Search Results

Search found 29749 results on 1190 pages for 'object pools'.

Page 41/1190 | < Previous Page | 37 38 39 40 41 42 43 44 45 46 47 48  | Next Page >

• Confusion about inheritance

  - by Samuel Adam

  I know I might get downvoted for this, but I'm really curious. I was taught that inheritance is a very powerful polymorphism tool, but I can't seem to use it well in real cases. So far, I can only use inheritance when the base class is an abstract class. Examples : If we're talking about Product and Inventory, I quickly assumed that a Product is an Inventory because a Product must be inventorized as well. But a problem occured when user wanted to sell their Inventory item. It just doesn't seem to be right to change an Inventory object to it's subtype (Product), it's almost like trying to convert a parent to it's child. Another case is Customer and Member. It is logical (at least for me) to think that a Member is a Customer with some more privileges. Same problem occurred when user wanted to upgrade an existing Customer to become a Member. A very trivial case is the Employee case. Where Manager, Clerk, etc can be derived from Employee. Still, the same upgrading issue. I tried to use composition instead for some cases, but I really wanted to know if I'm missing something for inheritance solution here. My composition solution for those cases : Create a reference of Inventory inside a Product. Here I'm making an assumption about that Product and Inventory is talking in a different context. While Product is in the context of sales (price, volume, discount, etc), Inventory is in the context of physical management (stock, movement, etc). Make a reference of Membership instead inside Customer class instead of previous inheritance solution. Therefor upgrading a Customer is only about instantiating the Customer's Membership property. This example is keep being taught in basic programming classes, but I think it's more proper to have those Manager, Clerk, etc derived from an abstract Role class and make it a property in Employee. I found it difficult to find an example of a concrete class deriving from another concrete class. Is there any inheritance solution in which I can solve those cases? Being new in this OOP thing, I really really need a guidance. Thanks!

  Read the article

• How far should an entity take care of its properties values by itself?

  - by Kharlos Dominguez

  Let's consider the following example of a class, which is an entity that I'm using through Entity Framework. - InvoiceHeader - BilledAmount (property, decimal) - PaidAmount (property, decimal) - Balance (property, decimal) I'm trying to find the best approach to keep Balance updated, based on the values of the two other properties (BilledAmount and PaidAmount). I'm torn between two practices here: Updating the balance amount every time BilledAmount and PaidAmount are updated (through their setters) Having a UpdateBalance() method that the callers would run on the object when appropriate. I am aware that I can just calculate the Balance in its getter. However, it isn't really possible because this is an entity field that needs to be saved back to the database, where it has an actual column, and where the calculated amount should be persisted to. My other worry about the automatically updating approach is that the calculated values might be a little bit different from what was originally saved to the database, due to rounding values (an older version of the software, was using floats, but now decimals). So, loading, let's say 2000 entities from the database could change their status and make the ORM believe that they have changed and be persisted back to the database the next time the SaveChanges() method is called on the context. It would trigger a mass of updates that I am not really interested in, or could cause problems, if the calculation methods changed (the entities fetched would lose their old values to be replaced by freshly recalculated ones, simply by being loaded). Then, let's take the example even further. Each invoice has some related invoice details, which also have BilledAmount, PaidAmount and Balance (I'm simplifying my actual business case for the sake of the example, so let's assume the customer can pay each item of the invoice separately rather than as a whole). If we consider the entity should take care of itself, any change of the child details should cause the Invoice totals to change as well. In a fully automated approach, a simple implementation would be looping through each detail of the invoice to recalculate the header totals, every time one the property changes. It probably would be fine for just a record, but if a lot of entities were fetched at once, it could create a significant overhead, as it would perform this process every time a new invoice detail record is fetched. Possibly worse, if the details are not already loaded, it could cause the ORM to lazy-load them, just to recalculate the balances. So far, I went with the Update() method-way, mainly for the reasons I explained above, but I wonder if it was right. I'm noticing I have to keep calling these methods quite often and at different places in my code and it is potential source of bugs. It also has a detrimental effect on data-binding because when the properties of the detail or header changes, the other properties are left out of date and the method has no way to be called. What is the recommended approach in this case?

  Read the article

• Should library classes be wrapped before using them in unit testing?

  - by Songo

  I'm doing unit testing and in one of my classes I need to send a mail from one of the methods, so using constructor injection I inject an instance of Zend_Mail class which is in Zend framework. Example: class Logger{ private $mailer; function __construct(Zend_Mail $mail){ $this->mail=$mail; } function toBeTestedFunction(){ //Some code $this->mail->setTo('some value'); $this->mail->setSubject('some value'); $this->mail->setBody('some value'); $this->mail->send(); //Some } } However, Unit testing demands that I test one component at a time, so I need to mock the Zend_Mail class. In addition I'm violating the Dependency Inversion principle as my Logger class now depends on concretion not abstraction. Does that mean that I can never use a library class directly and must always wrap it in a class of my own? Example: interface Mailer{ public function setTo($to); public function setSubject($subject); public function setBody($body); public function send(); } class MyMailer implements Mailer{ private $mailer; function __construct(){ $this->mail=new Zend_Mail; //The class isn't injected this time } function setTo($to){ $this->mailer->setTo($to); } //implement the rest of the interface functions similarly } And now my Logger class can be happy :D class Logger{ private $mailer; function __construct(Mailer $mail){ $this->mail=$mail; } //rest of the code unchanged } Questions: Although I solved the mocking problem by introducing an interface, I have created a totally new class Mailer that now needs to be unit tested although it only wraps Zend_Mail which is already unit tested by the Zend team. Is there a better approach to all this? Zend_Mail's send() function could actually have a Zend_Transport object when called (i.e. public function send($transport = null)). Does this make the idea of a wrapper class more appealing? The code is in PHP, but answers doesn't have to be. This is more of a design issue than a language specific feature

  Read the article

• PHP - Internal APIs/Libraries - What makes sense?

  - by Mark Locker

  I've been having a discussion lately with some colleagues about the best way to approach a new project, and thought it'd be interesting to get some external thoughts thrown into the mix. Basically, we're redeveloping a fairly large site (written in PHP) and have differing opinions on how the platform should be setup. Requirements: The platform will need to support multiple internal websites, as well as external (non-PHP) projects which at the moment consist of a mobile app and a toolbar. We have no plans/need in the foreseeable future to open up an API externally (for use in products other than our own). My opinion: We should have a library of well documented native model classes which can be shared between projects. These models will represent everything in our database and can take advantage of object orientated features such as inheritance, traits, magic methods, etc. etc. As well as employing ORM. We can then add an API layer on top of these models which can basically accept requests and route them to the appropriate methods, translating the response so that it can be used platform independently. This routing for each method can be setup as and when it's required. Their opinion: We should have a single HTTP API which is used by all projects (internal PHP ones or otherwise). My thoughts: To me, there are a number of issues with using the sole HTTP API approach: It will be very expensive performance wise. One page request will result in several additional http requests (which although local, are still ones that Apache will need to handle). You'll lose all of the best features PHP has for OO development. From simple inheritance, to employing the likes of ORM which can save you writing a lot of code. For internal projects, the actual process makes me cringe. To get a users name, for example, a request would go out of our box, over the LAN, back in, then run through a script which calls a method, JSON encodes the output and feeds that back. That would then need to be JSON decoded, and be presented as an array ready to use. Working with arrays, as appose to objects, makes me sad in a modern PHP framework. Their thoughts (and my responses): Having one method of doing thing keeps things simple. - You'd only do things differently if you were using a different language anyway. It will become robust. - Seeing as the API will run off the library of models, I think my option would be just as robust. What do you think? I'd be really interested to hear the thoughts of others on this, especially as opinions on both sides are not founded on any past experience.

  Read the article

• Does OO, TDD, and Refactoring to Smaller Functions affect Speed of Code?

  - by Dennis

  In Computer Science field, I have noticed a notable shift in thinking when it comes to programming. The advice as it stands now is write smaller, more testable code refactor existing code into smaller and smaller chunks of code until most of your methods/functions are just a few lines long write functions that only do one thing (which makes them smaller again) This is a change compared to the "old" or "bad" code practices where you have methods spanning 2500 lines, and big classes doing everything. My question is this: when it call comes down to machine code, to 1s and 0s, to assembly instructions, should I be at all concerned that my class-separated code with variety of small-to-tiny functions generates too much extra overhead? While I am not exactly familiar with how OO code and function calls are handled in ASM in the end, I do have some idea. I assume that each extra function call, object call, or include call (in some languages), generate an extra set of instructions, thereby increasing code's volume and adding various overhead, without adding actual "useful" code. I also imagine that good optimizations can be done to ASM before it is actually ran on the hardware, but that optimization can only do so much too. Hence, my question -- how much overhead (in space and speed) does well-separated code (split up across hundreds of files, classes, and methods) actually introduce compared to having "one big method that contains everything", due to this overhead? UPDATE for clarity: I am assuming that adding more and more functions and more and more objects and classes in a code will result in more and more parameter passing between smaller code pieces. It was said somewhere (quote TBD) that up to 70% of all code is made up of ASM's MOV instruction - loading CPU registers with proper variables, not the actual computation being done. In my case, you load up CPU's time with PUSH/POP instructions to provide linkage and parameter passing between various pieces of code. The smaller you make your pieces of code, the more overhead "linkage" is required. I am concerned that this linkage adds to software bloat and slow-down and I am wondering if I should be concerned about this, and how much, if any at all, because current and future generations of programmers who are building software for the next century, will have to live with and consume software built using these practices. UPDATE: Multiple files I am writing new code now that is slowly replacing old code. In particular I've noted that one of the old classes was a ~3000 line file (as mentioned earlier). Now it is becoming a set of 15-20 files located across various directories, including test files and not including PHP framework I am using to bind some things together. More files are coming as well. When it comes to disk I/O, loading multiple files is slower than loading one large file. Of course not all files are loaded, they are loaded as needed, and disk caching and memory caching options exist, and yet still I believe that loading multiple files takes more processing than loading a single file into memory. I am adding that to my concern.

  Read the article

• Server 2012 Storage Pools, Raid Controller... can the Storage Pool deal with it?

  - by TomTom

  Before trying it out - I don't find any documentation. Given that Storage Pools have serious performance problems with parity, and do not rebalance data at the moment when you add discs, my preferred way to use them would be as think provisioned space, ISCSI targets - with every "Pool" running against 1 RAID that comes from a Raid controller (who also introduces SSD read and write caching - another thing missing from Storage Pools). The main question is - how does a Storage Pool handle the change in the underlying disc that can happen? I mostly talk about OCE (Online Capacity Expansion), where a disc after an expansion suddenly reports a larger space. Standard Windows allows you to use this additional space (and expand the partitions). How does a storage pool handle it?

  Read the article

• Type Object does not support slicing Unity3D

  - by Vish

  I am getting the following error in my code and I can't seem to understand why. Can anyone help me with it? This is my current code. The line causing the error is marked in a comment near the end. var rows : int = 4; var cols : int = 4; var totalCards : int = cols * rows; var matchesNeedToWin : int = totalCards * 0.5; var matchesMade : int = 0; var cardW : int = 100; var cardH : int = 100; var aCards : Array; var aGrid : Array; // This Array will store the two cards that the player flipped var aCardsFlipped : ArrayList; // To prevent player from clicking buttons when we don't want him to var playerCanClick : boolean; var playerHasWon : boolean = false; class Card extends System.Object { var isFaceUp : boolean = false; var isMatched : boolean = false; var img : String; function Card () { img = "robot"; } } function Start () { var i : int = 0; var j : int = 0; playerCanClick = true; aCards = new Array (); aGrid = new Array (); aCardsFlipped = new ArrayList (); for ( i = 0; i < rows; i++) { aGrid [i] = new Array (); for (j = 0; j < cols; cols++ ) { aGrid [i] [j] = new Card (); // <------ Error over here } } } function Update () { Debug.Log("Game Screen has loaded"); } The error states as follows: Error BCE0048: Type 'Object' does not support slicing. (BCE0048) (Assembly-UnityScript)

  Read the article

• Transforming object world space matrix to a position in world space

  - by Fredrik Boston Westman

  Im trying to make a function for picking objects with a bounding sphere however I have run in to a problem. First I check against my my bounding sphere, then if it checks out then I test against the vertexes. I have already tested my vertex picking method and it work fine, however when I check first with my bounding sphere method it dosnt register anything. My conclusion is that when im transform my sphere position in to the position of the object in world space, the transformation goes wrong ( I base this on the fact the the x coordinate always becomes 1, even tho i translate non of my meshes along the x-axis to 1). So my question is: What is the proper way to transform a objects world space matrix to a position vector ? This is how i do it now: First i set my position vector to 0. XMVECTOR meshPos = XMVectorSet(0.0f, 0.0f, 0.0f, 0.0f); Then I trannsform it with my object space matrix, and then add the offset to the center of the mesh. meshPos = XMVector3TransformCoord(meshPos, meshWorld) + centerOffset;

  Read the article

• Oracle SQL Developer: Single Object Compare

  - by thatjeffsmith

  There’s a nasty rumor going around that you can’t compare database objects and/or code in Oracle SQL Developer. So let’s put that to bed right now. First, here’s how to compare: PL/SQL to PL/SQL or a SQL statement to another SQL statement So now that that’s settled, why don’t we take a look at how to compare a single table, to another table – whether it’s in the same database or a different database. Database Diff There’s no additional licensing requirement here. If you have SQL Developer, you can use this feature. if you’re going to compare 1 table to another, make sure you ONLY have ‘tables’ checked And then, use this dialog to select your table(s): Move over the object(s) you want to compare over to the right hand side. And now we can move onto the results. The differences, side-by-side, and the script to make B look like A Common lines with differences are highlighted in blue, new lines are highlighted in red. So that’s why they are different, but here’s the script to synch up the differences: Read the script, TEST the script, apply the script. And that’s it. Well, that’s mostly it. If you have questions about how to compare a database object in a schema you don’t have the login information for, read this post next.

  Read the article

• How to move the object around the screen

  - by Abhishek

  I am trying to move the object around the screen I try this code -(void) move { CGFloat upperLimit = mWinSize.height - (mGunda.contentSize.height / 2.0); CGFloat upperLimit1 = mWinSize.height; CGFloat lowerLimit = (mGunda.contentSize.height / 2.0); CGFloat RightLimit = mWinSize.width - (mGunda.contentSize.width/2.0); CGFloat Right = (mGunda.contentSize.width/2.0); if ( mImageGoingUpward ) { mGunda.position = ccp( mGunda.position.x, mGunda.position.y + 5); if ( mGunda.position.y >= upperLimit ) { mImageGoingUpward = NO; mHori = NO; } } else { mGunda.position = ccp( mGunda.position.x, mGunda.position.y - 5); if ( mGunda.position.y <= lowerLimit ) { mGunda.position = ccp(mGunda.position.x +5, lowerLimit); } if(mGunda.position.x >= RightLimit) { mGunda.position = ccp(mGunda.position.x, mGunda.position.y+10); mHori = YES; } if(mHori) { if(mGunda.position.y >= upperLimit) { mGunda.position = ccp(mGunda.position.x - 5,mGunda.position.y); } } } } } It move the object from bottom to top & top to bottom & bottom to right & right to right top of the screen here is problem I have got It not move to the right top to left side of screen this rotationis not happen. How can I do this

  Read the article

• Yet Another Way To Create An Object

  - by Ricardo Peres

  After I wrote this post, I come up with yet another way to create an object... Here it is: Stopwatch watch = new Stopwatch(); ConstructorInfo ci = typeof(StringBuilder).GetConstructor(new Type[0]); NewExpression expr = Expression.New(ci); Func<StringBuilder> func = Expression.Lambda(typeof(Func<StringBuilder>), expr).Compile() as Func<StringBuilder>; watch.Start(); for (Int32 i = 0; i < 100; ++i) { StringBuilder builder = func(); } Int64 time4 = watch.ElapsedTicks; watch.Reset(); I know of only one other way, which is by using CodeDOM. If you know of any other ways to create an object, let me know! SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

  Read the article

• Checking if an object is inside bounds of an isometric chunk

  - by gopgop

  How would I check if an object is inside the bounds of an isometric chunk? for example I have a player and I want to check if its inside the bounds of this isometric chunk. I draw the isometric chunk's tiles using OpenGL Quads. My first try was checking in a square pattern kind of thing: e = object; this = isometric chunk; if (e.getLocation().getX() < this.getLocation().getX()+World.CHUNK_WIDTH*World.TILE_WIDTH && e.getLocation().getX() > this.getLocation().getX()) { if (e.getLocation().getY() > this.getLocation().getY() && e.getLocation().getY() < this.getLocation().getY()+World.CHUNK_HEIGHT*World.TILE_HEIGHT) { return true; } } return false; What happens here is that it checks in a SQUARE around the chunk so not the real isometric bounds. Image example: (THE RED IS WHERE THE PROGRAM CHECKS THE BOUNDS) What I have now: Desired check: Ultimately I want to do the same for each tile in the chunk. EXTRA INFO: Till now what I had in my game is you could only move tile by tile but now I want them to move freely but I still need them to have a tile location so no matter where they are on the tile their tile location will be that certain tile. then when they are inside a different tile's bounding box then their tile location becomes the new tile. Same thing goes with chunks. the player does have an area but the area does not matter in this case. and as long as the X and Y are inside the bounding box then it should return true. they don't have to be completely on the tile.

  Read the article

• Switch or a Dictionary when assigning to new object

  - by KChaloux

  Recently, I've come to prefer mapping 1-1 relationships using Dictionaries instead of Switch statements. I find it to be a little faster to write and easier to mentally process. Unfortunately, when mapping to a new instance of an object, I don't want to define it like this: var fooDict = new Dictionary<int, IBigObject>() { { 0, new Foo() }, // Creates an instance of Foo { 1, new Bar() }, // Creates an instance of Bar { 2, new Baz() } // Creates an instance of Baz } var quux = fooDict[0]; // quux references Foo Given that construct, I've wasted CPU cycles and memory creating 3 objects, doing whatever their constructors might contain, and only ended up using one of them. I also believe that mapping other objects to fooDict[0] in this case will cause them to reference the same thing, rather than creating a new instance of Foo as intended. A solution would be to use a lambda instead: var fooDict = new Dictionary<int, Func<IBigObject>>() { { 0, () => new Foo() }, // Returns a new instance of Foo when invoked { 1, () => new Bar() }, // Ditto Bar { 2, () => new Baz() } // Ditto Baz } var quux = fooDict[0](); // equivalent to saying 'var quux = new Foo();' Is this getting to a point where it's too confusing? It's easy to miss that () on the end. Or is mapping to a function/expression a fairly common practice? The alternative would be to use a switch: IBigObject quux; switch(someInt) { case 0: quux = new Foo(); break; case 1: quux = new Bar(); break; case 2: quux = new Baz(); break; } Which invocation is more acceptable? Dictionary, for faster lookups and fewer keywords (case and break) Switch: More commonly found in code, doesn't require the use of a Func< object for indirection.

  Read the article

• Canonical representation of a class object containing a list element in XML

  - by dendini

  I see that most implementations of JAX-RS represent a class object containing a list of elements as follows (assume a class House containing a list of People) <houses> <house> <person> <name>Adam</name> </person> <person> <name>Blake</name> </person> </house> <house> </house> </houses> The result above is obtained for instance from Jersey 2 JAX-RS implementation, notice Jersey creates a wrapper class "houses" around each house, however strangely it doesn't create a wrapper class around each person! I don't feel this is a correct mapping of a list, in other words I'd feel more confortable with something like this: <houses> <house> <persons> <person> <name>Adam</name> </person> <person> <name>Blake</name> </person> </persons> </house> <house> </house> </houses> Is there any document explaining how an object should be correctly mapped apart from any opninion?

  Read the article

• Explicitly pass context object versus injecting with IoC

  - by SonOfPirate

  I have a layered service application where the service layer delegates operations into the domain layer for execution. Many of these operations need to know the context under which they are operation. (The context included the identity of the current user, culture information, etc. received from the caller.) For example, I have an API method that returns a list of announcements. The list is based on the current user's role and each announcement is localized to their culture. The API is a thin-facade that delegates to an Application Service in my domain layer. The Application Service method obviously needs to know the context of the current request/operation as another call to the same API from another user should result in a different list. Within this method, we also have logging that uses some of the context information so we a clear understanding of the context when the operation was performed (this is especially useful if something goes wrong.) While this is a contrived example, in the real world, my Application Services will coordinate operations with many collaborative components, any number of them also needing the context information. My choice is to pass the context to the Application Service which would then pass it with any calls to collaborators or have the IoC container satisfy the dependency the Application Service and any collaborators have on the context. I am wondering if it is considered good/bad, best practices/code smell, etc. if I pass the context object as a parameter to the domain methods or if injecting the context via an IoC container is preferred. (EDIT: I should mention that the context object is instantiated per-request.)

  Read the article

• TDD: Write a separate test for object initialization or relying on other tests exercising it

  - by DXM

  This seems to be the common pattern that's emerging in some of the tests I've worked on lately. We have a class, and quite often this is legacy code whose design can't be easily altered, which has a bunch of member variables. There's some kind of "Initialize" or "Load" function which would put an object into a valid state. Only after it is initialized/loaded, are the members in the proper state so that other methods can be exercised. So when we start writing tests, first test is "TestLoad" and all we put in there is exercising initialization logic. Then we might add one (or few) TestLoadFailureXXX tests and those are definitely valuable. Then we start writing tests to verify other behaviors but all of them require the object to be loaded. So they all start by running exactly the same code as "TestLoad". So my question: Is TestLoad even necessary? Do you take it and let other tests simply exercise the loading? Or leave it so things are more explicit? I know that each unit test function should have no (or as little as possible) overlap with other test functions, but it seems like in cases of loading, this is unavoidable. And whether we like it or not, if something in the loading code breaks, we will end up with a whole test suite of failures. Is there another approach that I might be missing here? Thank you for the responses. It definitely makes sense that you want to see "InitializationTest" and if that fails you know where to start looking. In case it matters, this question is mostly about C++ and we use CppUnit framework. And now, thanks to sleske, I'll be constantly wishing that CppUnit supported test dependencies. Might have to hack something in one of these days :)

  Read the article

• LibGdx, Texture an Object

  - by Gigi10012

  I want to set texture to an Object, this is my playerobject class: private boolean up; private float speed; private float fallacceleration = 20; private float acceleration = 15; private float maxSpeed = 300; SpriteBatch batch; public Player() { x = MyGdxGame.WIDTH - 9*MyGdxGame.WIDTH/10; y = MyGdxGame.HEIGHT - 3 * MyGdxGame.HEIGHT/10; shapex = new float[4]; shapey = new float[4]; radians = 2*MathUtils.PI; batch = new SpriteBatch(); } private void setShape() { //Simple Arrow Shape ...... } public void update(float dt) { setShape(); } public void draw(ShapeRenderer sr) { sr.setColor(0F, 0F, 0F, 1F); sr.begin(ShapeType.Line); //Drawing Shape .............. sr.end(); } What I have to do to add texture to that object? (I'm using LibGdx)

  Read the article

• How to adjust the shooting angle of an object

  - by Blue

  I've been trying to add an angle adjustment feature to a power bar that I got from unity3dStudents. But I can't seem to get the code right. I'm using addforce to rigidbody, it works but the power is too great. I also found that rotating the object it's shooting from changes the angle. But I don't know how to proceed from that. Can somebody show me the problem with the script below, as in how to add height to the addforce without it going to far up or to the side? Or how to change the angle of the object? var theAngle : int; var maxAngle : int = 130; var minAngle : int = 0; var angleIncreasing : boolean = false; var angleDecreasing : boolean = false; var rotationSpeed : float = 10; var ball : Rigidbody; var spawnPos : Transform; var shotForce : float = 25; function Update () { if(Input.GetKeyDown("k")){ angleIncreasing = true; angleDecreasing = false; } if(Input.GetKeyUp("k")){ angleIncreasing = false; } if(Input.GetKeyDown("l")){ angleIncreasing = false; angleDecreasing = true; } if(Input.GetKeyUp("l")){ angleDecreasing = false; } ------- if(angleIncreasing){ theAngle += Time.deltaTime * rotationSpeed; if(theAngle > maxAngle){ theAngle = maxAngle; } } if(angleDecreasing){ theAngle -= Time.deltaTime * rotationSpeed; if(theAngle < minAngle){ theAngle = minAngle; } } } function Shoot(power : float, angle : int){ ---- var forward : Vector3 = spawnPos.forward; var upward : Vector3 = spawnPos.up; pFab.AddForce(forward * power * shotForce); pFab.AddForce(upward * angle * 10); ---- }

  Read the article

• Calculating distance from viewer to object in a shader

  - by Jay

  Good morning, I'm working through creating the spherical billboards technique outlined in this paper. I'm trying to create a shader that calculates the distance from the camera to all objects in the scene and stores the results in a texture. I keep getting either a completely black or white texture. Here are my questions: I assume the position that's automatically sent to the vertex shader from ogre is in object space? The gpu interpolates the output position from the vertex shader when it sends it to the fragment shader. Does it do the same for my depth calculation or do I need to move that calculation to the fragment shader? Is there a way to debug shaders? I have no errors but I'm not sure I'm getting my parameters passed into the shaders correctly. Here's my shader code: void DepthVertexShader( float4 position : POSITION, uniform float4x4 worldViewProjMatrix, uniform float3 eyePosition, out float4 outPosition : POSITION, out float Depth ) { // position is in object space // outPosition is in camera space outPosition = mul( worldViewProjMatrix, position ); // calculate distance from camera to vertex Depth = length( eyePosition - position ); } void DepthFragmentShader( float Depth : TEXCOORD0, uniform float fNear, uniform float fFar, out float4 outColor : COLOR ) { // clamp output using clip planes float fColor = 1.0 - smoothstep( fNear, fFar, Depth ); outColor = float4( fColor, fColor, fColor, 1.0 ); } fNear is the near clip plane for the scene fFar is the far clip plane for the scene

  Read the article

• Best way to load application settings

  - by enzom83

  A simple way to keep the settings of a Java application is represented by a text file with ".properties" extension containing the identifier of each setting associated with a specific value (this value may be a number, string, date, etc..). C# uses a similar approach, but the text file must be named "App.config". In both cases, in source code you must initialize a specific class for reading settings: this class has a method that returns the value (as string) associated with the specified setting identifier. // Java example Properties config = new Properties(); config.load(...); String valueStr = config.getProperty("listening-port"); // ... // C# example NameValueCollection setting = ConfigurationManager.AppSettings; string valueStr = setting["listening-port"]; // ... In both cases we should parse strings loaded from the configuration file and assign the ??converted values to the related typed objects (parsing errors could occur during this phase). After the parsing step, we must check that the setting values ??belong to a specific domain of validity: for example, the maximum size of a queue should be a positive value, some values ??may be related (example: min < max), and so on. Suppose that the application should load the settings as soon as it starts: in other words, the first operation performed by the application is to load the settings. Any invalid values for the settings ??must be replaced automatically with default values??: if this happens to a group of related settings, those settings are all set with default values. The easiest way to perform these operations is to create a method that first parses all the settings, then checks the loaded values ??and finally sets any default values??. However maintenance is difficult if you use this approach: as the number of settings increases while developing the application, it becomes increasingly difficult to update the code. In order to solve this problem, I had thought of using the Template Method pattern, as follows. public abstract class Setting { protected abstract bool TryParseValues(); protected abstract bool CheckValues(); public abstract void SetDefaultValues(); /// <summary> /// Template Method /// </summary> public bool TrySetValuesOrDefault() { if (!TryParseValues() || !CheckValues()) { // parsing error or domain error SetDefaultValues(); return false; } return true; } } public class RangeSetting : Setting { private string minStr, maxStr; private byte min, max; public RangeSetting(string minStr, maxStr) { this.minStr = minStr; this.maxStr = maxStr; } protected override bool TryParseValues() { return (byte.TryParse(minStr, out min) && byte.TryParse(maxStr, out max)); } protected override bool CheckValues() { return (0 < min && min < max); } public override void SetDefaultValues() { min = 5; max = 10; } } The problem is that in this way we need to create a new class for each setting, even for a single value. Are there other solutions to this kind of problem? In summary: Easy maintenance: for example, the addition of one or more parameters. Extensibility: a first version of the application could read a single configuration file, but later versions may give the possibility of a multi-user setup (admin sets up a basic configuration, users can set only certain settings, etc..). Object oriented design.

  Read the article

• ActiveX component can't create Object Error? Check 64 bit Status

  - by Rick Strahl

  If you're running on IIS 7 and a 64 bit operating system you might run into the following error using ASP classic or ASP.NET with COM interop. In classic ASP applications the error will show up as: ActiveX component can't create object   (Error 429) (actually without error handling the error just shows up as 500 error page) In my case the code that's been giving me problems has been a FoxPro COM object I'd been using to serve banner ads to some of my pages. The code basically looks up banners from a database table and displays them at random. The ASP classic code that uses it looks like this: <% Set banner = Server.CreateObject("wwBanner.aspBanner") banner.BannerFile = "wwsitebanners" Response.Write(banner.GetBanner(-1)) %> Originally this code had no specific error checking as above so the ASP pages just failed with 500 error pages from the Web server. To find out what the problem is this code is more useful at least for debugging: <% ON ERROR RESUME NEXT Set banner = Server.CreateObject("wwBanner.aspBanner") Response.Write(err.Number & " - " & err.Description) banner.BannerFile = "wwsitebanners" Response.Write(banner.GetBanner(-1)) %> which results in: 429 - ActiveX component can't create object which at least gives you a slight clue. In ASP.NET invoking the same COM object with code like this: <% dynamic banner = wwUtils.CreateComInstance("wwBanner.aspBanner") as dynamic; banner.cBANNERFILE = "wwsitebanners"; Response.Write(banner.getBanner(-1)); %> results in: Retrieving the COM class factory for component with CLSID {B5DCBB81-D5F5-11D2-B85E-00600889F23B} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)). The class is in fact registered though and the COM server loads fine from a command prompt or other COM client. This error can be caused by a COM server that doesn't load. It looks like a COM registration error. There are a number of traditional reasons why this error can crop up of course. The server isn't registered (run regserver32 to register a DLL server or /regserver on an EXE server) Access permissions aren't set on the COM server (Web account has to be able to read the DLL ie. Network service) The COM server fails to load during initialization ie. failing during startup One thing I always do to check for COM errors fire up the server in a COM client outside of IIS and ensure that it works there first - it's almost always easier to debug a server outside of the Web environment. In my case I tried the server in Visual FoxPro on the server with: loBanners = CREATEOBJECT("wwBanner.aspBanner") loBanners.cBannerFile = "wwsitebanners" ? loBanners.GetBanner(-1) and it worked just fine. If you don't have a full dev environment on the server you can also use VBScript do the same thing and run the .vbs file from the command prompt: Set banner = Server.CreateObject("wwBanner.aspBanner") banner.BannerFile = "wwsitebanners" MsgBox(banner.getBanner(-1)) Since this both works it tells me the server is registered and working properly. This leaves startup failures or permissions as the problem. I double checked permissions for the Application Pool and the permissions of the folder where the DLL lives and both are properly set to allow access by the Application Pool impersonated user. Just to be sure I assigned an Admin user to the Application Pool but still no go. So now what? 64 bit Servers Ahoy A couple of weeks back I had set up a few of my Application pools to 64 bit mode. My server is Server 2008 64 bit and by default Application Pools run 64 bit. Originally when I installed the server I set up most of my Application Pools to 32 bit mainly for backwards compatibility. But as more of my code migrates to 64 bit OS's I figured it'd be a good idea to see how well code runs under 64 bit code. The transition has been mostly painless. Until today when I noticed the problem with the code above when scrolling to my IIS logs and noticing a lot of 500 errors on many of my ASP classic pages. The code in question in most of these pages deals with this single simple COM object. It took a while to figure out that the problem is caused by the Application Pool running in 64 bit mode. The issue is that 32 bit COM objects (ie. my old Visual FoxPro COM component) cannot be loaded in a 64 bit Application Pool. The ASP pages using this COM component broke on the day I switched my main Application Pool into 64 bit mode but I didn't find the problem until I searched my logs for errors by pure chance. To fix this is easy enough once you know what the problem is by switching the Application Pool to Enable 32-bit Applications: Once this is done the COM objects started working correctly again. 64 bit ASP and ASP.NET with DCOM Servers This is kind of off topic, but incidentally it's possible to load 32 bit DCOM (out of process) servers from ASP.NET and ASP classic even if those applications run in 64 bit application pools. In fact, in West Wind Web Connection I use this capability to run a 64 bit ASP.NET handler that talks to a 32 bit FoxPro COM server which allows West Wind Web Connection to run in native 64 bit mode without custom configuration (which is actually quite useful). It's probably not a common usage scenario but it's good to know that you can actually access 32 bit COM objects this way from ASP.NET. For West Wind Web Connection this works out well as the DCOM interface only makes one non-chatty call to the backend server that handles all the rest of the request processing. Application Pool Isolation is your Friend For me the recent incident of failure in the classic ASP pages has just been another reminder to be very careful with moving applications to 64 bit operation. There are many little traps when switching to 64 bit that are very difficult to track and test for. I described one issue I had a couple of months ago where one of the default ASP.NET filters was loading the wrong version (32bit instead of 64bit) which was extremely difficult to track down and was caused by a very sneaky configuration switch error (basically 3 different entries for the same ISAPI filter all with different bitness settings). It took me almost a full day to track this down). Recently I've been taken to isolate individual applications into separate Application Pools rather than my past practice of combining many apps into shared AppPools. This is a good practice assuming you have enough memory to make this work. Application Pool isolate provides more modularity and allows me to selectively move applications to 64 bit. The error above came about precisely because I moved one of my most populous app pools to 64 bit and forgot about the minimal COM object use in some of my old pages. It's easy to forget. To 64bit or Not Is it worth it to move to 64 bit? Currently I'd say -not really. In my - admittedly limited - testing I don't see any significant performance increases. In fact 64 bit apps just seem to consume considerably more memory (30-50% more in my pools on average) and performance is minimally improved (less than 5% at the very best) in the load testing I've performed on a couple of sites in both modes. The only real incentive for 64 bit would be applications that require huge data spaces that exceed the 32 bit 4 gigabyte memory limit. However I have a hard time imagining an application that needs 4 gigs of memory in a single Application Pool :-). Curious to hear other opinions on benefits of 64 bit operation. © Rick Strahl, West Wind Technologies, 2005-2011Posted in COM   ASP.NET  FoxPro  

  Read the article

• System.Reflection and InvokeMember, storing type, assembly, and object in a class

  - by Cyclone

  I have tested code to call a method inside of a compiled DLL, and it works. I created a class to store the object, type, and loaded assembly, but something is lost in translation because it is unable to find the member I wish to invoke. If I create a type, object, and assembly, and properly load everything into these and perform InvokeMember on the type, it works just fine. However, when I use the things inside of my class, it throws a MissingMemberException and does not invoke the member, obviously. What am I doing wrong? The member in question is a subroutine which takes one argument, a string. This is quite frustrating. Code being called: Dim MyLoadedAssembly As New LoadedAssembly() MyLoadedAssembly.MyAssembly = Assembly.LoadFrom("display.dll") MyLoadedAssembly.MyObject = MyLoadedAssembly.MyAssembly.CreateInstance("Display.UI.Window") MyLoadedAssembly.MyType = MyLoadedAssembly.MyAssembly.GetType("Display.UI.Window") Dim args() As Object = {"test"} MyLoadedAssembly.InvokeMember("Show", args) Private Class LoadedAssembly Public MyType As Type Public MyObject As Object Public MyAssembly As Assembly Public Function InvokeMember(ByVal name As String, ByVal args() As Object) Return MyType.InvokeMember(name, BindingFlags.Default Or BindingFlags.InvokeMethod Or BindingFlags.GetProperty Or BindingFlags.Instance, Nothing, MyObject, args) End Function End Class Code inside of display.dll: Namespace UI Public Class Window Private wind As New System.Windows.Forms.Form Public FullScreen As Boolean = False Public Overloads Sub Show(ByVal text As String) wind.Show() wind.Text = text End Sub Public Overloads Sub Show() wind.Show() End Sub End Class End Namespace The root namespace for display.dll is Display. Why is my code only working when not within this class? System.MissingMethodException was unhandled Message="Method 'Display.UI.Window.Show' not found." Source="mscorlib" StackTrace: at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams) at System.Type.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args) at IDE.IDE.LoadedAssembly.InvokeMember(String name, Object[] args) in C:\Documents and Settings\Davey\Desktop\RaptorScript\RaptorScript\RaptorScript\IDE.vb:line 69 at IDE.IDE.IDE_Load(Object sender, EventArgs e) in C:\Documents and Settings\Davey\Desktop\RaptorScript\RaptorScript\RaptorScript\IDE.vb:line 50 at System.EventHandler.Invoke(Object sender, EventArgs e) at System.Windows.Forms.Form.OnLoad(EventArgs e) at System.Windows.Forms.Form.OnCreateControl() at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at System.Windows.Forms.Control.CreateControl() at System.Windows.Forms.Control.WmShowWindow(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ContainerControl.WndProc(Message& m) at System.Windows.Forms.Form.WmShowWindow(Message& m) at System.Windows.Forms.Form.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.SafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow) at System.Windows.Forms.Control.SetVisibleCore(Boolean value) at System.Windows.Forms.Form.SetVisibleCore(Boolean value) at System.Windows.Forms.Control.set_Visible(Boolean value) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.Run(ApplicationContext context) at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun() at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel() at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine) at IDE.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException:

  Read the article

• IE doesnot clear Flash Object from memory

  - by Abhi

  Hi, I have dynamically added a Flex Object in a HTML page through JavaScript. The Flex object is located in a "div" tag. Now when I call the "removeChild" JavScript function to remove the dynamically added "Object" tag, the object tag gets removed succesfully; however the memory that has increased due to the loading of the Flex Object is never recollected by IE. Even if I refresh the browser the memory is still not cleared. How do I recollect the memory that was allocayed to my Flex Object?

  Read the article

• Is it a good object-oriented-design practice to send a pointer to private data to another class?

  - by Denis

  Hello everyone, There is well known recommendation not to include into class interface method that returns a pointer (or a reference) to private data of the class. But what do you think about public method of a class that sends to another class a pointer to the private data of the first one. For example: class A { public: void fA(void) {_b.fB(&_var)}; private: B _b; int _var; }; I think that it is some sort of data hiding damage: the private data define state of their own class, so why should one class delegate changes of its own state to another one? What do you think? Denis

  Read the article

• iphone - testing if an object exists

  - by Mike

  I have several apps in my app that can become nil at some point and I have methods that in theory are used to put these objects to nil. But, if I try to put to nil an object that does not exist, the app will crash. for example... [object1 release]; object1 = nil; //... and after that [object removeFromSuperview]; // this will crash Then I thought, why not testing to see if the object exists before removing... if (object1 != nil) [object removeFromSuperview]; // this will crash too, because object1 cannot be tested for nil because it does not exist How can I check if the object exists before testing if it is nil? something as if (object exists( { if(object != nil)) [object removeFromSuperview) } is this possible?

  Read the article

< Previous Page | 37 38 39 40 41 42 43 44 45 46 47 48  | Next Page >