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  • Calculating collission for a moving circle, without overlapping the boundaries

    - by Robert Vella
    Let's say I have circle bouncing around inside a rectangular area. At some point this circle will collide with one of the surfaces of the rectangle and reflect back. The usual way I'd do this would be to let the circle overlap that boundary and then reflect the velocity vector. The fact that the circle actually overlaps the boundary isn't usually a problem, nor really noticeable at low velocity. At high velocity it becomes quite clear that the circle is doing something it shouldn't. What I'd like to do is to programmitically take reflection into account and place the circle at it's proper position before displaying it on the screen. This means that I have to calculate the point where it hits the boundary between it's current position and it's future position -- rather than calculating it's new position and then checking if it has hit the boundary. This is a little bit more complicated than the usual circle/rectangle collission problem. I have a vague idea of how I should do it -- basically create a bounding rectangle between the current position and the new position, which brings up a slew of problems of it's own (Since the rectangle is rotated according to the direction of the circle's velocity). However, I'm thinking that this is a common problem, and that a common solution already exists. Is there a common solution to this kind of problem? Perhaps some basic theories which I should look into?

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  • What technologies to use for a particle system with enormous calculation demand?

    - by Amir Rezaei
    I have a particle system with X particles. Each particle tests for collision with other particles. This gives X*X = X^2 collision tests per frame. For 60f/s, this corresponds to 60*X^2 collision detection per second. What is the best technological approach for these intensive calculations? Should I use F#, C, C++ or C#, or something else? The following are constraints The code is written in C# with the latest XNA Multi-threaded may be considered No special algorithm that tests the collision with the nearest neighbors or that reduces the problem The last constraint may be strange, so let me explain. Regardless constraint 3, given a problem with enormous computational requirement what would be the best approach to solve the problem. An algorithm reduces the problem; still the same algorithm may behave different depending on technology. Consider pros and cons of CLR vs native C.

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  • Collision Handling in Javascript - Particles Get Stuck

    - by Conner Ruhl
    I am trying to recreate this, and I have been fairly successful. I am having issues with the collision handling though. Although the collision handling seems to work, it has very strange behavior. Here is what I have so far. This is the code that handles collisions: var dx = particle2.getX() - particle1.getX(); var dy = particle2.getY() - particle1.getY(); var angle = Math.atan2(dy, dx); var newP2X = particle1.getX() + (particle1.getRadius() + particle2.getRadius()) * Math.cos(angle); var newP2Y = particle1.getY() + (particle1.getRadius() + particle2.getRadius()) * Math.sin(angle); particle2.setX(newP2X); particle2.setY(newP2Y); var p1Vxi = particle1.getVx(); var p1Vyi = particle1.getVy(); var p1Mass = particle1.getMass(); var p2Vxi = particle2.getVx(); var p2Vyi = particle2.getVy(); var p2Mass = particle2.getMass(); var vxf = (p1Mass * p1Vxi + p2Mass * p2Vxi) / (p1Mass + p2Mass); var vyf = (p1Mass * p1Vyi + p2Mass * p2Vyi) / (p1Mass + p2Mass); particle1.setVx(vxf); particle1.setVy(vyf); particle2.setVx(vxf); particle2.setVy(vyf); EDIT: I have tried to change it to inelastic collisions like suggested, but for some reason the balls collide erratically. Check it out here. Any help is much appreciated!

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  • How to calculate deceleration rate of a flipping coin (in c)?

    - by Horace Ho
    A flipping coin on table will slow down and drop to the table surface, facing up or down. How can I calculate the flip-per-second declaration rate over time? For example, assuming the coin is at 10 flipping per second when it starts how long will it take to stop? For each second (9, 8, 7, 6 ... 3, 2, 1, stop), how is the flipping rate changed? Friction can be approximated as some real world objects (say, a metallic coin on a wooden table). Thanks!

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  • Is this a good way to do a game loop for an iPhone game?

    - by Danny Tuppeny
    Hi all, I'm new to iPhone dev, but trying to build a 2D game. I was following a book, but the game loop it created basically said: function gameLoop update() render() sleep(1/30th second) gameLoop The reasoning was that this would run at 30fps. However, this seemed a little mental, because if my frame took 1/30th second, then it would run at 15fps (since it'll spend as much time sleeping as updating). So, I did some digging and found the CADisplayLink class which would sync calls to my gameLoop function to the refresh rate (or a fraction of it). I can't find many samples of it, so I'm posting here for a code review :-) It seems to work as expected, and it includes passing the elapsed (frame) time into the Update method so my logic can be framerate-independant (however I can't actually find in the docs what CADisplayLink would do if my frame took more than its allowed time to run - I'm hoping it just does its best to catch up, and doesn't crash!). // // GameAppDelegate.m // // Created by Danny Tuppeny on 10/03/2010. // Copyright Danny Tuppeny 2010. All rights reserved. // #import "GameAppDelegate.h" #import "GameViewController.h" #import "GameStates/gsSplash.h" @implementation GameAppDelegate @synthesize window; @synthesize viewController; - (void) applicationDidFinishLaunching:(UIApplication *)application { // Create an instance of the first GameState (Splash Screen) [self doStateChange:[gsSplash class]]; // Set up the game loop displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(gameLoop)]; [displayLink setFrameInterval:2]; [displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; } - (void) gameLoop { // Calculate how long has passed since the previous frame CFTimeInterval currentFrameTime = [displayLink timestamp]; CFTimeInterval elapsed = 0; // For the first frame, we want to pass 0 (since we haven't elapsed any time), so only // calculate this in the case where we're not the first frame if (lastFrameTime != 0) { elapsed = currentFrameTime - lastFrameTime; } // Keep track of this frames time (so we can calculate this next time) lastFrameTime = currentFrameTime; NSLog([NSString stringWithFormat:@"%f", elapsed]); // Call update, passing the elapsed time in [((GameState*)viewController.view) Update:elapsed]; } - (void) doStateChange:(Class)state { // Remove the previous GameState if (viewController.view != nil) { [viewController.view removeFromSuperview]; [viewController.view release]; } // Create the new GameState viewController.view = [[state alloc] initWithFrame:CGRectMake(0, 0, IPHONE_WIDTH, IPHONE_HEIGHT) andManager:self]; // Now set as visible [window addSubview:viewController.view]; [window makeKeyAndVisible]; } - (void) dealloc { [viewController release]; [window release]; [super dealloc]; } @end Any feedback would be appreciated :-) PS. Bonus points if you can tell me why all the books use "viewController.view" but for everything else seem to use "[object name]" format. Why not [viewController view]?

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  • The most efficient method of drawing multiple quads in OpenGL

    - by CPatton
    I'm not very keen with OpenGL and I was wondering if someone could give me some insight on this. I'm a 'seasoned' programmer, I've read the redbook about VBOs and the like, but I was wondering from a more experienced person about the best/most efficient way of achieving this. I've been producing this 2d tile-based game engine to be used in several projects. I have a class called "ScreenObject" which is mainly composed of a Dictionary<Point, Tile> The Point key is to show where to render the Tile on the screen, and the Tile contains one or more textures to be drawn at that point. This ScreenObject is where the tiles will be modified, deleted, added, etc.. My original method of drawing the tiles in the testing I've done was to iterate through the ScreenObject and draw each quad at each location separately. From what I've read, this is a massive waste of resources. It wasn't horribly slow in the testing, but after I've completed the animation classes and effect classes, I'm sure it would be extremely slow. And one last thing, if you wouldn't mind.. As I said before, the Tile class can contain multiple textures to be drawn at the Point location on the screen. I recognize possibly two options for me here. Either add a quad at that location for each texture to be drawn, or, somehow.. use a multiple texture for the same quad (if it's possible). Even if each tile contained one texture only, that would be 64 quads to be drawn on the screen. Most of the tiles will contain 2-5 textures, so the number of total quads would increase dramatically with this method. Would it be feasible to add a quad for each new texture, or am I ignoring a better way to do this? Just need some help understanding this if you don't mind :) I've tried to be as concise as possible, and I'd greatly appreciate any responses.. and even some criticism. Programming is often a learning process and one who develops seems to never stops learning. Thanks for your time.

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  • iphone quartz drawing 2 lines on top of each other causes worm effect

    - by Leonard
    I'm using Quartz-2D for iPhone to display a route on a map. The route is colored according to temperature. Because some streets are colored yellow, I am using a slightly thicker black line under the route line to create a border effect, so that yellow parts of the route are spottable on yellow streets. But, even if the black line is as thick as the route line, the whole route looks like a worm (very ugly). I tought this was because I was drawing lines from waypoint to waypoint, instead using the last waypoint as the next starting waypoint. That way if there is a couple of waypoints missing, the route will still have no cuts. What do I need to do to display both lines without a worm effect? -(void) drawRect:(CGRect) rect { CSRouteAnnotation* routeAnnotation = (CSRouteAnnotation*)self.routeView.annotation; // only draw our lines if we're not int he moddie of a transition and we // acutally have some points to draw. if(!self.hidden && nil != routeAnnotation.points && routeAnnotation.points.count > 0) { CGContextRef context = UIGraphicsGetCurrentContext(); Waypoint* fromWaypoint = [[Waypoint alloc] initWithDictionary:[routeAnnotation.points objectAtIndex:0]]; Waypoint* toWaypoint; for(int idx = 1; idx < routeAnnotation.points.count; idx++) { toWaypoint = [[Waypoint alloc] initWithDictionary:[routeAnnotation.points objectAtIndex:idx]]; CLLocation* fromLocation = [fromWaypoint getLocation]; CGPoint fromPoint = [self.routeView.mapView convertCoordinate:fromLocation.coordinate toPointToView:self]; CLLocation* toLocation = [toWaypoint getLocation]; CGPoint toPoint = [self.routeView.mapView convertCoordinate:toLocation.coordinate toPointToView:self]; routeAnnotation.lineColor = [fromWaypoint.weather getTemperatureColor]; CGContextBeginPath(context); CGContextSetLineWidth(context, 3.0); CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor); CGContextMoveToPoint(context, fromPoint.x, fromPoint.y); CGContextAddLineToPoint(context, toPoint.x, toPoint.y); CGContextStrokePath(context); CGContextClosePath(context); CGContextBeginPath(context); CGContextSetLineWidth(context, 3.0); CGContextSetStrokeColorWithColor(context, routeAnnotation.lineColor.CGColor); CGContextMoveToPoint(context, fromPoint.x, fromPoint.y); CGContextAddLineToPoint(context, toPoint.x, toPoint.y); CGContextStrokePath(context); CGContextClosePath(context); fromWaypoint = toWaypoint; } [fromWaypoint release]; [toWaypoint release]; } } Also, I get a <Error>: CGContextClosePath: no current point. error, which I think is bullshit. Please hint me! :)

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  • Problem intialising 2D array

    - by TeeJay
    Ok, so I have a 2D Array that is initialised with values from a file (format: x y z). My file reads in the values correctly but when adding the z value to the matrix/2DArray, I run into a segfault and I have no idea why. It is possibly incorrect use of pointers? I still don't quite have the hang of them yet. This is my intialiser, works fine, even intialises all "z" values to 0. int** make2DArray(int rows, int columns) { int** newArray; newArray = (int**)malloc(rows*sizeof(int*)); if (newArray == NULL) { printf("out of memory for newArray.\n"); } for (int i = 0; i < rows; i++) { newArray[i] = (int*)malloc(columns*sizeof(int)); if (newArray[i] == NULL) { printf("out of memory for newArray[%d].\n", i); } } //intialise all values to 0 for (int i = 0; i < rows; i++) { for (int j = 0; j < columns; j++) { newArray[i][j] = 0; } } return newArray; } This is how I call the initialiser (and problem function). int** map = make2DArray(rows, columns); fillMatrix(&map, mapFile); And this is the problem code. void fillMatrix(int*** inMatrix, FILE* inFile) { int x, y, z; char line[100]; while(fgets(line, sizeof(line), inFile) != NULL) { sscanf(line, "%d %d %d", &x, &y, &z); *inMatrix[x][y] = z; } } From what I can gather through the use of ddd, the problem comes when y gets to 47. The map file has a max "x" value of 47 and a max "y" value of 63, I'm pretty sure I haven't got the order mixed up, so I don't know why the program is segfault-ing? I'm sure it's some newbie mistake...

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  • Joystick input in Java

    - by typoknig
    Hi all, I am making a 2D game in Java and I want to use a joystick to control the movement of some crosshairs. Right now I have it so the mouse can control those crosshairs. My only criteria for this is that the control for the crosshair must stay in the game window unless a user clicks off into another window. Basically I want my game to capture whatever device is controlling the crosshairs much like a virtual machine captures a mouse. The joystick I am using (Thrustmaster Hotas Cougar) comes with some pretty advanced features, so that may make this easier (or harder). I have tried the solution listed on this page, but I am using a 64bit computer and for some reason it does not like that. I have also tried to use the key emulation feature of my joystick, but with little success. Here is what I have so far, any pointer would be appreciated. Main Class: import java.awt.Color; import java.awt.Cursor; import java.awt.event.MouseEvent; import java.awt.event.MouseMotionListener; import java.awt.Graphics; import java.awt.Image; import java.awt.image.BufferStrategy; import java.awt.image.MemoryImageSource; import java.awt.Point; import java.awt.Toolkit; import javax.swing.JFrame; public class Game extends JFrame implements MouseMotionListener{ private int windowWidth = 1280; private int windowHeight = 1024; private Crosshair crosshair; public static void main(String[] args) { new Game(); } public Game() { this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setSize(windowWidth, windowHeight); this.setResizable(false); this.setLocation(0,0); this.setVisible(true); this.createBufferStrategy(2); addMouseMotionListener(this); initGame(); while(true) { long start = System.currentTimeMillis(); gameLoop(); while(System.currentTimeMillis()-start < 5) { //empty while loop } } } private void initGame() { hideCursor(); crosshair = new Crosshair (windowWidth/2, windowHeight/2); } private void gameLoop() { //game logic drawFrame(); } private void drawFrame() { BufferStrategy bf = this.getBufferStrategy(); Graphics g = (Graphics)bf.getDrawGraphics(); try { g = bf.getDrawGraphics(); Color darkBlue = new Color(0x010040); g.setColor(darkBlue); g.fillRect(0, 0, windowWidth, windowHeight); drawCrossHair(g); } finally { g.dispose(); } bf.show(); Toolkit.getDefaultToolkit().sync(); } private void drawCrossHair(Graphics g){ Color yellow = new Color (0xEDFF62); g.setColor(yellow); g.drawOval(crosshair.x, crosshair.y, 40, 40); g.fillArc(crosshair.x + 10, crosshair.y + 21 , 20, 20, -45, -90); g.fillArc(crosshair.x - 1, crosshair.y + 10, 20, 20, -135, -90); g.fillArc(crosshair.x + 10, crosshair.y - 1, 20, 20, -225, -90); g.fillArc(crosshair.x + 21, crosshair.y + 10, 20, 20, -315, -90); } @Override public void mouseDragged(MouseEvent e) { //empty method } @Override public void mouseMoved(MouseEvent e) { crosshair.x = e.getX(); crosshair.y = e.getY(); } private void hideCursor() { int[] pixels = new int[16 * 16]; Image image = Toolkit.getDefaultToolkit().createImage(new MemoryImageSource(16, 16, pixels, 0, 16)); Cursor transparentCursor = Toolkit.getDefaultToolkit().createCustomCursor(image, new Point(0, 0), "invisiblecursor"); getContentPane().setCursor(transparentCursor); } } Another Class: public class Crosshair{ public int x; public int y; public Crosshair(int x, int y) { this.x = x; this.y = y; } }

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  • Algorithm to select groups of similar items in 2d array

    - by mafutrct
    There is a 2d array of items (in my case they are called Intersections). A certain item is given as a start. The task is to find all items directly or indirectly connected to this item that satisfy a certain function. So the basic algorithm is like this: Add the start to the result list. Repeat until no modification: Add each item in the array that satisfies the function and touches any item in the result list to the result list. My current implementation looks like this: private IList<Intersection> SelectGroup ( Intersection start, Func<Intersection, Intersection, bool> select) { List<Intersection> result = new List<Intersection> (); Queue<Intersection> source = new Queue<Intersection> (); source.Enqueue (start); while (source.Any ()) { var s = source.Dequeue (); result.Add (s); foreach (var neighbour in Neighbours (s)) { if (select (start, neighbour) && !result.Contains (neighbour) && !source.Contains (neighbour)) { source.Enqueue (neighbour); } } } Debug.Assert (result.Distinct ().Count () == result.Count ()); Debug.Assert (result.All (x => select (x, result.First ()))); return result; } private List<Intersection> Neighbours (IIntersection intersection) { int x = intersection.X; int y = intersection.Y; List<Intersection> list = new List<Intersection> (); if (x > 1) { list.Add (GetIntersection (x - 1, y)); } if (y > 1) { list.Add (GetIntersection (x, y - 1)); } if (x < Size) { list.Add (GetIntersection (x + 1, y)); } if (y < Size) { list.Add (GetIntersection (x, y + 1)); } return list; } (The select function takes a start item and returns true iff the second item satisfies.) This does its job and turned out to be reasonable fast for the usual array sizes (about 20*20). However, I'm interested in further improvements. Any ideas? Example (X satisfies in relation to other Xs, . does never satisfy): .... XX.. .XX. X... In this case, there are 2 groups: a central group of 4 items and a group of a single item in the lower left. Selecting the group (for instance by starting item [2, 2]) returns the former, while the latter can be selected using the starting item and sole return value [0, 3]. Example 2: .A.. ..BB A.AA This time there are 4 groups. The 3 A groups are not connected, so they are returned as separate groups. The bigger A and B groups are connected, but A does not related to B so they are returned as separate groups.

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  • texture colours opengl

    - by user1324894
    Hi I am making a simple 2D game in c++ and for the map I am doing texture mapping by using tiles and assigning textures to those tiles. However, when I run the programme the textures become black and white when I want them to be the colour they are in the .png image. This is my code: int worldMap[10][10] = { {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0,0,0}, }; void background() { glClearColor(0.0,0.0,0.0,0.0); /**********************************************************************************************/ // Texture loading object nv::Image img; // Return true on success if(img.loadImageFromFile("Image_Loading/field.png")) { glGenTextures(1, &myTexture); glBindTexture(GL_TEXTURE_2D, myTexture); glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE); glTexImage2D(GL_TEXTURE_2D, 0, img.getInternalFormat(), img.getWidth(), img.getHeight(), 0, img.getFormat(), img.getType(), img.getLevel(0)); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT ); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, 16.0f); } else MessageBox(NULL, "Failed to load texture", "End of the world", MB_OK | MB_ICONINFORMATION); /**********************************************************************************************/ } void drawTiles (void) { //our function to draw the tiles for (int i = 0; i < 10; i++) //loop through the height of the map { for (int j = 0; j < 10; j++) //loop through the width of the map { if (worldMap[i][j] == 0) //if the map at this position contains a 0 { glBindTexture( GL_TEXTURE_2D, myTexture ); //bind our grass texture to our shape } glPushMatrix(); //push the matrix so that our translations only affect this tile glTranslatef(j, -i, 0); //translate the tile to where it should belong glBegin (GL_QUADS); //begin drawing our quads glTexCoord2d(10, 0); glVertex2f((-10 + mapX),(-10 + mapY)); //with our vertices we have to assign a texcoord glTexCoord2d(10, 0); glVertex2f((10 + mapX),(-10 + mapY)); //so that our texture has some points to draw to glTexCoord2d(10, 10); glVertex2f((10 + mapX),(10 + mapY)); glTexCoord2d(0, 10); glVertex2f((-10 + mapX),(10 + mapY)); glEnd(); glPopMatrix(); //pop the matrix } //end first loop } //end second loop } void display() { glClearColor (0.0,0.0,0.0,1.0); glClear(GL_COLOR_BUFFER_BIT); /**********************************************************************************************/ glMatrixMode( GL_PROJECTION ); glLoadIdentity(); gluOrtho2D( -5, 5, -5, 5); glMatrixMode( GL_MODELVIEW ); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, myTexture); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); drawTiles(); glDisable(GL_TEXTURE_2D); glDisable(GL_BLEND); /**********************************************************************************************/ } void character () { glBegin(GL_POLYGON); glVertex2f((-0.5+characterX),(-0.5 +characterY)); glVertex2f((-0.5+characterX),(0.5+characterY)); glVertex2f((0.5+characterX),(0.5+characterY)); glVertex2f((0.5+characterX),(-0.5+characterY)); glTranslatef(characterX, characterY, 0.0f); glEnd(); } Can anybody help please?

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  • Confusion testing fftw3 - poisson equation 2d test

    - by user3699736
    I am having trouble explaining/understanding the following phenomenon: To test fftw3 i am using the 2d poisson test case: laplacian(f(x,y)) = - g(x,y) with periodic boundary conditions. After applying the fourier transform to the equation we obtain : F(kx,ky) = G(kx,ky) /(kx² + ky²) (1) if i take g(x,y) = sin (x) + sin(y) , (x,y) \in [0,2 \pi] i have immediately f(x,y) = g(x,y) which is what i am trying to obtain with the fft : i compute G from g with a forward Fourier transform From this i can compute the Fourier transform of f with (1). Finally, i compute f with the backward Fourier transform (without forgetting to normalize by 1/(nx*ny)). In practice, the results are pretty bad? (For instance, the amplitude for N = 256 is twice the amplitude obtained with N = 512) Even worse, if i try g(x,y) = sin(x)*sin(y) , the curve has not even the same form of the solution. (note that i must change the equation; i divide by two the laplacian in this case : (1) becomes F(kx,ky) = 2*G(kx,ky)/(kx²+ky²) Here is the code: /* * fftw test -- double precision */ #include <iostream> #include <stdio.h> #include <stdlib.h> #include <math.h> #include <fftw3.h> using namespace std; int main() { int N = 128; int i, j ; double pi = 3.14159265359; double *X, *Y ; X = (double*) malloc(N*sizeof(double)); Y = (double*) malloc(N*sizeof(double)); fftw_complex *out1, *in2, *out2, *in1; fftw_plan p1, p2; double L = 2.*pi; double dx = L/((N - 1)*1.0); in1 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); out2 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); out1 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); in2 = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*(N*N) ); p1 = fftw_plan_dft_2d(N, N, in1, out1, FFTW_FORWARD,FFTW_MEASURE ); p2 = fftw_plan_dft_2d(N, N, in2, out2, FFTW_BACKWARD,FFTW_MEASURE); for(i = 0; i < N; i++){ X[i] = -pi + (i*1.0)*2.*pi/((N - 1)*1.0) ; for(j = 0; j < N; j++){ Y[j] = -pi + (j*1.0)*2.*pi/((N - 1)*1.0) ; in1[i*N + j][0] = sin(X[i]) + sin(Y[j]) ; // row major ordering //in1[i*N + j][0] = sin(X[i]) * sin(Y[j]) ; // 2nd test case in1[i*N + j][1] = 0 ; } } fftw_execute(p1); // FFT forward for ( i = 0; i < N; i++){ // f = g / ( kx² + ky² ) for( j = 0; j < N; j++){ in2[i*N + j][0] = out1[i*N + j][0]/ (i*i+j*j+1e-16); in2[i*N + j][1] = out1[i*N + j][1]/ (i*i+j*j+1e-16); //in2[i*N + j][0] = 2*out1[i*N + j][0]/ (i*i+j*j+1e-16); // 2nd test case //in2[i*N + j][1] = 2*out1[i*N + j][1]/ (i*i+j*j+1e-16); } } fftw_execute(p2); //FFT backward // checking the results computed double erl1 = 0.; for ( i = 0; i < N; i++) { for( j = 0; j < N; j++){ erl1 += fabs( in1[i*N + j][0] - out2[i*N + j][0]/N/N )*dx*dx; cout<< i <<" "<< j<<" "<< sin(X[i])+sin(Y[j])<<" "<< out2[i*N+j][0]/N/N <<" "<< endl; // > output } } cout<< erl1 << endl ; // L1 error fftw_destroy_plan(p1); fftw_destroy_plan(p2); fftw_free(out1); fftw_free(out2); fftw_free(in1); fftw_free(in2); return 0; } I can't find any (more) mistakes in my code (i installed the fftw3 library last week) and i don't see a problem with the maths either but i don't think it's the fft's fault. Hence my predicament. I am all out of ideas and all out of google as well. Any help solving this puzzle would be greatly appreciated. note : compiling : g++ test.cpp -lfftw3 -lm executing : ./a.out output and i use gnuplot in order to plot the curves : (in gnuplot ) splot "output" u 1:2:4 ( for the computed solution )

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  • Converting a WPFToolkit DataGrid from 1D list to 2D matrix

    - by user61073
    Hello - I am wondering if anyone has attempted the following or has an idea as to how to do it. I have a WPFToolkit DataGrid which is bound to an ObservableCollection of items. As such, the DataGrid is shown with as many rows in the ObservableCollection, and as many columns as I have defined in for the DataGrid. That all is good. What I now need is to provide another view of the same data, only, instead, the DataGrid is shown with as many cells in the ObservableCollection. So let's say, my ObservableCollection has 100 items in it. The original scenario showed the DataGrid with 100 rows and 1 column. In the modified scenario, I need to show it with 10 rows and 10 columns, where each cell shows the value that was in the original representation. In other words, I need to transform my 1D ObservableCollection to a 2D ObservableCollection and display it in the DataGrid. I know how to do that programmatically in the code behind, but can it be done in XAML? Let me simplify the problem a little, in case anybody can have a crack at this. The XAML below does the following: * Defines an XmlDataProvider just for dummy data * Creates a DataGrid with 10 columns o each column is a DataGridTemplateColumn using the same CellTemplate * The CellTemplate is a simple TextBlock bound to an XML element If you run the XAML below, you will find that the DataGrid ends up with 5 rows, one for each book, and 10 columns that have identical content (all showing the book titles). However, what I am trying to accomplish, albeit with a different data set, is that in this case, I would end up with one row, with each book title appearing in a single cell in row 1, occupying cells 0-4, and nothing in cells 5-9. Then, if I added more data and had 12 books in my XML data source, I would get row 1 completely filled (cells covering the first 10 titles) and row 2 would get the first 2 cells filled. Can my scenario be accomplished primarily in XAML, or should I resign myself to working in the code behind? Any guidance would greatly be appreciated. Thanks so much! <UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:custom="http://schemas.microsoft.com/wpf/2008/toolkit" mc:Ignorable="d" x:Name="UserControl" d:DesignWidth="600" d:DesignHeight="400" > <UserControl.Resources> <XmlDataProvider x:Key="InventoryData" XPath="Inventory/Books"> <x:XData> <Inventory xmlns=""> <Books> <Book ISBN="0-7356-0562-9" Stock="in" Number="9"> <Title>XML in Action</Title> <Summary>XML Web Technology</Summary> </Book> <Book ISBN="0-7356-1370-2" Stock="in" Number="8"> <Title>Programming Microsoft Windows With C#</Title> <Summary>C# Programming using the .NET Framework</Summary> </Book> <Book ISBN="0-7356-1288-9" Stock="out" Number="7"> <Title>Inside C#</Title> <Summary>C# Language Programming</Summary> </Book> <Book ISBN="0-7356-1377-X" Stock="in" Number="5"> <Title>Introducing Microsoft .NET</Title> <Summary>Overview of .NET Technology</Summary> </Book> <Book ISBN="0-7356-1448-2" Stock="out" Number="4"> <Title>Microsoft C# Language Specifications</Title> <Summary>The C# language definition</Summary> </Book> </Books> <CDs> <CD Stock="in" Number="3"> <Title>Classical Collection</Title> <Summary>Classical Music</Summary> </CD> <CD Stock="out" Number="9"> <Title>Jazz Collection</Title> <Summary>Jazz Music</Summary> </CD> </CDs> </Inventory> </x:XData> </XmlDataProvider> <DataTemplate x:Key="GridCellTemplate"> <TextBlock> <TextBlock.Text> <Binding XPath="Title"/> </TextBlock.Text> </TextBlock> </DataTemplate> </UserControl.Resources> <Grid x:Name="LayoutRoot"> <custom:DataGrid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" IsSynchronizedWithCurrentItem="True" Background="{DynamicResource WindowBackgroundBrush}" HeadersVisibility="All" RowDetailsVisibilityMode="Collapsed" SelectionUnit="CellOrRowHeader" CanUserResizeRows="False" GridLinesVisibility="None" RowHeaderWidth="35" AutoGenerateColumns="False" CanUserReorderColumns="False" CanUserSortColumns="False"> <custom:DataGrid.Columns> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="01" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="02" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="03" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="04" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="05" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="06" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="07" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="08" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="09" /> <custom:DataGridTemplateColumn CellTemplate="{StaticResource GridCellTemplate}" Header="10" /> </custom:DataGrid.Columns> <custom:DataGrid.ItemsSource> <Binding Source="{StaticResource InventoryData}" XPath="Book"/> </custom:DataGrid.ItemsSource> </custom:DataGrid> </Grid>

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  • How to render axometric/isometric tiles that are a 2d array in logic, but inclined 45º visually?

    - by TheLima
    I am making a tile-based strategy game which i plan to have 2.5D visuals in an axometric/isometric fashion. Right now i'm programming it's logic and rendering it as a literal 2-dimensional array (perfect squares, like an isometric top-down-view). In short, i have something like this: And i want to turn it to something like this: Do i keep going on the 2d-array logic? Is it all just a change in rendering behavior, as i'm thinking it is? or 2d-array is the wrong approach for my objective and I should change before it's too late? What are the ways of doing it, anyways? How should i apply the 2.5D axometric/isometric view (45º rotation to the side, and 45º rotation upwards)?

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  • How can I create and animate 2D skeletons for HTML5 Javascript games? [on hold]

    - by user414209
    I'm trying to make a 2D fighting game in HTML5(somewhat like street fighter). So basically there are two players, one AI and one Human. The players need to have animations for the body movements. Also, there needs to be some collision detection system. I'm using createjs for coding but to design models/objects/animations, I need some other software. So I'm looking for a software that can: easily make custom animation of 2d objects. The objects structure(skeleton etc.) will be same once defined but need to be defined once. Can export the animations and models in a js readable format(preferably json) Collision detection can be done easily after the exported format is loaded in a game engine. For point 1, I'm looking for some generic skeleton based animation. Sprite-sheet based animations will be difficult for collision detection.

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  • Getting Started with 2d Game Dev (C++): DirectX or OpenGL?

    - by Dfowj
    So, i'm a student looking to get my foot in the door of game development and im looking to do something 2D, maybe a tetris/space invaders/something-with-a-little-mouse-interaction clone. I pointed my searches in the direction of C++ and 2d and was eventually lead to DirectX/OpenGL Now as i understand it, all these packages will do for me is draw stuff on a screen. And thats all i really care about at this point. Sound isn't necessary. Input can be handled with stdlib probably. So, for a beginner trying to create a basic game in C++, would you recommend DirectX or OpenGL? Why? What are some key feature differences between the two? Which is more usable?

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  • How to snap a 2D Quad to the mouse cursor using OpenGL 3.0/WIN32?

    - by NoobScratcher
    I've been having issues trying to snap a 2D Quad to the mouse cursor position I'm able : 1.) To get values into posX, posY, posZ 2.) Translate with the values from those 3 variables But the quad positioning I'm not able to do correctly in such a way that the 2D Quad is near the mouse cursor using those values from those 3 variables eg."posX, posY, posZ" I need the mouse cursor in the center of the 2D Quad. I'm hoping someone can help me achieve this. I've tried searching around with no avail. Heres the function that is ment to do the snapping but instead creates weird flicker or shows nothing at all only the 3d models show up : void display() { glClearColor(0.0,0.0,0.0,1.0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); for(std::vector<GLuint>::iterator I = cube.begin(); I != cube.end(); ++I) { glCallList(*I); } if(DrawArea == true) { glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ); cerr << winZ << endl; glGetDoublev(GL_MODELVIEW_MATRIX, modelview); glGetDoublev(GL_PROJECTION_MATRIX, projection); glGetIntegerv(GL_VIEWPORT, viewport); gluUnProject(winX, winY, winZ , modelview, projection, viewport, &posX, &posY, & posZ); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, DrawAreaSurface->w, DrawAreaSurface->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, DrawAreaSurface->pixels); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glTranslatef(posX , posY, posZ); glBegin(GL_QUADS); glTexCoord2f (0.0, 0.0); glVertex3f(0.5, 0.5, 0); glTexCoord2f (1.0, 0.0); glVertex3f(0, 0.5, 0); glTexCoord2f (1.0, 1.0); glVertex3f(0, 0, 0); glTexCoord2f (0.0, 1.0); glVertex3f(0.5, 0, 0); glEnd(); } SwapBuffers(hDC); } I'm using : OpenGL 3.0 WIN32 API C++ GLSL if you really want the full source here it is - http://pastebin.com/1Ncm9HNf , Its pretty messy.

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  • How to snap a 2D Quad to the mouse cursor using OpenGL 3.0?

    - by NoobScratcher
    I've been having issues trying to snap a 2D Quad to the mouse cursor position I'm able : 1.) To get values into posX, posY, posZ 2.) Translate with the values from those 3 variables But the quad positioning I'm not able to do correctly in such a way that the 2D Quad is near the mouse cursor using those values from those 3 variables eg."posX, posY, posZ" I need the mouse cursor in the center of the 2D Quad. I'm hoping someone can help me achieve this. I've tried searching around with no avail. Heres the function that is ment to do the snapping but instead creates weird flicker or shows nothing at all only the 3d models show up : void display() { glClearColor(0.0,0.0,0.0,1.0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); for(std::vector<GLuint>::iterator I = cube.begin(); I != cube.end(); ++I) { glCallList(*I); } if(DrawArea == true) { glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ); cerr << winZ << endl; glGetDoublev(GL_MODELVIEW_MATRIX, modelview); glGetDoublev(GL_PROJECTION_MATRIX, projection); glGetIntegerv(GL_VIEWPORT, viewport); gluUnProject(winX, winY, winZ , modelview, projection, viewport, &posX, &posY, & posZ); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, DrawAreaSurface->w, DrawAreaSurface->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, DrawAreaSurface->pixels); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glTranslatef(posX , posY, posZ); glBegin(GL_QUADS); glTexCoord2f (0.0, 0.0); glVertex3f(0.5, 0.5, 0); glTexCoord2f (1.0, 0.0); glVertex3f(0, 0.5, 0); glTexCoord2f (1.0, 1.0); glVertex3f(0, 0, 0); glTexCoord2f (0.0, 1.0); glVertex3f(0.5, 0, 0); glEnd(); } SwapBuffers(hDC); } I'm using : OpenGL 3.0 WIN32 API C++ GLSL if you really want the full source here it is - http://pastebin.com/1Ncm9HNf , Its pretty messy.

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  • VMware Data Recovery error -3960 and Event ID 8193 on Windows Server 2003

    - by flooooo
    I've been trying to solve this problem since a few days now without any success. What I'm trying is to make a backup of a virtual machine running Windows Server 2003 SP 2 using VMware Data Recovery 2.0.0.1861. When starting the backup task it tries to make a snapshot of the virtual machine using VSS which fails with error: Event Type: Error Event Source: VSS Event Category: None Event ID: 8193 Date: 05.06.2012 Time: 12:12:01 User: N/A Computer: LEGOLAS Description: Volume Shadow Copy Service error: Unexpected error calling routine RegSaveKeyExW. hr = 0x800703f8. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. Data: 0000: 2d 20 43 6f 64 65 3a 20 - Code: 0008: 57 52 54 52 45 47 52 43 WRTREGRC 0010: 30 30 30 30 30 33 39 36 00000396 0018: 2d 20 43 61 6c 6c 3a 20 - Call: 0020: 57 52 54 52 45 47 52 43 WRTREGRC 0028: 30 30 30 30 30 33 31 38 00000318 0030: 2d 20 50 49 44 3a 20 20 - PID: 0038: 30 30 30 30 36 34 38 38 00006488 0040: 2d 20 54 49 44 3a 20 20 - TID: 0048: 30 30 30 30 34 33 38 34 00004384 0050: 2d 20 43 4d 44 3a 20 20 - CMD: 0058: 43 3a 5c 57 49 4e 44 4f C:\WINDO 0060: 57 53 5c 53 79 73 74 65 WS\Syste 0068: 6d 33 32 5c 76 73 73 76 m32\vssv 0070: 63 2e 65 78 65 20 20 20 c.exe 0078: 2d 20 55 73 65 72 3a 20 - User: 0080: 4e 54 20 41 55 54 48 4f NT AUTHO 0088: 52 49 54 59 5c 53 59 53 RITY\SYS 0090: 54 45 4d 20 20 20 20 20 TEM 0098: 2d 20 53 69 64 3a 20 20 - Sid: 00a0: 53 2d 31 2d 35 2d 31 38 S-1-5-18 This machine was converted p2v. I have no idea where to search for the problem and what to do. Google showed a few result but none of them were useful for me. Please help me. If you need further information I'll tell you - just ask!

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  • converting 2D mouse coordinates to 3D space in OpenGL ES

    - by Jayesh
    I want to convert mouse's current X and Y coordinates into the 3D space I have drawn in the viewport. I need to do this on the OpenGL ES platform. I found following possible solutions implemented in OpenGL, but none fits what I am looking for. I found NeHe's tutorial on doing exactly this, but in traditional OpenGL way. It uses gluUnProject. http://nehe.gamedev.net/data/articles/article.asp?article=13 Although gluUnProject is not available in OpenGL ES, its implementation seems simple enough to port back. But before calling it, we need to call glReadPixels with GL_DEPTH_COMPONENT and that is not possible in OpenGL ES. (The reason I found in this thread: http://www.khronos.org/message_boards/viewtopic.php?f=4&t=771) What I want to do is similar to picking, except that I don't want to select the object but I want exact coordinates so that I can recognize particular portion of the object that is currently under mouse cursor. I went through the Picking tutorials in this answer. http://stackoverflow.com/posts/2211312/revisions But they need glRenderMode, which I believe is absent in OpenGL ES. If you know how to solve this problem in OpenGL ES, please let me know. Thanks.

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  • C++ Direct 2D How To Resize ID2D1Bitmap

    - by Nkosi Dean
    I'm making myself a simple GUI library for a game I'm making and each control needs to have a Bitmap to draw to when the control needs redrawing. When it does not need to be redrawn, it will have an already made bitmap ready to display to the screen. Since controls can be resized, this Bitmap also needs to be resized so the control can be fully drawn into it properly. How can I achieve this since it does not appear to be a Resize method to resize a bitmap, unlike an ID2D1HwndRenderTarget, which can be resized?

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  • Simplest Algorithm for 2D Interpolation

    - by Gayan
    I have two shapes which are cross sections of a channel. I want to calculate the cross section of an intermediate point between the two defined points. What's the simplest algorithm to use in this situation? P.S. I came across several algorithms like natural neighbor and poisson which seemed complex. I'm looking for a simple solution which could be implemented quickly

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  • Simple iPhone drawing app with Quartz 2D

    - by Mr guy 4
    I am making a simple iPhone drawing program as a personal side-project. I capture touches event in a subclassed UIView and render the actual stuff to a seperate CGLayer. After each render, I call [self setNeedsLayout] and in the drawRect: method I draw the CGLayer to the screen context. This all works great and performs decently for drawing rectangles. However, I just want a simple "freehand" mode like a lot of other iPhone applications have. The way I thought to do this was to create a CGMutablePath, and simply: CGMutablePathRef path; -(void)touchBegan { path = CGMutablePathCreate(); } -(void)touchMoved { CGPathMoveToPoint(path,NULL,x,y); CGPathAddLineToPoint(path,NULL,x,y); } -(void)drawRect:(CGContextRef)context { CGContextBeginPath(context); CGContextAddPath(context,path); CGContextStrokePath(context); } However, after drawing for more than 1 second, performance degrades miserably. I would just draw each line into the off-screen CGLayer, if it were not for variable opacity! The less-than-100% opacity causes dots to be left on the screen connecting the lines. I have looked at CGContextSetBlendingMode() but alas I cannot find an answer. Can anyone point me in the right direction? Other iPhone apps are able to do this with very good efficiency.

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