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• How to find data usage of a user on my website?

  - by Dharmik

  I have a website (project) where users get logged in, do their work and then they log out. I need to build a report that displays how much each person has used of data. (bandwidth, how much was downloaded in Kb, etc) So the process may be like counting start of usage from user login to user logout. I have seen a little about Webalizer and AWStats for something like this, But I am not sure how they work. I have tried Content-Length but some pages don't send content-length.I have also seen mod_bandwidth but still I am little confused. This process is needed for my site because now, our company is thinking of charging per usage and also bandwidth allocation for each users (according to their membership). I haven't worked with this type of tools, I am newbie in this matter. I have done only simple websites not any setting like this in Apache or Linux. My project is in Codeigniter.

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• Blending textures together, texture fade over / fade in

  - by Deukalion

  What is the best way to render a texture overlapping effect? Like in this example: I want either the grass to fade in to the snow texture, or the other way around. No rough edges. Somehow make them blend over. So the grass has a bit of snow or the snow has a bit of grass How is this possible during runtime? If that's possible. I don't render this by using the SpriteBatch, since the ground isn't rectangles (they can be moved). This is the way I render each shape (each one of those squares): // LoadTexture // Apply EffectPass device.DrawUserIndexedPrimitives<VertexPositionNormalTexture> ( PrimitiveType.TriangleList, render.Item.Points, // Array of VertexPositionNormalTexture 0, render.Item.Points.Length, render.Item.Indexes, // Array of int indexes (triangulation) 0, render.Item.Indexes.Length / 3, VertexPositionNormalTexture.VertexDeclaration );

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• What is the exception in java code? [closed]

  - by Karandeep Singh

  This java code is for reverse the string but it returning concat null with returned string. import java.util.*; import java.util.logging.Level; import java.util.logging.Logger; public class Practice { public static void main(String[] args) { String str = ""; try { str = reverse("Singh"); } catch (Exception ex) { Logger.getLogger(Practice.class.getName()).log(Level.SEVERE, null, ex); System.out.print(ex.getMessage()); }finally{ System.out.println(str); } } public static String reverse(String str) throws Exception{ String temp = null; if(str.length()<=0){ throw new Exception("empty"); }else{ for(int i=str.length()-1;i>=0;i--){ temp+=str.charAt(i); } } return temp.trim(); } } Output: nullhgniS

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• Sniffing out SQL Code Smells: Inconsistent use of Symbolic names and Datatypes

  - by Phil Factor

  It is an awkward feeling. You’ve just delivered a database application that seems to be working fine in production, and you just run a few checks on it. You discover that there is a potential bug that, out of sheer good chance, hasn’t kicked in to produce an error; but it lurks, like a smoking bomb. Worse, maybe you find that the bug has started its evil work of corrupting the data, but in ways that nobody has, so far detected. You investigate, and find the damage. You are somehow going to have to repair it. Yes, it still very occasionally happens to me. It is not a nice feeling, and I do anything I can to prevent it happening. That’s why I’m interested in SQL code smells. SQL Code Smells aren’t necessarily bad practices, but just show you where to focus your attention when checking an application. Sometimes with databases the bugs can be subtle. SQL is rather like HTML: the language does its best to try to carry out your wishes, rather than to be picky about your bugs. Most of the time, this is a great benefit, but not always. One particular place where this can be detrimental is where you have implicit conversion between different data types. Most of the time it is completely harmless but we’re  concerned about the occasional time it isn’t. Let’s give an example: String truncation. Let’s give another even more frightening one, rounding errors on assignment to a number of different precision. Each requires a blog-post to explain in detail and I’m not now going to try. Just remember that it is not always a good idea to assign data to variables, parameters or even columns when they aren’t the same datatype, especially if you are relying on implicit conversion to work its magic.For details of the problem and the consequences, see here:  SR0014: Data loss might occur when casting from {Type1} to {Type2} . For any experienced Database Developer, this is a more frightening read than a Vampire Story. This is why one of the SQL Code Smells that makes me edgy, in my own or other peoples’ code, is to see parameters, variables and columns that have the same names and different datatypes. Whereas quite a lot of this is perfectly normal and natural, you need to check in case one of two things have gone wrong. Either sloppy naming, or mixed datatypes. Sure it is hard to remember whether you decided that the length of a log entry was 80 or 100 characters long, or the precision of a number. That is why a little check like this I’m going to show you is excellent for tidying up your code before you check it back into source Control! 1/ Checking Parameters only If you were just going to check parameters, you might just do this. It simply groups all the parameters, either input or output, of all the routines (e.g. stored procedures or functions) by their name and checks to see, in the HAVING clause, whether their data types are all the same. If not, it lists all the examples and their origin (the routine) Even this little check can occasionally be scarily revealing. ;WITH userParameter AS  ( SELECT   c.NAME AS ParameterName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  t.name + ' '     + CASE     --we may have to put in the length            WHEN t.name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.max_length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.name IN ('nchar', 'nvarchar')                      THEN c.max_length / 2 ELSE c.max_length                    END)                END + ')'         WHEN t.name IN ('decimal', 'numeric')             THEN '(' + CONVERT(VARCHAR(4), c.precision)                   + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = c.XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType]  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'   AND parameter_id>0)SELECT CONVERT(CHAR(80),objectName+'.'+ParameterName),DataType FROM UserParameterWHERE ParameterName IN   (SELECT ParameterName FROM UserParameter    GROUP BY ParameterName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY ParameterName   so, in a very small example here, we have a @ClosingDelimiter variable that is only CHAR(1) when, by the looks of it, it should be up to ten characters long, or even worse, a function that should be a char(1) and seems to let in a string of ten characters. Worth investigating. Then we have a @Comment variable that can't decide whether it is a VARCHAR(2000) or a VARCHAR(MAX) 2/ Columns and Parameters Actually, once we’ve cleared up the mess we’ve made of our parameter-naming in the database we’re inspecting, we’re going to be more interested in listing both columns and parameters. We can do this by modifying the routine to list columns as well as parameters. Because of the slight complexity of creating the string version of the datatypes, we will create a fake table of both columns and parameters so that they can both be processed the same way. After all, we want the datatypes to match Unfortunately, parameters do not expose all the attributes we are interested in, such as whether they are nullable (oh yes, subtle bugs happen if this isn’t consistent for a datatype). We’ll have to leave them out for this check. Voila! A slight modification of the first routine ;WITH userObject AS  ( SELECT   Name AS DataName,--the actual name of the parameter or column ('@' removed)  --and the qualified object name of the routine  OBJECT_SCHEMA_NAME(ObjectID) + '.' + OBJECT_NAME(ObjectID) AS ObjectName,  --now the harder bit: the definition of the datatype.  TypeName + ' '     + CASE     --we may have to put in the length. e.g. CHAR (10)           WHEN TypeName IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN MaxLength = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN TypeName IN ('nchar', 'nvarchar')                      THEN MaxLength / 2 ELSE MaxLength                    END)                END + ')'         WHEN TypeName IN ('decimal', 'numeric')--a BCD number!             THEN '(' + CONVERT(VARCHAR(4), Precision)                   + ',' + CONVERT(VARCHAR(4), Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0 --tush tush. XML         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT TOP 1 QUOTENAME(ss.name) + '.' + QUOTENAME(sc.Name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType],       DataObjectType  FROM   (Select t.name AS TypeName, REPLACE(c.name,'@','') AS Name,          c.max_length AS MaxLength, c.precision AS [Precision],           c.scale AS [Scale], c.[Object_id] AS ObjectID, XML_collection_ID,          is_XML_Document,'P' AS DataobjectType  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  AND parameter_id>0  UNION all  Select t.name AS TypeName, c.name AS Name, c.max_length AS MaxLength,          c.precision AS [Precision], c.scale AS [Scale],          c.[Object_id] AS ObjectID, XML_collection_ID,is_XML_Document,          'C' AS DataobjectType            FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID   WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'  )f)SELECT CONVERT(CHAR(80),objectName+'.'   + CASE WHEN DataobjectType ='P' THEN '@' ELSE '' END + DataName),DataType FROM UserObjectWHERE DataName IN   (SELECT DataName FROM UserObject   GROUP BY DataName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY DataName     Hmm. I can tell you I found quite a few minor issues with the various tabases I tested this on, and found some potential bugs that really leap out at you from the results. Here is the start of the result for AdventureWorks. Yes, AccountNumber is, for some reason, a Varchar(10) in the Customer table. Hmm. odd. Why is a city fifty characters long in that view?  The idea of the description of a colour being 256 characters long seems over-ambitious. Go down the list and you'll spot other mistakes. There are no bugs, but just mess. We started out with a listing to examine parameters, then we mixed parameters and columns. Our last listing is for a slightly more in-depth look at table columns. You’ll notice that we’ve delibarately removed the indication of whether a column is persisted, or is an identity column because that gives us false positives for our code smells. If you just want to browse your metadata for other reasons (and it can quite help in some circumstances) then uncomment them! ;WITH userColumns AS  ( SELECT   c.NAME AS columnName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  REPLACE(t.name + ' '   + CASE WHEN is_computed = 1 THEN ' AS ' + --do DDL for a computed column          (SELECT definition FROM sys.computed_columns cc           WHERE cc.object_id = c.object_id AND cc.column_ID = c.column_ID)     --we may have to put in the length            WHEN t.Name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.Max_Length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.Name IN ('nchar', 'nvarchar')                      THEN c.Max_Length / 2 ELSE c.Max_Length                    END)                END + ')'       WHEN t.name IN ('decimal', 'numeric')       THEN '(' + CONVERT(VARCHAR(4), c.precision) + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'       ELSE ''      END + CASE WHEN c.is_rowguidcol = 1          THEN ' ROWGUIDCOL'          ELSE ''         END + CASE WHEN XML_collection_ID <> 0            THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                THEN 'DOCUMENT '                ELSE 'CONTENT '               END + COALESCE((SELECT                QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM                sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE                sc.xml_collection_ID = c.XML_collection_ID),                'NULL') + ')'            ELSE ''           END + CASE WHEN is_identity = 1             THEN CASE WHEN OBJECTPROPERTY(object_id,                'IsUserTable') = 1 AND COLUMNPROPERTY(object_id,                c.name,                'IsIDNotForRepl') = 0 AND OBJECTPROPERTY(object_id,                'IsMSShipped') = 0                THEN ''                ELSE ' NOT FOR REPLICATION '               END             ELSE ''            END + CASE WHEN c.is_nullable = 0               THEN ' NOT NULL'               ELSE ' NULL'              END + CASE                WHEN c.default_object_id <> 0                THEN ' DEFAULT ' + object_Definition(c.default_object_id)                ELSE ''               END + CASE                WHEN c.collation_name IS NULL                THEN ''                WHEN c.collation_name <> (SELECT                collation_name                FROM                sys.databases                WHERE                name = DB_NAME()) COLLATE Latin1_General_CI_AS                THEN COALESCE(' COLLATE ' + c.collation_name,                '')                ELSE ''                END,'  ',' ') AS [DataType]FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys')SELECT CONVERT(CHAR(80),objectName+'.'+columnName),DataType FROM UserColumnsWHERE columnName IN (SELECT columnName FROM UserColumns  GROUP BY columnName  HAVING MIN(Datatype)<>MAX(DataType))ORDER BY columnName If you take a look down the results against Adventureworks, you'll see once again that there are things to investigate, mostly, in the illustration, discrepancies between null and non-null datatypes So I here you ask, what about temporary variables within routines? If ever there was a source of elusive bugs, you'll find it there. Sadly, these temporary variables are not stored in the metadata so we'll have to find a more subtle way of flushing these out, and that will, I'm afraid, have to wait!

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• Ball bouncing at a certain angle and efficiency computations

  - by X Y

  I would like to make a pong game with a small twist (for now). Every time the ball bounces off one of the paddles i want it to be under a certain angle (between a min and a max). I simply can't wrap my head around how to actually do it (i have some thoughts and such but i simply cannot implement them properly - i feel i'm overcomplicating things). Here's an image with a small explanation . One other problem would be that the conditions for bouncing have to be different for every edge. For example, in the picture, on the two small horizontal edges i do not want a perfectly vertical bounce when in the middle of the edge but rather a constant angle (pi/4 maybe) in either direction depending on the collision point (before the middle of the edge, or after). All of my collisions are done with the Separating Axes Theorem (and seem to work fine). I'm looking for something efficient because i want to add a lot of things later on (maybe polygons with many edges and such). So i need to keep to a minimum the amount of checking done every frame. The collision algorithm begins testing whenever the bounding boxes of the paddle and the ball intersect. Is there something better to test for possible collisions every frame? (more efficient in the long run,with many more objects etc, not necessarily easy to code). I'm going to post the code for my game: Paddle Class public class Paddle : Microsoft.Xna.Framework.DrawableGameComponent { #region Private Members private SpriteBatch spriteBatch; private ContentManager contentManager; private bool keybEnabled; private bool isLeftPaddle; private Texture2D paddleSprite; private Vector2 paddlePosition; private float paddleSpeedY; private Vector2 paddleScale = new Vector2(1f, 1f); private const float DEFAULT_Y_SPEED = 150; private Vector2[] Normals2Edges; private Vector2[] Vertices = new Vector2[4]; private List<Vector2> lst = new List<Vector2>(); private Vector2 Edge; #endregion #region Properties public float Speed { get {return paddleSpeedY; } set { paddleSpeedY = value; } } public Vector2[] Normal2EdgesVector { get { NormalsToEdges(this.isLeftPaddle); return Normals2Edges; } } public Vector2[] VertexVector { get { return Vertices; } } public Vector2 Scale { get { return paddleScale; } set { paddleScale = value; NormalsToEdges(this.isLeftPaddle); } } public float X { get { return paddlePosition.X; } set { paddlePosition.X = value; } } public float Y { get { return paddlePosition.Y; } set { paddlePosition.Y = value; } } public float Width { get { return (Scale.X == 1f ? (float)paddleSprite.Width : paddleSprite.Width * Scale.X); } } public float Height { get { return ( Scale.Y==1f ? (float)paddleSprite.Height : paddleSprite.Height*Scale.Y ); } } public Texture2D GetSprite { get { return paddleSprite; } } public Rectangle Boundary { get { return new Rectangle((int)paddlePosition.X, (int)paddlePosition.Y, (int)this.Width, (int)this.Height); } } public bool KeyboardEnabled { get { return keybEnabled; } } #endregion private void NormalsToEdges(bool isLeftPaddle) { Normals2Edges = null; Edge = Vector2.Zero; lst.Clear(); for (int i = 0; i < Vertices.Length; i++) { Edge = Vertices[i + 1 == Vertices.Length ? 0 : i + 1] - Vertices[i]; if (Edge != Vector2.Zero) { Edge.Normalize(); //outer normal to edge !! (origin in top-left) lst.Add(new Vector2(Edge.Y, -Edge.X)); } } Normals2Edges = lst.ToArray(); } public float[] ProjectPaddle(Vector2 axis) { if (Vertices.Length == 0 || axis == Vector2.Zero) return (new float[2] { 0, 0 }); float min, max; min = Vector2.Dot(axis, Vertices[0]); max = min; for (int i = 1; i < Vertices.Length; i++) { float p = Vector2.Dot(axis, Vertices[i]); if (p < min) min = p; else if (p > max) max = p; } return (new float[2] { min, max }); } public Paddle(Game game, bool isLeftPaddle, bool enableKeyboard = true) : base(game) { contentManager = new ContentManager(game.Services); keybEnabled = enableKeyboard; this.isLeftPaddle = isLeftPaddle; } public void setPosition(Vector2 newPos) { X = newPos.X; Y = newPos.Y; } public override void Initialize() { base.Initialize(); this.Speed = DEFAULT_Y_SPEED; X = 0; Y = 0; NormalsToEdges(this.isLeftPaddle); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); paddleSprite = contentManager.Load<Texture2D>(@"Content\pongBar"); } public override void Update(GameTime gameTime) { //vertices array Vertices[0] = this.paddlePosition; Vertices[1] = this.paddlePosition + new Vector2(this.Width, 0); Vertices[2] = this.paddlePosition + new Vector2(this.Width, this.Height); Vertices[3] = this.paddlePosition + new Vector2(0, this.Height); // Move paddle, but don't allow movement off the screen if (KeyboardEnabled) { float moveDistance = Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState newKeyState = Keyboard.GetState(); if (newKeyState.IsKeyDown(Keys.Down) && Y + paddleSprite.Height + moveDistance <= Game.GraphicsDevice.Viewport.Height) { Y += moveDistance; } else if (newKeyState.IsKeyDown(Keys.Up) && Y - moveDistance >= 0) { Y -= moveDistance; } } else { if (this.Y + this.Height > this.GraphicsDevice.Viewport.Height) { this.Y = this.Game.GraphicsDevice.Viewport.Height - this.Height - 1; } } base.Update(gameTime); } public override void Draw(GameTime gameTime) { spriteBatch.Begin(SpriteSortMode.Texture,null); spriteBatch.Draw(paddleSprite, paddlePosition, null, Color.White, 0f, Vector2.Zero, Scale, SpriteEffects.None, 0); spriteBatch.End(); base.Draw(gameTime); } } Ball Class public class Ball : Microsoft.Xna.Framework.DrawableGameComponent { #region Private Members private SpriteBatch spriteBatch; private ContentManager contentManager; private const float DEFAULT_SPEED = 50; private float speedIncrement = 0; private Vector2 ballScale = new Vector2(1f, 1f); private const float INCREASE_SPEED = 50; private Texture2D ballSprite; //initial texture private Vector2 ballPosition; //position private Vector2 centerOfBall; //center coords private Vector2 ballSpeed = new Vector2(DEFAULT_SPEED, DEFAULT_SPEED); //speed #endregion #region Properties public float DEFAULTSPEED { get { return DEFAULT_SPEED; } } public Vector2 ballCenter { get { return centerOfBall; } } public Vector2 Scale { get { return ballScale; } set { ballScale = value; } } public float SpeedX { get { return ballSpeed.X; } set { ballSpeed.X = value; } } public float SpeedY { get { return ballSpeed.Y; } set { ballSpeed.Y = value; } } public float X { get { return ballPosition.X; } set { ballPosition.X = value; } } public float Y { get { return ballPosition.Y; } set { ballPosition.Y = value; } } public Texture2D GetSprite { get { return ballSprite; } } public float Width { get { return (Scale.X == 1f ? (float)ballSprite.Width : ballSprite.Width * Scale.X); } } public float Height { get { return (Scale.Y == 1f ? (float)ballSprite.Height : ballSprite.Height * Scale.Y); } } public float SpeedIncreaseIncrement { get { return speedIncrement; } set { speedIncrement = value; } } public Rectangle Boundary { get { return new Rectangle((int)ballPosition.X, (int)ballPosition.Y, (int)this.Width, (int)this.Height); } } #endregion public Ball(Game game) : base(game) { contentManager = new ContentManager(game.Services); } public void Reset() { ballSpeed.X = DEFAULT_SPEED; ballSpeed.Y = DEFAULT_SPEED; ballPosition.X = Game.GraphicsDevice.Viewport.Width / 2 - ballSprite.Width / 2; ballPosition.Y = Game.GraphicsDevice.Viewport.Height / 2 - ballSprite.Height / 2; } public void SpeedUp() { if (ballSpeed.Y < 0) ballSpeed.Y -= (INCREASE_SPEED + speedIncrement); else ballSpeed.Y += (INCREASE_SPEED + speedIncrement); if (ballSpeed.X < 0) ballSpeed.X -= (INCREASE_SPEED + speedIncrement); else ballSpeed.X += (INCREASE_SPEED + speedIncrement); } public float[] ProjectBall(Vector2 axis) { if (axis == Vector2.Zero) return (new float[2] { 0, 0 }); float min, max; min = Vector2.Dot(axis, this.ballCenter) - this.Width/2; //center - radius max = min + this.Width; //center + radius return (new float[2] { min, max }); } public void ChangeHorzDirection() { ballSpeed.X *= -1; } public void ChangeVertDirection() { ballSpeed.Y *= -1; } public override void Initialize() { base.Initialize(); ballPosition.X = Game.GraphicsDevice.Viewport.Width / 2 - ballSprite.Width / 2; ballPosition.Y = Game.GraphicsDevice.Viewport.Height / 2 - ballSprite.Height / 2; } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); ballSprite = contentManager.Load<Texture2D>(@"Content\ball"); } public override void Update(GameTime gameTime) { if (this.Y < 1 || this.Y > GraphicsDevice.Viewport.Height - this.Height - 1) this.ChangeVertDirection(); centerOfBall = new Vector2(ballPosition.X + this.Width / 2, ballPosition.Y + this.Height / 2); base.Update(gameTime); } public override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.Draw(ballSprite, ballPosition, null, Color.White, 0f, Vector2.Zero, Scale, SpriteEffects.None, 0); spriteBatch.End(); base.Draw(gameTime); } } Main game class public class gameStart : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; public gameStart() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; this.Window.Title = "Pong game"; } protected override void Initialize() { ball = new Ball(this); paddleLeft = new Paddle(this,true,false); paddleRight = new Paddle(this,false,true); Components.Add(ball); Components.Add(paddleLeft); Components.Add(paddleRight); this.Window.AllowUserResizing = false; this.IsMouseVisible = true; this.IsFixedTimeStep = false; this.isColliding = false; base.Initialize(); } #region MyPrivateStuff private Ball ball; private Paddle paddleLeft, paddleRight; private int[] bit = { -1, 1 }; private Random rnd = new Random(); private int updates = 0; enum nrPaddle { None, Left, Right }; private nrPaddle PongBar = nrPaddle.None; private ArrayList Axes = new ArrayList(); private Vector2 MTV; //minimum translation vector private bool isColliding; private float overlap; //smallest distance after projections private Vector2 overlapAxis; //axis of overlap #endregion protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); paddleLeft.setPosition(new Vector2(0, this.GraphicsDevice.Viewport.Height / 2 - paddleLeft.Height / 2)); paddleRight.setPosition(new Vector2(this.GraphicsDevice.Viewport.Width - paddleRight.Width, this.GraphicsDevice.Viewport.Height / 2 - paddleRight.Height / 2)); paddleLeft.Scale = new Vector2(1f, 2f); //scale left paddle } private bool ShapesIntersect(Paddle paddle, Ball ball) { overlap = 1000000f; //large value overlapAxis = Vector2.Zero; MTV = Vector2.Zero; foreach (Vector2 ax in Axes) { float[] pad = paddle.ProjectPaddle(ax); //pad0 = min, pad1 = max float[] circle = ball.ProjectBall(ax); //circle0 = min, circle1 = max if (pad[1] <= circle[0] || circle[1] <= pad[0]) { return false; } if (pad[1] - circle[0] < circle[1] - pad[0]) { if (Math.Abs(overlap) > Math.Abs(-pad[1] + circle[0])) { overlap = -pad[1] + circle[0]; overlapAxis = ax; } } else { if (Math.Abs(overlap) > Math.Abs(circle[1] - pad[0])) { overlap = circle[1] - pad[0]; overlapAxis = ax; } } } if (overlapAxis != Vector2.Zero) { MTV = overlapAxis * overlap; } return true; } protected override void Update(GameTime gameTime) { updates += 1; float ftime = 5 * (float)gameTime.ElapsedGameTime.TotalSeconds; if (updates == 1) { isColliding = false; int Xrnd = bit[Convert.ToInt32(rnd.Next(0, 2))]; int Yrnd = bit[Convert.ToInt32(rnd.Next(0, 2))]; ball.SpeedX = Xrnd * ball.SpeedX; ball.SpeedY = Yrnd * ball.SpeedY; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; } else { updates = 100; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; } //autorun :) paddleLeft.Y = ball.Y; //collision detection PongBar = nrPaddle.None; if (ball.Boundary.Intersects(paddleLeft.Boundary)) { PongBar = nrPaddle.Left; if (!isColliding) { Axes.Clear(); Axes.AddRange(paddleLeft.Normal2EdgesVector); //axis from nearest vertex to ball's center Axes.Add(FORMULAS.NormAxisFromCircle2ClosestVertex(paddleLeft.VertexVector, ball.ballCenter)); } } else if (ball.Boundary.Intersects(paddleRight.Boundary)) { PongBar = nrPaddle.Right; if (!isColliding) { Axes.Clear(); Axes.AddRange(paddleRight.Normal2EdgesVector); //axis from nearest vertex to ball's center Axes.Add(FORMULAS.NormAxisFromCircle2ClosestVertex(paddleRight.VertexVector, ball.ballCenter)); } } if (PongBar != nrPaddle.None && !isColliding) switch (PongBar) { case nrPaddle.Left: if (ShapesIntersect(paddleLeft, ball)) { isColliding = true; if (MTV != Vector2.Zero) ball.X += MTV.X; ball.Y += MTV.Y; ball.ChangeHorzDirection(); } break; case nrPaddle.Right: if (ShapesIntersect(paddleRight, ball)) { isColliding = true; if (MTV != Vector2.Zero) ball.X += MTV.X; ball.Y += MTV.Y; ball.ChangeHorzDirection(); } break; default: break; } if (!ShapesIntersect(paddleRight, ball) && !ShapesIntersect(paddleLeft, ball)) isColliding = false; ball.X += ftime * ball.SpeedX; ball.Y += ftime * ball.SpeedY; //check ball movement if (ball.X > paddleRight.X + paddleRight.Width + 2) { //IncreaseScore(Left); ball.Reset(); updates = 0; return; } else if (ball.X < paddleLeft.X - 2) { //IncreaseScore(Right); ball.Reset(); updates = 0; return; } base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.Aquamarine); spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend); spriteBatch.End(); base.Draw(gameTime); } } And one method i've used: public static Vector2 NormAxisFromCircle2ClosestVertex(Vector2[] vertices, Vector2 circle) { Vector2 temp = Vector2.Zero; if (vertices.Length > 0) { float dist = (circle.X - vertices[0].X) * (circle.X - vertices[0].X) + (circle.Y - vertices[0].Y) * (circle.Y - vertices[0].Y); for (int i = 1; i < vertices.Length;i++) { if (dist > (circle.X - vertices[i].X) * (circle.X - vertices[i].X) + (circle.Y - vertices[i].Y) * (circle.Y - vertices[i].Y)) { temp = vertices[i]; //memorize the closest vertex dist = (circle.X - vertices[i].X) * (circle.X - vertices[i].X) + (circle.Y - vertices[i].Y) * (circle.Y - vertices[i].Y); } } temp = circle - temp; temp.Normalize(); } return temp; } Thanks in advance for any tips on the 4 issues. EDIT1: Something isn't working properly. The collision axis doesn't come out right and the interpolation also seems to have no effect. I've changed the code a bit: private bool ShapesIntersect(Paddle paddle, Ball ball) { overlap = 1000000f; //large value overlapAxis = Vector2.Zero; MTV = Vector2.Zero; foreach (Vector2 ax in Axes) { float[] pad = paddle.ProjectPaddle(ax); //pad0 = min, pad1 = max float[] circle = ball.ProjectBall(ax); //circle0 = min, circle1 = max if (pad[1] < circle[0] || circle[1] < pad[0]) { return false; } if (Math.Abs(pad[1] - circle[0]) < Math.Abs(circle[1] - pad[0])) { if (Math.Abs(overlap) > Math.Abs(-pad[1] + circle[0])) { overlap = -pad[1] + circle[0]; overlapAxis = ax * (-1); } //to get the proper axis } else { if (Math.Abs(overlap) > Math.Abs(circle[1] - pad[0])) { overlap = circle[1] - pad[0]; overlapAxis = ax; } } } if (overlapAxis != Vector2.Zero) { MTV = overlapAxis * Math.Abs(overlap); } return true; } And part of the Update method: if (ShapesIntersect(paddleRight, ball)) { isColliding = true; if (MTV != Vector2.Zero) { ball.X += MTV.X; ball.Y += MTV.Y; } //test if (overlapAxis.X == 0) //collision with horizontal edge { } else if (overlapAxis.Y == 0) //collision with vertical edge { float factor = Math.Abs(ball.ballCenter.Y - paddleRight.Y) / paddleRight.Height; if (factor > 1) factor = 1f; if (overlapAxis.X < 0) //left edge? ball.Speed = ball.DEFAULTSPEED * Vector2.Normalize(Vector2.Reflect(ball.Speed, (Vector2.Lerp(new Vector2(-1, -3), new Vector2(-1, 3), factor)))); else //right edge? ball.Speed = ball.DEFAULTSPEED * Vector2.Normalize(Vector2.Reflect(ball.Speed, (Vector2.Lerp(new Vector2(1, -3), new Vector2(1, 3), factor)))); } else //vertex collision??? { ball.Speed = -ball.Speed; } } What seems to happen is that "overlapAxis" doesn't always return the right one. So instead of (-1,0) i get the (1,0) (this happened even before i multiplied with -1 there). Sometimes there isn't even a collision registered even though the ball passes through the paddle... The interpolation also seems to have no effect as the angles barely change (or the overlapAxis is almost never (-1,0) or (1,0) but something like (0.9783473, 0.02743843)... ). What am i missing here? :(

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• Can one draw a cube using different method/drawing mode?

  - by den-javamaniac

  Hi. I've just started learning gamedev (in particular android EGL based) and have ran over a code from Pro Android Games 2 that looks as follows: /* * Copyright (C) 2007 Google Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package opengl.scenes.cubes; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.IntBuffer; import javax.microedition.khronos.opengles.GL10; public class Cube { public Cube(){ int one = 0x10000; int vertices[] = { -one, -one, -one, one, -one, -one, one, one, -one, -one, one, -one, -one, -one, one, one, -one, one, one, one, one, -one, one, one, }; int colors[] = { 0, 0, 0, one, one, 0, 0, one, one, one, 0, one, 0, one, 0, one, 0, 0, one, one, one, 0, one, one, one, one, one, one, 0, one, one, one, }; byte indices[] = { 0, 4, 5, 0, 5, 1, 1, 5, 6, 1, 6, 2, 2, 6, 7, 2, 7, 3, 3, 7, 4, 3, 4, 0, 4, 7, 6, 4, 6, 5, 3, 0, 1, 3, 1, 2 }; // Buffers to be passed to gl*Pointer() functions // must be direct, i.e., they must be placed on the // native heap where the garbage collector cannot vbb.asIntBuffer() // move them. // // Buffers with multi-byte datatypes (e.g., short, int, float) // must have their byte order set to native order ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length*4); vbb.order(ByteOrder.nativeOrder()); mVertexBuffer = vbb.asIntBuffer(); mVertexBuffer.put(vertices); mVertexBuffer.position(0); ByteBuffer cbb = ByteBuffer.allocateDirect(colors.length*4); cbb.order(ByteOrder.nativeOrder()); mColorBuffer = cbb.asIntBuffer(); mColorBuffer.put(colors); mColorBuffer.position(0); mIndexBuffer = ByteBuffer.allocateDirect(indices.length); mIndexBuffer.put(indices); mIndexBuffer.position(0); } public void draw(GL10 gl) { gl.glFrontFace(GL10.GL_CW); gl.glVertexPointer(3, GL10.GL_FIXED, 0, mVertexBuffer); gl.glColorPointer(4, GL10.GL_FIXED, 0, mColorBuffer); gl.glDrawElements(GL10.GL_TRIANGLES, 36, GL10.GL_UNSIGNED_BYTE, mIndexBuffer); } private IntBuffer mVertexBuffer; private IntBuffer mColorBuffer; private ByteBuffer mIndexBuffer;} So it suggests to draw a cube using triangles. My question is: can I draw the same cube using GL_TPOLYGON? If so, isn't that an easier/more understandable way to do things?

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• SpriteBatch.end() generating null pointer exception

  - by odaymichael

  I am getting a null pointer exception using libGDX that the debugger points as the SpriteBatch.end() line. I was wondering what would cause this. Here is the offending code block, specifically the batch.end() line: batch.begin(); for (int j = 0; j < 3; j++) for (int i = 0; i < 3; i++) if (zoomgrid[i][j].getPiece().getImage() != null) zoomgrid[i][j].getPiece().getImage().draw(batch); batch.end(); The top of the stack is actually a line that calls lastTexture.bind(); In the flush() method of com.badlogic.gdx.graphics.g2d.SpriteBatch. I appreciate any input, let me know if I haven't included enough information.

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• Unable to find valid certification path to requested target while CAS authentication

  - by Dmitriy Sukharev

  I'm trying to configure CAS authentication. It requires both CAS and client application to use HTTPS protocol. Unfortunately we should use self-signed certificate (with CN that doesn't have anything in common with our server). Also the server is behind firewall and we have only two ports (ssh and https) visible. As far as there're several application that should be visible externally, we use Apache for ajp reverse proxying requests to these applications. Secure connections are managed by Apache, and all Tomcat are not configured to work with SSL. But I obtained exception while authentication, therefore desided to set keystore in CATALINA_OPTS: export CATALINA_OPTS="-Djavax.net.ssl.keyStore=/path/to/tomcat/ssl/cert.pfx -Djavax.net.ssl.keyStoreType=PKCS12 -Djavax.net.ssl.keyStorePassword=password -Djavax.net.ssl.keyAlias=alias -Djavax.net.debug=ssl" cert.pfx was obtained from certificate and key that are used by Apache HTTP Server: $ openssl pkcs12 -export -out /path/to/tomcat/ssl/cert.pfx -inkey /path/to/apache2/ssl/server-key.pem -in /path/to/apache2/ssl/server-cert.pem When I try to authenticate a user I obtain the following exception: Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:174) ~[na:1.6.0_32] at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:238) ~[na:1.6.0_32] at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:318) ~[na:1.6.0_32] Meanwhile I can see in catalina.out that Tomcat see certificate in cert.pfx and it's the same as the one that is used while authentication: 09:11:38.886 [http-bio-8080-exec-2] DEBUG o.j.c.c.v.Cas20ProxyTicketValidator - Constructing validation url: https://external-ip/cas/proxyValidate?pgtUrl=https%3A%2F%2Fexternal-ip%2Fclient%2Fj_spring_cas_security_proxyreceptor&ticket=ST-17-PN26WtdsZqNmpUBS59RC-cas&service=https%3A%2F%2Fexternal-ip%2Fclient%2Fj_spring_cas_security_check 09:11:38.886 [http-bio-8080-exec-2] DEBUG o.j.c.c.v.Cas20ProxyTicketValidator - Retrieving response from server. keyStore is : /path/to/tomcat/ssl/cert.pfx keyStore type is : PKCS12 keyStore provider is : init keystore init keymanager of type SunX509 *** found key for : 1 chain [0] = [ [ Version: V1 Subject: CN=wrong.domain.name, O=Our organization, L=Location, ST=State, C=Country Signature Algorithm: SHA1withRSA, OID = 1.2.840.113549.1.1.5 Key: Sun RSA public key, 1024 bits modulus: 13??a lot of digits here??19 public exponent: ????7 Validity: [From: Tue Apr 24 16:32:18 CEST 2012, To: Wed Apr 24 16:32:18 CEST 2013] Issuer: CN=wrong.domain.name, O=Our organization, L=Location, ST=State, C=Country SerialNumber: [ d??????? ????????] ] Algorithm: [SHA1withRSA] Signature: 0000: 65 Signature is here 0070: 96 . ] *** trustStore is: /jdk-home-folder/jre/lib/security/cacerts Here is a lot of trusted CAs. Here is nothing related to our certicate or our (not trusted) CA. ... 09:11:39.731 [http-bio-8080-exec-4] DEBUG o.j.c.c.v.Cas20ProxyTicketValidator - Retrieving response from server. Allow unsafe renegotiation: false Allow legacy hello messages: true Is initial handshake: true Is secure renegotiation: false %% No cached client session *** ClientHello, TLSv1 RandomCookie: GMT: 1347433643 bytes = { 63, 239, 180, 32, 103, 140, 83, 7, 109, 149, 177, 80, 223, 79, 243, 244, 60, 191, 124, 139, 108, 5, 122, 238, 146, 1, 54, 218 } Session ID: {} Cipher Suites: [SSL_RSA_WITH_RC4_128_MD5, SSL_RSA_WITH_RC4_128_SHA, TLS_RSA_WITH_AES_128_CBC_SHA, TLS_DHE_RSA_WITH_AES_128_CBC_SHA, TLS_DHE_DSS_WITH_AES_128_CBC_SHA, SSL_RSA_WITH_3DES_EDE_CBC_SHA, SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA, SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA, SSL_RSA_WITH_DES_CBC_SHA, SSL_DHE_RSA_WITH_DES_CBC_SHA, SSL_DHE_DSS_WITH_DES_CBC_SHA, SSL_RSA_EXPORT_WITH_RC4_40_MD5, SSL_RSA_EXPORT_WITH_DES40_CBC_SHA, SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA, SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA, TLS_EMPTY_RENEGOTIATION_INFO_SCSV] Compression Methods: { 0 } *** http-bio-8080-exec-4, WRITE: TLSv1 Handshake, length = 75 http-bio-8080-exec-4, WRITE: SSLv2 client hello message, length = 101 http-bio-8080-exec-4, READ: TLSv1 Handshake, length = 81 *** ServerHello, TLSv1 RandomCookie: GMT: 1347433643 bytes = { 145, 237, 232, 63, 240, 104, 234, 201, 148, 235, 12, 222, 60, 75, 174, 0, 103, 38, 196, 181, 27, 226, 243, 61, 34, 7, 107, 72 } Session ID: {79, 202, 117, 79, 130, 216, 168, 38, 68, 29, 182, 82, 16, 25, 251, 66, 93, 108, 49, 133, 92, 108, 198, 23, 120, 120, 135, 151, 15, 13, 199, 87} Cipher Suite: SSL_RSA_WITH_RC4_128_SHA Compression Method: 0 Extension renegotiation_info, renegotiated_connection: <empty> *** %% Created: [Session-2, SSL_RSA_WITH_RC4_128_SHA] ** SSL_RSA_WITH_RC4_128_SHA http-bio-8080-exec-4, READ: TLSv1 Handshake, length = 609 *** Certificate chain chain [0] = [ [ Version: V1 Subject: CN=wrong.domain.name, O=Our organization, L=Location, ST=State, C=Country Signature Algorithm: SHA1withRSA, OID = 1.2.840.113549.1.1.5 Key: Sun RSA public key, 1024 bits modulus: 13??a lot of digits here??19 public exponent: ????7 Validity: [From: Tue Apr 24 16:32:18 CEST 2012, To: Wed Apr 24 16:32:18 CEST 2013] Issuer: CN=wrong.domain.name, O=Our organization, L=Location, ST=State, C=Country SerialNumber: [ d??????? ????????] ] Algorithm: [SHA1withRSA] Signature: 0000: 65 Signature is here 0070: 96 . ] *** http-bio-8080-exec-4, SEND TLSv1 ALERT: fatal, description = certificate_unknown http-bio-8080-exec-4, WRITE: TLSv1 Alert, length = 2 http-bio-8080-exec-4, called closeSocket() http-bio-8080-exec-4, handling exception: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target I tried to convert our pem certificate to der format and imported it to trustedKeyStore (cacerts) (without private key), but it didn't change anything. But I'm not confident that I did it rigth. Also I must inform you that I don't know passphrase for our servier-key.pem file, and probably it differs from password for keystore created by me. OS: CentOS 6.2 Architecture: x64 Tomcat version: 7 Apache HTTP Server version: 2.4 Is there any way to make Tomcat accepts our certificate?

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• Beat detection and FFT

  - by Quincy

  So I am working on a platformer game which includes music with beat detection. I am currently using a simple if the energy that is stored in the history buffer is smaller then the current energy there is a beat. The problem with this is that ofcourse if you use songs like rock songs where you have a pretty steady amplitude this isn't going to work. So I looked further and found algorithms splitting the sound into multiple bands using FFT. I then found this : http://en.literateprograms.org/Cooley-Tukey_FFT_algorithm_(C) The only problem I'm having is that I am quite new to audio and I have no idea how to use that to split the signal up into multiple signals. So my question is : How do you use a FFT to split a signal into multiple bands ? Also for the guys interested, this is my algorithm in c# : // C = threshold, N = size of history buffer / 1024 public void PlaceBeatMarkers(float C, int N) { List<float> instantEnergyList = new List<float>(); short[] samples = soundData.Samples; float timePerSample = 1 / (float)soundData.SampleRate; int sampleIndex = 0; int nextSamples = 1024; // Calculate instant energy for every 1024 samples. while (sampleIndex + nextSamples < samples.Length) { float instantEnergy = 0; for (int i = 0; i < nextSamples; i++) { instantEnergy += Math.Abs((float)samples[sampleIndex + i]); } instantEnergy /= nextSamples; instantEnergyList.Add(instantEnergy); if(sampleIndex + nextSamples >= samples.Length) nextSamples = samples.Length - sampleIndex - 1; sampleIndex += nextSamples; } int index = N; int numInBuffer = index; float historyBuffer = 0; //Fill the history buffer with n * instant energy for (int i = 0; i < index; i++) { historyBuffer += instantEnergyList[i]; } // If instantEnergy / samples in buffer < instantEnergy for the next sample then add beatmarker. while (index + 1 < instantEnergyList.Count) { if(instantEnergyList[index + 1] > (historyBuffer / numInBuffer) * C) beatMarkers.Add((index + 1) * 1024 * timePerSample); historyBuffer -= instantEnergyList[index - numInBuffer]; historyBuffer += instantEnergyList[index + 1]; index++; } }

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• Arrive steering behavior

  - by dbostream

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

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• problem in array of shooter sprites which contain different colour bubbles

  - by prakash s

  everyone i am developing bubble shooter game in cocos2d I have placed shooter array which contain different color bubbles like this 00000000 it is 8 bubbles array if i tap the screen, first bubbles should move for shooting the target .png .And if i again tap the screen again 2nd position bubble should move for shooting the target.png bubbles,how it will possible for me because i have already created the array of target which contain different color bubbles, here i write the code : - (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { // Choose one of the touches to work with UITouch *touch = [touches anyObject]; CGPoint location = [touch locationInView:[touch view]]; location = [[CCDirector sharedDirector] convertToGL:location]; // Set up initial location of projectile CGSize winSize = [[CCDirector sharedDirector] winSize]; NSMutableArray * movableSprites = [[NSMutableArray alloc] init]; NSArray *images = [NSArray arrayWithObjects:@"1.png", @"2.png", @"3.png", @"4.png",@"5.png",@"6.png",@"7.png", @"8.png", nil]; for(int i = 0; i < images.count; ++i) { int index = (arc4random() % 8)+1; NSString *image = [NSString stringWithFormat:@"%d.png", index]; CCSprite*projectile = [CCSprite spriteWithFile:image]; //CCSprite *projectile = [CCSprite spriteWithFile:@"3.png" rect:CGRectMake(0, 0,256,256)]; [self addChild:projectile]; [movableSprites addObject:projectile]; float offsetFraction = ((float)(i+1))/(images.count+1); //projectile.position = ccp(20, winSize.height/2); //projectile.position = ccp(18,0 ); //projectile.position = ccp(350*offsetFraction, 20.0f); projectile.position = ccp(10/offsetFraction, 20.0f); // projectile.position = ccp(projectile.position.x,projectile.position.y); // Determine offset of location to projectile int offX = location.x - projectile.position.x; int offY = location.y - projectile.position.y; // Bail out if we are shooting down or backwards if (offX <= 0) return; // Ok to add now - we've double checked position //[self addChild:projectile]; // Determine where we wish to shoot the projectile to int realX = winSize.width + (projectile.contentSize.width/2); float ratio = (float) offY / (float) offX; int realY = (realX * ratio) + projectile.position.y; CGPoint realDest = ccp(realX, realY); // Determine the length of how far we're shooting int offRealX = realX - projectile.position.x; int offRealY = realY - projectile.position.y; float length = sqrtf((offRealX*offRealX)+(offRealY*offRealY)); float velocity = 480/1; // 480pixels/1sec float realMoveDuration = length/velocity; // Move projectile to actual endpoint [projectile runAction:[CCSequence actions: [CCMoveTo actionWithDuration:realMoveDuration position:realDest], [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)], nil]]; // Add to projectiles array projectile.tag = 1; [_projectiles addObject:projectile]; } }

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• install error wubi 12.10 rev273

  - by Doug

  Keep getting this error when installing wubi 12.10 rev273 11-09 14:16 ERROR TaskList: Error executing command command=C:\Windows\sysnative\bcdedit.exe /set {31400a42-f78f-11e0-9f68-e8757c793044} device partition=F: retval=1 stderr=An error has occurred setting the element data. The request is not supported. stdout= Traceback (most recent call last): File "\lib\wubi\backends\common\tasklist.py", line 197, in call File "\lib\wubi\backends\win32\backend.py", line 697, in modify_bcd File "\lib\wubi\backends\common\utils.py", line 66, in run_command Exception: Error executing command command=C:\Windows\sysnative\bcdedit.exe /set {31400a42-f78f-11e0-9f68-e8757c793044} device partition=F: retval=1 stderr=An error has occurred setting the element data. The request is not supported. Am trying to install in F drive Doug

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• Join Us for the Next Quarterly Customer Update Webcast

  - by michelle.huff

  Join us for the next Oracle Content Management Quarterly Customer Update Webcast scheduled for this coming January 19 & 20, 2010. In this webcast we'll bring you up to speed on the latest updates and changes made available these past few months. Additionally, we'll cover the new features and certifications in the latest ODC & ODDC 10.1.3.5.1 release, as well as the upcoming Enterprise Content Management Suite 11gR1 PS3 (patch set 3) release. Register Today! Americas / EMEA time zones: Customer Update January 19, 2010 9:00am US PT / 12:00pm US ET / 17:00 London Length: 1 hour *Please use your corporate email address to register. Asia-Pacific time zones: Customer Update (Repeat Webcast) January 20, 2010 1:00pm Sydney AET, 10:00am Singapore (Jan 19, 2010 @ 6:00pm US PT) Length: 1 hour *Please use your corporate email address to register Missed Previous Customer Quarterly Updates? Get caught up on Oracle & ECM news. View a recording or the presentation from previous Webcasts held since June 2008 (available from My Oracle Support).

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• Drawing on a webpage – HTML5 - IE9

  - by nmarun

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

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• Solaris 11.2: Functional Deprecation

  - by alanc

  In Solaris 11.1, I updated the system headers to enable use of several attributes on functions, including noreturn and printf format, to give compilers and static analyzers more information about how they are used to give better warnings when building code. In Solaris 11.2, I've gone back in and added one more attribute to a number of functions in the system headers: __attribute__((__deprecated__)). This is used to warn people building software that they’re using function calls we recommend no longer be used. While in many cases the Solaris Binary Compatibility Guarantee means we won't ever remove these functions from the system libraries, we still want to discourage their use. I made passes through both the POSIX and C standards, and some of the Solaris architecture review cases to come up with an initial list which the Solaris architecture review committee accepted to start with. This set is by no means a complete list of Obsolete function interfaces, but should be a reasonable start at functions that are well documented as deprecated and seem useful to warn developers away from. More functions may be flagged in the future as they get deprecated, or if further passes are made through our existing deprecated functions to flag more of them. Header Interface Deprecated by Alternative Documented in <door.h> door_cred(3C) PSARC/2002/188 door_ucred(3C) door_cred(3C) <kvm.h> kvm_read(3KVM), kvm_write(3KVM) PSARC/1995/186 Functions on kvm_kread(3KVM) man page kvm_read(3KVM) <stdio.h> gets(3C) ISO C99 TC3 (Removed in ISO C11), POSIX:2008/XPG7/Unix08 fgets(3C) gets(3C) man page, and just about every gets(3C) reference online from the past 25 years, since the Morris worm proved bad things happen when it’s used. <unistd.h> vfork(2) PSARC/2004/760, POSIX:2001/XPG6/Unix03 (Removed in POSIX:2008/XPG7/Unix08) posix_spawn(3C) vfork(2) man page. <utmp.h> All functions from getutent(3C) man page PSARC/1999/103 utmpx functions from getutentx(3C) man page getutent(3C) man page <varargs.h> varargs.h version of va_list typedef ANSI/ISO C89 standard <stdarg.h> varargs(3EXT) <volmgt.h> All functions PSARC/2005/672 hal(5) API volmgt_check(3VOLMGT), etc. <sys/nvpair.h> nvlist_add_boolean(3NVPAIR), nvlist_lookup_boolean(3NVPAIR) PSARC/2003/587 nvlist_add_boolean_value, nvlist_lookup_boolean_value nvlist_add_boolean(3NVPAIR) & (9F), nvlist_lookup_boolean(3NVPAIR) & (9F). <sys/processor.h> gethomelgroup(3C) PSARC/2003/034 lgrp_home(3LGRP) gethomelgroup(3C) <sys/stat_impl.h> _fxstat, _xstat, _lxstat, _xmknod PSARC/2009/657 stat(2) old functions are undocumented remains of SVR3/COFF compatibility support If the above table is cut off when viewing in the blog, try viewing this standalone copy of the table. To See or Not To See To see these warnings, you will need to be building with either gcc (versions 3.4, 4.5, 4.7, & 4.8 are available in the 11.2 package repo), or with Oracle Solaris Studio 12.4 or later (which like Solaris 11.2, is currently in beta testing). For instance, take this oversimplified (and obviously buggy) implementation of the cat command: #include <stdio.h> int main(int argc, char **argv) { char buf[80]; while (gets(buf) != NULL) puts(buf); return 0; } Compiling it with the Studio 12.4 beta compiler will produce warnings such as: % cc -V cc: Sun C 5.13 SunOS_i386 Beta 2014/03/11 % cc gets_test.c "gets_test.c", line 6: warning: "gets" is deprecated, declared in : "/usr/include/iso/stdio_iso.h", line 221 The exact warning given varies by compilers, and the compilers also have a variety of flags to either raise the warnings to errors, or silence them. Of couse, the exact form of the output is Not An Interface that can be relied on for automated parsing, just shown for example. gets(3C) is actually a special case — as noted above, it is no longer part of the C Standard Library in the C11 standard, so when compiling in C11 mode (i.e. when __STDC_VERSION__ >= 201112L), the <stdio.h> header will not provide a prototype for it, causing the compiler to complain it is unknown: % gcc -std=c11 gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-declaration] while (gets(buf) != NULL) ^ The gets(3C) function of course is still in libc, so if you ignore the error or provide your own prototype, you can still build code that calls it, you just have to acknowledge you’re taking on the risk of doing so yourself. Solaris Studio 12.4 Beta % cc gets_test.c "gets_test.c", line 6: warning: "gets" is deprecated, declared in : "/usr/include/iso/stdio_iso.h", line 221 % cc -errwarn=E_DEPRECATED_ATT gets_test.c "gets_test.c", line 6: "gets" is deprecated, declared in : "/usr/include/iso/stdio_iso.h", line 221 cc: acomp failed for gets_test.c This warning is silenced in the 12.4 beta by cc -erroff=E_DEPRECATED_ATT No warning is currently issued by Studio 12.3 & earler releases. gcc 3.4.3 % /usr/sfw/bin/gcc gets_test.c gets_test.c: In function `main': gets_test.c:6: warning: `gets' is deprecated (declared at /usr/include/iso/stdio_iso.h:221) Warning is completely silenced with gcc -Wno-deprecated-declarations gcc 4.7.3 % /usr/gcc/4.7/bin/gcc gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: warning: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Wdeprecated-declarations] % /usr/gcc/4.7/bin/gcc -Werror=deprecated-declarations gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: error: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Werror=deprecated-declarations] cc1: some warnings being treated as errors Warning is completely silenced with gcc -Wno-deprecated-declarations gcc 4.8.2 % /usr/bin/gcc gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: warning: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Wdeprecated-declarations] while (gets(buf) != NULL) ^ % /usr/bin/gcc -Werror=deprecated-declarations gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: error: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Werror=deprecated-declarations] while (gets(buf) != NULL) ^ cc1: some warnings being treated as errors Warning is completely silenced with gcc -Wno-deprecated-declarations

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• How to efficiently map tokens to code in a script interpreter?

  - by lithander

  I'm writing an interpreter for a simple scripting language where each line is a complete, executable command. (Like the instructions in assembler) When parsing a line I have to map the requested command to actual code. My current solution looks like this: std::string op, param1, param2; //parse line, identify op, param1, param2 ... //call command specific code if(op == "MOV") ExecuteMov(AsNumber(param1)); else if(op == "ROT") ExecuteRot(AsNumber(param1)); else if(op == "SZE") ExecuteSze(AsNumber(param1)); else if(op == "POS") ExecutePos((AsNumber(param1), AsNumber(param2)); else if(op == "DIR") ExecuteDir((AsNumber(param1), AsNumber(param2)); else if(op == "SET") ExecuteSet(param1, AsNumber(param2)); else if(op == "EVL") ... The more commands are supported the more string comparisions I'll have to do to identify and call the associated method. Can you point me to a more efficient implementation in the described scenario?

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• ROracle support for TimesTen In-Memory Database

  - by Sam Drake

  Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

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• Using the full tty real estate with sqlplus

  - by katsumii

  I believe 'rlwrap' is widely used for adding 'sqlplus' the history function and command line editing. 'rlwrap' has other functions and here's my kludgy alias to force sqlplus to use the full real estate of yourtty. Be it PuTTy session from Windows or Linux gnome terminal. $ declare -f sqlplus sqlplus () { PRE_TEXT=$(resize |sed -n "1s/COLUMNS=/set linesize /p;2s/LINES=/set pagesize /p"|while read line; do printf "%s \ " "$line";done); if [ -z "$1" ]; then rlwrap -m -P "$PRE_TEXT" sqlplus /nolog; else if ! echo $1 | grep '^-' > /dev/null; then rlwrap -m -P "$PRE_TEXT connect $*" sqlplus /nolog; else command sqlplus $*; fi; fi }

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• Using Delegates in C# (Part 1)

  - by rajbk

  This post provides a very basic introduction of delegates in C#. Part 2 of this post can be read here. A delegate is a class that is derived from System.Delegate.  It contains a list of one or more methods called an invocation list. When a delegate instance is “invoked” with the arguments as defined in the signature of the delegate, each of the methods in the invocation list gets invoked with the arguments. The code below shows example with static and instance methods respectively: Static Methods 1: using System; 2: using System.Linq; 3: using System.Collections.Generic; 4: 5: public delegate void SayName(string name); 6: 7: public class Program 8: { 9: [STAThread] 10: static void Main(string[] args) 11: { 12: SayName englishDelegate = new SayName(SayNameInEnglish); 13: SayName frenchDelegate = new SayName(SayNameInFrench); 14: SayName combinedDelegate =(SayName)Delegate.Combine(englishDelegate, frenchDelegate); 15: 16: combinedDelegate.Invoke("Tom"); 17: Console.ReadLine(); 18: } 19: 20: static void SayNameInFrench(string name) { 21: Console.WriteLine("J'ai m'appelle " + name); 22: } 23: 24: static void SayNameInEnglish(string name) { 25: Console.WriteLine("My name is " + name); 26: } 27: } We have declared a delegate of type SayName with return type of void and taking an input parameter of name of type string. On line 12, we create a new instance of this delegate which refers to a static method - SayNameInEnglish.  SayNameInEnglish has the same return type and parameter list as the delegate declaration.  Once a delegate is instantiated, the instance will always refer to the same target. Delegates are immutable. On line 13, we create a new instance of the delegate but point to a different static method. As you may recall, a delegate instance encapsulates an invocation list. You create an invocation list by combining delegates using the Delegate.Combine method (there is an easier syntax as you will see later). When two non null delegate instances are combined, their invocation lists get combined to form a new invocation list. This is done in line 14.  On line 16, we invoke the delegate with the Invoke method and pass in the required string parameter. Since the delegate has an invocation list with two entries, each of the method in the invocation list is invoked. If an unhandled exception occurs during the invocation of one of these methods, the exception gets bubbled up to the line where the invocation was made (line 16). If a delegate is null and you try to invoke it, you will get a System.NullReferenceException. We see the following output when the method is run: My name is TomJ'ai m'apelle Tom Instance Methods The code below outputs the same results as before. The only difference here is we are creating delegates that point to a target object (an instance of Translator) and instance methods which have the same signature as the delegate type. The target object can never be null. We also use the short cut syntax += to combine the delegates instead of Delegate.Combine. 1: public delegate void SayName(string name); 2: 3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Translator translator = new Translator(); 9: SayName combinedDelegate = new SayName(translator.SayNameInEnglish); 10: combinedDelegate += new SayName(translator.SayNameInFrench); 11:  12: combinedDelegate.Invoke("Tom"); 13: Console.ReadLine(); 14: } 15: } 16: 17: public class Translator { 18: public void SayNameInFrench(string name) { 19: Console.WriteLine("J'ai m'appelle " + name); 20: } 21: 22: public void SayNameInEnglish(string name) { 23: Console.WriteLine("My name is " + name); 24: } 25: } A delegate can be removed from a combination of delegates by using the –= operator. Removing a delegate from an empty list or removing a delegate that does not exist in a non empty list will not result in an exception. Delegates are invoked synchronously using the Invoke method. We can also invoke them asynchronously using the BeginInvoke and EndInvoke methods which are compiler generated.

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• Join Us for the Next Quarterly Customer Update Webcast

  - by michelle.huff

  Join us for the next Oracle Content Management Quarterly Customer Update Webcast scheduled for this coming June 30 / July 1 2010. Don't miss this chance to get an overview on the latest updates to Oracle Content Management. We'll be covering the latest ECM Suite 11g release - highlighting the Universal Content Management (UCM) and Universal Records Management releases. Register Today! Americas / EMEA time zones: Customer Update June 30, 2010 9:00am US PDT / 12:00pm US EDT / 16:00 GMT Length: 1 hour *Please use your corporate email address to register. Asia-Pacific time zones: Customer Update (Repeat Webcast) July 1, 2010 12:00pm Sydney AEST, 10:00am Singapore (June 30, 2010 @ 7:00pm US PDT) Length: 1 hour *Please use your corporate email address to register Please Note: If you have attended previous Quarterly Customer Update Webcasts, we are now using a new web conference system, WebEx, to host the meeting. Missed Previous Customer Quarterly Updates? Get caught up on Oracle & ECM news. View a recording or the presentation from previous Webcasts held since June 2008 (available from My Oracle Support).

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• Quickly compute added and removed lines

  - by Philippe Marschall

  I'm trying to compare two text files. I want to compute how many lines were added and removed. Basically what git diff --stat is doing. Bonus points for not having to store the entire file contents in memory. The approach I'm currently having in mind is: read each line of the old file compute a hash (probably MD5 or SHA-1) for each line store the hashes in a set do the same for each line in the new file every hash from the old file set that's missing in the new file set was removed every hash from the new file set that's missing in the old file set was added I'll probably want to exclude empty and all white space lines. There is a small issue with duplicated lines. This can either be solved by additionally storing how often a hash appears or comparing the number of lines in the old and new file and adjust either the added or removed lines so that the numbers add up. Do you see room for improvements or a better approach?

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• Which of these algorithms is best for my goal?

  - by JonathonG

  I have created a program that restricts the mouse to a certain region based on a black/white bitmap. The program is 100% functional as-is, but uses an inaccurate, albeit fast, algorithm for repositioning the mouse when it strays outside the area. Currently, when the mouse moves outside the area, basically what happens is this: A line is drawn between a pre-defined static point inside the region and the mouse's new position. The point where that line intersects the edge of the allowed area is found. The mouse is moved to that point. This works, but only works perfectly for a perfect circle with the pre-defined point set in the exact center. Unfortunately, this will never be the case. The application will be used with a variety of rectangles and irregular, amorphous shapes. On such shapes, the point where the line drawn intersects the edge will usually not be the closest point on the shape to the mouse. I need to create a new algorithm that finds the closest point to the mouse's new position on the edge of the allowed area. I have several ideas about this, but I am not sure of their validity, in that they may have far too much overhead. While I am not asking for code, it might help to know that I am using Objective C / Cocoa, developing for OS X, as I feel the language being used might affect the efficiency of potential methods. My ideas are: Using a bit of trigonometry to project lines would work, but that would require some kind of intense algorithm to test every point on every line until it found the edge of the region... That seems too resource intensive since there could be something like 200 lines that would have each have to have as many as 200 pixels checked for black/white.... Using something like an A* pathing algorithm to find the shortest path to a black pixel; however, A* seems resource intensive, even though I could probably restrict it to only checking roughly in one direction. It also seems like it will take more time and effort than I have available to spend on this small portion of the much larger project I am working on, correct me if I am wrong and it would not be a significant amount of code (100 lines or around there). Mapping the border of the region before the application begins running the event tap loop. I think I could accomplish this by using my current line-based algorithm to find an edge point and then initiating an algorithm that checks all 8 pixels around that pixel, finds the next border pixel in one direction, and continues to do this until it comes back to the starting pixel. I could then store that data in an array to be used for the entire duration of the program, and have the mouse re-positioning method check the array for the closest pixel on the border to the mouse target position. That last method would presumably execute it's initial border mapping fairly quickly. (It would only have to map between 2,000 and 8,000 pixels, which means 8,000 to 64,000 checked, and I could even permanently store the data to make launching faster.) However, I am uncertain as to how much overhead it would take to scan through that array for the shortest distance for every single mouse move event... I suppose there could be a shortcut to restrict the number of elements in the array that will be checked to a variable number starting with the intersecting point on the line (from my original algorithm), and raise/lower that number to experiment with the overhead/accuracy tradeoff. Please let me know if I am over thinking this and there is an easier way that will work just fine, or which of these methods would be able to execute something like 30 times per second to keep mouse movement smooth, or if you have a better/faster method. I've posted relevant parts of my code below for reference, and included an example of what the area might look like. (I check for color value against a loaded bitmap that is black/white.) // // This part of my code runs every single time the mouse moves. // CGPoint point = CGEventGetLocation(event); float tX = point.x; float tY = point.y; if( is_in_area(tX,tY, mouse_mask)){ // target is inside O.K. area, do nothing }else{ CGPoint target; //point inside restricted region: float iX = 600; // inside x float iY = 500; // inside y // delta to midpoint between iX,iY and tX,tY float dX; float dY; float accuracy = .5; //accuracy to loop until reached do { dX = (tX-iX)/2; dY = (tY-iY)/2; if(is_in_area((tX-dX),(tY-dY),mouse_mask)){ iX += dX; iY += dY; } else { tX -= dX; tY -= dY; } } while (abs(dX)>accuracy || abs(dY)>accuracy); target = CGPointMake(roundf(tX), roundf(tY)); CGDisplayMoveCursorToPoint(CGMainDisplayID(),target); } Here is "is_in_area(int x, int y)" : bool is_in_area(NSInteger x, NSInteger y, NSBitmapImageRep *mouse_mask){ NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSUInteger pixel[4]; [mouse_mask getPixel:pixel atX:x y:y]; if(pixel[0]!= 0){ [pool release]; return false; } [pool release]; return true; }

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• Throwing exception from a property when my object state is invalid

  - by Rumi P.

  Microsoft guidelines say: "Avoid throwing exceptions from property getters", and I normally follow that. But my application uses Linq2SQL, and there is the case where my object can be in invalid state because somebody or something wrote nonsense into the database. Consider this toy example: [Table(Name="Rectangle")] public class Rectangle { [Column(Name="ID", IsPrimaryKey = true, IsDbGenerated = true)] public int ID {get; set;} [Column(Name="firstSide")] public double firstSide {get; set;} [Column(Name="secondSide")] public double secondSide {get; set;} public double sideRatio { get { return firstSide/secondSide; } } } Here, I could write code which ensures that my application never writes a Rectangle with a zero-length side into the database. But no matter how bulletproof I make my own code, somebody could open the database with a different application and create an invalid Rectangle, especially one with a 0 for secondSide. (For this example, please forget that it is possible to design the database in a way such that writing a side length of zero into the rectangle table is impossible; my domain model is very complex and there are constraints on model state which cannot be expressed in a relational database). So, the solution I am gravitating to is to change the getter to: get { if(firstSide > 0 && secondSide > 0) return firstSide/secondSide; else throw new System.InvalidOperationException("All rectangle sides should have a positive length"); } The reasoning behind not throwing exceptions from properties is that programmers should be able to use them without having to make precautions about catching and handling them them. But in this case, I think that it is OK to continue to use this property without such precautions: if the exception is thrown because my application wrote a non-zero rectangle side into the database, then this is a serious bug. It cannot and shouldn't be handled in the application, but there should be code which prevents it. It is good that the exception is visibly thrown, because that way the bug is caught. if the exception is thrown because a different application changed the data in the database, then handling it is outside of the scope of my application. So I can't do anything about it if I catch it. Is this a good enough reasoning to get over the "avoid" part of the guideline and throw the exception? Or should I turn it into a method after all? Note that in the real code, the properties which can have an invalid state feel less like the result of a calculation, so they are "natural" properties, not methods.

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• Unable to locate package lightread

  - by TENG PENG

  I have changed my source to local server. I'm using Ubuntu 12.10. When I type apt-cache search in terminal, it shows nothing. When I install lightread it shows Unable to locate package lightread. When I install lightread manually by python. It shows python '/home/peng/Downloads/quickly_trunk/setup.py' Traceback (most recent call last): File "/home/peng/Downloads/quickly_trunk/setup.py", line 93, in <module> data_files=[('share/icons/hicolor/128x128/apps', ['data/media/lightread.png'])] File "/usr/lib/python2.7/dist-packages/DistUtilsExtra/auto.py", line 71, in setup src_mark(src, 'setup.py') File "/usr/lib/python2.7/dist-packages/DistUtilsExtra/auto.py", line 527, in src_mark src.remove(path) KeyError: 'setup.py' How to solve the problem?

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• IsNullOrEmpty generic method for Array to avoid Re-Sharper warning

  - by Michael Freidgeim

  I’ve used the following extension method in many places. public static bool IsNullOrEmpty(this Object[] myArr) { return (myArr == null || myArr.Length == 0); }Recently I’ve noticed that Resharper shows warning covariant array conversion to object[] may cause an exception for the following codeObjectsOfMyClass.IsNullOrEmpty()I’ve resolved the issue by creating generic extension method public static bool IsNullOrEmpty<T>(this T[] myArr) { return (myArr == null || myArr.Length == 0); }Related linkshttp://connect.microsoft.com/VisualStudio/feedback/details/94089/add-isnullorempty-to-array-class    public static bool IsNullOrEmpty(this System.Collections.IEnumerable source)        {            if (source == null)                return true;            else            {                return !source.GetEnumerator().MoveNext();            }        }http://stackoverflow.com/questions/8560106/isnullorempty-equivalent-for-array-c-sharp

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