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  • Change storyboard UIImageView to own class with backgroundcolor

    - by Thomas
    I want to draw the background image on my own, so I decided to implement a UIImageView class and connect it in the Storyboard. As first task I just want to set the backgroundcolor of the image on my own, but it's never shown. Image just stays blank. That's the class: class FirstBackgroundImage : UIImageView { required init(coder aDecoder: NSCoder) { super.init(coder: aDecoder) self.backgroundColor = UIColor.redColor() } override init() { super.init() self.backgroundColor = UIColor.redColor() } override required init(image: UIImage!) { super.init(image: image) self.backgroundColor = UIColor.redColor() } } That's how i connected it:

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  • XNA 3D model collision is inaccurate

    - by Daniel Lopez
    I am creating a classic game in 3d that deals with asteriods and you have to shoot them and avoid being hit from them. I can generate the asteroids just fine and the ship can shoot bullets just fine. But the asteroids always hit the ship even it doesn't look they are even close. I know 2D collision very well but not 3D so can someone please shed some light to my problem. Thanks in advance. Code For ModelRenderer: using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace _3D_Asteroids { class ModelRenderer { private float aspectratio; private Model model; private Vector3 camerapos; private Vector3 modelpos; private Matrix rotationy; float radiansy = 0; private bool isalive; public ModelRenderer(Model m, float AspectRatio, Vector3 initial_pos, Vector3 initialcamerapos) { isalive = true; model = m; if (model.Meshes.Count == 0) { throw new Exception("Invalid model because it contains zero meshes!"); } modelpos = initial_pos; camerapos = initialcamerapos; aspectratio = AspectRatio; return; } public float RadiusOfSphere { get { return model.Meshes[0].BoundingSphere.Radius; } } public BoundingBox BoxBounds { get { return BoundingBox.CreateFromSphere(model.Meshes[0].BoundingSphere); } } public BoundingSphere SphereBounds { get { return model.Meshes[0].BoundingSphere; } } public Vector3 CameraPosition { set { camerapos = value; } get { return camerapos; } } public bool IsAlive { get { return isalive; } } public Vector3 ModelPosition { set { modelpos = value; } get { return modelpos; } } public void RotateY(float radians) { radiansy += radians; rotationy = Matrix.CreateRotationY(radiansy); } public Matrix RotationY { set { rotationy = value; } get { return rotationy; } } public float AspectRatio { set { aspectratio = value; } get { return aspectratio; } } public void Kill() { isalive = false; } public void Draw(float scale) { Matrix world; if (rotationy == new Matrix(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)) { world = Matrix.CreateScale(scale) * Matrix.CreateTranslation(modelpos); } else { world = rotationy * Matrix.CreateScale(scale) * Matrix.CreateTranslation(modelpos); } Matrix view = Matrix.CreateLookAt(camerapos, Vector3.Zero, Vector3.Up); Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), this.AspectRatio, 1f, 100000f); foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = world; effect.View = view; effect.Projection = projection; } mesh.Draw(); } } public void Draw() { Matrix world; if (rotationy == new Matrix(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)) { world = Matrix.CreateTranslation(modelpos); } else { world = rotationy * Matrix.CreateTranslation(modelpos); } Matrix view = Matrix.CreateLookAt(camerapos, Vector3.Zero, Vector3.Up); Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), this.AspectRatio, 1f, 100000f); foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = world; effect.View = view; effect.Projection = projection; } mesh.Draw(); } } } Code For Game1: using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace _3D_Asteroids { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; int score = 0, lives = 5; SpriteBatch spriteBatch; GameState gstate = GameState.OnMenuScreen; Menu menu = new Menu(Color.Yellow, Color.White); SpriteFont font; Texture2D background; ModelRenderer ship; Model b, a; List<ModelRenderer> bullets = new List<ModelRenderer>(); List<ModelRenderer> asteriods = new List<ModelRenderer>(); float time = 0.0f; int framecount = 0; SoundEffect effect; public Game1() { graphics = new GraphicsDeviceManager(this); graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 796; graphics.ApplyChanges(); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); font = Content.Load<SpriteFont>("Fonts\\Lucida Console"); background = Content.Load<Texture2D>("Textures\\B1_stars"); Model p1 = Content.Load<Model>("Models\\p1_wedge"); b = Content.Load<Model>("Models\\pea_proj"); a = Content.Load<Model>("Models\\asteroid1"); effect = Content.Load<SoundEffect>("Audio\\tx0_fire1"); ship = new ModelRenderer(p1, GraphicsDevice.Viewport.AspectRatio, new Vector3(0, 0, 0), new Vector3(0, 0, 9000)); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { KeyboardState state = Keyboard.GetState(PlayerIndex.One); switch (gstate) { case GameState.OnMenuScreen: { if (state.IsKeyDown(Keys.Enter)) { switch (menu.SelectedChoice) { case MenuChoices.Play: { gstate = GameState.GameStarted; break; } case MenuChoices.Exit: { this.Exit(); break; } } } if (state.IsKeyDown(Keys.Down)) { menu.MoveSelectedMenuChoiceDown(gameTime); } else if(state.IsKeyDown(Keys.Up)) { menu.MoveSelectedMenuChoiceUp(gameTime); } else { menu.KeysReleased(); } break; } case GameState.GameStarted: { foreach (ModelRenderer bullet in bullets) { if (bullet.ModelPosition.X < (ship.ModelPosition.X + 4000) && bullet.ModelPosition.Z < (ship.ModelPosition.X + 4000) && bullet.ModelPosition.X > (ship.ModelPosition.Z - 4000) && bullet.ModelPosition.Z > (ship.ModelPosition.Z - 4000)) { bullet.ModelPosition += (bullet.RotationY.Forward * 120); } else if (collidedwithasteriod(bullet)) { bullet.Kill(); } else { bullet.Kill(); } } foreach (ModelRenderer asteroid in asteriods) { if (ship.SphereBounds.Intersects(asteroid.BoxBounds)) { lives -= 1; asteroid.Kill(); // This always hits no matter where the ship goes. } else { asteroid.ModelPosition -= (asteroid.RotationY.Forward * 50); } } for (int index = 0; index < asteriods.Count; index++) { if (asteriods[index].IsAlive == false) { asteriods.RemoveAt(index); } } for (int index = 0; index < bullets.Count; index++) { if (bullets[index].IsAlive == false) { bullets.RemoveAt(index); } } if (state.IsKeyDown(Keys.Left)) { ship.RotateY(0.1f); if (state.IsKeyDown(Keys.Space)) { if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0; } } else if (state.IsKeyDown(Keys.Right)) { ship.RotateY(-0.1f); if (state.IsKeyDown(Keys.Space)) { if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0; } } else if (state.IsKeyDown(Keys.Up)) { ship.ModelPosition += (ship.RotationY.Forward * 50); if (state.IsKeyDown(Keys.Space)) { if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0; } } else if (state.IsKeyDown(Keys.Space)) { time += gameTime.ElapsedGameTime.Milliseconds; if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0.0f; } if ((framecount % 60) == 0) { createasteroid(); framecount = 0; } framecount++; break; } } base.Update(gameTime); } void firebullet() { if (bullets.Count < 3) { ModelRenderer bullet = new ModelRenderer(b, GraphicsDevice.Viewport.AspectRatio, ship.ModelPosition, new Vector3(0, 0, 9000)); bullet.RotationY = ship.RotationY; bullets.Add(bullet); } } void createasteroid() { if (asteriods.Count < 2) { Random random = new Random(); float z = random.Next(-13000, -11000); float x = random.Next(-9000, -8000); Random random2 = new Random(); int degrees = random.Next(0, 45); float radians = MathHelper.ToRadians(degrees); ModelRenderer asteroid = new ModelRenderer(a, GraphicsDevice.Viewport.AspectRatio, new Vector3(x, 0, z), new Vector3(0,0, 9000)); asteroid.RotateY(radians); asteriods.Add(asteroid); } } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); switch (gstate) { case GameState.OnMenuScreen: { spriteBatch.Begin(); spriteBatch.Draw(background, Vector2.Zero, Color.White); menu.DrawMenu(ref spriteBatch, font, new Vector2(GraphicsDevice.Viewport.Width / 2, GraphicsDevice.Viewport.Height / 2) - new Vector2(50f), 100f); spriteBatch.End(); break; } case GameState.GameStarted: { spriteBatch.Begin(); spriteBatch.Draw(background, Vector2.Zero, Color.White); spriteBatch.DrawString(font, "Score: " + score.ToString() + "\nLives: " + lives.ToString(), Vector2.Zero, Color.White); spriteBatch.End(); ship.Draw(); foreach (ModelRenderer bullet in bullets) { bullet.Draw(); } foreach (ModelRenderer asteroid in asteriods) { asteroid.Draw(0.1f); } break; } } base.Draw(gameTime); } bool collidedwithasteriod(ModelRenderer bullet) { foreach (ModelRenderer asteroid in asteriods) { if (bullet.SphereBounds.Intersects(asteroid.BoxBounds)) { score += 10; asteroid.Kill(); return true; } } return false; } } } }

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  • OpenGL/SharpGL - Points only on -near surface of Ortho projection?

    - by FTLPhysicsGuy
    When you create points using three dimensions for each point and you use an Ortho projection to view the points, would there be a reason that only the points on the -near surface would appear? For example, if you use (the SharpGL method) gl.Ortho(0, width, height, 0, -10, 10), only the points at z=10 (because the near surface is at -10) actually show up. I'm currently using SharpGL - but I'm hoping the issue I'm having isn't with that particular implementation/library. EDIT: I'm adding the code below that demonstrates the issue. Note that this example requires SharpGL and is in fact a modification of a WPF sample project that comes with the current SharpGL source code (the original sample project is called TwoDSample). The project requires a MainWindow.xaml and a MainWindow.xaml.cs. Here's the xaml: <Window x:Class="TwoDSample.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525" xmlns:my="clr-namespace:SharpGL.WPF;assembly=SharpGL.WPF"> <Grid> <my:OpenGLControl Name="openGLControl1" OpenGLDraw="openGLControl1_OpenGLDraw" OpenGLInitialized="openGLControl1_OpenGLInitialized" Resized="openGLControl1_Resized"/> </Grid> </Window> Here is the code behind: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; using SharpGL.Enumerations; namespace TwoDSample { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } // NOTE: I use this to restrict the openGLControl1_OpenGLDraw method to // drawing only once after m_drawCount is set to zero; int m_drawCount = 0; private void openGLControl1_OpenGLDraw(object sender, SharpGL.SceneGraph.OpenGLEventArgs args) { // NOTE: Only draw once after m_drawCount is set to zero if (m_drawCount < 1) { // Get the OpenGL instance. var gl = args.OpenGL; gl.Color(1f, 0f, 0f); gl.PointSize(2.0f); // Draw 10000 random points. gl.Begin(BeginMode.Points); Random random = new Random(); for (int i = 0; i < 10000; i++) { double x = 10 + 400 * random.NextDouble(); double y = 10 + 400 * random.NextDouble(); double z = (double)random.Next(-10, 0); // Color the point according to z value gl.Color(0f, 0f, 1f); // default to blue if (z == -10) gl.Color(1f, 0f, 0f); // Red for z = -10 else if (z == -1) gl.Color(0f, 1f, 0f); // Green for z = -1 gl.Vertex(x, y, z); } gl.End(); m_drawCount++; } } private void openGLControl1_OpenGLInitialized(object sender, SharpGL.SceneGraph.OpenGLEventArgs args) { } private void openGLControl1_Resized(object sender, SharpGL.SceneGraph.OpenGLEventArgs args) { // NOTE: force the draw routine to happen again when resize occurs m_drawCount = 0; // Get the OpenGL instance. var gl = args.OpenGL; // Create an orthographic projection. gl.MatrixMode(MatrixMode.Projection); gl.LoadIdentity(); // NOTE: Basically no matter what I do, the only points I see are those at // the "near" surface (with z = -zNear)--in this case, I only see green points gl.Ortho(0, openGLControl1.ActualWidth, openGLControl1.ActualHeight, 0, 1, 10); // Back to the modelview. gl.MatrixMode(MatrixMode.Modelview); } } }

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  • How to get image's coordinate on JPanel

    - by Jessy
    This question is related to my previous question http://stackoverflow.com/questions/2376027/how-to-generate-cartesian-coordinate-x-y-from-gridbaglayout I have successfully get the coordinate of each pictures, however when I checked the coordinate through (System.out.println) and the placement of the images on the screen, it seems to be wrong. e.g. if on the screen it was obvious that the x point of the first picture is on cell 2 which is on coordinate of 20, but the program shows x=1. Here is part of the code: public Grid (){ setPreferredSize(new Dimension(600,600)); .... setLayout(new GridBagLayout()); GridBagConstraints gc = new GridBagConstraints(); gc.weightx = 1d; gc.weighty = 1d; gc.insets = new Insets(0, 0, 0, 0);//top, left, bottom, and right gc.fill = GridBagConstraints.BOTH; JLabel[][] label = new JLabel[ROWS][COLS]; Random rand = new Random(); // fill the panel with labels for (int i=0;i<IMAGES;i++){ ImageIcon icon = createImageIcon("myPics.jpg"); int r, c; do{ //pick random cell which is empty r = (int)Math.floor(Math.random() * ROWS); c = (int)Math.floor(Math.random() * COLS); } while (label[r][c]!=null); //randomly scale the images int x = rand.nextInt(50)+30; int y = rand.nextInt(50)+30; Image image = icon.getImage().getScaledInstance(x,y, Image.SCALE_SMOOTH); icon.setImage(image); JLabel lbl = new JLabel(icon); // Instantiate GUI components gc.gridx = r; gc.gridy = c; add(lbl, gc); //add(component, constraintObj); label[r][c] = lbl; } I checked the coordinate through this code: Component[] components = getComponents(); for (Component component : components) { System.out.println(component.getBounds()); }

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  • vtk glyphs 3D, indenpently color and rotation

    - by user3684219
    I try to display thanks to vtk (python wrapper) several glyphs in a scene with each their own colour and rotation. Unfortunately, just the rotation (using vtkTensorGlyph) is taken in consideration by vtk. Reversely, just color is taken in consideration when I use a vtkGlyph3D. Here is a ready to use piece of code with a vtkTensorGlyph. Each cube should have a random color but there all will be in the same color. I read and read again the doc of vtk but I found no solution. Thanks in advance for any idea #!/usr/bin/env python # -*- coding: utf-8 -*- import vtk import scipy.linalg as sc import random as ra import numpy as np import itertools points = vtk.vtk.vtkPoints() # where to locate each glyph in the scene tensors = vtk.vtkDoubleArray() # rotation for each glyph tensors.SetNumberOfComponents(9) colors = vtk.vtkUnsignedCharArray() # should be the color for each glyph colors.SetNumberOfComponents(3) # let's make 10 cubes in the scene for i in range(0, 50, 5): points.InsertNextPoint(i, i, i) # position of a glyph colors.InsertNextTuple3(ra.randint(0, 255), ra.randint(0, 255), ra.randint(0, 255) ) # pick random color rot = list(itertools.chain(*np.reshape(sc.orth(np.random.rand(3, 3)).transpose(), (1, 9)).tolist())) # random rotation matrix (row major) tensors.InsertNextTuple9(*rot) polydata = vtk.vtkPolyData() # create the polydatas polydata.SetPoints(points) polydata.GetPointData().SetTensors(tensors) polydata.GetPointData().SetScalars(colors) cubeSource = vtk.vtkCubeSource() cubeSource.Update() glyphTensor = vtk.vtkTensorGlyph() glyphTensor.SetColorModeToScalars() # is it really work ? try: glyphTensor.SetInput(polydata) except AttributeError: glyphTensor.SetInputData(polydata) glyphTensor.SetSourceConnection(cubeSource.GetOutputPort()) glyphTensor.ColorGlyphsOn() # should not color all cubes independently ? glyphTensor.ThreeGlyphsOff() glyphTensor.ExtractEigenvaluesOff() glyphTensor.Update() # next is usual vtk code mapper = vtk.vtkPolyDataMapper() mapper.SetInputConnection(glyphTensor.GetOutputPort()) actor = vtk.vtkActor() actor.SetMapper(mapper) ren = vtk.vtkRenderer() ren.SetBackground(0.2, 0.5, 0.3) ren.AddActor(actor) renwin = vtk.vtkRenderWindow() renwin.AddRenderer(ren) iren = vtk.vtkRenderWindowInteractor() iren.SetInteractorStyle(vtk.vtkInteractorStyleTrackballCamera()) iren.SetRenderWindow(renwin) renwin.Render() iren.Initialize() renwin.Render() iren.Start()

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  • Creating a protected link

    - by user303907
    Is there a way to create a protected download link which is random, expiry, requires a password and pointing to a specific file in C# that is associated with IIS 7.0? Several random links can link to the same file. Built-in codes or perhaps 3rd party libraries? For example, http://www.example.com/<some random gibberish>/<md5 of file>/file.jpg

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  • Recursive XSLT, part 2

    - by Eric
    Ok, following on from my question here. Lets say my pages are now like this: A.xml: <page> <header>Page A</header> <content-a>Random content for page A</content-a> <content-b>More of page A's content</content-b> <content-c>More of page A's content</content-c> <!-- This doesn't keep going: there are a predefined number of sections --> </page> B.xml: <page include="A.xml"> <header>Page B</header> <content-a>Random content for page B</content-a> <content-b>More of page B's content</content-b> <content-c>More of page B's content</content-c> </page> C.xml: <page include="B.xml"> <header>Page C</header> <content-a>Random content for page C</content-a> <content-b>More of page C's content</content-b> <content-c>More of page C's content</content-c> </page> After the transform (on C.xml), I'd like to end up with this: <h1>Page C</h1> <div> <p>Random content for page C</p> <p>Random content for page B</p> <p>Random content for page A</p> </div> <div> <p>More of page C's content</p> <p>More of page B's content</p> <p>More of page A's content</p> </div> <div> <p>Yet more of page C's content</p> <p>Yet more of page B's content</p> <p>Yet more of page A's content</p> </div> I know that I can use document(@include) to include another document. However, the recursion is a bit beyond me. How would I go about writing such a transform?

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  • Best practice for assigning A/B test variation based on IP address

    - by mojones
    I am starting to write some code for A/B testing in a Grails web application. I want to ensure that requests from the same IP address always see the same variation. Rather than store a map of IP-variant, is it OK to simply turn the IP address into an integer by removing the dots, then use that as the seed for a random number generator? The following is taking place in a Grails Filter: def ip = request.remoteAddr def random = new Random(ip.replaceAll(/\./, '').toInteger()) def value = random.nextBoolean() session.assignment = value // value should always be the same for a given IP address I know that identifying users by IP address is not reliable, and I will be using session variables/cookies as well, but this seems to be useful for the case where we have a new session, and no cookies set (or the user has cookies disabled).

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  • Python/Biophysics- Trying to code a simple stochastic simulation!

    - by user359597
    Hey guys- I'm trying to figure out what to make of the following code- this is not the clear, intuitive python I've been learning. Was it written in C or something then wrapped in a python fxn? The code I wrote (not shown) is using the same math, but I couldn't figure out how to write a conditional loop. If anyone could explain/decipher/clean this up, I'd be really appreciative. I mean- is this 'good' python- or does it look funky? I'm brand new to this- but it's like the order of the fxns is messed up? I understand Gillespie's- I've successfully coded several simpler simulations. So in a nutshell- good code-(pythonic)? order? c? improvements? am i being an idiot? The code shown is the 'answer,' to the following question from a biophysics text (petri-net not shown and honestly not necessary to understand problem): "In a programming language of your choice, implement Gillespie’s First Reaction Algorithm to study the temporal behaviour of the reaction A---B in which the transition from A to B can only take place if another compound, C, is present, and where C dynamically interconverts with D, as modelled in the Petri-net below. Assume that there are 100 molecules of A, 1 of C, and no B or D present at the start of the reaction. Set kAB to 0.1 s-1 and both kCD and kDC to 1.0 s-1. Simulate the behaviour of the system over 100 s." def sim(): # Set the rate constants for all transitions kAB = 0.1 kCD = 1.0 kDC = 1.0 # Set up the initial state A = 100 B = 0 C = 1 D = 0 # Set the start and end times t = 0.0 tEnd = 100.0 print "Time\t", "Transition\t", "A\t", "B\t", "C\t", "D" # Compute the first interval transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) # Loop until the end time is exceded or no transition can fire any more while t <= tEnd and transition >= 0: print t, '\t', transition, '\t', A, '\t', B, '\t', C, '\t', D t += interval if transition == 0: A -= 1 B += 1 if transition == 1: C -= 1 D += 1 if transition == 2: C += 1 D -= 1 transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) def transitionData(A, B, C, D, kAB, kCD, kDC): """ Returns nTransition, the number of the firing transition (0: A->B, 1: C->D, 2: D->C), and interval, the interval between the time of the previous transition and that of the current one. """ RAB = kAB * A * C RCD = kCD * C RDC = kDC * D dt = [-1.0, -1.0, -1.0] if RAB > 0.0: dt[0] = -math.log(1.0 - random.random())/RAB if RCD > 0.0: dt[1] = -math.log(1.0 - random.random())/RCD if RDC > 0.0: dt[2] = -math.log(1.0 - random.random())/RDC interval = 1e36 transition = -1 for n in range(len(dt)): if dt[n] > 0.0 and dt[n] < interval: interval = dt[n] transition = n return transition, interval if __name__ == '__main__': sim()

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  • Help needed in grokking password hashes and salts

    - by javafueled
    I've read a number of SO questions on this topic, but grokking the applied practice of storing a salted hash of a password eludes me. Let's start with some ground rules: a password, "foobar12" (we are not discussing the strength of the password). a language, Java 1.6 for this discussion a database, postgreSQL, MySQL, SQL Server, Oracle Several options are available to storing the password, but I want to think about one (1): Store the password hashed with random salt in the DB, one column Found on SO and elsewhere is the automatic fail of plaintext, MD5/SHA1, and dual-columns. The latter have pros and cons MD5/SHA1 is simple. MessageDigest in Java provides MD5, SHA1 (through SHA512 in modern implementations, certainly 1.6). Additionally, most RDBMSs listed provide methods for MD5 encryption functions on inserts, updates, etc. The problems become evident once one groks "rainbow tables" and MD5 collisions (and I've grokked these concepts). Dual-column solutions rest on the idea that the salt does not need to be secret (grok it). However, a second column introduces a complexity that might not be a luxury if you have a legacy system with one (1) column for the password and the cost of updating the table and the code could be too high. But it is storing the password hashed with a random salt in single DB column that I need to understand better, with practical application. I like this solution for a couple of reasons: a salt is expected and considers legacy boundaries. Here's where I get lost: if the salt is random and hashed with the password, how can the system ever match the password? I have theory on this, and as I type I might be grokking the concept: Given a random salt of 128 bytes and a password of 8 bytes ('foobar12'), it could be programmatically possible to remove the part of the hash that was the salt, by hashing a random 128 byte salt and getting the substring of the original hash that is the hashed password. Then re hashing to match using the hash algorithm...??? So... any takers on helping. :) Am I close?

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  • Select Table Rows by Grouping them Adjacent to each Other using XPath

    - by Adnan Yaseen
    I am not clear how to express my problem correctly in the question so forgive me if I am not able to properly convey my problem. I have following data. <tr class="header">Random Value 1</tr> <tr class="item">1</tr> <tr class="item">2</tr> <tr class="item">3</tr> <tr class="header">Random Value 2</tr> <tr class="item">4</tr> <tr class="item">5</tr> <tr class="item">6</tr> <tr class="header">Random Value 3</tr> <tr class="item">7</tr> <tr class="item">8</tr> <tr class="item">9</tr> What I want to acheive is that I want to select the with class header. I have achieved this by using the following line of code, HtmlNodeCollection headerNodes = doc.DocumentNode.SelectNodes("//tr[@class='header']"); Now I have all the header rows in the collection. Now I loop through all the header nodes and I want to get the table rows which are adjacent to the respective header rows. foreach (HtmlNode node in headerNodes) { HtmlNodeCollection itemNodes = ??? } My question is that what I should write here so that for header row with text "Random Value 1" I get the item rows 1,2 and 3. Similarly for header row with text "Random Value 2" I get the item row 4,5 and 6 and so on.

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  • How to determine position (x,y) relative to the page of every character inside spans through javascript?

    - by Fernando
    This is as simple as I can get. I will have several spans randomly positioned on the screen through something like: $(".hidden:first").css('-webkit-transform','rotate('+((0.5-Math.random())*40)+'deg)'); $(".hidden:first").animate({ left: '+=' + (((screen.width-800-224)/2) + Math.random()*800), top: '+=' + (50+Math.random()*600) } [...] and later on I would like to iterate through every char of every of those elements (that are randomly position and have random rotation), and I would need to discover the (x,y) position of every character on the screen so I can colorize it, forming certain draws according to certain functions. Is this easily achievable? I am really inexperienced at javascript. Thanks. Fernando.

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  • non static method cannot be referenced from a static context.

    - by David
    First some code: import java.util.*; ... class TicTacToe { ... public static void main (String[]arg) { Random Random = new Random() ; toerunner () ; // this leads to a path of methods that eventualy gets us to the rest of the code } ... public void CompTurn (int type, boolean debug) { ... boolean done = true ; int a = 0 ; while (!done) { a = Random.nextInt(10) ; if (debug) { int i = 0 ; while (i<20) { System.out.print (a+", ") ; i++; }} if (possibles[a]==1) done = true ; } this.board[a] = 2 ; } ... } //to close the class Here is the error message: TicTacToe.java:85: non-static method nextInt(int) cannot be referenced from a static context a = Random.nextInt(10) ; ^ What exactly went wrong? What does that error message "non static method cannot be referenced from a static context" mean?

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  • My first c# app and first null object exception

    - by Fresheyeball
    Total noob here. This is my first c# attempt, its a console application that simulates a drinking game called 'Left Right Center'. In the console I receive the following: CONSOLE Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object at LeftRightCenter.MainClass.Main (System.String[] args) [0x00038] in /Users/apple/Projects/LearningC/LearningC/Main.cs:80 [ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object at LeftRightCenter.MainClass.Main (System.String[] args) [0x00038] in /Users/apple/Projects/LearningC/LearningC/Main.cs:80 C# using System; namespace LeftRightCenter { class Player { //fields private int _quarters = 4; public int Quarters { get{ return _quarters; } set{ _quarters += value; } } public Player (string name) { } } class Dice { Random random = new Random(); public int Roll () { random = new Random (); int diceSide; diceSide = random.Next (0, 6); diceSide = (diceSide > 2) ? 3 : diceSide; return diceSide; } } class MainClass { static int activePlayer = 0; static int theCup = 0; static Player[] thePlayers = { new Player ("Jessica"), new Player ("Isaac"), new Player ("Ed"), new Player ("Bella"), new Player ("Elisa"), new Player ("Fake RedHead"), new Player ("Linda"), new Player ("MJ"), new Player ("Irene"), new Player("Devin") }; static Dice[] theDice = new Dice[2]; private static void MoveQuarter (int direction) { int numberOfPlayers = thePlayers.Length - 1; switch (direction) { case 0: thePlayers [activePlayer].Quarters = -1; theCup++; break; case 1: thePlayers [activePlayer].Quarters = -1; int leftPlayer = (activePlayer == 0) ? numberOfPlayers : activePlayer - 1; thePlayers [leftPlayer].Quarters = +1; break; case 2: thePlayers [activePlayer].Quarters = -1; int rightPlayer = (activePlayer == numberOfPlayers) ? 0 : activePlayer + 1; thePlayers [rightPlayer].Quarters = +1; break; } } public static void Main (string[] args) { int cupEndPoint = thePlayers.Length * 4 - 1; while (theCup < cupEndPoint) { foreach (Dice rattle in theDice) { if (thePlayers [activePlayer].Quarters > 0) { MoveQuarter (rattle.Roll ()); // this line seems to be the problem } } Console.WriteLine ("{0} Quarters In the Cup", theCup); } } } } I have no idea what the problem is or why, and my googling have proven more use confusing than helpful.

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  • C++ ofstream cannot write to file....

    - by user69514
    Hey I am trying to write some numbers to a file, but when I open the file it is empty. Can you help me out here? Thanks. /** main function **/ int main(){ /** variables **/ RandGen* random_generator = new RandGen; int random_numbers; string file_name; /** ask user for quantity of random number to produce **/ cout << "How many random number would you like to create?" << endl; cin >> random_numbers; /** ask user for the name of the file to store the numbers **/ cout << "Enter name of file to store random number" << endl; cin >> file_name; /** now create array to store the number **/ int random_array [random_numbers]; /** file the array with random integers **/ for(int i=0; i<random_numbers; i++){ random_array[i] = random_generator -> randInt(-20, 20); cout << random_array[i] << endl; } /** open file and write contents of random array **/ const char* file = file_name.c_str(); ofstream File(file); /** write contents to the file **/ for(int i=0; i<random_numbers; i++){ File << random_array[i] << endl; } /** close the file **/ File.close(); return 0; /** END OF PROGRAM **/ }

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  • How to import your own non-packaged Java classes in Jython

    - by thepandaatemyface
    I know in Jython you can do import java.util.Random as Random Random().nextInt() But if I have a class I wrote myself, how can I import it into Jython without putting the class itself in a package? If I have a testclass Test: public class Test { public void foo() { System.out.println("bar"); } } that's not inside a package. Can I even import that into jython by using something along the lines offrom Test import Test?

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  • Exception error in Erlang

    - by Jim
    So I've been using Erlang for the last eight hours, and I've spent two of those banging my head against the keyboard trying to figure out the exception error my console keeps returning. I'm writing a dice program to learn erlang. I want it to be able to call from the console through the erlang interpreter. The program accepts a number of dice, and is supposed to generate a list of values. Each value is supposed to be between one and six. I won't bore you with the dozens of individual micro-changes I made to try and fix the problem (random engineering) but I'll post my code and the error. The Source: -module(dice2). -export([d6/1]). d6(1) - random:uniform(6); d6(Numdice) - Result = [], d6(Numdice, [Result]). d6(0, [Finalresult]) - {ok, [Finalresult]}; d6(Numdice, [Result]) - d6(Numdice - 1, [random:uniform(6) | Result]). When I run the program from my console like so... dice2:d6(1). ...I get a random number between one and six like expected. However when I run the same function with any number higher than one as an argument I get the following exception... **exception error: no function clause matching dice2:d6(1, [4|3]) ... I know I I don't have a function with matching arguments but I don't know how to write a function with variable arguments, and a variable number of arguments. I tried modifying the function in question like so.... d6(Numdice, [Result]) - Newresult = [random:uniform(6) | Result], d6(Numdice - 1, Newresult). ... but I got essentially the same error. Anyone know what is going on here?

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  • Python/Biomolecular Physics- Trying to code a simple stochastic simulation of a system exhibiting co

    - by user359597
    *edited 6/17/10 I'm trying to understand how to improve my code (make it more pythonic). Also, I'm interested in writing more intuitive 'conditionals' that would describe scenarios that are commonplace in biochemistry. The conditional criteria in the below program is explained in Answer #2, but I am not satisfied with it- it is correct, but isn't obvious and isn't easy to implement for more complicated conditional scenarios. Ideas welcome. Comments/criticisms welcome. First posting experience @ stackoverflow- please comment on etiquette if needed. The code generates a list of values that are the solution to the following exercise: "In a programming language of your choice, implement Gillespie’s First Reaction Algorithm to study the temporal behaviour of the reaction A---B in which the transition from A to B can only take place if another compound, C, is present, and where C dynamically interconverts with D, as modelled in the Petri-net below. Assume that there are 100 molecules of A, 1 of C, and no B or D present at the start of the reaction. Set kAB to 0.1 s-1 and both kCD and kDC to 1.0 s-1. Simulate the behaviour of the system over 100 s." def sim(): # Set the rate constants for all transitions kAB = 0.1 kCD = 1.0 kDC = 1.0 # Set up the initial state A = 100 B = 0 C = 1 D = 0 # Set the start and end times t = 0.0 tEnd = 100.0 print "Time\t", "Transition\t", "A\t", "B\t", "C\t", "D" # Compute the first interval transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) # Loop until the end time is exceded or no transition can fire any more while t <= tEnd and transition >= 0: print t, '\t', transition, '\t', A, '\t', B, '\t', C, '\t', D t += interval if transition == 0: A -= 1 B += 1 if transition == 1: C -= 1 D += 1 if transition == 2: C += 1 D -= 1 transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) def transitionData(A, B, C, D, kAB, kCD, kDC): """ Returns nTransition, the number of the firing transition (0: A->B, 1: C->D, 2: D->C), and interval, the interval between the time of the previous transition and that of the current one. """ RAB = kAB * A * C RCD = kCD * C RDC = kDC * D dt = [-1.0, -1.0, -1.0] if RAB > 0.0: dt[0] = -math.log(1.0 - random.random())/RAB if RCD > 0.0: dt[1] = -math.log(1.0 - random.random())/RCD if RDC > 0.0: dt[2] = -math.log(1.0 - random.random())/RDC interval = 1e36 transition = -1 for n in range(len(dt)): if dt[n] > 0.0 and dt[n] < interval: interval = dt[n] transition = n return transition, interval if __name__ == '__main__': sim()

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  • how to generate unique numbers less than 8 characters long.

    - by loudiyimo
    hi I want to generate unique id's everytime i call methode generateCustumerId(). The generated id must be 8 characters long or less than 8 characters. This requirement is necessary because I need to store it in a data file and schema is determined to be 8 characters long for this id. Option 1 works fine. Instead of option 1, I want to use UUID. The problem is that UUID generates an id which has to many characters. Does someone know how to generate a unique id which is less then 99999999? option 1 import java.util.HashSet; import java.util.Random; import java.util.Set; public class CustomerIdGenerator { private static Set<String> customerIds = new HashSet<String>(); private static Random random = new Random(); // XXX: replace with java.util.UUID public static String generateCustumerId() { String customerId = null; while (customerId == null || customerIds.contains(customerId)) { customerId = String.valueOf(random.nextInt(89999999) + 10000000); } customerIds.add(customerId); return customerId; } } option2 generates an unique id which is too long public static String generateCustumerId() { String ownerId = UUID.randomUUID().toString(); System.out.println("ownerId " + ownerId); return ownerId }

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  • The reason for MonadState get and put?

    - by CiscoIPPhone
    I'm reading the Monads chapter in Real World Haskell (chapter 14). A function is defined as follows: type RandomState a = State StdGen a getRandom :: Random a => RandomState a getRandom = get >>= \gen -> let (val, gen')= random gen in put gen' >> return val I don't really understand the purpose of the get and put functions here. I rewrote the function as following which seems to do the same thing and is more concise: getRandom2 :: Random a => RandomState a getRandom2= State $ \ s -> random s So my question is: What is the purpose of get and put?

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  • Data Structures for Junior Java Developer

    - by user1639637
    Ok,still learning Arrays. I wrote this code which fills the array named "rand" with random numbers between 0 and 1( exclusive). I want to start learning Complexity. the For loop executes n times (100 times) ,every time it takes O(1) time,so the worse case scenario is O(n),am I right? Also,I used ArrayList to store the 100 elements and I imported "Collections" and used Collections.sort() method to sort the elements. import java.util.Arrays; public class random { public static void main(String args[]) { double[] rand=new double[10]; for(int i=0;i<rand.length;i++) { rand[i]=(double) Math.random(); System.out.println(rand[i]); } Arrays.sort(rand); System.out.println(Arrays.toString(rand)); } } ArrayList: import java.util.ArrayList; import java.util.Collections; public class random { public static void main(String args[]) { ArrayList<Double> MyArrayList=new ArrayList<Double>(); for(int i=0;i<100;i++) { MyArrayList.add(Math.random()); } Collections.sort(MyArrayList); for(int j=0;j<MyArrayList.size();j++) { System.out.println(MyArrayList.get(j)); } } }

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  • Why is my simple python gtk+cairo program running so slowly/stutteringly?

    - by synapz
    My program draws circles moving on the window. I think I must be missing some basic gtk/cairo concept because it seems to be running too slowly/stutteringly for what I am doing. Any ideas? Thanks for any help! #!/usr/bin/python import gtk import gtk.gdk as gdk import math import random import gobject # The number of circles and the window size. num = 128 size = 512 # Initialize circle coordinates and velocities. x = [] y = [] xv = [] yv = [] for i in range(num): x.append(random.randint(0, size)) y.append(random.randint(0, size)) xv.append(random.randint(-4, 4)) yv.append(random.randint(-4, 4)) # Draw the circles and update their positions. def expose(*args): cr = darea.window.cairo_create() cr.set_line_width(4) for i in range(num): cr.set_source_rgb(1, 0, 0) cr.arc(x[i], y[i], 8, 0, 2 * math.pi) cr.stroke_preserve() cr.set_source_rgb(1, 1, 1) cr.fill() x[i] += xv[i] y[i] += yv[i] if x[i] > size or x[i] < 0: xv[i] = -xv[i] if y[i] > size or y[i] < 0: yv[i] = -yv[i] # Self-evident? def timeout(): darea.queue_draw() return True # Initialize the window. window = gtk.Window() window.resize(size, size) window.connect("destroy", gtk.main_quit) darea = gtk.DrawingArea() darea.connect("expose-event", expose) window.add(darea) window.show_all() # Self-evident? gobject.idle_add(timeout) gtk.main()

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  • Is it safe to call a function to intialize a class in a ctor list?

    - by Michael Dorgan
    I have Angle class that I want initialized to a random value. The Angle constructor can accept an int from a random() function. Is it safe to place this call in the ctor list: foo::foo() : Angle(random(0xFFFF)) {...} or do I have to do it in the body of the constructor? foo::foo() { Angle = Angle(random(0xFFFF)); ...} If it matters, the foo class is derived from another class and does have virtual methods. In addition, no exception handling is allowed in our app.

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  • is this a correct way to generate rsa keys?

    - by calccrypto
    is this code going to give me correct values for RSA keys (assuming that the other functions are correct)? im having trouble getting my program to decrypt properly, as in certain blocks are not decrypting properly this is in python: import random def keygen(bits): p = q = 3 while p == q: p = random.randint(2**(bits/2-2),2**(bits/2)) q = random.randint(2**(bits/2-2),2**(bits/2)) p += not(p&1) # changes the values from q += not(q&1) # even to odd while MillerRabin(p) == False: # checks for primality p -= 2 while MillerRabin(q) == False: q -= 2 n = p * q tot = (p-1) * (q-1) e = tot while gcd(tot,e) != 1: e = random.randint(3,tot-1) d = getd(tot,e) # gets the multiplicative inverse while d<0: # i can probably replace this with mod d = d + tot return e,d,n one set of keys generated: e = 3daf16a37799d3b2c951c9baab30ad2d d = 16873c0dd2825b2e8e6c2c68da3a5e25 n = dc2a732d64b83816a99448a2c2077ced

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  • Is there any way to add a MouseListener to a Graphic object ?

    - by Fahad
    Hi, Is there any way to add a MouseListener to a Graphic object. I have this simple GUI that draw an oval. What I want is handling the event when the user clicks on the oval import java.awt.*; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import javax.swing.*; public class Gui2 extends JFrame { JFrame frame = new JFrame(); MyDrawPanel drawpanel = new MyDrawPanel(); public static void main(String[] args) { Gui2 gui = new Gui2(); gui.go(); } public void go() { frame.getContentPane().add(drawpanel); // frame.addMouseListener(this); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(300, 300); frame.setVisible(true); } } class MyDrawPanel extends JComponent implements MouseListener { public void paintComponent(Graphics g) { int red = (int) (Math.random() * 255); int green = (int) (Math.random() * 255); int blue = (int) (Math.random() * 255); Color startrandomColor = new Color(red, green, blue); red = (int) (Math.random() * 255); green = (int) (Math.random() * 255); blue = (int) (Math.random() * 255); Color endrandomColor = new Color(red, green, blue); Graphics2D g2d = (Graphics2D) g; this.addMouseListener(this); GradientPaint gradient = new GradientPaint(70, 70, startrandomColor, 150, 150, endrandomColor); g2d.setPaint(gradient); g2d.fillOval(70, 70, 100, 100); } @Override public void mouseClicked(MouseEvent e) { if ((e.getButton() == 1) && (e.getX() >= 70 && e.getX() <= 170 && e.getY() >= 70 && e .getY() <= 170)) { this.repaint(); // JOptionPane.showMessageDialog(null,e.getX()+ "\n" + e.getY()); } } @Override public void mouseEntered(MouseEvent e) { // TODO Auto-generated method stub } @Override public void mouseExited(MouseEvent e) { // TODO Auto-generated method stub } @Override public void mousePressed(MouseEvent e) { // TODO Auto-generated method stub } @Override public void mouseReleased(MouseEvent e) { // TODO Auto-generated method stub } } This Works Except it fires when the click is within a virtual box around the oval. Could anyone help me to have it fire when the click is EXACTLY on the oval. Thanks in advance.

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