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  • Collision point of 2 curves in a 3d-room

    - by Frank
    Hello, i am programming a small game for quite some time. We started coding a small FPS-Shooter inside of a project at school to get a bit experience using directX. I dont know why, but i couldnt stop the project and started programming at home aswell. At the moment i am trying to create some small AI. Of cause thats definatlly not easy, but thats my personal goal anyways. The topic could prolly fill multiple books hehe. I've got the walking part of my bots done so far. They walk along a scriped path. I am not working on the "aiming" of the bots. While programming that i hit on some math problem i couldnt solve yet. I hope of your input on this to help me get further. Concepts, ideas and everything else are highly appreciated. Problem: Calculate the position (D3DXVECTOR3) where the curve of the projectile (depends on gravity, speed), hit the curved of the enemys walking path (depends on speed). We assume that the enemy walks in a constant line. Known variables: float projectilSpeed = 2000 m/s //speed of the projectile per second float gravitation = 9.81 m/s^2 //of cause the gravity lol D3DXVECTOR3 targetPosition //position of the target stored in a vector (x,y,z) D3DXVECTOR3 projectilePosition //position of the projectile D3DXVECTOR3 targetSpeed //stores the change of the targets position in the last second Variabledefinition ProjectilePosition at time of collision = ProjectilePos_t TargetPosition at time of collision = TargetPos_t ProjectilePosition at time 0, now = ProjectilePos_0 TargetPosition at time 0, now = TargetPos_0 Time to impact = t Aim-angle = theta My try: Found a formular to calculate "drop" (Drop of the projectile based on the gravity) on Wikipedia: float drop = 0.5f * gravity * t * t The speed of the projectile has a horizontal and a vertical part.. Found a formular for that on wikipedia aswell: ProjectilVelocity.x = projectilSpeed * cos(theta) ProjectilVelocity.y = projectilSpeed * sin(theta) So i would assume this is true for the projectile curve: ProjectilePos_t.x = ProjectilePos_0.x + ProjectileSpeed * t ProjectilePos_t.y = ProjectilePos_0.y + ProjectileSpeed * t + 0.5f * gravity * t * t ProjectilePos_t.z = ProjectilePos_0.z + ProjectileSpeed * t The target walk with a constant speed, so we can determine his curve by this: TargetPos_t = TargetPos_0 + TargetSpeed * D3DXVECTOR3(t, t, t) Now i dont know how to continue. I have to solve it somehow to get a hold on the time to impact somehow. As a basic formular i could use: float time = distanz / projectileSpeed But that wouldnt be truly correct as it would assume a linear "Trajectory". We just find this behaivor when using a rocket. I hope i was able to explain the problem as much as possible. If there are questions left, feel free to ask me! Greets from germany, Frank

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  • Implement a simple class in your favorite language.

    - by Oscar Reyes
    I'm doing this to learn syntax of different programming languages. So, how would you defined the following class along with with it's operations in your favorite programming language? Image generated by http://yuml.me/ And a main method or equivalent to invoke it: For instance, for Java it would be: ... public static void main( String [] args ) { Fraction f = new Fraction(); f.numerator( 2 ); f.denominator( 5 ); f.print(); } ....

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  • How can I transition from a front-end career to back-end career?

    - by jexx2345
    Hello, In 2004, I received my B.S. in Computer Science using mostly Java for programming. Since then, I have been hired for purely front-end positions in large companies through recruiters, doing primarily HTML/CSS, Javascript/jQuery, and OOP Actionscript 3. While I definitely have respect for the front-end, and have learned much, I feel very unfulfilled and would love to move into back-end for the more complex programming I was doing in school. My target platform of choice is ASP.Net 3.5 (C#). With a resume that has absolutely no .Net or back-end experience, how can I transition into a junior back-end job? I am currently freelancing a .Net e-commerce site, and plan to build a portfolio showcasing some apps (e-commerce mvc, blog, etc), while learning the technology. Is having a Bachelors in CS enough or should I look into getting .Net certified? Is showing course-work still relevant to an employer even though it was from 6 years ago? Thank you

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  • MVC Entity Framework Model not returning correct data

    - by quagland
    Hi, Run into a strange problem while writing an ASP.NET MVC site. I have a view in my SQL Server database that returns a few date ranges. The view works fine when running the query in SSMS. When the view data is returned by the Entity Framework Model, It returns the correct number of rows but some of the rows are duplicated. Here is an example of what I have done: SQL Server code: CREATE TABLE [dbo].[A]( [ID] [int] NOT NULL, [PhID] [int] NULL, [FromDate] [datetime] NULL, [ToDate] [datetime] NULL, CONSTRAINT [PK_A] PRIMARY KEY CLUSTERED ([ID] ASC)) ON [PRIMARY] go CREATE TABLE [dbo].[B]( [PhID] [int] NOT NULL, [FromDate] [datetime] NULL, [ToDate] [datetime] NULL, CONSTRAINT [PK_B] PRIMARY KEY CLUSTERED ( [PhID] ASC )) ON [PRIMARY] go CREATE VIEW C as SELECT A.ID, CASE WHEN A.PhID IS NULL THEN A.FromDate ELSE B.FromDate END AS FromDate, CASE WHEN A.PhID IS NULL THEN A.ToDate ELSE B.ToDate END AS ToDate FROM A LEFT OUTER JOIN B ON A.PhID = B.PhID go INSERT INTO B (PhID, FromDate, ToDate) VALUES (100, '20100615', '20100715') INSERT INTO A (ID, PhID, FromDate, ToDate) VALUES (1, NULL, '20100101', '20100201') INSERT INTO A (ID, PhID, FromDate, ToDate) VALUES (1, 100, '20100615', '20100715') INSERT INTO B (PhID, FromDate, ToDate) VALUES (101, '20101201', '20101231') INSERT INTO A (ID, PhID, FromDate, ToDate) VALUES (2, NULL, '20100801', '20100901') INSERT INTO A (ID, PhID, FromDate, ToDate) VALUES (2, 101, '20101201', '20101231') So now, if you select all from C, you get 4 separate date ranges In the Entity Framework Model (which I call 'Core'), the view 'C' is added. in MVC Controller: public class HomeController : Controller { public ActionResult Index() { CoreEntities db = new CoreEntities(); var clist = from c in db.C select c; return View(clist.ToList()); } } in MVC View: @model List<RM.Models.C> @{ foreach (RM.Models.C c in Model) { @String.Format("{0:dd-MMM-yyyy}", c.FromDate) <span>-</span> @String.Format("{0:dd-MMM-yyyy}", c.ToDate) <br /> } } When I run all this, it outputs this: 01-Jan-2010 - 01-Feb-2010 01-Jan-2010 - 01-Feb-2010 01-Aug-2010 - 01-Sep-2010 01-Aug-2010 - 01-Sep-2010 When it should do this (this is what the view returns): 01-Jan-2010 - 01-Feb-2010 15-Jun-2010 - 15-Jul-2010 01-Aug-2010 - 01-Sep-2010 01-Dec-2010 - 31-Dec-2010 Also, I've run the SQL profiler over it and according to that, the query being executed is: SELECT [Extent1].[ID] AS [ID], [Extent1].[FromDate] AS [FromDate], [Extent1].[ToDate] AS [ToDate] FROM (SELECT [C].[ID] AS [ID], [C].[FromDate] AS [FromDate], [C].[ToDate] AS [ToDate] FROM [dbo].[C] AS [C]) AS [Extent1] Which returns the correct data So it seems that the entity framework is doing something to the data in the meantime. To me, everything looks fine! Have I missed something? Cheers, Ben

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  • How to learn to program C the right way

    - by sfactor
    i have been programming in C/C++ for my academic courses a lot and was under the impression i had a pretty good grasp of it. but lately i had to work in a bluetooth application that had a server and client implementation in a Linux box and an embedded system. i learned bluez bluetooth API, socket/network programming and coded it. however i ran into a lot of problems with memory leaks and segmentation faults and other memory related errors along the way.as the code grew more complex i all but lost control of the pointers and threads and sockets. this got me wondering that i had a lot to learn that they didn't say in the basic C/C++ books. so i wanted to ask for the resources that are available that'll help be code better in a professional way in C/C++ .especially for the Linux/Mac environment (gcc compiler).

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  • Why people don't use LabView for purposes other than data acquisition and virtualization?

    - by Anzurio
    This is marked as a subjective question, I hope I won't get too many down votes though. LV seems to offer a nice graphic alternative to traditional text based programming. As I understand, it's not a just-virtualization/data acquisition programming language. Nonetheless, it seems to have that paradigm pegged to its creator's name. My question comes up because it doesn't seem to be widely used for multi-purpose applications. I'm not a LV-expert of any kind, I'm more like a learner. I'm still getting used to LV.

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  • What application domains are CPU bound and will tend to benefit from multi-core technologies?

    - by Glomek
    I hear a lot of people talking about the revolution that is coming in programming due to multi-core processors and parallelism, but I can't shake the feeling that for most of us, CPU cycles aren't the bottleneck. Pretty much all of my programs have been I/O bound in one way or another (database, filesystem, network, user interaction, etc.) for a very long time. Now I can think of a few areas where CPU cycles are a limiting factor, like code breaking, graphics, sound, some forms of simulation (weather, physics, etc.), and some forms of mathematical research, but they all seem like fairly specialized application domains. My general impression is that most programs are still I/O bound and that for most of our industry CPUs have been plenty fast for quite a while now. Am I off my rocker? What other application domains are CPU bound today? Do any of them include a large portion of the programming population? In essence, I'm wondering whether the multi-core CPUs will impact very many of us, and if so, how?

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  • JPA entity design / cannot delete entity

    - by timaschew
    I though its simple what I want, but I cannot find any solution for my problem. I'm using playframework 1.2.3 and it's using Hibernate as JPA. So I think playframework has nothing to do with the problem. I have some classes (I omit the nonrelevant fields) public class User { ... } public class Task { public DataContainer dataContainer; } public class DataContainer { public Session session; public User user; } public class Session { ... } So I have association from Task to DataContainer and from DataContainer to Sesssion and the DataContainer belongs to a User. The DataContainers can have always the same User, but the Session have to be different for each instance. And the DataContainer of a Task have also to be different in each instance. A DataContainer can have a Sesesion or not (it's optinal). I use only unidirectional assoc. It should be sufficient. In other words: Every Task must has one DataContainer. Every DataContainer must has one/the same User and can have one Session. To create a DB schema I use JPA annotations: @Entity public class User extends Model { ... } @Entity public class Task extends Model { @OneToOne(optional = false, cascade = CascadeType.ALL) public DataContainer dataContainer; } @Entity public class DataContainer extends Model { @OneToOne(optional = true, cascade = CascadeType.ALL) public Session session; @ManyToOne(optional = false, cascade = CascadeType.ALL) public User user; } @Entity public class Session extends Model { ... } BTW: Model is a play class and provides the primary id as long type. When I create some for each entity a object and 'connect them', I mean the associations, it works fine. But when I try to delete a Session, I get a constraint violation exception, because a DataContainer still refers to the Session I want to delete. I want that the Session (field) of the DataContainer will be set to null respectively the foreign key (session_id) should be unset in the database. This will be okay, because its optional. I don't know, I think I have multiple problems. Am I using the right annotation @OneToOne ? I found on the internet some additional annotation and attributes: @JoinColumn and a mappedBy attribute for the inverse relationship. But I don't have it, because its not bidirectional. Or is a bidirectional assoc. essentially? Another try was to use @OnDelete(action = OnDeleteAction.CASCADE) the the contraint changed from NO ACTIONs when update or delete to: ADD CONSTRAINT fk4745c17e6a46a56 FOREIGN KEY (session_id) REFERENCES annotation_session (id) MATCH SIMPLE ON UPDATE NO ACTION ON DELETE CASCADE; But in this case, when I delete a session, the DataContainer and User is deleted. That's wrong for me. EDIT: I'm using postgresql 9, the jdbc stuff is included in play, my only db config is db=postgres://app:app@localhost:5432/app

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  • MySQL forgot about automatically creating an index for a foreign key?

    - by bobo
    After running the following SQL statements, you will see that, MySQL has automatically created the non-unique index question_tag_tag_id_tag_id on the tag_id column for me after the first ALTER TABLE statement has run. But after the second ALTER TABLE statement has run, I think MySQL should also automatically create another non-unique index question_tag_question_id_question_id on the question_id column for me. But as you can see from the SHOW INDEXES statement output, it's not there. Why does MySQL forget about the second ALTER TABLE statement? By the way, since I have already created a unique index question_id_tag_id_idx used by both question_id and tag_id columns. Is creating a separate index for each of them redundant? mysql> DROP DATABASE mydatabase; Query OK, 1 row affected (0.00 sec) mysql> CREATE DATABASE mydatabase; Query OK, 1 row affected (0.00 sec) mysql> USE mydatabase; Database changed mysql> CREATE TABLE question (id BIGINT AUTO_INCREMENT, html TEXT, PRIMARY KEY(id)) ENGINE = INNODB; Query OK, 0 rows affected (0.05 sec) mysql> CREATE TABLE tag (id BIGINT AUTO_INCREMENT, name VARCHAR(10) NOT NULL, UNIQUE INDEX name_idx (name), PRIMARY KEY(id)) ENGINE = INNODB; Query OK, 0 rows affected (0.05 sec) mysql> CREATE TABLE question_tag (question_id BIGINT, tag_id BIGINT, UNIQUE INDEX question_id_tag_id_idx (question_id, tag_id), PRIMARY KEY(question_id, tag_id)) ENGINE = INNODB; Query OK, 0 rows affected (0.00 sec) mysql> ALTER TABLE question_tag ADD CONSTRAINT question_tag_tag_id_tag_id FOREIGN KEY (tag_id) REFERENCES tag(id); Query OK, 0 rows affected (0.10 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> ALTER TABLE question_tag ADD CONSTRAINT question_tag_question_id_question_id FOREIGN KEY (question_id) REFERENCES question(id); Query OK, 0 rows affected (0.13 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> SHOW INDEXES FROM question_tag; +--------------+------------+----------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | +--------------+------------+----------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ | question_tag | 0 | PRIMARY | 1 | question_id | A | 0 | NULL | NULL | | BTREE | | | question_tag | 0 | PRIMARY | 2 | tag_id | A | 0 | NULL | NULL | | BTREE | | | question_tag | 0 | question_id_tag_id_idx | 1 | question_id | A | 0 | NULL | NULL | | BTREE | | | question_tag | 0 | question_id_tag_id_idx | 2 | tag_id | A | 0 | NULL | NULL | | BTREE | | | question_tag | 1 | question_tag_tag_id_tag_id | 1 | tag_id | A | 0 | NULL | NULL | | BTREE | | +--------------+------------+----------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+ 5 rows in set (0.01 sec) mysql>

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  • Is it good to continue as MFC developer or good to know .NET as well?

    - by AKN
    Normally people say MFC is little clumsy. It makes UI developement slightly difficult to maintain since it has lot of auto generated code. It has good architecture (doc/view) but is not transparent like Win32 programming to understand how window program works in the background. So with this situation, is it good to extend the exposure on MFC programming or better to switch to .NET since for faster UI design with ease in maintenance. How globally companies are looking into MFC as a technology for UI developments. Are they comfortable in supporting their developers to continue with MFC or looking for changing their development technology.

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  • a quick overview on access

    - by masfenix
    Hey I am a university student (math major), but programming since I was little (read: 14). I am starting a new programming job tomorrow at a very big company. However I just found out that I might be just working with access for a couple of weeks (macros and whatnot). Can someone just give me a general rundown on how to create and use VB in access. What I mean is how do tables refer to themselves (as objects? as what name?) how to run queries through vb and such. thanks all.

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  • Can I constrain a route parameter to a certain type in ASP.net MVC?

    - by Paul Suart
    I have the following route: routes.MapRoute( "Search", // Route name "Search/{affiliateId}", // URL with parameters new { controller = "Syndication", action = "Search" } // Parameter defaults ); Is there a way I can ensure "affiliateId" is a valid Guid? I'm using MVCContrib elsewhere in my site and I'm fairly it provides a way to implement this kind of constraint.... I just don't know what it is!

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  • Did your masters degree help you as a programmer?

    - by Tim Sally
    There is a previous question ("Is a masters degree overkill?"), which is about the types of jobs available and the value of a masters when trying to get a job. What I am curious about the impact of programming ability. I know you usually write a masters thesis on some topic, which I imagine forces you to specialize. Do your programming skills actually get rusty while getting a masters, or is there some benefit? Would it be more beneficial to work for the two years instead?

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  • From .NET to Delphi, an ERP on Delphi

    - by emray
    I have learned programming on .NET. It's been 4 years since I have started (serious) programming, I gained experience in VBA, JavaScript but mainly C#. I have spent a lot of time trying to grasp the good coding practices, object orientation etc. Now finally I have a job. The job is fixing/upgrading an ERP on a daily basis. Creating reports and maybe sometimes new stuff. I have absolutely no experience in Delphi, and no motivation to learn it especially when people are moving to .NEt from Delphi not in the reverse direction sa my manager expects :) The question is that are there any tools that I write C# code and compile into this object pascal or whatever it is. Thanks in advance.

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  • Can someone please explain to me the basic function of Intents in the Android OS?

    - by K-RAN
    I'm new to programming applications for the Android OS. As far as general architecture of the OS goes, I understand that processes are implemented as Linux processes and that each one is sandboxed. However, I'm utterly confused on the IPCs and syscalls (if any) used. I know that the IBinder is a form of this; parcels are sent back and forth between processes and Bundles are array forms of parcels (?). But even that is still unfamiliar to me. Same with Intents. All in all, I don't understand what kinds of IPCs are implemented and how. Could someone briefly explain to me the specific methods used by user level applications in Android OS to communicate with each other and the OS? I've done kernel programming and played with various IPCs in Linux (Ubuntu and Debian) so it would help immensely if this was all explained in relation to what I'm familiar with... Thanks in advance!

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  • Integrate Python Projects Into Xcode

    - by Vynile
    Hi! I'm a Mac user, and one of my hobbies is programming. I use Xcode, the integrated IDE of Mac OS X. I started to learn Python programming langage, and I want to use Xcode for developing my scripts. I searched for weeks in the internet, but I didn't find something interesting. Firstly, I want to update the integrated interpreter of Mac OS X, that is on 2.6 version. And secondly, I want to create a Python project on Xcode easily, like I do with C & C++ projects. Can you help me? I really need help! Cordially.

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  • Modern Web Development + General question

    - by ritu
    I have been given a nasty wake up a while ago when I discovered that my 10 years of experience was really equivalent of about 4 (got trapped in a big company doing the same thing over and over without realizing it) and is now paying a huge price. Question 1: I did servlets/JSP programming back in the day (2001-2003). Since then there have been libraries like GWT, YUI, etc. Is JSP still the preferred way of building web apps using Java? Question 2: Because I enjoyed what I was doing and needed to pay the bills, I didn't realize that the ground below me has shifted. How do avoid this in the future? My years of C system programming doesn't seem to matter a lot now to the young guys who talk about design patterns.

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  • How do you get "in the zone"?

    - by Wayne Werner
    Hi, I've just started my first real programming job and am pleased to discover that this is exactly what I want to do for the rest of my life. When it comes round to ~1 hour before it's time to go home and I think "Man, do I have to go home already?" I'd say that's A Good Thing(tm). One thing I've discovered though is that it takes a little while for my brain to get "in gear" or "in the Zone", so I'm curious what other folks do to get programming at their prime. My current flow is when I get here I visit SO and look at the interesting problems - I find it helps get my brain moving. After 20-30 minutes I start looking at my code/specs/etc to decide what I want/need to work on first. So how do you get started?

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  • Is it practical to learn and use Forth?

    - by Workshop Alex
    When I was still a young developer, I started to focus on the many available programming languages. But in 1980 to 1990 there weren't many freely available compilers. So I started with several BASIC dialects for home computers, Pascal and C on my PC, I did an exam in COBOL and dabbled a bit in Assembly and a few other languages. And at one point I took a short look at Forth. That's over 20 years ago and I've learned a lot ever since. I know that Forth is still used these days. It's still a good programming language but since I focus mostly on Windows development, I just wonder if knowing Forth could be helpful for future projects of mine. So, would it be practical for an experienced developer to learn more about Forth?

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  • Get a random subset from a set in F#

    - by Cay
    I am trying to think of an elegant way of getting a random subset from a set in F# Any thoughts on this? Perhaps this would work: say we have a set of 2x elements and we need to pick a subset of y elements. Then if we could generate an x sized bit random number that contains exactly y 2n powers we effectively have a random mask with y holes in it. We could keep generating new random numbers until we get the first one satisfying this constraint but is there a better way?

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