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  • 3D zooming technique to maintain the relative position of an object on screen

    - by stark
    Is it possible to zoom to a certain point on screen by modifying the field of view and rotating the view of the camera as to keep that point/object in the same place on screen while zooming ? Changing the camera position is not allowed. I projected the 3D pos of the object on screen and remembered it. Then on each frame I calculate the direction to it in camera space and then I construct a rotation matrix to align this direction to Z axis (in cam space). After this, I calculate the direction from the camera to the object in world space and transform this vector with the matrix I obtained earlier and then use this final vector as the camera's new direction. And it's actually "kinda working", the problem is that it is more/less off than the camera's rotation before starting to zoom depending on the area you are trying to zoom in (larger error on edges/corners). It looks acceptable, but I'm not settling for only this. Any suggestions/resources for doing this technique perfectly? If some of you want to explain the math in detail, be my guest, I can understand these things well.

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  • Handling Types for Real and Complex Matrices in a BLAS Wrapper

    - by mga
    I come from a C background and I'm now learning OOP with C++. As an exercise (so please don't just say "this already exists"), I want to implement a wrapper for BLAS that will let the user write matrix algebra in an intuitive way (e.g. similar to MATLAB) e.g.: A = B*C*D.Inverse() + E.Transpose(); My problem is how to go about dealing with real (R) and complex (C) matrices, because of C++'s "curse" of letting you do the same thing in N different ways. I do have a clear idea of what it should look like to the user: s/he should be able to define the two separately, but operations would return a type depending on the types of the operands (R*R = R, C*C = C, R*C = C*R = C). Additionally R can be cast into C and vice versa (just by setting the imaginary parts to 0). I have considered the following options: As a real number is a special case of a complex number, inherit CMatrix from RMatrix. I quickly dismissed this as the two would have to return different types for the same getter function. Inherit RMatrix and CMatrix from Matrix. However, I can't really think of any common code that would go into Matrix (because of the different return types). Templates. Declare Matrix<T> and declare the getter function as T Get(int i, int j), and operator functions as Matrix *(Matrix RHS). Then specialize Matrix<double> and Matrix<complex>, and overload the functions. Then I couldn't really see what I would gain with templates, so why not just define RMatrix and CMatrix separately from each other, and then overload functions as necessary? Although this last option makes sense to me, there's an annoying voice inside my head saying this is not elegant, because the two are clearly related. Perhaps I'm missing an appropriate design pattern? So I guess what I'm looking for is either absolution for doing this, or advice on how to do better.

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  • Inheritance vs containment while extending a large legacy project

    - by Flot2011
    I have got a legacy Java project with a lot of code. The code uses MVC pattern and is well structured and well written. It also has a lot of unit tests and it is still actively maintained (bug fixing, minor features adding). Therefore I want to preserve the original structure and code style as much as possible. The new feature I am going to add is a conceptual one, so I have to make my changes all over the code. In order to minimize changes I decided not to extend existing classes but to use containment: class ExistingClass { // .... existing code // my code adding new functionality private ExistingClassExtension extension = new ExistingClassExtension(); public ExistingClassExtension getExtension() {return extension;} } ... // somewhere in code ExistingClass instance = new ExistingClass(); ... // when I need a new functionality instance.getExtension().newMethod1(); All functionality that I am adding is inside a new ExistingClassExtension class. Actually I am adding only these 2 lines to each class that needs to be extended. By doing so I also do not need to instantiate new, extended classes all over the code and I may use existing tests to make sure there is no regression. However my colleagues argue that in this situation doing so isn't a proper OOP approach, and I need to inherit from ExistingClass in order to add a new functionality. What do you think? I am aware of numerous inheritance/containment questions here, but I think my question is different.

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  • How to perform game object smoothing in multiplayer games

    - by spaceOwl
    We're developing an infrastructure to support multiplayer games for our game engine. In simple terms, each client (player) engine sends some pieces of data regarding the relevant game objects at a given time interval. On the receiving end, we step the incoming data to current time (to compensate for latency), followed by a smoothing step (which is the subject of this question). I was wondering how smoothing should be performed ? Currently the algorithm is similar to this: Receive incoming state for an object (position, velocity, acceleration, rotation, custom data like visual properties, etc). Calculate a diff between local object position and the position we have after previous prediction steps. If diff doesn't exceed some threshold value, start a smoothing step: Mark the object's CURRENT POSITION and the TARGET POSITION. Linear interpolate between these values for 0.3 seconds. I wonder if this scheme is any good, or if there is any other common implementation or algorithm that should be used? (For example - should i only smooth out the position? or other values, such as speed, etc) any help will be appreciated.

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  • How to make the members of my Data Access Layer object aware of their siblings

    - by Graham
    My team currently has a project with a data access object composed like so: public abstract class DataProvider { public CustomerRepository CustomerRepo { get; private set; } public InvoiceRepository InvoiceRepo { get; private set; } public InventoryRepository InventoryRepo { get; private set; } // couple more like the above } We have non-abstract classes that inherit from DataProvider, and the type of "CustomerRepo" that gets instantiated is controlled by that child class. public class FloridaDataProvider { public FloridaDataProvider() { CustomerRepo = new FloridaCustomerRepo(); // derived from base CustomerRepository InvoiceRepo = new InvoiceRespository(); InventoryRepo = new InventoryRepository(); } } Our problem is that some of the methods inside a given repo really would benefit from having access to the other repo's. Like, a method inside InventoryRepository needs to get to Customer data to do some determinations, so I need to pass in a reference to a CustomerRepository object. Whats the best way for these "sibling" repos to be aware of each other and have the ability to call each other's methods as-needed? Virtually all the other repos would benefit from having the CustomerRepo, for example, because it is where names/phones/etc are selected from, and these data elements need to be added to the various objects that are returned out of the other repos. I can't just new-up a plain "CustomerRepository" object inside a method within a different repo, because it might not be the base CustomerRepository that actually needs to run.

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  • How can I design my classes to include calendar events stored in a database?

    - by Gianluca78
    I'm developing a web calendar in php (using Symfony2) inspired by iCal for a project of mine. At this moment, I have two classes: a class "Calendar" and a class "CalendarCell". Here you are the two classes properties and method declarations. class Calendar { private $month; private $monthName; private $year; private $calendarCellList = array(); private $translator; public function __construct($month, $year, $translator) {} public function getCalendarCellList() {} public function getMonth() {} public function getMonthName() {} public function getNextMonth() {} public function getNextYear() {} public function getPreviousMonth() {} public function getPreviousYear() {} public function getYear() {} private function calculateDaysPreviousMonth() {} private function calculateNumericDayOfTheFirstDayOfTheWeek() {} private function isCurrentDay(\DateTime $dateTime) {} private function isDifferentMonth(\DateTime $dateTime) {} } class CalendarCell { private $day; private $month; private $dayNameAbbreviation; private $numericDayOfTheWeek; private $isCurrentDay; private $isDifferentMonth; private $translator; public function __construct(array $parameters) {} public function getDay() {} public function getMonth() {} public function getDayNameAbbreviation() {} public function isCurrentDay() {} public function isDifferentMonth() {} } Each calendar day can includes many calendar events (such as appointments or schedules) stored in a database. My question is: which is the best way to manage these calendar events in my classes? I think to add a eventList property in CalendarCell and populate it with an array of CalendarEvent objects fetched by the database. This kind of solution doesn't allow other coders to reuse the classes without db (because I should inject at least a repository services also) just to create and visualize a calendar... so maybe it could be better to extend CalendarCell (for instance in CalendarCellEvent) and add the database features? I feel like I'm missing some crucial design pattern! Any suggestion will be very appreciated!

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  • Graphical Interface and Object Selection/Manipulation

    - by ToriArendt
    I have a project I want to try to implement, but I'm kind of stuck on how to get started. I know there are probably a lot of resources that I can look at, but I'm really just stuck on what to even search for and where to begin. Basically, I have a program written in Java that separates 3D coordinates from a 3D reconstructed model into different objects. I then want to be able to perform a logistic regression on these objects to determine if they are type A or type B. But first, I need to classify a training set of objects as type A or B by hand. I don't know ANYTHING about graphing or user interfaces in Java, so I have been plotting the coordinates of a given object in MATLAB so that I can visualize the object and assign it a type. Now, as I am trying to make this program more "user friendly" I want to create an interface in Java where I can simply graph all the coordinates of the objects from the entire 3D model (on the same graph). I then want to be able to click on the each object and assign it to be either of type A or type B. I hope this description makes sense and someone can point me in the direction of something that will help me. I'm sorry if some of this terminology is off; I'm a bit new to software development. P.S. If anyone also has some tips on implementing logistic regression in Java, I'm sure I'll need them down the road :).

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  • Entity Object Extension in Oracle Application R12

    - by Manoj Madhusoodanan
    In this blog I will explain how to perform Entity Object ( EO ) Extension.As a prerequisite please read my previous blog.I am doing this exercise based on PL/SQL EO. Following attributes are part of FndUserEO. Here I will add a validation to UserName attribute "Length should be > 5". Following steps need to perform. 1) Download all files of  "Entity Object Based on PL/SQL" to JDEV_USER_HOME/myprojects and JDEV_USER_HOME/myclasses.If you want to see the content of source java file decompile it and save it in JDEV_USER_HOME/myprojects. 2) Create new Entity Object XXFndUserEO as follows. Include all attributes of parent EO. 3) Add the validation code snippet to XXFndUserEOImpl.java as follows. 4) Create the substitution as follows. 5) Migrate files to $JAVA_TOP. xxcustom.oracle.apps.fnd.user.schema.server.XXFndUserEOImpl.javaxxcustom.oracle.apps.fnd.user.schema.server.XXFndUserEO.xml 6) Migrate the substitution.. 7) Bounce the server. 8) Verify the substitution has applied properly. Access Create User Page and create a User. You can see the validation message if user name length is less than 5. Give User Name as XXCUST4 and verify the table.   The FND_USER has created successfully.

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  • How can I design my classes for a calendar based on database events?

    - by Gianluca78
    I'm developing a web calendar in php (using Symfony2) inspired by iCal for a project of mine. At this moment, I have two classes: a class "Calendar" and a class "CalendarCell". Here you are the two classes properties and method declarations. class Calendar { private $month; private $monthName; private $year; private $calendarCellList = array(); private $translator; public function __construct($month, $year, $translator) {} public function getCalendarCells() {} public function getMonth() {} public function getMonthName() {} public function getNextMonth() {} public function getNextYear() {} public function getPreviousMonth() {} public function getPreviousYear() {} public function getYear() {} private function calculateDaysPreviousMonth() {} private function calculateNumericDayOfTheFirstDayOfTheWeek() {} private function isCurrentDay(\DateTime $dateTime) {} private function isDifferentMonth(\DateTime $dateTime) {} } class CalendarCell { private $day; private $month; private $dayNameAbbreviation; private $numericDayOfTheWeek; private $isCurrentDay; private $isDifferentMonth; private $translator; public function __construct(array $parameters) {} public function getDay() {} public function getMonth() {} public function getDayNameAbbreviation() {} public function isCurrentDay() {} public function isDifferentMonth() {} } Each calendar day can includes many events stored in a database. My question is: which is the best way to manage these events in my classes? I think to add a eventList property in CalendarCell and populate it with an array of CalendarEvent objects fetched by the database. This kind of solution doesn't allow other coders to reuse the classes without db (because I should inject at least a repository services also) just to create and visualize a calendar... so maybe it could be better to extend CalendarCell (for instance in CalendarCellEvent) and add the database features? I feel like I'm missing some crucial design pattern! Any suggestion will be very appreciated!

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  • Best practice to collect information from child objects

    - by Markus
    I'm regularly seeing the following pattern: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) c.AddRequiredStuff(collection); // do something with the collection ... } public abstract void AddRequiredStuff(StuffCollection collection); } public class ConcreteItem : BaseItem { // ... public override void AddRequiredStuff(StuffCollection collection) { Stuff stuff; // ... collection.Add(stuff); } } Where I would use something like this, for better information hiding: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) collection.AddRange(c.RequiredStuff()); // do something with the collection ... } public abstract StuffCollection RequiredStuff(); } public class ConcreteItem : BaseItem { // ... public override StuffCollection RequiredStuff() { StuffCollection stuffCollection; Stuff stuff; // ... stuffCollection.Add(stuff); return stuffCollection; } } What are pros and cons of each solution? For me, giving the implementation access to parent's information is some how disconcerting. On the other hand, initializing a new list, just to collect the items is a useless overhead ... What is the better design? How would it change, if DoSomethingWithStuff wouldn't be part of BaseItem but a third class? PS: there might be missing semicolons, or typos; sorry for that! The above code is not meant to be executed, but just for illustration.

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  • How to dynamically override a method in an object

    - by Ace Takwas
    If this is possible, how can I change what a method does after I might have created an instance of that class and wish to keep the reference to that object but override a public method in it's class' definition? Here's my code: package time_applet; public class TimerGroup implements Runnable{ private Timer hour, min, sec; private Thread hourThread, minThread, secThread; public TimerGroup(){ hour = new HourTimer(); min = new MinuteTimer(); sec = new SecondTimer(); } public void run(){ hourThread.start(); minThread.start(); secThread.start(); } /*Please pay close attention to this method*/ private Timer activateHourTimer(int start_time){ hour = new HourTimer(start_time){ public void run(){ while (true){ if(min.changed)//min.getTime() == 0) changeTime(); } } }; hourThread = new Thread(hour); return hour; } private Timer activateMinuteTimer(int start_time){ min = new MinuteTimer(start_time){ public void run(){ while (true){ if(sec.changed)//sec.getTime() == 0) changeTime(); } } }; minThread = new Thread(min); return min; } private Timer activateSecondTimer(int start_time){ sec = new SecondTimer(start_time); secThread = new Thread(sec); return sec; } public Timer addTimer(Timer timer){ if (timer instanceof HourTimer){ hour = timer; return activateHourTimer(timer.getTime()); } else if (timer instanceof MinuteTimer){ min = timer; return activateMinuteTimer(timer.getTime()); } else{ sec = timer; return activateSecondTimer(timer.getTime()); } } } So for example in the method activateHourTimer(), I would like to override the run() method of the hour object without having to create a new object. How do I go about that?

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  • Designing object oriented programming

    - by Pota Onasys
    Basically, I want to make api calls using an SDK I am writing. I have the following classes: Car CarData (stores input values needed to create a car like model, make, etc) Basically to create a car I do the following: [Car carWithData: cardata onSuccess: successHandler onError: errorHandler] that basically is a factory method that creates instance of Car after making an API call request and populating the new Car class with the response and passes that instance to the successHandler. So "Car" has the above static method to create that car, but also has non-static methods to edit, delete cars (which would make edit, delete API calls to the server) So when the Car create static method passes a new car to the successHandler by doing the following: successHandler([[Car alloc] initWithDictionary: dictionary) The success handler can go ahead and use that new car to do the following: [car update: cardata] [car delete] considering the new car object now has an ID for each car that it can pass to the update and delete API calls. My questions: Do I need a cardata object to store user inputs or can I store them in the car object that would also later store the response from all of the api calls? How can I improve this model? With regards to CarData, note that there might be different inputs for the different API calls. So create function might need to know model, make, etc, but find function might need to know the number of items to find, the limit, the start id, etc.

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  • Adding rows to a data-bound DataGridView [Winforms]

    - by Mishko
    I want to bind a table from a database to a DataGridView, but I want to also add one more row with a sum of the values in the columns with indexes 3,4,7,8,9... How can I do that? Thanks! DataTable table1 = new DataTable(); double brutoUkupno1 = 0; double porezUkupno1 = 0; double doprinosUkupno1 = 0; double netoUkupno1 = 0; double doprinosTeretUkupno1 = 0; double topliObrokUkupno1 = 0; double regresUkupno1 = 0; Connection con = new Connection(); table1 = con.boundTable(month, Convert.ToInt32(year)); //This is method which returns DataTable table1.Rows.Add(null, null, null, null, null, null, null, null, null, null, null, null, null, null); table1.Rows.Add(null, null, null, null, null, null, null, null, null, null, null, null, null, null); dgv2.Visible = true; dgv2.DataSource = table1; for (int i = 0; i < dgv2.RowCount - 2; i++) { topliObrokUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[7].Value); regresUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[8].Value); brutoUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[9].Value); porezUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[10].Value); doprinosUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[11].Value); netoUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[12].Value); doprinosTeretUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[13].Value); //Now I am having problems with this below, putting things above to dgv2 : } dgv2.Rows[dgv2.Rows.Count - 1].Cells[0].Value = "Ukupno"; dgv2.Rows[dgv2.Rows.Count - 1].Cells[3].Value = month.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[4].Value = year.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[7].Value = topliObrokUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[8].Value = regresUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[9].Value = brutoUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[10].Value = porezUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[11].Value = doprinosUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[12].Value = netoUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[13].Value = doprinosTeretUkupno1.ToString(); dgv2.Rows[dgv2.RowCount - 2].Height = 3; dgv2.Rows[dgv2.RowCount - 2].DefaultCellStyle.BackColor = Color.Black;

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  • deleting an object

    - by Nima
    Hi, First, when you want to free the memory assigned to an object in C++, which one is preferred? Explicitly calling deconstructor or using delete? Object* object = new Object(...); ... delete object; OR object->~Object(); Second, does the delete operator call the deconstructor implicitly? Thanks,

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  • Javascript expression to define object's property name?

    - by Kirzilla
    Hello, I'd like to create this object... object = { 'object[1][var_name_1]' : 'value1', 'object[1][var_name_2]' : 'value2', }; I'm trying to it this way, but I'm getting error missing : after property id... function getPrefix() { return 'object[1]'; } object = { getPrefix() + '[var_name_1]' : 'value1', getPrefix() + '[var_name_2]' : 'value2', } What am I doing wrong? Or maybbe it is impossible to set object property name using js experession? Thank you

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  • I have problems with adding rows to data-binded DataGridView in desktop app.

    - by Mishko
    DataTable table1 = new DataTable(); double brutoUkupno1 = 0; double porezUkupno1 = 0; double doprinosUkupno1 = 0; double netoUkupno1 = 0; double doprinosTeretUkupno1 = 0; double topliObrokUkupno1 = 0; double regresUkupno1 = 0; Connection con = new Connection(); table1 = con.boundTable(month, Convert.ToInt32(year)); //This is method which returns DataTable table1.Rows.Add(null, null, null, null, null, null, null, null, null, null, null, null, null, null); table1.Rows.Add(null, null, null, null, null, null, null, null, null, null, null, null, null, null); dgv2.Visible = true; dgv2.DataSource = table1; for (int i = 0; i < dgv2.RowCount - 2; i++) { topliObrokUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[7].Value); regresUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[8].Value); brutoUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[9].Value); porezUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[10].Value); doprinosUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[11].Value); netoUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[12].Value); doprinosTeretUkupno1 += Convert.ToDouble(dgv2.Rows[i].Cells[13].Value); //Now I am having problems with this below, putting things above to dgv2 : } dgv2.Rows[dgv2.Rows.Count - 1].Cells[0].Value = "Ukupno"; dgv2.Rows[dgv2.Rows.Count - 1].Cells[3].Value = month.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[4].Value = year.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[7].Value = topliObrokUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[8].Value = regresUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[9].Value = brutoUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[10].Value = porezUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[11].Value = doprinosUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[12].Value = netoUkupno1.ToString(); dgv2.Rows[dgv2.Rows.Count - 1].Cells[13].Value = doprinosTeretUkupno1.ToString(); dgv2.Rows[dgv2.RowCount - 2].Height = 3; dgv2.Rows[dgv2.RowCount - 2].DefaultCellStyle.BackColor = Color.Black;

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  • How to load cascading style sheet into C# object?

    - by Krishnaraj
    Hello, I am developing a web application, where i want to give freedom of changing style elements of css linked to a page via an admin screen. So I am wondering is there any way I can load CSS file into a C# object or into XML passable formate and update it from the admin screen inputs? Thank you, Krishnaraj

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