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  • Passing C++ object to C++ code through Python?

    - by cornail
    Hi all, I have written some physics simulation code in C++ and parsing the input text files is a bottleneck of it. As one of the input parameters, the user has to specify a math function which will be evaluated many times at run-time. The C++ code has some pre-defined function classes for this (they are actually quite complex on the math side) and some limited parsing capability but I am not satisfied with this construction at all. What I need is that both the algorithm and the function evaluation remain speedy, so it is advantageous to keep them both as compiled code (and preferrably, the math functions as C++ function objects). However I thought of glueing the whole simulation together with Python: the user could specify the input parameters in a Python script, while also implementing storage, visualization of the results (matplotlib) and GUI, too, in Python. I know that most of the time, exposing C++ classes can be done, e.g. with SWIG but I still have a question concerning the parsing of the user defined math function in Python: Is it possible to somehow to construct a C++ function object in Python and pass it to the C++ algorithm? E.g. when I call f = WrappedCPPGaussianFunctionClass(sigma=0.5) WrappedCPPAlgorithm(f) in Python, it would return a pointer to a C++ object which would then be passed to a C++ routine requiring such a pointer, or something similar... (don't ask me about memory management in this case, though :S) The point is that no callback should be made to Python code in the algorithm. Later I would like to extend this example to also do some simple expression parsing on the Python side, such as sum or product of functions, and return some compound, parse-tree like C++ object but let's stay at the basics for now. Sorry for the long post and thx for the suggestions in advance.

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  • Silverlight Cream for March 24, 2010 -- #819

    - by Dave Campbell
    In this Issue: Nokola, Tim Heuer, Christian Schormann, Brad Abrams, David Kelley, Phil Middlemiss, Michael Klucher, Brandon Watson, Kunal Chowdhury, Jacek Ciereszko, and Unni. Shoutouts: Michael Klucher has a short post up For Love of the Game (Development)…, where he's looking for some input from the developer community. Shawn Hargreaves has a link post up of all the Windows Phone MIX10 presentations Chris Cavanagh has a Soft-Body Physics for Windows Phone 7 post up that goes along with one he did 1-1/2 years ago! Jeff Weber posted An Open Letter To Microsoft Regarding The Silverlight Game Development Community Pete Brown posted his MIX10 Recap ... lots of information, and discussion of what he was up to ... I liked the Trivia app Pete... glad to hear that was yours :) I've changed my mind and added a WP7 tag to SilverlightCream. I'll straighten out all the Mobile plus Silverlight links to point at the WP7 tab hopefully tonight. From SilverlightCream.com: EasyPainter Source Pack 3: Adorners, Mouse Cursors and Frames Nokola has been busy with EasyPainter adding in Custom, Extensible Mouse Cursors and Customizable Adorners with extensible adorner frames, and best of all... all with source code! Simulate Geo Location in Silverlight Windows Phone 7 emulator Among the things we don't have in our WP7 emulators is Geo Location... Tim Heuer comes to the rescue with a simulator for it... too cool, Tim! Blend 4: About Path Layout, Part II Christian Schormann is back with Part 2 of his tutorial sequence on the new Path Layout. Really good info and definitely cool presentations of the control. Silverlight 4 + RIA Services - Ready for Business: Exposing OData Services Brad Abrams continues his series with a post on exposing OData services. This looks like a great tutorial on the topic... will probably resolve some questions I've been having :) No Silverlight and Preloader Experience(ish) - in 10 seconds... David Kelley exposes the code he uses on his site, designed to be friendly to Silverlight and non-Silverlight users alike. Merged Dictionaries of Style Resources and Blend Phil Middlemiss has a nice article up on Merged Dictionaries and using multiple resource dictionaries that the app chooses, but also be compatible with Prism and Blend while not eating your system resources out of house and home. XNA Game Studio and Windows Phone Emulator Compatibility Michael Klucher has a definitive post up about getting your XNA and system up-to-speed for WP7... a must-read if you've been running any of the other XNA drops. Windows Phone 7 301 Redirect Bug Brandon Watson reports a 301 Redirect bug on WP7 ... see the code and how he got it, then follow along as he explains all the debug paths he took and what the resolution (?) really is :) Silverlight 4: How to use the new Printing API? Kunal Chowdhury has a tutorial up on printing with Silverlight 4 RC... from the project layout to printing and then printing a smaller section... all good Printing problem in Silverlight 4.0 RC - loading images in code behind Jacek Ciereszko also is writing about printing, and in his case he had problems with loading an image dynamically and printing it... plus he provides a solution to the 'blank page' problem. ToolboxExampleAttribute - a new extension point in Blend 4 (and a few other extensibility related changes) Unni has an article up about Expression Blend 4's new ToolboxExampleAttribute which allow you to have multiple examples of the same type resulting in different XAML produced. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone    MIX10

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  • F# in ASP.NET, mathematics and testing

    - by DigiMortal
    Starting from Visual Studio 2010 F# is full member of .NET Framework languages family. It is functional language with syntax specific to functional languages but I think it is time for us also notice and study functional languages. In this posting I will show you some examples about cool things other people have done using F#. F# and ASP.NET As I am ASP/ASP.NET MVP I am – of course – interested in how people use different languages and technologies with ASP.NET. C# MVP Tomáš Petrícek writes about developing ASP.NET MVC applications using F#. He also shows how to use LINQ To SQL in F# (using F# PowerPack) and provides sample solution and Visual Studio 2010 template for F# MVC web applications. You may also find interesting how you can create controllers in F#. Excellent work, Tomáš! Vladimir Matveev has interesting example about how to use F# and ApplicationHost class to process ASP.NET requests ouside of IIS. This is simple and very straight-forward example and I strongly suggest you to take a look at it. Very cool example is project Strom in Codeplex. Storm is web services testing tool that is fully written on F#. Take a look at this site because Codeplex offers also source code besides binaries. Math Functional languages are strong in fields like mathematics and physics. When I wrote my C# example about BigInteger class I found out that recursive version of Fibonacci algorithm in C# is not performing well. In same time I made same experiment on F# and in F# there were no performance problems with recursive version. You can find F# version of Fibonacci algorithm from Bob Palmer’s blog posting Fibonacci numbers in F#. Although golden spiral is useful for solving many problems I looked for some practical code example and found one. Kean Walmsley published in his Through the Interface blog very interesting posting Creating Fibonacci spirals in AutoCAD using F#. There are also other cool examples you may be interested in. Using numerical components by Extreme Optimization  it is possible to make some numerical integration (quadrature method) using F# (also C# example is available). fsharp.it introduces factorials calculation on F#. Robert Pickering has made very good work on programming The Game of Life in Silverlight and F# – I definitely suggest you to try out this example as it is very illustrative too. Who wants something more complex may take a look at Newton basin fractal example in F# by Jonathan Birge. Testing After some searching and surfing I found out that there is almost everything available for F# to write tests and test your F# code. FsCheck - FsCheck is a port of Haskell's QuickCheck. Important parts of the manual for using FsCheck is almost literally "adapted" from the QuickCheck manual and paper. Any errors and omissions are entirely my responsibility. FsTest - This project is designed to Language Oriented Programming constructs around unit testing and behavior testing in F#. The goal of this project is to create a Domain Specific Language for testing F# code in a way that makes sense for functional programming. FsUnit - FsUnit makes unit-testing with F# more enjoyable. It adds a special syntax to your favorite .NET testing framework. xUnit.NET - xUnit.net is a developer testing framework, built to support Test Driven Development, with a design goal of extreme simplicity and alignment with framework features. It is compatible with .NET Framework 2.0 and later, and offers several runners: console, GUI, MSBuild, and Visual Studio integration via TestDriven.net, CodeRush Test Runner and Resharper. It also offers test project integration for ASP.NET MVC. Getting started Well, as a first thing you need Visual Studio 2010. Then take a look at these resources: F# samples @ MSDN Microsoft F# Developer Center @ MSDN F# Language Reference @ MSDN F# blog F# forums Real World Functional Programming: With Examples in F# and C# (Amazon) Happy F#-ing! :)

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  • Silverlight Cream for January 04, 2011 -- #1022

    - by Dave Campbell
    In this Issue: Dennis Doomen, Doug Holland, Kunal Chowdhury, Sacha Barber, Paul Sheriff, Mike Snow(-2-), Peter Kuhn(-2-), and Mike Ormond. Above the Fold: Silverlight: "Silverlight: Fixing the BookShelf Sample" Peter Kuhn WP7: "Searching the Windows Phone 7 Marketplace Programmatically" Doug Holland Prism/Cinch: "PRISM 4 Custom Transitioning Region" Sacha Barber Shoutouts: Sacha Barber the author of Cinch asks for some advice from users: Cinch V2 : Question For The Reader Michael Crump introduces us to SnippetManager as a way to organize your Silverlight snippets... I'm thinking any snippet: A better way to organize your Silverlight Code Snippets. Andy Beaulieu announced an update of Physics Helper 4.2 using Farseer 3.2 ... check out the breaking changes though! Dennis Doomen blogged about a new release of his Fluent Assertions: A new year with a new release of Fluent Assertions, with a blog post about it below From SilverlightCream.com: Verifying PropertyChanged events in Silverlight using Fluent Assertions Dennis Doomen release his latest Fluent Assertions for .NET and Silverlight and wrote up a big post about the new event monitoring syntax. Searching the Windows Phone 7 Marketplace Programmatically Doug Holland has a post up on MSDN blogs talking about searching the WP7 Marketplace programmatically... ya know you should be able to do it... here's how. Beginners Guide to Visual Studio LightSwitch (Part - 5) Kunal Chowdhury has Part 5 of a tutorial series on Lightswitch up at SilverlightShow... working with custom validation this time, and for the first time in this series so far actually writes some code! PRISM 4 Custom Transitioning Region Sacha Barber took time to look at Prism4/MEF and Cinch2 and found things to be fine then wrote a custom PRISM region adaptor that uses a TransitionalElement from the Microsoft Transitionals project... code available, blog post to come. Get Application Title from Windows Phone Paul Sheriff has a cool chunk of code up... getting the Application's title programmatically... and other attributes as well, if you were wondering why you might wanna do that. Detecting Users Win7 Mobile Theme Color Mike Snow has a couple as well... first up is how to detect your user's theme... obviously useful if you wanna match it. Selecting an Item in a ComboBox after Adding Items Second for Mike Snow is a general Silverlight issue... setting the selected item on a ComboBox after filling it... if you haven't stumbled across this yet, you will... A Simplified Grid Markup Reloaded Peter Kuhn has a pair of posts up since last time... this first is an extension of Colin Eberhardt's simplified Grid markup system, but it's only useful if you don't plan on using Blend... can we get a show of hands? :) Silverlight: Fixing the BookShelf Sample Next Peter Kuhn has some changes to the Bookshelf code, but more importantly has some excelling tips about shader effects, Effects on Visual Elements and how to make best use of all the above. Displaying HTML Content in Windows Phone 7 Mike Ormond has a WP7 post up describing problems a customer had early on displaying rich text and an attempt to use the WebBrowser control to pull it off and the problems that caused... check out the resultant code, and read the comments as well. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Why are my Unity procedural animations jerky?

    - by Phoenix Perry
    I'm working in Unity and getting some crazy weird motion behavior. I have a plane and I'm moving it. It's ever so slightly getting about 1 pixel bigger and smaller. It looks like the it's kind of getting squeezed sideways by a pixel. I'm moving a plane by cos and sin so it will spin on the x and z axes. If the planes are moving at Time.time, everything is fine. However, if I put in slower speed multiplier, I get an amazingly weird jerk in my animation. I get it with or without the lerp. How do I fix it? I want it to move very slowly. Is there some sort of invisible grid in unity? Some sort of minimum motion per frame? I put a visual sample of the behavior here. Here's the relevant code: public void spin() { for (int i = 0; i < numPlanes; i++ ) { GameObject g = planes[i] as GameObject; //alt method //currentRotation += speed * Time.deltaTime * 100; //rotation.eulerAngles = new Vector3(0, currentRotation, 0); //g.transform.position = rotation * rotationRadius; //sine method g.GetComponent<PlaneSetup>().pos.x = g.GetComponent<PlaneSetup>().radiusX * (Mathf.Cos((Time.time*speed) + g.GetComponent<PlaneSetup>().startAngle)); g.GetComponent<PlaneSetup>().pos.z = g.GetComponent<PlaneSetup>().radius * Mathf.Sin((Time.time*speed) + g.GetComponent<PlaneSetup>().startAngle); g.GetComponent<PlaneSetup>().pos.y = g.GetComponent<Transform>().position.y; ////offset g.GetComponent<PlaneSetup>().pos.z += 20; g.GetComponent<PlaneSetup>().posLerp.x = Mathf.Lerp(g.transform.position.x,g.GetComponent<PlaneSetup>().pos.x, .5f); g.GetComponent<PlaneSetup>().posLerp.z = Mathf.Lerp(g.transform.position.z, g.GetComponent<PlaneSetup>().pos.z, .5f); g.GetComponent<PlaneSetup>().posLerp.y = g.GetComponent<Transform>().position.y; g.transform.position = g.GetComponent<PlaneSetup>().posLerp; } Invoke("spin",0.0f); } The full code is on github. There is literally nothing else going on. I've turned off all other game objects so it's only the 40 planes with a texture2D shader. I removed it from Invoke and tried it in Update -- still happens. With a set frame rate or not, the same problem occurs. Tested it in Fixed Update. Same issue. The script on the individual plane doesn't even have an update function in it. The data on it could functionally live in a struct. I'm getting between 90 and 123 fps. Going to investigate and test further. I put this in an invoke function to see if I could get around it just occurring in update. There are no physics on these shapes. It's a straight procedural animation. Limited it to 1 plane - still happens. Thoughts? Removed the shader - still happening.

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  • Where to start with game development?

    - by steven_desu
    I asked this earlier in this thread at stackoverflow.com. One of the early comments redirected me here to gamedev.stackexchange.com, so I'm reposting here. Searching for related questions I found a number of very specific questions, but I'm afraid the specifics have proved fruitless for me and after 4 hours on Google I'm no closer than I started, so I felt reaching out to a community might be in order. First, my goal: I've never made a game before, although I've muddled over the possibility several times. I decided to finally sit down and start learning how to code games, use game engines, etc. All so that one day (hopefully soon) I'll be able to make functional (albeit simple) games. I can start adding complexity later, for now I'd be glad to have a keyboard-controlled camera moving in a 3D world with no interaction beyond that. My background: I've worked in SEVERAL programming languages ranging from PHP to C++ to Java to ASM. I'm not afraid of any challenges that come with learning the new syntax or limitations inherent in a new language. All of my past programming experience, however, has been strictly non-graphical and usually with little or extremely simple interaction during execution. I've created extensive and brilliant algorithms for solving logical and mathematical problems as well as graphing problems. However in every case input was either defined in a file, passed form an HTML form, or typed into the console. Real-time interaction with the user is something with which I have no experience. My question: Where should I start in trying to make games? Better yet- where should I start in trying to create a keyboard-navigable 3D environment? In searching online I've found several resources linking to game engines, graphics engines, and physics engines. Here's a brief summary of my experiences with a few engines I tried: Unreal SDK: The tutorial videos assume that you already have in-depth knowledge of 3D modeling, graphics engines, animations, etc. The "Getting Started" page offers no formal explanation of game development but jumps into how Unreal can streamline processes it assumes you're already familiar with. After downloading the SDK and launching it to see if the tools were as intuitive as they claimed, I was greeted with about 60 buttons and a blank void for my 3D modeling. Clicking on "add volume" (to attempt to add a basic cube) I was met with a menu of 30 options. Panicking, I closed the editor. Crystal Space: The website seemed rather informative, explaining that Crystal Space was just for graphics and the companion software, CEL, provided entity logic for making games. A demo game was provided, which was built using "CELStart", their simple tool for people with no knowledge of game programming. I launched the game to see what I might look forward to creating. It froze several times, the menus were buggy, there were thousands of graphical glitches, enemies didn't respond to damage, and when I closed the game it locked up. Gave up on that engine. IrrLicht: The tutorial assumes I have Visual Studio 6.0 (I have Visual Studio 2010). Following their instructions I was unable to properly import the library into Visual Studio and unable to call any of the functions that they kept using. Manually copying header files, class files, and DLLs into my project's folder - the project failed to properly compile. Clearly I'm not off to a good start and I'm going in circles. Can someone point me in the right direction? Should I start by downloading a program like Blender and learning 3D modeling, or should I be learning how to use a graphics engine? Should I look for an all-inclusive game engine, or is it better to try and code my own game logic? If anyone has actually made their own games, I would prefer to hear how they got their start. Also- taking classes at my school is not an option. Nothing is offered.

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  • Where to start with game development?

    - by steven_desu
    Searching for related questions I found a number of very specific questions, but I'm afraid the specifics have proved fruitless for me and after 4 hours on Google I'm no closer than I started, so I felt reaching out to a community might be in order. First, my goal: I've never made a game before, although I've muddled over the possibility several times. I decided to finally sit down and start learning how to code games, use game engines, etc. All so that one day (hopefully soon) I'll be able to make functional (albeit simple) games. I can start adding complexity later, for now I'd be glad to have a keyboard-controlled camera moving in a 3D world with no interaction beyond that. My background: I've worked in SEVERAL programming languages ranging from PHP to C++ to Java to ASM. I'm not afraid of any challenges that come with learning the new syntax or limitations inherent in a new language. All of my past programming experience, however, has been strictly non-graphical and usually with little or extremely simple interaction during execution. I've created extensive and brilliant algorithms for solving logical and mathematical problems. However in every case input was either defined in a file, passed form an HTML form, or typed into the console. Real-time interaction with the user is something with which I have no experience. My question: Where should I start in trying to make games? Better yet- where should I start in trying to create a keyboard-navigable 3D environment? In searching online I've found several resources linking to game engines, graphics engines, and physics engines. Here's a brief summary of my experiences with a few engines I tried: Unreal SDK: The tutorial videos assume that you already have in-depth knowledge of 3D modeling, graphics engines, animations, etc. The "Getting Started" page offers no formal explanation of game development but jumps into how Unreal can streamline processes it assumes you're already familiar with. After downloading the SDK and launching it to see if the tools were as intuitive as they claimed, I was greeted with about 60 buttons and a blank void for my 3D modeling. Clicking on "add volume" (to attempt to add a basic cube) I was met with a menu of 30 options. Panicking, I closed the editor. Crystal Space: The website seemed rather informative, explaining that Crystal Space was just for graphics and the companion software, CEL, provided entity logic for making games. A demo game was provided, which was built using "CELStart", their simple tool for people with no knowledge of game programming. I launched the game to see what I might look forward to creating. It froze several times, the menus were buggy, there were thousands of graphical glitches, enemies didn't respond to damage, and when I closed the game it locked up. Gave up on that engine. IrrLicht: The tutorial assumes I have Visual Studio 6.0 (I have Visual Studio 2010). Following their instructions I was unable to properly import the library into Visual Studio and unable to call any of the functions that they kept using. Manually copying header files, class files, and DLLs into my project's folder - the project failed to properly compile. Clearly I'm not off to a good start and I'm going in circles. Can someone point me in the right direction? Should I start by downloading a program like Blender and learning 3D modeling, or should I be learning how to use a graphics engine? Should I look for an all-inclusive game engine, or is it better to try and code my own game logic? If anyone has actually made their own games, I would prefer to hear how they got their start. Also- taking classes at my school is not an option. Nothing is offered.

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  • Move a sphere along the swipe?

    - by gameOne
    I am trying to get a sphere curl based on the swipe. I know this has been asked many times, but still it's yearning to be answered. I have managed to add force on the direction of the swipe and it works near perfect. I also have all the swipe positions stored in a list. Now I would like to know how can the curl be achieved. I believe the the curve in the swipe can be calculated by the Vector dot product If theta is 0, then there is no need to add the swipe. If it is not, then add the curl. Maybe this condition is redundant if I managed to find how to curl the sphere along the swipe position The code that adds the force to sphere based on the swipe direction is as below: using UnityEngine; using System.Collections; using System.Collections.Generic; public class SwipeControl : MonoBehaviour { //First establish some variables private Vector3 fp; //First finger position private Vector3 lp; //Last finger position private Vector3 ip; //some intermediate finger position private float dragDistance; //Distance needed for a swipe to register public float power; private Vector3 footballPos; private bool canShoot = true; private float factor = 40f; private List<Vector3> touchPositions = new List<Vector3>(); void Start(){ dragDistance = Screen.height*20/100; Physics.gravity = new Vector3(0, -20, 0); footballPos = transform.position; } // Update is called once per frame void Update() { //Examine the touch inputs foreach (Touch touch in Input.touches) { /*if (touch.phase == TouchPhase.Began) { fp = touch.position; lp = touch.position; }*/ if (touch.phase == TouchPhase.Moved) { touchPositions.Add(touch.position); } if (touch.phase == TouchPhase.Ended) { fp = touchPositions[0]; lp = touchPositions[touchPositions.Count-1]; ip = touchPositions[touchPositions.Count/2]; //First check if it's actually a drag if (Mathf.Abs(lp.x - fp.x) > dragDistance || Mathf.Abs(lp.y - fp.y) > dragDistance) { //It's a drag //Now check what direction the drag was //First check which axis if (Mathf.Abs(lp.x - fp.x) > Mathf.Abs(lp.y - fp.y)) { //If the horizontal movement is greater than the vertical movement... if ((lp.x>fp.x) && canShoot) //If the movement was to the right) { //Right move float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,10,16))*power); Debug.Log("right "+(lp.x-fp.x));//MOVE RIGHT CODE HERE canShoot = false; //rigidbody.AddForce((new Vector3((lp.x-fp.x)/30,10,16))*power); StartCoroutine(ReturnBall()); } else { //Left move float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,10,16))*power); Debug.Log("left "+(lp.x-fp.x));//MOVE LEFT CODE HERE canShoot = false; //rigidbody.AddForce(new Vector3((lp.x-fp.x)/30,10,16)*power); StartCoroutine(ReturnBall()); } } else { //the vertical movement is greater than the horizontal movement if (lp.y>fp.y) //If the movement was up { //Up move float y = (lp.y-fp.y)/Screen.height*factor; float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,y,16))*power); Debug.Log("up "+(lp.x-fp.x));//MOVE UP CODE HERE canShoot = false; //rigidbody.AddForce(new Vector3((lp.x-fp.x)/30,10,16)*power); StartCoroutine(ReturnBall()); } else { //Down move Debug.Log("down "+lp+" "+fp);//MOVE DOWN CODE HERE } } } else { //It's a tap Debug.Log("none");//TAP CODE HERE } } } } IEnumerator ReturnBall() { yield return new WaitForSeconds(5.0f); rigidbody.velocity = Vector3.zero; rigidbody.angularVelocity = Vector3.zero; transform.position = footballPos; canShoot =true; isKicked = false; } }

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  • 2D Tile Based Collision Detection

    - by MrPlosion1243
    There are a lot of topics about this and it seems each one addresses a different problem, this topic does the same. I was looking into tile collision detection and found this where David Gouveia explains a great way to get around the person's problem by separating the two axis. So I implemented the solution and it all worked perfectly from all the testes I through at it. Then I implemented more advanced platforming physics and the collision detection broke down. Unfortunately I have not been able to get it to work again which is where you guys come in :)! I will present the code first: public void Update(GameTime gameTime) { if(Input.GetKeyDown(Keys.A)) { velocity.X -= moveAcceleration; } else if(Input.GetKeyDown(Keys.D)) { velocity.X += moveAcceleration; } if(Input.GetKeyDown(Keys.Space)) { if((onGround && isPressable) || (!onGround && airTime <= maxAirTime && isPressable)) { onGround = false; airTime += (float)gameTime.ElapsedGameTime.TotalSeconds; velocity.Y = initialJumpVelocity * (1.0f - (float)Math.Pow(airTime / maxAirTime, Math.PI)); } } else if(Input.GetKeyReleased(Keys.Space)) { isPressable = false; } if(onGround) { velocity.X *= groundDrag; velocity.Y = 0.0f; } else { velocity.X *= airDrag; velocity.Y += gravityAcceleration; } velocity.Y = MathHelper.Clamp(velocity.Y, -maxFallSpeed, maxFallSpeed); velocity.X = MathHelper.Clamp(velocity.X, -maxMoveSpeed, maxMoveSpeed); position += velocity * (float)gameTime.ElapsedGameTime.TotalSeconds; position = new Vector2((float)Math.Round(position.X), (float)Math.Round(position.Y)); if(Math.Round(velocity.X) != 0.0f) { HandleCollisions2(Direction.Horizontal); } if(Math.Round(velocity.Y) != 0.0f) { HandleCollisions2(Direction.Vertical); } } private void HandleCollisions2(Direction direction) { int topTile = (int)Math.Floor((float)Bounds.Top / Tile.PixelTileSize); int bottomTile = (int)Math.Ceiling((float)Bounds.Bottom / Tile.PixelTileSize) - 1; int leftTile = (int)Math.Floor((float)Bounds.Left / Tile.PixelTileSize); int rightTile = (int)Math.Ceiling((float)Bounds.Right / Tile.PixelTileSize) - 1; for(int x = leftTile; x <= rightTile; x++) { for(int y = topTile; y <= bottomTile; y++) { Rectangle tileBounds = new Rectangle(x * Tile.PixelTileSize, y * Tile.PixelTileSize, Tile.PixelTileSize, Tile.PixelTileSize); Vector2 depth; if(Tile.IsSolid(x, y) && Intersects(tileBounds, direction, out depth)) { if(direction == Direction.Horizontal) { position.X += depth.X; } else { onGround = true; isPressable = true; airTime = 0.0f; position.Y += depth.Y; } } } } } From the code you can see when velocity.X is not equal to zero the HandleCollisions() Method is called along the horizontal axis and likewise for the vertical axis. When velocity.X is not equal to zero and velocity.Y is equal to zero it works fine. When velocity.Y is not equal to zero and velocity.X is equal to zero everything also works fine. However when both axis are not equal to zero that's when it doesn't work and I don't know why. I basically teleport to the left side of a tile when both axis are not equal to zero and there is a air block next to me. Hopefully someone can see the problem with this because I sure don't as far as I'm aware nothing has even changed from what I'm doing to what the linked post's solution is doing. Thanks.

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  • Platform jumping problems with AABB collisions

    - by Vee
    See the diagram first: When my AABB physics engine resolves an intersection, it does so by finding the axis where the penetration is smaller, then "push out" the entity on that axis. Considering the "jumping moving left" example: If velocityX is bigger than velocityY, AABB pushes the entity out on the Y axis, effectively stopping the jump (result: the player stops in mid-air). If velocityX is smaller than velocitY (not shown in diagram), the program works as intended, because AABB pushes the entity out on the X axis. How can I solve this problem? Source code: public void Update() { Position += Velocity; Velocity += World.Gravity; List<SSSPBody> toCheck = World.SpatialHash.GetNearbyItems(this); for (int i = 0; i < toCheck.Count; i++) { SSSPBody body = toCheck[i]; body.Test.Color = Color.White; if (body != this && body.Static) { float left = (body.CornerMin.X - CornerMax.X); float right = (body.CornerMax.X - CornerMin.X); float top = (body.CornerMin.Y - CornerMax.Y); float bottom = (body.CornerMax.Y - CornerMin.Y); if (SSSPUtils.AABBIsOverlapping(this, body)) { body.Test.Color = Color.Yellow; Vector2 overlapVector = SSSPUtils.AABBGetOverlapVector(left, right, top, bottom); Position += overlapVector; } if (SSSPUtils.AABBIsCollidingTop(this, body)) { if ((Position.X >= body.CornerMin.X && Position.X <= body.CornerMax.X) && (Position.Y + Height/2f == body.Position.Y - body.Height/2f)) { body.Test.Color = Color.Red; Velocity = new Vector2(Velocity.X, 0); } } } } } public static bool AABBIsOverlapping(SSSPBody mBody1, SSSPBody mBody2) { if(mBody1.CornerMax.X <= mBody2.CornerMin.X || mBody1.CornerMin.X >= mBody2.CornerMax.X) return false; if (mBody1.CornerMax.Y <= mBody2.CornerMin.Y || mBody1.CornerMin.Y >= mBody2.CornerMax.Y) return false; return true; } public static bool AABBIsColliding(SSSPBody mBody1, SSSPBody mBody2) { if (mBody1.CornerMax.X < mBody2.CornerMin.X || mBody1.CornerMin.X > mBody2.CornerMax.X) return false; if (mBody1.CornerMax.Y < mBody2.CornerMin.Y || mBody1.CornerMin.Y > mBody2.CornerMax.Y) return false; return true; } public static bool AABBIsCollidingTop(SSSPBody mBody1, SSSPBody mBody2) { if (mBody1.CornerMax.X < mBody2.CornerMin.X || mBody1.CornerMin.X > mBody2.CornerMax.X) return false; if (mBody1.CornerMax.Y < mBody2.CornerMin.Y || mBody1.CornerMin.Y > mBody2.CornerMax.Y) return false; if(mBody1.CornerMax.Y == mBody2.CornerMin.Y) return true; return false; } public static Vector2 AABBGetOverlapVector(float mLeft, float mRight, float mTop, float mBottom) { Vector2 result = new Vector2(0, 0); if ((mLeft > 0 || mRight < 0) || (mTop > 0 || mBottom < 0)) return result; if (Math.Abs(mLeft) < mRight) result.X = mLeft; else result.X = mRight; if (Math.Abs(mTop) < mBottom) result.Y = mTop; else result.Y = mBottom; if (Math.Abs(result.X) < Math.Abs(result.Y)) result.Y = 0; else result.X = 0; return result; }

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  • Problems with moving 2D circle/box collision detection

    - by dario3004
    This is my first game ever and I'm a newbie in computer physics. I've got this code for the collision detection and it works fine for BOTTOM and TOP collision.It miss the collision detection with the paddle's edge and angles so I've (roughly) tried to implement it. Main method that is called for bouncing, it checks if it bounce with wall, or with top (+ right/left side) or with bottom (+ right/left side): protected void handleBounces(float px, float py) { handleWallBounce(px, py); if(mBall.y < getHeight()/4){ if (handleRedFastBounce(mRed, px, py)) return; if (handleRightSideBounce(mRed,px,py)) return; if (handleLeftSideBounce(mRed,px,py)) return; } if(mBall.y > getHeight()/4 * 3){ if (handleBlueFastBounce(mBlue, px, py)) return; if (handleRightSideBounce(mBlue,px,py)) return; if (handleLeftSideBounce(mBlue,px,py)) return; } } This is the code for the BOTTOM bounce: protected boolean handleRedFastBounce(Paddle paddle, float px, float py) { if (mBall.goingUp() == false) return false; // next position tx = mBall.x; ty = mBall.y - mBall.getRadius(); // actual position ptx = px; pty = py - mBall.getRadius(); dyp = ty - paddle.getBottom(); xc = tx + (tx - ptx) * dyp / (ty - pty); if ((ty < paddle.getBottom() && pty > paddle.getBottom() && xc > paddle.getLeft() && xc < paddle.getRight())) { mBall.x = xc; mBall.y = paddle.getBottom() + mBall.getRadius(); mBall.bouncePaddle(paddle); playSound(mPaddleSFX); increaseDifficulty(); return true; } else return false; } As long as I understood it should be something like this: So I tried to make the "left side" and "right side" bounce method: protected boolean handleLeftSideBounce(Paddle paddle, float px, float py){ // next position tx = mBall.x + mBall.getRadius(); ty = mBall.y; // actual position ptx = px + mBall.getRadius(); pty = py; dyp = tx - paddle.getLeft(); yc = ty + (pty - ty) * dyp / (ptx - tx); if (ptx < paddle.getLeft() && tx > paddle.getLeft()){ System.out.println("left side bounce1"); System.out.println("yc: " + yc + "top: " + paddle.getTop() + " bottom: " + paddle.getBottom()); if (yc > paddle.getTop() && yc < paddle.getBottom()){ System.out.println("left side bounce2"); mBall.y = yc; mBall.x = paddle.getLeft() - mBall.getRadius(); mBall.bouncePaddle(paddle); playSound(mPaddleSFX); increaseDifficulty(); return true; } } return false; } I think I'm quite near to the solution but I'm having big troubles with the new "yc" formula. I tried so many versions of it but since I don't know the theory behind it I can't adjust for the Y axis. Since the Y axis is inverted I even tried this: yc = ty - (pty - ty) * dyp / (ptx - tx); I tried Googling it but I can't seem to find a solution for it. Also this method fails when ball touches the angle and I don't think is a nice way because it just test "one" point of the ball and probably there will be many cases in which the ball won't bounce.

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  • Feynman's inbox

    - by user12607414
    Here is Richard Feynman writing on the ease of criticizing theories, and the difficulty of forming them: The problem is not just to say something might be wrong, but to replace it by something — and that is not so easy. As soon as any really definite idea is substituted it becomes almost immediately apparent that it does not work. The second difficulty is that there is an infinite number of possibilities of these simple types. It is something like this. You are sitting working very hard, you have worked for a long time trying to open a safe. Then some Joe comes along who knows nothing about what you are doing, except that you are trying to open the safe. He says ‘Why don’t you try the combination 10:20:30?’ Because you are busy, you have tried a lot of things, maybe you have already tried 10:20:30. Maybe you know already that the middle number is 32 not 20. Maybe you know as a matter of fact that it is a five digit combination… So please do not send me any letters trying to tell me how the thing is going to work. I read them — I always read them to make sure that I have not already thought of what is suggested — but it takes too long to answer them, because they are usually in the class ‘try 10:20:30’. (“Seeking New Laws”, page 161 in The Character of Physical Law.) As a sometime designer (and longtime critic) of widely used computer systems, I have seen similar difficulties appear when anyone undertakes to publicly design a piece of software that may be used by many thousands of customers. (I have been on both sides of the fence, of course.) The design possibilities are endless, but the deep design problems are usually hidden beneath a mass of superfluous detail. The sheer numbers can be daunting. Even if only one customer out of a thousand feels a need to express a passionately held idea, it can take a long time to read all the mail. And it is a fact of life that many of those strong suggestions are only weakly supported by reason or evidence. Opinions are plentiful, but substantive research is time-consuming, and hence rare. A related phenomenon commonly seen with software is bike-shedding, where interlocutors focus on surface details like naming and syntax… or (come to think of it) like lock combinations. On the other hand, software is easier than quantum physics, and the population of people able to make substantial suggestions about software systems is several orders of magnitude bigger than Feynman’s circle of colleagues. My own work would be poorer without contributions — sometimes unsolicited, sometimes passionately urged on me — from the open source community. If a Nobel prize winner thought it was worthwhile to read his mail on the faint chance of learning a good idea, I am certainly not going to throw mine away. (In case anyone is still reading this, and is wondering what provoked a meditation on the quality of one’s inbox contents, I’ll simply point out that the volume has been very high, for many months, on the Lambda-Dev mailing list, where the next version of the Java language is being discussed. Bravo to those of my colleagues who are surfing that wave.) I started this note thinking there was an odd parallel between the life of the physicist and that of a software designer. On second thought, I’ll bet that is the story for anybody who works in public on something requiring special training. (And that would be pretty much anything worth doing.) In any case, Feynman saw it clearly and said it well.

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  • Fun with Python

    - by dotneteer
    I am taking a class on Coursera recently. My formal education is in physics. Although I have been working as a developer for over 18 years and have learnt a lot of programming on the job, I still would like to gain some systematic knowledge in computer science. Coursera courses taught by Standard professors provided me a wonderful chance. The three languages recommended for assignments are Java, C and Python. I am fluent in Java and have done some projects using C++/MFC/ATL in the past, but I would like to try something different this time. I first started with pure C. Soon I discover that I have to write a lot of code outside the question that I try to solve because the very limited C standard library. For example, to read a list of values from a file, I have to read characters by characters until I hit a delimiter. If I need a list that can grow, I have to create a data structure myself, something that I have taking for granted in .Net or Java. Out of frustration, I switched to Python. I was pleasantly surprised to find that Python is very easy to learn. The tutorial on the official Python site has the exactly the right pace for me, someone with experience in another programming. After a couple of hours on the tutorial and a few more minutes of toying with IDEL, I was in business. I like the “battery supplied” philosophy that gives everything that I need out of box. For someone from C# or Java background, curly braces are replaced by colon(:) and tab spaces. Although I tend to miss colon from time to time, I found that the idea of tab space is actually very nice once I get use to them. I also like to feature of multiple assignment and multiple return parameters. When I need to return a by-product, I just add it to the list of returns. When would use Python? I would use Python if I need to computer anything quick. The language is very easy to use. Python has a good collection of libraries (packages). The REPL of the interpreter allows me test ideas quickly before committing them into script. Lots of computer science work have been ported from Lisp to Python. Some universities are even teaching SICP in Python. When wouldn’t I use Python? I mostly would not use it in a managed environment, such as Ironpython or Jython. Both .Net and Java already have a rich library so one has to make a choice which library to use. If we use the managed runtime library, the code will tie to the particular runtime and thus not portable. If we use the Python library, then we will face the relatively long start-up time. For this reason, I would not recommend to use Ironpython for WP7 development. The only situation that I see merit with managed Python is in a server application where I can preload Python so that the start-up time is not a concern. Using Python as a managed glue language is an over-kill most of the time. A managed Scheme could be a better glue language as it is small enough to start-up very fast.

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  • Arcball Problems with UDK

    - by opdude
    I'm trying to re-create an arcball example from a Nehe, where an object can be rotated in a more realistic way while floating in the air (in my game the object is attached to the player at a distance like for example the Physics Gun) however I'm having trouble getting this to work with UDK. I have created an LGArcBall which follows the example from Nehe and I've compared outputs from this with the example code. I think where my problem lies is what I do to the Quaternion that is returned from the LGArcBall. Currently I am taking the returned Quaternion converting it to a rotation matrix. Getting the product of the last rotation (set when the object is first clicked) and then returning that into a Rotator and setting that to the objects rotation. If you could point me in the right direction that would be great, my code can be found below. class LGArcBall extends Object; var Quat StartRotation; var Vector StartVector; var float AdjustWidth, AdjustHeight, Epsilon; function SetBounds(float NewWidth, float NewHeight) { AdjustWidth = 1.0f / ((NewWidth - 1.0f) * 0.5f); AdjustHeight = 1.0f / ((NewHeight - 1.0f) * 0.5f); } function StartDrag(Vector2D startPoint, Quat rotation) { StartVector = MapToSphere(startPoint); } function Quat Update(Vector2D currentPoint) { local Vector currentVector, perp; local Quat newRot; //Map the new point to the sphere currentVector = MapToSphere(currentPoint); //Compute the vector perpendicular to the start and current perp = startVector cross currentVector; //Make sure our length is larger than Epsilon if (VSize(perp) > Epsilon) { //Return the perpendicular vector as the transform newRot.X = perp.X; newRot.Y = perp.Y; newRot.Z = perp.Z; //In the quaternion values, w is cosine (theta / 2), where //theta is the rotation angle newRot.W = startVector dot currentVector; } else { //The two vectors coincide, so return an identity transform newRot.X = 0.0f; newRot.Y = 0.0f; newRot.Z = 0.0f; newRot.W = 0.0f; } return newRot; } function Vector MapToSphere(Vector2D point) { local float x, y, length, norm; local Vector result; //Transform the mouse coords to [-1..1] //and inverse the Y coord x = (point.X * AdjustWidth) - 1.0f; y = 1.0f - (point.Y * AdjustHeight); length = (x * x) + (y * y); //If the point is mapped outside of the sphere //( length > radius squared) if (length > 1.0f) { norm = 1.0f / Sqrt(length); //Return the "normalized" vector, a point on the sphere result.X = x * norm; result.Y = y * norm; result.Z = 0.0f; } else //It's inside of the sphere { //Return a vector to the point mapped inside the sphere //sqrt(radius squared - length) result.X = x; result.Y = y; result.Z = Sqrt(1.0f - length); } return result; } DefaultProperties { Epsilon = 0.000001f } I'm then attempting to rotate that object when the mouse is dragged, with the following update code in my PlayerController. //Get Mouse Position MousePosition.X = LGMouseInterfacePlayerInput(PlayerInput).MousePosition.X; MousePosition.Y = LGMouseInterfacePlayerInput(PlayerInput).MousePosition.Y; newQuat = ArcBall.Update(MousePosition); rotMatrix = MakeRotationMatrix(QuatToRotator(newQuat)); rotMatrix = rotMatrix * LastRot; LGMoveableActor(movingPawn.CurrentUseableObject).SetPhysics(EPhysics.PHYS_Rotating); LGMoveableActor(movingPawn.CurrentUseableObject).SetRotation(MatrixGetRotator(rotMatrix));

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  • Come up with a real-world problem in which only the best solution will do (a problem from Introduction to algorithms) [closed]

    - by Mike
    EDITED (I realized that the question certainly needs a context) The problem 1.1-5 in the book of Thomas Cormen et al Introduction to algorithms is: "Come up with a real-world problem in which only the best solution will do. Then come up with one in which a solution that is “approximately” the best is good enough." I'm interested in its first statement. And (from my understanding) it is asked to name a real-world problem where only the exact solution will work as opposed to a real-world problem where good-enough solution will be ok. So what is the difference between the exact and good enough solution. Consider some physics problem for example the simulation of the fulid flow in the permeable medium. To make this simulation happen some simplyfing assumptions have to be made when deriving a mathematical model. Otherwise the model becomes at least complex and unsolvable. Virtually any particle in the universe has its influence on the fluid flow. But not all particles are equal. Those that form the permeable medium are much more influental than the ones located light years away. Then when the mathematical model needs to be solved an exact solution can rarely be found unless the mathematical model is simple enough (wich probably means the model isn't close to reality). We take an approximate numerical method and after hours of coding and days of verification come up with the program or algorithm which is a solution. And if the model and an algorithm give results close to a real problem by some degree that is good enough soultion. Its worth noting the difference between exact solution algorithm and exact computation result. When considering real-world problems and real-world computation machines I believe all physical problems solutions where any calculations are taken can not be exact because universal physical constants are represented approximately in the computer. Any numbers are represented with the limited precision, at least limited by amount of memory available to computing machine. I can imagine plenty of problems where good-enough, good to some degree solution will work, like train scheduling, automated trading, satellite orbit calculation, health care expert systems. In that cases exact solutions can't be derived due to constraints on computation time, limitations in computer memory or due to the nature of problems. I googled this question and like what this guy suggests: there're kinds of mathematical problems that need exact solutions (little note here: because the question is taken from the book "Introduction to algorithms" the term "solution" means an algorithm or a program, which in this case gives exact answer on each input). But that's probably more of theoretical interest. So I would like to narrow down the question to: What are the real-world practical problems where only the best (exact) solution algorithm or program will do (but not the good-enough solution)? There are problems like breaking of cryptographic ciphers where only exact solution matters in practice and again in practice the process of deciphering without knowing a secret should take reasonable amount of time. Returning to the original question this is the problem where good-enough (fast-enough) solution will do there's no practical need in instant crack though it's desired. So the quality of "best" can be understood in any sense: exact, fastest, requiring least memory, having minimal possible network traffic etc. And still I want this question to be theoretical if possible. In a sense that there may be example of computer X that has limited resource R of amount Y where the best solution to problem P is the one that takes not more than available Y for inputs of size N*Y. But that's the problem of finding solution for P on computer X which is... well, good enough. My final thought that we live in a world where it is required from programming solutions to practical purposes to be good enough. In rare cases really very very good but still not the best ones. Isn't it? :) If it's not can you provide an example? Or can you name any such unsolved problem of practical interest?

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  • Wiimote accelerometer input on Windows? (in 2013 - Glovepie alternative?)

    - by user568458
    There were a few options for getting accelerometer input into Windows using a Nintendo Wiimote. As of mid 2013, these projects seem to be dead, corrupted with malware, or both. Are there any tools out there that can do this that are still available (and not full of malware)? Quick roundup of the options that used to exist, or that still exist but aren't suitable: Glovepie, which used to be the most recommended option, appears to be dead: it's own website hacked, its creator's googlepages page full of strange stuff that sounds like hacker-humour about the end of the world... (I'd rather not link to them, very dubious stuff...), and lots of forum threads asking if it's a dead project with comments along the lines of "I heard that the author intends to return to it" dated 2011... Wiiuse seems to be dead: its sourceforge page simply says "Error.", its own website has turned into a squatter page. There apparently was an extension for Autohotkey that allowed Wiimote input, but I've seen warnings that this too is now full of malware (see final commentin above link) Everything else I can find about using Wiimotes as input on Windows - for example, Johnny Lee Cheng's work - seems to be exclusively about using infrared or sensor bar, or tied to a specific purpose (e.g. FPS gaming). My main interest is in the accelerometer, and buttons if possible (although something that supports the IR stuff too would be ideal). Is there anything that works for getting Wiimote accelerometer input into Windows that is reliable and not a malware-fest? If anyone's interested in "Why?", it's to use the Wiimote as an audio / midi controller: to use movement, pitch, roll etc to modulate lots of different sound variables at once with one hand. Wiimotes are great for this, and Glovepie used to be the standard way to make this work (e.g. see for example this tutorial, and this one, ignore the unrelated video; I've also seen musicians using wiimote/glovepie setups at gigs, creating some really unique sounds). As of 2013, however, Glovepie seems to be a dead and thoroughly hacked project, sadly. Is there anything else? With or without MotionPlus is fine (with would be better). If anyone knows of any worthy alternatives to Wiimotes in terms of price and quality that can be made to work with a PC, that would also be great: but in my research I coulnd't find any (here's a link to someone reaching the same conclusion). found some potentially relevant stuff here, not had time to test any of it yet though - http://stackoverflow.com/questions/2984450/using-accelerometer-in-wiimote-for-physics-practicals

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  • Cooling Server Rack with Water? Sensible? Reuse energy for small installation?

    - by TomTom
    First - this is not a shopping question, this is not so much about concrete prices but about general feasibility. Makes no sense to get looking fo ra manufacturer it the approach is bad. I am moving my company to new Offices in September, and among them we will expand and consolidate our number crunch cluster. It is so far in a data center. I have a nice room in the basement prepared now. I think about cooling. We will likely run up a power usage of around 10kw by end of the year. That is a LOT of stuff, and cooling will be expensive. I am located in south Poland, close to the German border. This is an area where water is available for relatively cheap price - "wasting water" is not a concern here. My situation is thus a lot different for example than in Spain ;) Physics tells me that to heat 1 liter of water by 1 degree I use 1 Calorie (1KCal), and a kwh power is (and we can assume 100% efficiency - water heaters are pretty efficient) 750 Calories. That means that 1 KWH is 750 liter by 1 degree. 10kw and a 20 degree heat would mean that per hour I need 375 liters. That is 6.25 liters per minute and not WHAT much ;) We talk 270 cubic meters here. Even in summer, the significant underground pipes really cool down the water a LOT more ;) Question: This such an approach feasible? Anyone done that? We talk of a 10kw installation for now. Is it feasible to reuse that heat? The alternative is a decent cooling system that WILL use around 2.5kwh for running. Dropping the water would basically (a) get me a quite cold input compared to the outside air even in summer (I.e. a lower temperature medium to drop the heat in) and (b) replace the need to actually have the outside cooling (which may b problematic - if the air is 22 degree, that is a LOT to fight off, but OTOH the water will be quite cold). I also would possibly save the investment for the outside part of the cooling circuit. Now, second question - is there a feasible way to heat a house with that? ;) After all, brutally speaking, it is a LOT of energy in that water ;) If it is a bad idea, I stop here - if it is not, I start looking for suppliers. Maybe my math is wrong?

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  • XNA Notes 006

    - by George Clingerman
    If you used to think the XNA community was small and inactive, hopefully these XNA Notes are opening your eyes. And I honestly feel like I’m still only catching the tail end of everything that’s going on. It’s a large and active community and you can be so mired down in one part of it you miss all sorts of cool stuff another part is doing. XNA is many things to a lot of people and that makes for a lot of really awesome things going on. So here’s what I saw going on this last week! Time Critical XNA New: XNA Team - Peer Review now closes for XNA 3.1 games http://blogs.msdn.com/b/xna/archive/2011/02/08/peer-review-pipeline-closed-for-new-xna-gs-3-1-games-or-updates-on-app-hub.aspx http://twitter.com/XNACommunity/statuses/34649816529256448 The XNA Team posts about a meet up with Microsoft for Creator’s going to be at GDC, March 3rd at the Lobby Bar http://on.fb.me/fZungJ XNA Team: @mklucher is busying playing the the bubblegum on WP7 made by a member of the XNA team (although reportedly made in Silverlight? Crazy! ;) ) http://twitter.com/mklucher/statuses/34645662737895426 http://bubblegum.me Shawn Hargreaves posts multiple posts (is this a sign that something new is coming from the XNA team? Usually when Shawn has time to post, something has just wrapped up…) Random Shuffle http://blogs.msdn.com/b/shawnhar/archive/2011/02/09/random-shuffle.aspx Doing the right thing: resume, rewind or skip ahead http://blogs.msdn.com/b/shawnhar/archive/2011/02/10/doing-the-right-thing-resume-rewind-or-skip-ahead.aspx XNA Developers: Andrew Russel was on .NET Rocks recently talking with Carl and Richard about developing games for Xbox, iPhone and Android http://www.dotnetrocks.com/default.aspx?ShowNum=635 Eric W. releases the Fishing Girl source code into the wild http://ericw.ca/blog/posts/fishing-girl-now-open-source/ http://forums.create.msdn.com/forums/p/74642/454512.aspx#454512 BinaryTweedDeej reminds that XNA community that Indie City wants you involved http://twitter.com/BinaryTweedDeej/statuses/34596114028044288 http://www.indiecity.com Mike McLaughlin (@mikebmcl) releases his first two XNA articles on the TechNet wiki http://social.technet.microsoft.com/wiki/contents/articles/xna-framework-overview.aspx http://social.technet.microsoft.com/wiki/contents/articles/content-pipeline-overview.aspx John Watte plays around with the Content Pipeline and Music Visualization exploring just what can be done. http://www.enchantedage.com/xna-content-pipeline-fft-song-analysis http://www.enchantedage.com/fft-in-xna-content-pipeline-for-beat-detection-for-the-win Simon Stevens writes up his talk on Vector Collision Physics http://www.simonpstevens.com/News/VectorCollisionPhysics @domipheus puts together an XNA Task Manager http://www.flickr.com/photos/domipheus/5405603197/ MadNinjaSkillz releases his fork of Nick's Easy Storage component on CodePlex http://twitter.com/MadNinjaSkillz/statuses/34739039068229634 http://ezstorage.codeplex.com @ActiveNick was interviewed by Rob Cameron and discusses Windows Phone 7, Bing Maps and XNA http://twitter.com/ActiveNick/statuses/35348548526546944 http://msdn.microsoft.com/en-us/cc537546 Radiangames (Luke Schneider) posts about converting his games from XNA to Unity http://radiangames.com/?p=592 UberMonkey (@ElementCy) posts about a new project in the works, CubeTest a Minecraft style terrain http://www.ubergamermonkey.com/personal-projects/new-project-in-the-works/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Ubergamermonkey+%28UberGamerMonkey%29 Xbox LIVE Indie Games (XBLIG): VideoGamer Rob review Bonded Realities http://videogamerrob.wordpress.com/2011/02/05/xblig-review-bonded-realities/ XBLIG Round Up on Gamergeddon http://www.gamergeddon.com/2011/02/06/xbox-indie-game-round-up-february-6th/ Are gamers still rating Indie Games after the Xbox Dashboard update? http://www.gamemarx.com/news/2011/02/06/are-gamers-still-rating-indie-games-after-the-xbox-dashboard-update.aspx Joystiq - Xbox Live Indie Gems: Corrupted http://www.joystiq.com/2011/02/04/xbox-live-indie-gems-corrupted/ Raymond Matthews of DarkStarMatryx reviews (Almost) Total Mayhem and Aban Hawkins & the 1000 Spikes http://www.darkstarmatryx.com/?p=225 http://www.darkstarmatryx.com/?p=229 8 Bit Horse reviews Aban Hawkins & the 1000 spikes http://8bithorse.blogspot.com/2011/01/aban-hawkins-1000-spikes-xbl-indie.html 2010 wrap-up for FunInfused Games http://www.krissteele.net/blogdetails.aspx?id=245 NeoGaf roundup of January's XBLIGs http://www.neogaf.com/forum/showthread.php?t=420528 Armless Ocotopus interviews Michael Ventnor creator of Bonded Realities http://www.armlessoctopus.com/2011/02/07/interview-michael-ventnor-of-red-crest-studios/ @recharge_media posts about the new city music for Woodvale in Sin Rising http://rechargemedia.com/2011/02/08/new-city-theme-woodvale/ @DrMisty posts some footage of YoYoYo in action http://www.mstargames.co.uk/mistryblogmain/54-yoyoyoblogs/184-video-update.html Xona Games - Decimation X3 on Reviews on the Run http://video.citytv.com/video/detail/782443063001.000000/reviews-on-the-run--february-8-2011/g4/ @benkane gives an early peek at his action RPG coming to XBLIG http://www.youtube.com/watch?v=bDF_PrvtwU8 Rock, Paper Shotgun talks to Zeboyd games about bringing Cthulhu Saves the World to PC http://www.rockpapershotgun.com/2011/02/11/summoning-cthulhu-natter-with-zeboyd/ Xbox LIVE Indieverse interviews the creator of Bonded Realities http://xbl-indieverse.blogspot.com/2011/02/xbl-indieverse-interview-red-crest.html XNA Game Development: Dream-In-Code posts about an upcoming XNA Challenge/Coding contest http://www.dreamincode.net/forums/blog/1385/entry-3192-xna-challengecontest/ Sgt.Conker covers Fishing Girl and IndieFreaks Game Framework release http://www.sgtconker.com/2011/02/fishing-girl-did-not-sell-a-single-copy/ http://www.sgtconker.com/2011/02/indiefreaks-game-framework-v0-2-0-0/ @slyprid releases Transmute v0.40a with lots of new features and fixes http://twitter.com/slyprid/statuses/34125423067533312 http://twitter.com/slyprid/statuses/35326876243337216 http://forgottenstarstudios.com/ Jeff Brown writes an XNA 4.0 tutorial on Saving/Loading on the Xbox 360 http://www.robotfootgames.com/xna-tutorials/92-xna-tutorial-savingloading-on-xbox-360-40 XNA for Silverlight Developers: Part 3- Animation http://www.silverlightshow.net/items/XNA-for-Silverlight-developers-Part-3-Animation-transforms.aspx?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+xna-connection-twitter-specific-stream+%28XNA+Connection%27s+Twitter+specific+stream%29 The news from Nokia is definitely something XNA developers will want to keep their eye on http://blogs.forum.nokia.com/blog/nokia-developer-news/2011/02/11/letter-to-developers?sf1066337=1

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  • CodePlex Daily Summary for Sunday, March 07, 2010

    CodePlex Daily Summary for Sunday, March 07, 2010New ProjectsAlgorithminator: Universal .NET algorithm visualizer, which helps you to illustrate any algorithm, written in any .NET language. Still in development.ALToolkit: Contains a set of handy .NET components/classes. Currently it contains: * A Numeric Text Box (an Extended NumericUpDown) * A Splash Screen base fo...Automaton Home: Automaton is a home automation software built with a n-Tier, MVVM pattern utilzing WCF, EF, WPF, Silverlight and XBAP.Developer Controls: Developer Controls contains various controls to help build applications that can script/write code.Dynamic Reference Manager: Dynamic Reference Manager is a set (more like a small group) of classes and attributes written in C# that allows any .NET program to reference othe...indiologic: Utilities of an IndioNeural Cryptography in F#: This project is my magistracy resulting work. It is intended to be an example of using neural networks in cryptography. Hashing functions are chose...Particle Filter Visualization: Particle Filter Visualization Program for the Intel Science and Engineering FairPólya: Efficient, immutable, polymorphic collections. .Net lacks them, we provide them*. * By we, we mean I; and by efficient, I mean hopefully so.project euler solutions from mhinze: mhinze project euler solutionsSilverlight 4 and WCF multi layer: Silverlight 4 and WCF multi layersqwarea: Project for a browser-based, minimalistic, massively multiplayer strategy game. Part of the "Génie logiciel et Cloud Computing" course of the ENS (...SuperSocket: SuperSocket, a socket application framework can build FTP/SMTP/POP server easilyToast (for ASP.NET MVC): Dynamic, developer & designer friendly content injection, compression and optimization for ASP.NET MVCNew ReleasesALToolkit: ALToolkit 1.0: Binary release of the libraries containing: NumericTextBox SplashScreen Based on the VB.NET code, but that doesn't really matter.Blacklist of Providers: 1.0-Milestone 1: Blacklist of Providers.Milestone 1In this development release implemented - Main interface (Work Item #5453) - Database (Work Item #5523)C# Linear Hash Table: Linear Hash Table b2: Now includes a default constructor, and will throw an exception if capacity is not set to a power of 2 or loadToMaintain is below 1.Composure: CassiniDev-Trunk-40745-VS2010.rc1.NET4: A simple port of the CassiniDev portable web server project for Visual Studio 2010 RC1 built against .NET 4.0. The WCF tests currently fail unless...Developer Controls: DevControls: These are the version 1.0 releases of these controls. Download the individually or all together (in a .zip file). More releases coming soon!Dynamic Reference Manager: DRM Alpha1: This is the first release. I'm calling it Alpha because I intend implementing other functions, but I do not intend changing the way current functio...ESB Toolkit Extensions: Tellago SOA ESB Extenstions v0.3: Windows Installer file that installs Library on a BizTalk ESB 2.0 system. This Install automatically configures the esb.config to use the new compo...GKO Libraries: GKO Libraries 0.1 Alpha: 0.1 AlphaHome Access Plus+: v3.0.3.0: Version 3.0.3.0 Release Change Log: Added Announcement Box Removed script files that aren't needed Fixed & issue in directory path Stylesheet...Icarus Scene Engine: Icarus Scene Engine 1.10.306.840: Icarus Professional, Icarus Player, the supporting software for Icarus Scene Engine, with some included samples, and the start of a tutorial (with ...mavjuz WndLpt: wndlpt-0.2.5: New: Response to 5 LPT inputs "test i 1" New: Reaction to 12 LPT outputs "test q 8" New: Reaction to all LPT pins "test pin 15" New: Syntax: ...Neural Cryptography in F#: Neural Cryptography 0.0.1: The most simple version of this project. It has a neural network that works just like logical AND and a possibility to recreate neural network from...Password Provider: 1.0.3: This release fixes a bug which caused the program to crash when double clicking on a generic item.RoTwee: RoTwee 6.2.0.0: New feature is as next. 16649 Add hashtag for tweet of tune.Now you can tweet your playing tune with hashtag.Visual Studio DSite: Picture Viewer (Visual C++ 2008): This example source code allows you to view any picture you want in the click of a button. All you got to do is click the button and browser via th...WatchersNET CKEditor™ Provider for DotNetNuke: CKEditor Provider 1.8.00: Whats New File Browser: Folders & Files View reworked File Browser: Folders & Files View reworked File Browser: Folders are displayed as TreeVi...WSDLGenerator: WSDLGenerator 0.0.0.4: - replaced CommonLibrary.dll by CommandLineParser.dll - added better support for custom complex typesMost Popular ProjectsMetaSharpSilverlight ToolkitASP.NET Ajax LibraryAll-In-One Code FrameworkWindows 7 USB/DVD Download Toolニコ生アラートWindows Double ExplorerVirtual Router - Wifi Hot Spot for Windows 7 / 2008 R2Caliburn: An Application Framework for WPF and SilverlightArkSwitchMost Active ProjectsUmbraco CMSRawrSDS: Scientific DataSet library and toolsBlogEngine.NETjQuery Library for SharePoint Web Servicespatterns & practices – Enterprise LibraryIonics Isapi Rewrite FilterFarseer Physics EngineFasterflect - A Fast and Simple Reflection APIFluent Assertions

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  • Initial Review - Mastering Unreal Technology I: Introduction to Level Design with Unreal Engine 3

    - by Matt Christian
    Recently I purchased 3 large volumes on using the Unreal 3 Engine to create levels and custom games.  This past weekend I cracked the spine of the first and started reading.  Here are my early impressions (I'm ~250 pages into it, with appendices it's about 900). Pros Interestingly, the book starts with an overview of the Unreal engines leading up to Unreal 3 (including Gears of War) and follows with some discussion on planning a mod and what goes into the game development process.  This is nice for an intro to the book and is much preferred rather than a simple chapter detailing what is on the included CD, how to install and setup UnrealEd, etc...  While the chapter on Unreal history and planning can be considered 'fluff', it's much less 'fluffy' than most books provide. I need to mention one thing here that is pretty crucial in the way I'm going to continue reviewing this book.  Most technical books like this are used as a shelf reference; as a thick volume you use for looking up techniques every now and again.  Even so, I prefer reading from cover to cover, including chapters I may already be knowledgable on (I'm sure this is typical for most people).  If there was a chapter on installing UnrealEd (the previously mentioned 'fluff'), I would probably force myself to read it, even though I've installed the game and engine multiple times on different systems. Chapter 3 is where we really get to the introduction piece of UnrealEd, creating your first basic level.  This large chapter details creating two small rooms, adding static meshes, adding lighting, creating and adding particle emitters, creating a door that animates with Unreal Matinee and Kismet, static meshes with physics, and other little additions to make your level look less beginner.  This really is a chapter that overviews the entire rest of the book, as each chapter following details the creation and intermediate usages of Static Meshes, Materials, Lighting, etc... One other very nice part to this book is the way the tutorials are setup.  Each tutorial builds off the previous and all are step-by-step.  If you haven't completed one yet, you can find all the starting files on the CD that comes with the book. Cons While the description of the overview chapter (Chapter 3) is fresh in your mind, let me start the cons by saying this chapter is setup extremely confusing for the noob.  At one point, you end up creating a door mesh and setting it up as a InteropMesh so that it is ready to be animated, only to switch to particles and spend a good portion of time working on a different piece of the level.  Yes, this is actually how I develop my levels (jumping back and forth), though it's very odd for a book to jump out of sequence. The next item might be a positive or a negative depending on your skill level with UnrealEd.  Most of the introduction to the editor layout is found in one of the Appendices instead of before Chapter 3.  For new readers, this might lead to confusion as Appendix A would typically be read between Chapter 2 and 3.  However, this is a positive for those with some experience in UnrealEd as they don't have to force themselves through a 'learn every editor button' chapter.  I'm listing this in the Cons section as the book is 'Introduction to...' and is probably going to be directed toward a lot of very beginner developers. Finally, there's a lack of general description to a lot of the underlying engine and what each piece in UnrealEd is or does.  Sometimes you'll be performing Tutorial after Tutorial with barely a paragraph in between describing ANY of what you've just done.  Tutorial 1.1 Step 6 says to press Button X, so you do.  But why?  This is in part a problem with the structure of the tutorials rather than the content of the book.  Since the tutorials are so focused on a step-by-step (or procedural) description of a process, you learn the process and not why you're doing that.  For example, you might learn how to size a material to a surface, but will only learn what buttons to press and not what each one does. This becomes extremely apparent in the chapter on Static Meshes as most of the chapter is spent in 3D Studio Max.  Since there are books on 3DSM and modelling, the book really only tells you the steps and says to go grab a book on modelling if you're really interested in 3DSM.  Again, I've learned the process to develop my own meshes in 3DSM, but I don't know the why behind the steps. Conclusion So far the book is very good though I would have a hard time recommending it to a complete beginner.  I would suggest anyone looking at this book (obviously including the other 2, more advanced volumes) to pick up a copy of UDK or Unreal 3 (available online or via download services such as Steam) and watch some online tutorials and play with it first.  You'll find plenty of online videos available that were created by the authors and may suit as a better introduction to the editor.

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  • Mixed Emotions: Humans React to Natural Language Computer

    - by Applications User Experience
    There was a big event in Silicon Valley on Tuesday, November 15. Watson, the natural language computer developed at IBM Watson Research Center in Yorktown Heights, New York, and its inventor and principal research investigator, David Ferrucci, were guests at the Computer History Museum in Mountain View, California for another round of the television game Jeopardy. You may have read about or watched on YouTube how Watson beat Ken Jennings and Brad Rutter, two top Jeopardy competitors, last February. This time, Watson swept the floor with two Silicon Valley high-achievers, one a venture capitalist with a background  in math, computer engineering, and physics, and the other a technology and finance writer well-versed in all aspects of culture and humanities. Watson is the product of the DeepQA research project, which attempts to create an artificially intelligent computing system through advances in natural language processing (NLP), among other technologies. NLP is a computing strategy that seeks to provide answers by processing large amounts of unstructured data contained in multiple large domains of human knowledge. There are several ways to perform NLP, but one way to start is by recognizing key words, then processing  contextual  cues associated with the keyword concepts so that you get many more “smart” (that is, human-like) deductions,  rather than a series of “dumb” matches.  Jeopardy questions often require more than key word matching to get the correct answer; typically several pieces of information put together, often from vastly different categories, to come up with a satisfactory word string solution that can be rephrased as a question.  Smarter than your average search engine, but is it as smart as a human? Watson was especially fast at descrambling mixed-up state capital names, and recalling and pairing movie titles where one started and the other ended in the same word (e.g., Billion Dollar Baby Boom, where both titles used the word Baby). David said they had basically removed the variable of how fast Watson hit the buzzer compared to human contestants, but frustration frequently appeared on the faces of the contestants beaten to the punch by Watson. David explained that top Jeopardy winners like Jennings achieved their success with a similar strategy, timing their buzz to the end of the reading of the clue,  and “running the board”, being first to respond on about 60% of the clues.  Similar results for Watson. It made sense that Watson would be good at the technical and scientific stuff, so I figured the venture capitalist was toast. But I thought for sure Watson would lose to the writer in categories such as pop culture, wines and foods, and other humanities. Surprisingly, it held its own. I was amazed it could recognize a word definition of a syllogism in the category of philosophy. So what was the audience reaction to all of this? We started out expecting our formidable human contestants to easily run some of their categories; however, they started off on the wrong foot with the state capitals which Watson could unscramble so efficiently. By the end of the first round, contestants and the audience were feeling a little bit, well, …. deflated. Watson was winning by about $13,000, and the humans had gone into negative dollars. The IBM host said he was going to “slow Watson down a bit,” and the humans came back with respectable scores in Double Jeopardy. This was partially thanks to a very sympathetic audience (and host, also a human) providing “group-think” on many questions, especially baseball ‘s most valuable players, which by the way, couldn’t have been hard because even I knew them.  Yes, that’s right, the humans cheated. Since Watson could speak but not hear us (it didn’t have speech recognition capability), it was probably unaware of this. In Final Jeopardy, the single question had to do with law. I was sure Watson would blow this one, but all contestants were able to answer correctly about a copyright law. In a career devoted to making computers more helpful to people, I think I may have seen how a computer can do too much. I’m not sure I’d want to work side-by-side with a Watson doing my job. Certainly listening and empathy are important traits we humans still have over Watson.  While there was great enthusiasm in the packed room of computer scientists and their friends for this standing-room-only show, I think it made several of us uneasy (especially the poor human contestants whose egos were soundly bashed in the first round). This computer system, by the way , only took 4 years to program. David Ferrucci mentioned several practical uses for Watson, including medical diagnoses and legal strategies. Are you “the expert” in your job? Imagine NLP computing on an Oracle database.   This may be the user interface of the future to enable users to better process big data. How do you think you’d like it? Postscript: There were three little boys sitting in front of me in the very first row. They looked, how shall I say it, … unimpressed!

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  • Collision Detection, player correction

    - by DoomStone
    I am having some problems with collision detection, I have 2 types of objects excluding the player. Tiles and what I call MapObjects. The tiles are all 16x16, where the MapObjects can be any size, but in my case they are all 16x16. When my player runs along the mapobjects or tiles, it get verry jaggy. The player is unable to move right, and will get warped forward when moving left. I have found the problem, and that is my collision detection will move the player left/right if colliding the object from the side, and up/down if collision from up/down. Now imagine that my player is sitting on 2 tiles, at (10,12) and (11,12), and the player is mostly standing on the (11,12) tile. The collision detection will first run on then (10,12) tile, it calculates the collision depth, and finds that is is a collision from the side, and therefore move the object to the right. After, it will do the collision detection with (11,12) and it will move the character up. So the player will not fall down, but are unable to move right. And when moving left, the same problem will make the player warp forward. This problem have been bugging me for a few days now, and I just can't find a solution! Here is my code that does the collision detection. public void ApplyObjectCollision(IPhysicsObject obj, List<IComponent> mapObjects, TileMap map) { PhysicsVariables physicsVars = GetPhysicsVariables(); Rectangle bounds = ((IComponent)obj).GetBound(); int leftTile = (int)Math.Floor((float)bounds.Left / map.GetTileSize()); int rightTile = (int)Math.Ceiling(((float)bounds.Right / map.GetTileSize())) - 1; int topTile = (int)Math.Floor((float)bounds.Top / map.GetTileSize()); int bottomTile = (int)Math.Ceiling(((float)bounds.Bottom / map.GetTileSize())) - 1; // Reset flag to search for ground collision. obj.IsOnGround = false; // For each potentially colliding tile, for (int y = topTile; y <= bottomTile; ++y) { for (int x = leftTile; x <= rightTile; ++x) { IComponent tile = map.Get(x, y); if (tile != null) { bounds = HandelCollision(obj, tile, bounds, physicsVars); } } } // Handel collision for all Moving objects foreach (IComponent mo in mapObjects) { if (mo == obj) continue; if (mo.GetBound().Intersects(((IComponent)obj).GetBound())) { bounds = HandelCollision(obj, mo, bounds, physicsVars); } } } private Rectangle HandelCollision(IPhysicsObject obj, IComponent objb, Rectangle bounds, PhysicsVaraibales physicsVars) { // If this tile is collidable, SpriteCollision collision = ((IComponent)objb).GetCollisionType(); if (collision != SpriteCollision.Passable) { // Determine collision depth (with direction) and magnitude. Rectangle tileBounds = ((IComponent)objb).GetBound(); Vector2 depth = bounds.GetIntersectionDepth(tileBounds); if (depth != Vector2.Zero) { float absDepthX = Math.Abs(depth.X); float absDepthY = Math.Abs(depth.Y); // Resolve the collision along the shallow axis. if (absDepthY <= absDepthX || collision == SpriteCollision.Platform) { // If we crossed the top of a tile, we are on the ground. if (obj.PreviousBound.Bottom <= tileBounds.Top) obj.IsOnGround = true; // Ignore platforms, unless we are on the ground. if (collision == SpriteCollision.Impassable || obj.IsOnGround) { // Resolve the collision along the Y axis. ((IComponent)obj).Position = new Vector2(((IComponent)obj).Position.X, ((IComponent)obj).Position.Y + depth.Y); // If we hit something about us, remove all velosity upwards if (depth.Y > 0 && obj.IsJumping) { obj.Velocity = new Vector2(obj.Velocity.X, 0); obj.JumpTime = physicsVars.MaxJumpTime; } // Perform further collisions with the new bounds. return ((IComponent)obj).GetBound(); } } else if (collision == SpriteCollision.Impassable) // Ignore platforms. { // Resolve the collision along the X axis. ((IComponent)obj).Position = new Vector2(((IComponent)obj).Position.X + depth.X, ((IComponent)obj).Position.Y); // Perform further collisions with the new bounds. return ((IComponent)obj).GetBound(); } } } return bounds; } Update: I have uploaded the source code, if you want to look that through. I think that my general approach might be wrong when i am working with small tiles, I have also be unable to find any good information on physics and collision detection in Platform games. http://dl.dropbox.com/u/3181816/Sogaard.Games.SuperMario.rar

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  • Most efficient way to implement delta time

    - by Starkers
    Here's one way to implement delta time: /// init /// var duration = 5000, currentTime = Date.now(); // and create cube, scene, camera ect ////// function animate() { /// determine delta /// var now = Date.now(), deltat = now - currentTime, currentTime = now, scalar = deltat / duration, angle = (Math.PI * 2) * scalar; ////// /// animate /// cube.rotation.y += angle; ////// /// update /// requestAnimationFrame(render); ////// } Could someone confirm I know how it works? Here what I think is going on: Firstly, we set duration at 5000, which how long the loop will take to complete in an ideal world. With a computer that is slow/busy, let's say the animation loop takes twice as long as it should, so 10000: When this happens, the scalar is set to 2.0: scalar = deltat / duration scalar = 10000 / 5000 scalar = 2.0 We now times all animation by twice as much: angle = (Math.PI * 2) * scalar; angle = (Math.PI * 2) * 2.0; angle = (Math.PI * 4) // which is 2 rotations When we do this, the cube rotation will appear to 'jump', but this is good because the animation remains real-time. With a computer that is going too quickly, let's say the animation loop takes half as long as it should, so 2500: When this happens, the scalar is set to 0.5: scalar = deltat / duration scalar = 2500 / 5000 scalar = 0.5 We now times all animation by a half: angle = (Math.PI * 2) * scalar; angle = (Math.PI * 2) * 0.5; angle = (Math.PI * 1) // which is half a rotation When we do this, the cube won't jump at all, and the animation remains real time, and doesn't speed up. However, would I be right in thinking this doesn't alter how hard the computer is working? I mean it still goes through the loop as fast as it can, and it still has render the whole scene, just with different smaller angles! So this a bad way to implement delta time, right? Now let's pretend the computer is taking exactly as long as it should, so 5000: When this happens, the scalar is set to 1.0: angle = (Math.PI * 2) * scalar; angle = (Math.PI * 2) * 1; angle = (Math.PI * 2) // which is 1 rotation When we do this, everything is timsed by 1, so nothing is changed. We'd get the same result if we weren't using delta time at all! My questions are as follows Mostly importantly, have I got the right end of the stick here? How do we know to set the duration to 5000 ? Or can it be any number? I'm a bit vague about the "computer going too quickly". Is there a way loop less often rather than reduce the animation steps? Seems like a better idea. Using this method, do all of our animations need to be timesed by the scalar? Do we have to hunt down every last one and times it? Is this the best way to implement delta time? I think not, due to the fact the computer can go nuts and all we do is divide each animation step and because we need to hunt down every step and times it by the scalar. Not a very nice DSL, as it were. So what is the best way to implement delta time? Below is one way that I do not really get but may be a better way to implement delta time. Could someone explain please? // Globals INV_MAX_FPS = 1 / 60; frameDelta = 0; clock = new THREE.Clock(); // In the animation loop (the requestAnimationFrame callback)… frameDelta += clock.getDelta(); // API: "Get the seconds passed since the last call to this method." while (frameDelta >= INV_MAX_FPS) { update(INV_MAX_FPS); // calculate physics frameDelta -= INV_MAX_FPS; } How I think this works: Firstly we set INV_MAX_FPS to 0.01666666666 How we will use this number number does not jump out at me. We then intialize a frameDelta which stores how long the last loop took to run. Come the first loop frameDelta is not greater than INV_MAX_FPS so the loop is not run (0 = 0.01666666666). So nothing happens. Now I really don't know what would cause this to happen, but let's pretend that the loop we just went through took 2 seconds to complete: We set frameDelta to 2: frameDelta += clock.getDelta(); frameDelta += 2.00 Now we run an animation thanks to update(0.01666666666). Again what is relevance of 0.01666666666?? And then we take away 0.01666666666 from the frameDelta: frameDelta -= INV_MAX_FPS; frameDelta = frameDelta - INV_MAX_FPS; frameDelta = 2 - 0.01666666666 frameDelta = 1.98333333334 So let's go into the second loop. Let's say it took 2(? Why not 2? Or 12? I am a bit confused): frameDelta += clock.getDelta(); frameDelta = frameDelta + clock.getDelta(); frameDelta = 1.98333333334 + 2 frameDelta = 3.98333333334 This time we enter the while loop because 3.98333333334 = 0.01666666666 We run update We take away 0.01666666666 from frameDelta again: frameDelta -= INV_MAX_FPS; frameDelta = frameDelta - INV_MAX_FPS; frameDelta = 3.98333333334 - 0.01666666666 frameDelta = 3.96666666668 Now let's pretend the loop is super quick and runs in just 0.1 seconds and continues to do this. (Because the computer isn't busy any more). Basically, the update function will be run, and every loop we take away 0.01666666666 from the frameDelta untill the frameDelta is less than 0.01666666666. And then nothing happens until the computer runs slowly again? Could someone shed some light please? Does the update() update the scalar or something like that and we still have to times everything by the scalar like in the first example?

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  • How to properly add texture to multi-fixture/shape b2Body

    - by Blazej Wdowikowski
    Hello to everyone this is my first poste here I hope that will be not fail start. At start I must say I make part 1 in Ray's Tutorial "How To Make A Game Like Fruit Ninja With Box2D and Cocos2D". But I wonder what when I want make more complex body with texture? Simple just add n b2FixtureDef to the same body. OK but what about texture? If I will take code from that tutorial it only fill last fixture. Probably it does not takes every b2Vec2 point. I was right, it did not. So quick refactor and from that -(id)initWithTexture:(CCTexture2D*)texture body:(b2Body*)body original:(BOOL)original { // gather all the vertices from our Box2D shape b2Fixture *originalFixture = body->GetFixtureList(); b2PolygonShape *shape = (b2PolygonShape*)originalFixture->GetShape(); int vertexCount = shape->GetVertexCount(); NSMutableArray *points = [NSMutableArray arrayWithCapacity:vertexCount]; for(int i = 0; i < vertexCount; i++) { CGPoint p = ccp(shape->GetVertex(i).x * PTM_RATIO, shape->GetVertex(i).y * PTM_RATIO); [points addObject:[NSValue valueWithCGPoint:p]]; } if ((self = [super initWithPoints:points andTexture:texture])) { _body = body; _body->SetUserData(self); _original = original; // gets the center of the polygon _centroid = self.body->GetLocalCenter(); // assign an anchor point based on the center self.anchorPoint = ccp(_centroid.x * PTM_RATIO / texture.contentSize.width, _centroid.y * PTM_RATIO / texture.contentSize.height); } return self; } I came up with that -(id)initWithTexture:(CCTexture2D*)texture body:(b2Body*)body original:(BOOL)original { int vertexCount = 0; //gather total number of b2Vect2 points b2Fixture *currentFixture = body->GetFixtureList(); while (currentFixture) { //new b2PolygonShape *shape = (b2PolygonShape*)currentFixture->GetShape(); vertexCount += shape->GetVertexCount(); currentFixture = currentFixture->GetNext(); } NSMutableArray *points = [NSMutableArray arrayWithCapacity:vertexCount]; // gather all the vertices from our Box2D shape b2Fixture *originalFixture = body->GetFixtureList(); while (originalFixture) { //new NSLog((NSString*)@"-"); b2PolygonShape *shape = (b2PolygonShape*)originalFixture->GetShape(); int currentVertexCount = shape->GetVertexCount(); for(int i = 0; i < currentVertexCount; i++) { CGPoint p = ccp(shape->GetVertex(i).x * PTM_RATIO, shape->GetVertex(i).y * PTM_RATIO); [points addObject:[NSValue valueWithCGPoint:p]]; } originalFixture = originalFixture->GetNext(); } if ((self = [super initWithPoints:points andTexture:texture])) { _body = body; _body->SetUserData(self); _original = original; // gets the center of the polygon _centroid = self.body->GetLocalCenter(); // assign an anchor point based on the center self.anchorPoint = ccp(_centroid.x * PTM_RATIO / texture.contentSize.width,_centroid.y * PTM_RATIO / texture.contentSize.height); } return self; } I was working for simple two fixtures body like b2BodyDef bodyDef; bodyDef.type = b2_dynamicBody; bodyDef.position = position; bodyDef.angle = rotation; b2Body *body = world->CreateBody(&bodyDef); b2FixtureDef fixtureDef; fixtureDef.density = 1.0; fixtureDef.friction = 0.5; fixtureDef.restitution = 0.2; fixtureDef.filter.categoryBits = 0x0001; fixtureDef.filter.maskBits = 0x0001; b2Vec2 vertices[] = { b2Vec2(0.0/PTM_RATIO,50.0/PTM_RATIO), b2Vec2(0.0/PTM_RATIO,0.0/PTM_RATIO), b2Vec2(50.0/PTM_RATIO,30.1/PTM_RATIO), b2Vec2(60.0/PTM_RATIO,60.0/PTM_RATIO) }; b2PolygonShape shape; shape.Set(vertices, 4); fixtureDef.shape = &shape; body->CreateFixture(&fixtureDef); b2Vec2 vertices2[] = { b2Vec2(20.0/PTM_RATIO,50.0/PTM_RATIO), b2Vec2(20.0/PTM_RATIO,0.0/PTM_RATIO), b2Vec2(70.0/PTM_RATIO,30.1/PTM_RATIO), b2Vec2(80.0/PTM_RATIO,60.0/PTM_RATIO) }; shape.Set(vertices2, 4); fixtureDef.shape = &shape; body->CreateFixture(&fixtureDef); But if I try put secondary shape upper than first it starting wierd, texture goes crazy. For example not mention about more complex shapes. What's more if shapes have one common point texture will not render for them at all [For that I use Physics Edytor like in tutorial part1] BTW. I use PolygonSprite and in method createWithWorld... another shapes. Uff.. Question So my question is, why texture coords are in such a mess up? It's my modify method or just wrong approach? Maybe I should remove duplicated from points array?

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  • Best programming aids for a quadriplegic programmer

    - by Peter Rowell
    Before you jump to conclusions, yes, this is programming related. It covers a situation that comes under the heading of, "There, but for the grace of God, go you or I." This is brand new territory for me so I'm asking for some serious help here. A young man, Honza Ripa, in a nearby town did the classic Dumb Thing two weeks after graduating from High School -- he dove into shallow water in the Russian River and had a C-4/C-5 break, sometimes called a Swimming Pool break. In a matter of seconds he went from an exceptional golfer and wrestler to a quadriplegic. (Read the story ... all of us should have been so lucky as to have a girlfriend like Brianna.) That was 10 months ago and he has regained only tiny amounts of control of his right index finger and a couple of other hand/foot motions, none of them fine-grained. His total control of his computer (currently running Win7, but we can change that as needed) is via voice command. Honza's not dumb. He had a 3.7 GPA with AP math and physics. The Problems: Since all of his input is via voice command, he is concerned that the predominance of special characters in programming will require vast amount of verbose commands. Does anyone know of any well done voice input system specifically designed for programmers? I'm thinking about something that might be modal--e.g. you say "Python input" and it goes into a macro mode for doing class definitions, etc. Given all of the RSI in programmer-land there's got to be something out there. What OS(es) does it run on? I am planning on teaching him Python, which is my preferred language for programming and teaching. Are there any applications / whatevers that are written in Python and would be a particularly good match for engaging him mentally while supporting his disability? One of his expressed interests is in stock investing, but that not might be a good starting point for a brand-new programmer. There are a lot of environments (Flash, JavaScript, etc) that are not particularly friendly to people with accessibility challenges. I vaguely remember (but cannot find) a research project that basically created an overlay system on top of a screen environment and then allowed macro command construction on top of the screen image. If we can get/train this system, we may be able to remove many hurdles to using the net. I am particularly interested in finding open source Python-based robotics and robotic prostheses projects so that he can simultaneously learn advanced programming concepts while learning to solve some of his own immediate problems. I've done a ton of googling on this, but I know there things I'm missing. I'm asking the SO community to step up to the plate here. I know this group has the answers, so let me hear them! Overwhelm me with the opportunities that any of us might have/need to still program after such a life-changing event.

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