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• Is it conceivable to have millions of lists of data in memory in Python?

  - by Codemonkey

  I have over the last 30 days been developing a Python application that utilizes a MySQL database of information (specifically about Norwegian addresses) to perform address validation and correction. The database contains approximately 2.1 million rows (43 columns) of data and occupies 640MB of disk space. I'm thinking about speed optimizations, and I've got to assume that when validating 10,000+ addresses, each validation running up to 20 queries to the database, networking is a speed bottleneck. I haven't done any measuring or timing yet, and I'm sure there are simpler ways of speed optimizing the application at the moment, but I just want to get the experts' opinions on how realistic it is to load this amount of data into a row-of-rows structure in Python. Also, would it even be any faster? Surely MySQL is optimized for looking up records among vast amounts of data, so how much help would it even be to remove the networking step? Can you imagine any other viable methods of removing the networking step? The location of the MySQL server will vary, as the application might well be run from a laptop at home or at the office, where the server would be local.

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• Oracle as a Service in the Cloud

  - by Jason Williamson

  This should really be a Tweet, but I guess I'm writing a bit more. In theme of data migration and legacy modernization, I am seeing more and more of a push to consolidate data sources, especially from non-oracle to oracle in an effort to save dollars. From a modernization perspective, this fits in quite well. We are able to migrate things like Terradata, Sybase and DB2 and put that all into an Oracle database and then provide that as a OaaS (Oracle as a Service) Cloud offering. This seems to be a growing trend, and not unlike the cool RDS Amazon Database cloud being built on Oracle as well. We again find ourselves back in the similar theme of migration, however. The target technology sounds like a winner (COBOL to Java/SOA...DB2/Datacom/Adabas to Oracle) but the age-old problem of how to get there still persists. It it not trivial to migrate large amounts of pre-relational or "devolved" relational data. To do this, we again must revert back to a tight roadmap to migration and leverage the growing tools and services that we have. I'm working on a couple of new sections and chapters for a book that Tom and Prakash and I are writing around Database Migration and Consolidation. I'll share some snipits shortly.

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• Big level objects collision system for 2d game

  - by Aristarhys

  I read many variants today and get some knowledge in general, so here is a steps of mine thoughts in pictures (horrible paint.net ones). We need to develop grid system, so we check only thing near, perform simple check to cut out deep check, and at - last deep check like per-pixel collision check. Step 1 - Let p1, p2 are some sprites lets first just check with circle collision - because large distance between p1, p2 this fails and of course so we don't need test more deeply. But if we have not 2, but 20 objects, why we need to even circle test something so far outside of our view. Step 2 - Add basic column system, now we don't bother with p2 if it's in a column far from p1 column, so we even don't do circle test. But p3 is in the same col, so let do circle test, which of course will fail. Step 3 - Lets improve column system to the grid system with grid cell size just like p1, p2, p3 collision boxes, so we cut out things much top or below p1. And this is all great until comes BIG OBJs which is some kind of platforms. They are much bigger then grid cell. Circle test for will be successful, but deep check for whole big obj will fail And that the part I can't get. How do I store the grid position of big object? Like 4 grid coords for big object vertexes? And if one of them close to p1 do circle check for centre of big object then a deep one if succeed? Am I do it wrong? My possible solution:

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• How to shift a vector based on the rotation of another vector?

  - by bpierre

  I’m learning 2D programming, so excuse my approximations, and please, don’t hesitate to correct me. I am just trying to fire a bullet from a player. I’m using HTML canvas (top left origin). Here is a representation of my problem: The black vector represent the position of the player (the grey square). The green vector represent its direction. The red disc represents the target. The red vector represents the direction of a bullet, which will move in the direction of the target (red and dotted line). The blue cross represents the point from where I really want to fire the bullet (and the blue and dotted line represents its movement). This is how I draw the player (this is the player object. Position, direction and dimensions are 2D vectors): ctx.save(); ctx.translate(this.position.x, this.position.y); ctx.rotate(this.direction.getAngle()); ctx.drawImage(this.image, Math.round(-this.dimensions.x/2), Math.round(-this.dimensions.y/2), this.dimensions.x, this.dimensions.y); ctx.restore(); This is how I instanciate a new bullet: var bulletPosition = playerPosition.clone(); // Copy of the player position var bulletDirection = Vector2D.substract(targetPosition, playerPosition).normalize(); // Difference between the player and the target, normalized new Bullet(bulletPosition, bulletDirection); This is how I move the bullet (this is the bullet object): var speed = 5; this.position.add(Vector2D.multiply(this.direction, speed)); And this is how I draw the bullet (this is the bullet object): ctx.save(); ctx.translate(this.position.x, this.position.y); ctx.rotate(this.direction.getAngle()); ctx.fillRect(0, 0, 3, 3); ctx.restore(); How can I change the direction and position vectors of the bullet to ensure it is on the blue dotted line? I think I should represent the shift with a vector, but I can’t see how to use it.

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• Fast determination of whether objects are onscreen in 2D

  - by Ben Ezard

  So currently, I have this in each object's renderer's update method: float a = transform.position.x * Main.scale; float b = transform.position.y * Main.scale; float c = Camera.main.transform.position.x * Main.scale; float d = Camera.main.transform.position.y * Main.scale; onscreen = a + width - c > 0 && a - c < GameView.width && b + height - d > 0 && b - d < GameView.height; transform.position is a 2D vector containing the game engine's definition of where the object is - this is then multiplied by Main.scale to translate that coordinate into actual screen space Similarly, Camera.main.transform.position is the in-engine representation of where the main camera is, and this is also multiplied by Main.scale The problem is, as my game is tile-based, thousands of these updates get called every frame, just to determine whether or not each object should be drawn - how can I improve this please?

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• Is a "model" branch a common practice?

  - by dukeofgaming

  I just thought it could be a good thing to have a dedicated version control branch for all database schema changes and I wanted to know if anyone else is doing the same and what have the results been. Say that you are working with: Schema model/documentation (some file where you model the database visually to generate the schema source, say MySQL Workbench, with a .mwb file, which is binary) Schema source (a .sql file) Schema-based code generation The normal way we were working was with feature branches, so we would do changes to the model files (the database specific ones), and then have to regenerate points 2 and 3, dealing with the possible conflicts (or even code rewriting). Now say that your workflow goes the same way as the previous item numbering. With a model branch you wouldn't have to reconcile the schema model with binaries in other feature branches, or have to regenerate schema source and regenerate code (which might have human code on top of it). It makes so much sense to me it feels weird not having seen this earlier as a common practice. Edit: I'm counting on branch merges to be the assertions for the model matching the code. I use a DVCS, so I don't fear long-lived branches or scary-looking merges. I'm also doing feature branching.

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• How can I ensure my Collada model fits on an iPhone screen?

  - by rakeshNS

  Hi I am new to game development. I see many examples and tried myself like displaying triangle, cube etc. Now I am looking to render a Collada object. So I created a Collada object using Google Sketch up and trying to render that now. But the thing I am not understanding is, in all examples the vertices are between -1.0 and +1.0 values. But when I looked into that Collada file, the vertices were ranging from -30.0 to 90.0. I know any vertices greater than 1.0 will not display on iPhone. So can you pleas tell my the secret behind converting Object coordinate to normalized vector coordinate? My previous triangle defined as struct Vertex{ float Position[3]; float Color[4]; }; const Vertex Vertices[] = { {{-0.5, -0.866}, {1, 1, 0.5f, 1}}, {{0.5, -0.866}, {1, 1, 0.5, 1}}, {{0, 1}, {1, 1, 0.5, 1}}, {{-0.5, -0.866}, {0.5f, 0.5f, 0.5f}}, {{0.5, -0.866}, {0.5f, 0.5f, 0.5f}}, {{0, -0.4f}, {0.5f, 0.5f, 0.5f}}, }; And now triangle from collada is const Vertex Vertices[] = { {{39.4202092, 90.1263924, 0.0000000}, {1, 1, 0.5f, 1}}, {{-20.2205588, 90.1263924, 0.0000000}, {1, 1, 0.5, 1}}, {{-20.2205588, 176.3763924, 0.0000000}, {1, 1, 0.5, 1}}, {{-20.2205588, 176.3763924, 0.0000000}, {1, 1, 0.5, 1}}, {{-20.2205588, 90.1263924, 0.0000000}, {1, 1, 0.5, 1}}, {{39.4202092, 90.1263924, 0.0000000}, {1, 1, 0.5, 1}}, };

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• 3D physics engine for accurate collision handling on desktop/laptop computers (non-console)

  - by Georges Oates Larsen

  What are your suggestions for a physics engine that satisfies the following criteria? Capable of calculating collisions between multiple concave mesh-based colliders Handles many collisions going on at once (for instance one mesh being wedged between two others, which themselves may be wedged between two meshes) Does not allow for collider passthrough, even at high speeds. For instance, if I am applying force to a programmatically hinged object that makes it spin, I do not want it to pass through another rigidbody that it collides with while spinning. I have this problem using PhysX As implied before, reacts well to hinged objects, preferably has its own implementation of a hinge, but I am willing to program my own. The important part is that it has some sort of interface that guarantees accurate collision tracking even when dealing with these things Platform independent -- runs on mac as well as PC, also not tied down to specific graphics cards I think that's the best way to explain what I am looking for. Basically, I need SUPER reliable collisions. Something that can't be accomplished with a simple ray casting approach that sends a ray from the last position of the object to the current position (as this object may be potentially large and colliding with small objects via rotation) Bonus points for also including an OPEN SOURCE engine.

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• Confusion with floats converted into ints during collision detection

  - by TheBroodian

  So in designing a 2D platformer, I decided that I should be using a Vector2 to track the world location of my world objects to retain some sub-pixel precision for slow-moving objects and other such subtle nuances, yet representing their bodies with Rectangles, because as far as collision detection and resolution is concerned, I don't need sub-pixel precision. I thought that the following line of thought would work smoothly... Vector2 wrldLocation; Point WorldLocation; Rectangle collisionRectangle; public void Update(GameTime gameTime) { Vector2 moveAmount = velocity * (float)gameTime.ElapsedGameTime.TotalSeconds wrldLocation += moveAmount; WorldLocation = new Point((int)wrldLocation.X, (int)wrldLocation.Y); collisionRectangle = new Rectangle(WorldLocation.X, WorldLocation.Y, genericWidth, genericHeight); } and I guess in theory it sort of works, until I try to use it in conjunction with my collision detection, which works by using Rectangle.Offset() to project where collisionRectangle would supposedly end up after applying moveAmount to it, and if a collision is found, finding the intersection and subtracting the difference between the two intersecting sides to the given moveAmount, which would theoretically give a corrected moveAmount to apply to the object's world location that would prevent it from passing through walls and such. The issue here is that Rectangle.Offset() only accepts ints, and so I'm not really receiving an accurate adjustment to moveAmount for a Vector2. If I leave out wrldLocation from my previous example, and just use WorldLocation to keep track of my object's location, everything works smoothly, but then obviously if my object is being given velocities less than 1 pixel per update, then the velocity value may as well be 0, which I feel further down the line I may regret. Does anybody have any suggestions about how I might go about resolving this?

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• OpenGL - Rendering from part of an index and vertex array depending on an element count

  - by user1423893

  I'm currently drawing my shapes as lines by using a VAO and then assigning the dynamic vertices and indices each frame. // Bind VAO glBindVertexArray(m_vao); // Update the vertex buffer with the new data (Copy data into the vertex buffer object) glBufferData(GL_ARRAY_BUFFER, numVertices * sizeof(VertexPosition), m_vertices.data(), GL_DYNAMIC_DRAW); // Update the index buffer with the new data (Copy data into the index buffer object) glBufferData(GL_ELEMENT_ARRAY_BUFFER, numIndices * sizeof(unsigned short), indices.data(), GL_DYNAMIC_DRAW); glDrawElements(GL_LINES, numIndices, GL_UNSIGNED_SHORT, BUFFER_OFFSET(0)); // Unbind VAO glBindVertexArray(0); What I would like to do is draw the lines using only part of the data stored in the index and vertex buffer objects. The vertex buffer has its vertices set from an array of defined maximum size: std::array<VertexPosition, maxVertices> m_vertices; The index buffer has its elements set from an array of defined maximum size: std::array<unsigned short, maxIndices> indices = { 0 }; A running total is kept of the number of vertices and indices needed for each draw call numVertices numIndices Can I not specify that the buffer data contain the entire array and only read from part of it when drawing? For example using the vertex buffer object glBufferData(GL_ARRAY_BUFFER, numVertices * sizeof(VertexPosition), m_vertices.data(), GL_DYNAMIC_DRAW); m_vertices.data() = Entire array is stored numVertices * sizeof(VertexPosition) = Amount of data to read from the entire array Is this not the correct way to approach this? I do not wish to use std::vector if possible.

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• Triggering Data Changes in N-Tier

  - by Ryan Kinal

  I've been studying n-tier architectures as of late, particularly in VB.NET with Entity Framework and/or LINQ to SQL. I understand the basic concepts, but have been wondering about best practices in regard to triggering CRUD-type operations from user input/action. So, the arcitecture looks something like the following: [presentation layer] - [business layer] - [data layer] - (database) Getting information from the database into the presentation layer is simple and abstracted. It's just a matter of instantiating a new object from the business layer, which in turn uses the data layer to get at the correct information. However, saving (updating and inserting), and deleting seem to require particular APIs on the relevant business objects. I have to assume this is standard practice, unless a business object will save itself on various operations (which seems inefficient), or on disposal (which seems like it just wouldn't work, or may be unwieldy and unreliable). Should my "savable" business objects all implement a particular "ISavable" or "IDatabaseObject" interface? Is this a recognized (anti-)pattern? Are there other, better patterns I should be using that I'm just unaware of? The TLDR question, I suppose, is How does the presentation layer trigger database changes?

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• Correct way to use Farseer Physics in XNA

  - by user1640602

  I am using Farseer Physics for my 2D sidescroller game and I'm not sure how to proceed with it. I currently have a Sprite class (handles nothing but graphics), a GameObject class (contains specific object info like hit points), a World object which contains the list of Bodies, and a Level object which contains all of these objects. Originally I was trying to keep track of the Sprites, GameObjects, and Bodies separately because I felt that would provide loose coupling but it quickly became a headache. So my new idea was to add a Sprite member to the GameObject class but I'm still not sure how to maintain the Bodies because they have to communicate with GameObject. Specifically, my issue is this: The position of the Body is used to draw the Sprite inside of the Level. In order to do that I would have to maintain a link between GameObjects and Bodies. Is this correct or is there a better way to architect my game? If any of this is unclear please ask and I'll try to clarify. Thank you in advance for any help.

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• Should Developers Perform All Tasks or Should They Specialize?

  - by Bob Horn

  Disclaimer: The intent of this question isn't to discern what is better for the individual developer, but for the system as a whole. I've worked in environments where small teams managed certain areas. For example, there would be a small team for every one of these functions: UI Framework code Business/application logic Database I've also worked on teams where the developers were responsible for all of these areas and more (QA, analsyt, etc...). My current environment promotes agile development (specifically scrum) and everyone has their hands in every area mentioned above. While there are pros and cons to each approach, I'd be curious to know if there are more pros and cons than I list below, and also what the generally feeling is about which approach is better. Devs Do It All Pros 1. Developers may be more well-rounded 2. Developers know more of the system Cons 1. Everyone has their hands in all areas, increasing the probability of creating less-than-optimal results in that area 2. It can take longer to do something with which you are unfamiliar (jack of all trades, master of none) Devs Specialize Pros 1. Developers can create policies and procedures for their area of expertise and more easily enforce them 2. Developers have more of a chance to become deeply knowledgeable about their specific area and make it the best it can be 3. Other developers don't cross boundaries and degrade another area Cons 1. As one colleague put it: "Why would you want to pigeon-hole yourself like that?" (Meaning some developers won't get a chance to work in certain areas.) It's easy to say how wonderful agile is, and that we should do it all, but I'm somewhat of a fan of having areas of expertise. Without that expertise, I've seen code degrade, database schemas become difficult to manage, hack UI code, etc... Let's face it, some people make careers out of doing just UI work, or just database work. It's not that easy to just fill in and do as good of a job as an expert in that area.

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• FILESTREAM in SQL Server 2008 R2

  - by CatherineRussell

  Much data is unstructured, such as text documents, images, and videos. This unstructured data is often stored outside the database, separate from its structured data. This separation can cause data management complexities. Or, if the data is associated with structured storage, the file streaming capabilities and performance can be limited. FILESTREAM integrates the SQL Server Database Engine with an NTFS file system by storing varbinary(max) binary large object (BLOB) data as files on the file system. Transact-SQL statements can insert, update, query, search, and back up FILESTREAM data. Win32 file system interfaces provide streaming access to the data. FILESTREAM uses the NT system cache for caching file data. This helps reduce any effect that FILESTREAM data might have on Database Engine performance. The SQL Server buffer pool is not used; therefore, this memory is available for query processing. FILESTREAM data is not encrypted even when transparent data encryption is enabled. To read more, go to: http://technet.microsoft.com/en-us/library/bb933993.aspx

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• Architecture : am I doing things right?

  - by Jeremy D

  I'm trying to use a '~classic' layered arch using .NET and Entity Framework. We are starting from a legacy database which is a little bit crappy: Inconsistent naming Unneeded views (view referencing other views, select * views etc...) Aggregated columns Potatoes and Carrots in the same table etc... So I ended with fully isolating my database structure from my domain model. To do so EF entities are hidden from presentation layer. The goal is to permit an easier database refactoring while lowering the impact of it on applications. I'm now facing a lot of challenges and I'm starting to ask myself if I'm doing things right. My Domain Model is highly volatile, it keeps evolving with apps as new fields needs are arising. Complexity of it keeps raising and class it contains start to get a lot of properties. Creating include strategy and reprojecting to EF is very tricky (my domain objects don't have any kind of lazy/eager loading relationship properties): DomainInclude<Domain.Model.Bar>.Include("Customers").Include("Customers.Friends") // To... IFooContext.Bars.Include(...).Include(...).Where(...) Some framework are raping the isolation levels (Devexpress Grids which needs either XPO or IQueryable for filtering and paging large data sets) I'm starting to ask myself if : the isolation of EF auto-generated entities is an unneeded cost. I should allow frameworks to hit IQueryable? Slow slope to hell? (it's really hard to isolate DevExpress framework, any successful experience?) the high volatility of my domain model is normal? Did you have similar difficulties? Any advice based on experience?

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• Using Queries with Coherence Write-Behind Caches

  - by jpurdy

  Applications that use write-behind caching and wish to query the logical entity set have the option of querying the NamedCache itself or querying the database. In the former case, no particular restrictions exist beyond the limitations intrinsic to the Coherence query engine itself. In the latter case, queries may see partially committed transactions (e.g. with a parent-child relationship, the version of the parent may be different than the version of the child objects) and/or significant version skew (the query may see the current version of one object and a far older version of another object). This is consistent with "read committed" semantics, but the read skew may be far greater than would ever occur in a non-cached environment. As is usually the case, the application developer may choose to accept these limitations (with the hope that they are sufficiently infrequent), or they may choose to validate the reads (perhaps via a version flag on the objects). This also applies to situations where a third party application (such as a reporting tool) is querying the database. In many cases, the database may only be in a consistent state after the Coherence cluster has been halted.

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• How do you avoid name similarities between your classes and the native ones?

  - by Oscar

  I just ran into an "interesting problem", which I would like your opinion about: I am developing a system and for many reasons (meaning: abstraction, technology independence, etc) we create our own types for exchanging information. For instance: if there is a method which is called SendEmail and is invoked by the business logic, it way have a parameter of type OurCompany.EMailMessage, which is an object which is completely technology independent and contains only "business relevant data" (for instance, no information abut head encoding). Inside the SendEmail function, we get this information from our EMailMEssage object and create a MailMessage (this one is technolgy specific) object so it can be sent over the network. As you can already notice, our class has a very similar name to the "native" language class. The problem is: this is exactly what they are, email messages, so it is hard to find another meaningful name for them. Do you have this problem often? How do you manage it? Edit: @mgkrebbs just commented about using fully qualified names. This is our current approach, but a little bit too verbose, IMHO. I would like something cleaner, if possible.

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• Memory allocation strategy for the vertex buffers (DirectX 10/11)

  - by Alex

  I have the following question. I write CAD system. So I have a 3D scene and there are many different objects (walls, doors, windows and so on). User can add or delete some objects. The question is: how can I organise the keeping of vertices for all my objects. I can create vertex buffer for every object. But I think drawing/switching from one buffer to another would have performance penalty. Another way - I can create several big buffers for every object type. But I don't understand how to update such buffers. It is too big to update whole buffer (for example buffer for all walls). What I need to do if I want to delete the object from the middle of the buffer? Actually I have the similar question: http://stackoverflow.com/questions/5515700/how-to-properly-update-vertex-buffers-in-directx-10 Most examples I've found work with very static models. Therefore, they tend to create a single vertex buffer with their list of points, and then are just manipulated by matrix transformations. I, on the other hand, will be updating the scene very often.

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• How can I include my derived class type name in the serialized JSON?

  - by ChrisD

  Sometimes working with the js Serializer is easy, sometimes its not.   When I attempt to serialize an object that is derived from a base, the serializer decided whether or not to include the type name. When its present, the type name is represented by a ___type attribute in the serialized json like this: {"d":{"__type":"Commerce.Integration.Surfaces.OrderCreationRequest","RepId":0}} The missing type name is a problem if I intend to ship the object back into a web method that needs to deserialize the object.   Without the Type name, serialization will fail and result in a ugly web exception. The solution, which feels more like a work-around, is to explicitly tell the serializer to ALWAYS generate the type name for each derived type.  You make this declaration by adding a [GenerateScriptType())] attribute for each derived type to the top of the web page declaration.   For example, assuming I had 3 derivations of OrderCreationRequest; PersonalOrderCreationRequest, CompanyOrderCreationRequest, InternalOrderCreationRequestion, the code-behind for my web page would be decorated as follows: [GenerateScriptType(typeof(PersonalOrderCreationRequest))] [GenerateScriptType(typeof(CompanyOrderCreationRequest))] [GenerateScriptType(typeof(InternalOrderCreationRequest))] public partial class OrderMethods : Page { ... } With the type names generated in the serialized JSON, the serializer can successfully deserialize instances of any of these types passed into a web method. Hope this helps you as much as it did me.

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• Good design for class with similar constructors

  - by RustyTheBoyRobot

  I was reading this question and thought that good points were made, but most of the solutions involved renaming one of the methods. I am refactoring some poorly written code and I've run into this situation: public class Entity { public Entity(String uniqueIdentifier, boolean isSerialNumber) { if (isSerialNumber) { this.serialNumber = uniqueIdentifier; //Lookup other data } else { this.primaryKey = uniqueIdentifier; // Lookup other data with different query } } } The obvious design flaw is that someone needed two different ways to create the object, but couldn't overload the constructor since both identifiers were of the same type (String). Thus they added a flag to differentiate. So, my question is this: when this situation arises, what are good designs for differentiating between these two ways of instantiating an object? My First Thoughts You could create two different static methods to create your object. The method names could be different. This is weak because static methods don't get inherited. You could create different objects to force the types to be different (i.e., make a PrimaryKey class and a SerialNumber class). I like this because it seems to be a better design, but it also is a pain to refactor if serialNumber is a String everywhere else.

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• How do I interpolate air drag with a variable time step?

  - by Valentin Krummenacher

  So I have a little game which works with small steps, however those steps vary in time, so for example I sometimes have 10 Steps/second and then I have 20 Steps/second. This changes automatically depending on how many steps the user's computer can take. To avoid inaccurate positioning of the game's player object I use y=v0*dt+g*dt^2/2 to determine my objects y-position, where dt is the time since the last step, v0 is the velocity of my object in the beginning of my step and g is the gravity. To calculate the velocity in the end of a step I use v=v0+g*dt what also gives me correct results, independent of whether I use 2 steps with a dt of for example 20ms or one step with a dt of 40ms. Now I would like to introduce air drag. For simplicity's sake I use a=k*v^2 where a is the air drag's acceleration (I am aware that it would usually result in a force, but since I assume 1kg for my object's mass the force is the same as the resulting acceleration), k is a constant (in this case I'm using 0.001) and v is the speed. Now in an infinitely small time interval a is k multiplied by the velocity in this small time interval powered by 2. The problem is that v in the next time interval would depend on the drag of the last which again depends on the v of the last interval and so on... In other words: If I use a=k*v^2 I get different results for my position/velocity when I use 2 steps of 20ms than when I use one step of 40ms. I used to have this problem for my position too, but adding +g*dt^2/2 to the formula for my position fixed the problem since it takes into account that the position depends on the velocity which changes slightly in every infinitely small time interval. Does something like that exist for air drag too? And no, I dont mean anything like Adding air drag to a golf ball trajectory equation or similar, for that kind of method only gives correct results when all my steps are the same. (I hope you can understand my intermediate english, it's not my main language so I would like to say sorry for all the silly mistakes I might have made in my question)

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• Oracle OpenWorld 2012

  - by Maria Colgan

  I can't believe it's time for OpenWorld again! Oracle OpenWorld is the largest gathering of Oracle customers, partners, developers, and technology enthusiasts. This year it will take place between September 30th and October 4th in San Francisco. Of course, the Optimizer development group will be there and you will have multiple opportunities to meet the team, in one of our technical sessions, or at the Oracle Database demogrounds. This year the Optimizer team has 2 technical sessions, as well as a booth in the Oracle Database demogrounds. Tuesday, October 2nd at 1:15pm Oracle Optimizer: Harnessing the Power of Optimizer Hints Session CON8455 at Moscone South - room 103 In this session we will discuss in detail how optimizer hints are interpreted, when they should be used, and why they sometimes appear to be ignored. Thursday, October 4th at 12:45pm Oracle Optimizer: An Insider’s View of How the Optimizer Works Session CON8457 at Moscone South - room 104This session explains how the latest version of the optimizer works and the best ways you can influence its decisions to ensure you get optimal execution every time. It will also include a full history of the Cost Based Optimizer, so make sure you stick around for this one! If you have burning Optimizer or statistics related questions, or if you just want to pick up an Optimizer bumper sticker, you can stop by the Optimizer demo booth. This year we are located in booth 3157, in the Database area of the demogrounds, in Moscone South. Members of the Optimizer development team will be there Monday through Wednesday from 9:45 am until 6pm. The full Oracle OpenWorld catalog is on-line, or you can browse by speakers by name. So start planning your trip today! +Maria Colgan

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• Persisting high score table in flash game without a network. (Featuring: HttpListenerException)

  - by bearcdp

  Hi everyone, this question is very programming-centric, but it's for a game so I figured I might as well post it here. I'm doing polishing work on a GGJ '11 game because it will be shown at an indie arcade tomorrow afternoon, and they're expecting our final build in the morning. We'd like to have a high score table that displays during attract mode, but since it's Flash (Flixel) it would require some networking, Mochi, or something to keep a record of these scores. Only problem is the machine we'd be running on probably won't have network access. As a quick solution, I thought I'd just write up a dinky little high score server in C#/.NET that could take basic GET requests for submitting scores and getting the score list. We're talking REAL basic, like blocking while waiting for an incoming request, run & forget console app, etc. There's no guarantee that our .swf won't get reloaded, and we'd like the scores to persist, so this server would pretty much exists to keep a safe copy of the scores that the game can add to and request, and occasionally the server will write the scores to a flat text file. But, HttpListener is giving me Error Code 87 'The parameter is incorrect.' Have any idea what I'm doing wrong? Or better yet, am I barking up the wrong tree and missing an obviously simpler solution? This is all I've got so far in my Main(): HttpListener listener = new HttpListener(); listener.Prefixes.Add("http://localhost:66666/"); listener.Start(); The exception happens at listener.Start(); and the stack trace is: at System.Net.HttpListener.AddAllPrefixes() at System.Net.HttpListener.Start() at WOSEBCE_ScoreServer.Program.Main(String[] args) in C:\Users\Michael\Documents\Visual Studio 2010\VS2010 Projects\WOSEBCE_ScoreServer\WOSEBCE_ScoreServer\Program.cs:line 24 at System.AppDomain._nExecuteAssembly(RuntimeAssembly 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, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart()

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• how to calculate intersection time and place of multiple moving arcs

  - by user20733

  I have rocks orbiting moons, moons orbiting planets, planets orbiting suns, and suns orbiting black holes, and the current system could have many many layers of orbitage. the position of any object is a function of time and relative to the object it orbits. (so far so good). now I want to know for a given 2 objects(A,B), a start time and a speed, how can I work out the when and where to go. I can work out where A and B is given a time. so i just need. 1: direction to travel in from A to B(remember B is moving(not in a straight line)) 2: Time to get to b in a straight line. travel must be in a straight line with the shortest possible distance. as an extension to this question, how will i know if its better to wait, EG is it faster to stay on object A and wait for a hour when the objects may be closer, than to set off from A to B at the start. Cheers, it hurt my brain.

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• Vaadin Calendar events not shown if overnight [migrated]

  - by B_B

  In my vaadin project there is the possibility to create events that are shown by the calendar. It does works, except when the event is overnight, let's say the night from 23th to 24th, and the calendar shows as only day the 24th. In this case the part of the event that belongs to the 24th is supposed to be shown, but it is not. When I switch to weekly view, the event is shown properly. Here is the function where I get the data and use a container for the calendar: /* Fill Calendar from database */ void updateData() { final BeanItemContainer<TypeReservationEvent> container = new BeanItemContainer<TypeReservationEvent>(TypeReservationEvent.class); Map<String, Object> parameters = new HashMap<String, Object>(); parameters.put("roomParent",chosenRoom); String query = "SELECT DISTINCT res FROM EntityReservation res, EntityRoom r, EntityTable rt WHERE res.tableId = rt.id " + "AND rt.roomParent =:roomParent"; reservationList = facade.list(query, parameters); for(EntityReservation rt : reservationList) { container.addBean(new TypeReservationEvent(rt)); } container.sort(new Object[]{"start"}, new boolean[]{true}); cal.setContainerDataSource(container, "caption", "description", "start", "end", "styleName"); // Force calendar to refresh if(selectCalViewType.getValue() == chooseWeeklyView) { setViewType(calViewType.DAILY); setViewType(calViewType.WEEKLY); } else if (selectCalViewType.getValue() == chooseDailyView) { setViewType(calViewType.WEEKLY); setViewType(calViewType.DAILY); } } TIA

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