so on. 1 would be the last node found. Any ideas or pointers?

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  • Reverse Breadth First traversal in C#

    - by Ngu Soon Hui
    Anyone has a ready implementation of the Reverse Breadth First traversal algorithm in C#? By Reverse Breadth First traversal , I mean instead of searching a tree starting from a common node, I want to search the tree from the bottom and gradually converged to a common node. Let's see the below figure, this is the output of a Breadth First traversal : In my reverse breadth first traversal , 9,10,11 and 12 will be the first few nodes found ( the order of them are not important as they are all first order). 5, 6, 7 and 8 are the second few nodes found, and so on. 1 would be the last node found. Any ideas or pointers? Edit: Change "Breadth First Search" to "Breadth First traversal" to clarify the question

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  • Reverse Breath First Search in C#

    - by Ngu Soon Hui
    Anyone has a ready implementation of the Reverse Breath First Search algorithm in C#? By Reverse Breath First Search, I mean instead of searching a tree starting from a common node, I want to search the tree from the bottom and gradually converged to a common node. Let's see the below figure, this is the output of a Breath First Search: In my reverse breath first search, 9,10,11 and 12 will be the first few nodes found ( the order of them are not important as they are all first order). 5, 6, 7 and 8 are the second few nodes found, and so on. 1 would be the last node found. Any ideas or pointers?

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  • directed unweighted graphs C

    - by fang_dejavu
    Hi, I'm planning to write a program in C that builds the adjacency list, performs the depth first search, performs the breadth first search, and performs the topological sort. Where can I get some info about this subject in C? Any help is appreciated

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  • Bullet physics debug drawing not working

    - by Krishnabhadra
    Background I am following on from this question, which isn't answered yet. Basically I have a cube and a UVSphere in my scene, with UVSphere on the top of the cube without touching the cube. Both exported from blender. When I run the app The UVSphere does circle around the cube for 3 or 4 times and jump out of the scene. What I actually expect was the sphere to fall on top of the cube. What this question about From the comment to the linked question, I got to know about bullet debug drawing, which helps in debugging by drawing outline of physics bodies which are normally invisible. I did some research on that and came up with the code given below. From whatever I have read, below code should work, but it doesn't. My Code My bullet initialization code. -(void) initializeScene { /*Setup physics world*/ _physicsWorld = [[CC3PhysicsWorld alloc] init]; [_physicsWorld setGravity:0 y:-9.8 z:0]; /*Setting up debug draw*/ MyDebugDraw *draw = new MyDebugDraw; draw->setDebugMode(draw->getDebugMode() | btIDebugDraw::DBG_DrawWireframe ); _physicsWorld._discreteDynamicsWorld->setDebugDrawer(draw); /*Setup camera and lamb*/ ………….. //This simpleCube.pod contains the cube [self addContentFromPODFile: @"simpleCube.pod"]; //This file contains sphere [self addContentFromPODFile: @"SimpleSphere.pod"]; [self createGLBuffers]; CC3MeshNode* cubeNode = (CC3MeshNode*)[self getNodeNamed:@"Cube"]; CC3MeshNode* sphereNode = (CC3MeshNode*)[self getNodeNamed:@"Sphere"]; // both cubeNode and sphereNode are not nil from this point float *cVertexData = (float*)((CC3VertexArrayMesh*)cubeNode.mesh) .vertexLocations.vertices; int cVertexCount = ((CC3VertexArrayMesh*)cubeNode.mesh) .vertexLocations.vertexCount; btTriangleMesh* cTriangleMesh = new btTriangleMesh(); int offset = 0; for (int i = 0; i < (cVertexCount / 3); i++) { unsigned int index1 = offset; unsigned int index2 = offset+6; unsigned int index3 = offset+12; cTriangleMesh->addTriangle( btVector3(cVertexData[index1], cVertexData[index1+1], cVertexData[index1+2]), btVector3(cVertexData[index2], cVertexData[index2+1], cVertexData[index2+2]), btVector3(cVertexData[index3], cVertexData[index3+1], cVertexData[index3+2])); offset += 18; } [self releaseRedundantData]; /*Create a triangle mesh from the vertices*/ btBvhTriangleMeshShape* cTriMeshShape = new btBvhTriangleMeshShape(cTriangleMesh,true); btCollisionShape *sphereShape = new btSphereShape(1); gTriMeshObject = [_physicsWorld createPhysicsObjectTrimesh:cubeNode shape:cTriMeshShape mass:0 restitution:1.0 position:cubeNode.location]; sphereObject = [_physicsWorld createPhysicsObject:sphereNode shape:sphereShape mass:1 restitution:0.1 position:sphereNode.location]; sphereObject.rigidBody->setDamping(0.1,0.8); /*Enable debug drawing*/ _physicsWorld._discreteDynamicsWorld->debugDrawWorld(); } And My btIDebugDraw implementation (MyDebugDraw.h) //MyDebugDraw.h class MyDebugDraw: public btIDebugDraw{ int m_debugMode; public: virtual void drawLine(const btVector3& from,const btVector3& to ,const btVector3& color); virtual void drawContactPoint(const btVector3& PointOnB ,const btVector3& normalOnB,btScalar distance ,int lifeTime,const btVector3& color); virtual void reportErrorWarning(const char* warningString); virtual void draw3dText(const btVector3& location ,const char* textString); virtual void setDebugMode(int debugMode); virtual int getDebugMode() const; }; void MyDebugDraw::drawLine(const btVector3& from,const btVector3& to ,const btVector3& color){ LogInfo(@"Works!!"); glPushMatrix(); glColor4f(color.getX(), color.getY(), color.getZ(), 1.0); const GLfloat line[] = { from.getX()*1, from.getY()*1, from.getZ()*1, //point A to.getX()*1, to.getY()*1,to.getZ()*1 //point B }; glVertexPointer( 3, GL_FLOAT, 0, &line ); glPointSize( 5.0f ); glDrawArrays( GL_POINTS, 0, 2 ); glDrawArrays( GL_LINES, 0, 2 ); glPopMatrix(); } void MyDebugDraw::drawContactPoint(const btVector3 &PointOnB ,const btVector3 &normalOnB, btScalar distance ,int lifeTime, const btVector3 &color){ } void MyDebugDraw::reportErrorWarning(const char *warningString){ } void MyDebugDraw::draw3dText(const btVector3 &location , const char *textString){ } void MyDebugDraw::setDebugMode(int debugMode){ } int MyDebugDraw::getDebugMode() const{ return DBG_DrawWireframe; } My Problem The drawLine method is getting called. I can see the cube and sphere in place. Sphere again does some circling around the cube before jumping off. No debug lines are getting drawn.

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  • Drawing on a webpage – HTML5 - IE9

    - by nmarun
    So I upgraded to IE9 and continued exploring HTML5. Now there’s this ‘thing’ called Canvas in HTML5 with which you can do some cool stuff. Alright what IS this Canvas thing anyways? The Web Hypertext Application Technology Working Group says this: “The canvas element provides scripts with a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, or other visual images on the fly.” The Canvas element has two only attributes – width and height and when not specified they take up the default values of 300 and 150 respectively. Below is what my HTML file looks like: 1: <!DOCTYPE html> 2: <html lang="en-US"> 3: <head> 4: <script type="text/javascript" src="CustomScript.js"></script> 5: <script src="jquery-1.4.4.js" type="text/javascript"></script 6:  7: <title>Draw on a webpage</title> 8: </head> 9: <body> 10: <canvas id="canvas" width="500" height="500"></canvas> 11: <br /> 12: <input type="submit" id="submit" value="Clear" /> 13: <h4 id="currentPosition"> 14: 0, 0 15: </h4> 16: <div id="mousedownCoords"></div> 17: </body> 18: </html> In case you’re wondering, this is not a MVC or any kind of web application. This is plain ol’ HTML even though I’m writing all this in VS 2010. You see this is a very simple, ‘gimmicks-free’ html page. I have declared a Canvas element on line 10 and a button on line 11 to clear the drawing board. I’m using jQuery / JavaScript show the current position of the mouse on the screen. This will get updated in the ‘currentPosition’ <h4> tag and I’m using the ‘mousedownCoords’ to write all the places where the mouse was clicked. This is what my page renders as: The rectangle with a background is our canvas. The coloring is due to some javascript (which we’ll see in a moment). Now let’s get to our CustomScript.js file. 1: jQuery(document).ready(function () { 2: var isFirstClick = true; 3: var canvas = document.getElementById("canvas"); 4: // getContext: Returns an object that exposes an API for drawing on the canvas 5: var canvasContext = canvas.getContext("2d"); 6: fillBackground(); 7:  8: $("#submit").click(function () { 9: clearCanvas(); 10: fillBackground(); 11: }); 12:  13: $(document).mousemove(function (e) { 14: $('#currentPosition').html(e.pageX + ', ' + e.pageY); 15: }); 16: $(document).mouseup(function (e) { 17: // on the first click 18: // set the moveTo 19: if (isFirstClick == true) { 20: canvasContext.beginPath(); 21: canvasContext.moveTo(e.pageX - 7, e.pageY - 7); 22: isFirstClick = false; 23: } 24: else { 25: // on subsequent clicks, draw a line 26: canvasContext.lineTo(e.pageX - 7, e.pageY - 7); 27: canvasContext.stroke(); 28: } 29:  30: $('#mousedownCoords').text($('#mousedownCoords').text() + '(' + e.pageX + ',' + e.pageY + ')'); 31: }); 32:  33: function fillBackground() { 34: canvasContext.fillStyle = '#a1b1c3'; 35: canvasContext.fillRect(0, 0, 500, 500); 36: canvasContext.fill(); 37: } 38:  39: function clearCanvas() { 40: // wipe-out the canvas 41: canvas.width = canvas.width; 42: // set the isFirstClick to true 43: // so the next shape can begin 44: isFirstClick = true; 45: // clear the text 46: $('#mousedownCoords').text(''); 47: } 48: })   The script only looks long and complicated, but is not. I’ll go over the main steps. Get a ‘hold’ of your canvas object and retrieve the ‘2d’ context out of it. On mousemove event, write the current x and y coordinates to the ‘currentPosition’ element. On mouseup event, check if this is the first time the user has clicked on the canvas. The coloring of the canvas is done in the fillBackground() function. We first need to start a new path. This is done by calling the beginPath() function on our context. The moveTo() function sets the starting point of our path. The lineTo() function sets the end point of the line to be drawn. The stroke() function is the one that actually draws the line on our canvas. So if you want to play with the demo, here’s how you do it. First click on the canvas (nothing visible happens on the canvas). The second click draws a line from the first click to the current coordinates and so on and so forth. Click on the ‘Clear’ button, to reset the canvas and to give your creativity a clean slate. Here’s a sample output: Happy drawing! Verdict: HTML5 and IE9 – I think we’re on to something big and great here!

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  • Graph navigation problem

    - by affan
    I have graph of components and relation between them. User open graph and want to navigate through the graph base on his choice. He start with root node and click expand button which reveal new component that is related to current component. The problem is with when use decide to collapse a node. I have to choose a sub-tree to hide and at same time leave graph in consistent state so that there is no expanded node with missing relation to another node in graph. Now in case of cyclic/loop between component i have difficult of choosing sub-tree. For simplicity i choose the order in which they were expanded. So if a A expand into B and C collapse A will hide the nodes and edge that it has created. Now consider flowing scenario. [-] mean expanded state and [+] mean not yet expanded. A is expanded to reveal B and C. And then B is expanded to reveal D. C is expanded which create a link between C and exiting node D and also create node E. Now user decide to collapse B. Since by order of expansion D is child of B it will collapse and hide D. This leave graph in inconsistent state as C is expanded with edge to D but D is not anymore there if i remove CD edge it will still be inconsistent. If i collapse C. And E is again a cyclic link e.g to B will produce the same problem. /-----B[-]-----\ A[-] D[+] \-----C[-]-----/ \ E[+] So guys any idea how can i solve this problem. User need to navigate through graph and should be able to collapse but i am stuck with problem of cyclic nodes in which case any of node in loop if collapse will leave graph in inconsistent state.

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  • loading google maps drawing manager object

    - by psychok7
    So i am using Google Maps Drawing Manager to draw some polygons and i am saving the lat e long coordinates to my database. Now my question is, after i load that to my array, how can i rebuild the saved polygon back into my map? I can't seem to find a code to understand that. this is what i have now : window.initialize_2 = function () { var mapOptions = { center: new google.maps.LatLng(-34.397, 150.644), zoom: 8, mapTypeId: google.maps.MapTypeId.ROADMAP }; var map = maplimits; var drawingManager = new google.maps.drawing.DrawingManager({ drawingMode: google.maps.drawing.OverlayType.MARKER, drawingControl: true, drawingControlOptions: { position: google.maps.ControlPosition.TOP_CENTER, drawingModes: [ google.maps.drawing.OverlayType.POLYGON] }, markerOptions: { icon: 'images/beachflag.png' }, polygonOptions: { fillColor: '#ffff00', fillOpacity: 10, strokeWeight: 5, clickable: true, editable: true, zIndex: 1 } }); var coord_listener = google.maps.event.addListener(drawingManager, 'polygoncomplete', function (polygon) { var coordinates = (polygon.getPath().getArray()); console.log(coordinates); window.poly = polygon; }); //delete shape google.maps.event.addListener(drawingManager, 'overlaycomplete', function (e) { if (e.type != google.maps.drawing.OverlayType.MARKER) { // Switch back to non-drawing mode after drawing a shape. drawingManager.setDrawingMode(null); // Add an event listener that selects the newly-drawn shape when the user // mouses down on it. var newShape = e.overlay; newShape.type = e.type; google.maps.event.addListener(newShape, 'click', function () { setSelection(newShape); }); setSelection(newShape); } }); // Clear the current selection when the drawing mode is changed, or when the // map is clicked. google.maps.event.addListener(drawingManager, 'drawingmode_changed', clearSelection); google.maps.event.addListener(map, 'click', clearSelection); drawingManager.setMap(map); }

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  • Data structure for bubble shooter game

    - by SundayMonday
    I'm starting to make a bubble shooter game for a mobile OS. Assume this is just the basic "three or more same-color bubbles that touch pop" and all bubbles that are separated from their group fall/pop. What data structures are common for storing the bubbles? I've considered using an undirected, connected graph where each node is a bubble. This seems like it could help answer the question "which bubbles (if any) should fall now?" after some arbitrary bubbles are popped and corresponding nodes are removed from the graph. I think the answer is all bubbles that were just disconnected from the graph should fall. However the graph approach might be overkill so I'm not sure. Another consideration for the data structure is collision detection. Perhaps being able to grab a list of neighboring bubbles in constant time for a particular "bubble slot" is useful. So the collision detection would be something like "moving bubble is closest to slot ij, neighbors of slot ij are bubbles a,b,c, moving bubble is sufficiently close to bubble b hence moving bubble should come to rest in slot ij". A game like this could be probably be made with a relatively crude grid structure as the primary data structure. However it seems like answering "which bubbles (if any) should fall now?" would be trickier with this data structure.

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  • How do find the longest path in a cyclic Graph between two nodes?

    - by Nazgulled
    Hi, I already solved most the questions posted here, all but the longest path one. I've read the Wikipedia article about longest paths and it seems any easy problem if the graph was acyclic, which mine is not. How do I solve the problem then? Brute force, by checking all possible paths? How do I even begin to do that? I know it's going to take A LOT on a Graph with ~18000. But I just want to develop it anyway, cause it's required for the project and I'll just test it and show it to the instructor on a smaller scale graph where the execution time is just a second or two. At least I did all tasks required and I have a running proof of concept that it works but there's no better way on cyclic graphs. But I don't have clue where to start checking all these paths...

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  • Neo4j Performing shortest path calculations on stored data

    - by paddydub
    I would like to store the following graph data in the database, graph.makeEdge( "s", "c", "cost", (double) 7 ); graph.makeEdge( "c", "e", "cost", (double) 7 ); graph.makeEdge( "s", "a", "cost", (double) 2 ); graph.makeEdge( "a", "b", "cost", (double) 7 ); graph.makeEdge( "b", "e", "cost", (double) 2 ); Then run the Dijskra algorighm from a web servlet, to find shortest path calculations using the stored graph data. Then I will print the path to a html file from the servlet. Dijkstra<Double> dijkstra = getDijkstra( graph, 0.0, "s", "e" );

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  • Location tagging facebook open graph actions so that only friends in that location view in their feeds

    - by Arvind Srinivasan
    Is there a way to tag open graph actions so as to target certain recipients and not others? For example, if my app talks about new coffee shop openings in various cities, is there a way to publish the 'opening' action to the graph, perhaps with location / coordinates, such that this is only seen by friends in that locality? I really don't want to spam my friends in London about an opening I'm excited about in Portland. How can I help facebook with the feed relevance in these cases? I noticed that there is a "place" property on open graph objects - could this somehow be used?

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  • In a graph, how to find the nearest node to a group of nodes?

    - by Nikola
    Hello, I have an undirected, unweighted graph, which doesn't have to be planar. I also have a subset of graph's nodes (true subset) and I need to find a node not belonging to the subset, with minimum sum of distances to all nodes in the subset. So far, I have implemented breath-first search starting from each node in the subset, and the intersection that occurs first is the node I am looking for. Unfortunately, it is running too slow since the graph contains a large number of nodes. Any advice or comment will be appreciated. Thank you, Nikola

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  • How to detect if breaking an edge will make a graph disjoint?

    - by the_graph_guy
    I have a graph that starts off with a single, root node. Nodes are added one by one to the graph. At node creation time, they have to be linked either to the root node, or to another node, by a single edge. Edges can also be created and deleted (one by one, between any two nodes). Nodes can be deleted one at a time. Node and edge creation, deletion operations can happen in any arbitrary order. OK, so here's my question: When an edge is deleted, is it possible do determine, in constant time (i.e. with an O(1) algorithm), if doing this will divide the graph into two disjoint subgraphs? If it will, then which side of the edge will the root node belong? I'm willing to maintain, within reasonable limits, any additional data structure that can facilitate the derivation of this information. Maybe it is not possible to do it in O(1), if so any pointers to literature will be appreciated.

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