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  • Rotate sphere in Javascript / three.js while moving on x/z axes

    - by kaipr
    I have a sphere/ball in three.js which I want to "roll" arround on a x/z axis. For the z axe I could simply do this no matter what the current x and y rotation is: sphere.roll_z = function(distance) { sphere.position.z += distance; sphere.rotation.x += distance > 0 ? 0.05 : -0.05; } But how can I roll it along the x axe? And how could I properly do the roll_z? I've found a lot about quateration and matrixes, but I can't figure out how to use them properly to achieve my (rather simple) goal. I'm aware that I have to update multiple rotations and that I have to calculate how far to rotate the sphere to match the distance, but the "how" is the question. It's probably just lack of mathematical skills which I should train, but a working example/short explanation would help alot to start with.

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  • The Oracle Graduate Experience...A Graduates Perspective by Angelie Tierney

    - by david.talamelli
    [Note: Angelie has just recently joined Oracle in Australia in our 2011 Graduate Program. Last week I shared my thoughts on our 2011 Graduate Program, this week Angelie took some time to share her thoughts of our Graduate Program. The notes below are Angelie's overview from her experience with us starting with our first contact last year - David Talamelli] How does the 1 year program work? It consists of 3 weeks of training, followed by 2 rotations in 2 different Lines of Business (LoB's). The first rotation goes for 4 months, while your 2nd rotation goes for 7, when you are placed into your final LoB for the program. The interview process: After sorting through the many advertised graduate jobs, submitting so many resumes and studying at the same time, it can all be pretty stressful. Then there is the interview process. David called me on a Sunday afternoon and I spoke to him for about 30 minutes in a mini sort of phone interview. I was worried that working at Oracle would require extensive technical experience, but David stressed that even the less technical, and more business-minded person could, and did, work at Oracle. I was then asked if I would like to attend a group interview in the next weeks, to which I said of course! The first interview was a day long, consisting of a brief introduction, a group interview where we worked on a business plan with a group of other potential graduates and were marked by 3 Oracle employees, on our ability to work together and presentation. After lunch, we then had a short individual interview each, and that was the end of the first round. I received a call a few weeks later, and was asked to come into a second interview, at which I also jumped at the opportunity. This was an interview based purely on your individual abilities and would help to determine which Line of Business you would go to, should you land a graduate position. So how did I cope throughout the interview stages? I believe the best tool to prepare for the interview, was to research Oracle and its culture and to see if I thought I could fit into that. I personally found out about Oracle, its partners as well as competitors and along the way, even found out about their part (or Larry Ellison's specifically) in the Iron Man 2 movie. Armed with some Oracle information and lots of enthusiasm, I approached the Oracle Graduate Interview process. Why did I apply for an Oracle graduate position? I studied a Bachelor of Business/Bachelor of Science in IT, and wanted to be able to use both my degrees, while have the ability to work internationally in the future. Coming straight from university, I wasn't sure exactly what I wanted to do in terms of my career. With the program, you are rotated across various lines of business, to not only expose you to different parts of the business, but to also help you to figure out what you want to achieve out of your career. As a result, I thought Oracle was the perfect fit. So what can an Oracle ANZ Graduate expect? First things first, you can expect to line up for your visitor pass. Really. Next you enter a room full of unknown faces, graduates just like you, and then you realise you're in this with 18 other people, going through the same thing as you. 3 weeks later you leave with many memories, colleagues you can call your friends, and a video of your presentation. Vanessa, the Graduate Manager, will also take lots of photos and keep you (well) fed. Well that's not all you leave with, you are also equipped with a wealth of knowledge and contacts within Oracle, both that will help you throughout your career there. What training is involved? We started our Oracle experience with 3 weeks of training, consisting of employee orientation, extensive product training, presentations on the various lines of business (LoB's), followed by sales and presentation training. While there was potential for an information overload, maybe even death by Powerpoint, we were able to have access to the presentations for future reference, which was very helpful. This period also allowed us to start networking, not only with the graduates, but with the managers who presented to us, as well as through the monthly chinwag, HR celebrations and even with the sharing of tea facilities. We also had a team bonding day when we recorded a "commercial" within groups, and learned how to play an Irish drum. Overall, the training period helped us to learn about Oracle, as well as ourselves, and to prepare us for our transition into our rotations. Where to now? I'm now into my 2nd week of my first graduate rotation. It has been exciting to finally get out into the work environment and utilise that knowledge we gained from training. My manager has been a great mentor, extremely knowledgeable, and it has been good being able to participate in meetings, conference calls and make a contribution towards the business. And while we aren't necessarily working directly with the other graduates, they are still reachable via email, Pidgin and lunch and they are important as a resource and support, after all, they are going through a similar experience to you. While it is only the beginning, there is a lot more to learn and a lot more to experience along the way, especially because, as we learned during training, at Oracle, the only constant is change.

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  • How can I fade something to clear instead of white?

    - by Raven Dreamer
    I've got an XNA game which essentially has "floating combat text": short-lived messages that display for a fraction of a second and then disappear. I've recently added a gradual "fade-away" effect, like so: public void Update() { color.A -= 10; position.X += 3; if (color.A <= 10) isDead = true; } Where color is the Color int the message displays as. This works as expected, however, it fades the messages to white, which is very noticeable on my indigo background. Is there some way to fade it to transparent, rather than white? Lerp-ing towards the background color isn't an option, as there's a possibility there will be something between the text and the background, which would simply be the inverse of the current problem.

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  • Problem using glm::lookat

    - by omikun
    I am trying to rotate a sprite so it is always facing a 3D camera. Object GLfloat vertexData[] = { // X Y Z U V 0.0f, 0.8f, 0.0f, 0.5f, 1.0f, -0.8f,-0.8f, 0.0f, 0.0f, 0.0f, 0.8f,-0.8f, 0.0f, 1.0f, 0.0f, }; Per frame transform glm::mat4 newTransform = glm::lookAt(glm::vec3(0), gCamera.position(), gCamera.up()); shaders->setUniform("camera", gCamera.matrix()); shaders->setUniform("model", newTransform); In the vertex shader: gl_Position = camera * model * vec4(vert, 1); The object will track the camera if I move the camera up or down, but if I move the camera left/right (spin the camera around the object's y axis), it will rotate in the other direction so I end up seeing its front twice and its back twice as I rotate around it 360. If I use -gCamera.up() instead, it would track the camera side to side, but spin the opposite direction when I move the camera up/down. What am I doing wrong?

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  • Texture the quad with different parts of texture

    - by PolGraphic
    I have a 2D quad. Let say it's position is (5,10) and size is (7,11). I want to texture it with one texture, but using three different parts of it. I want to texture the part of quad from x = 5 to x = 7 with part of texture from U = 0 to U = 0.5 (replaying it after achieving 0.5, so I will have 4 same 0.5-lenght fragments). The second one with some other part of texture (also repeating it) and third in the same style. But, how to achieve it? I know that: float2 tc = fmod(input.TexCoord, textureCoordinates.zw - textureCoordinates.xy) + textureCoordinates.xy; //textureCoordinates.xy = fragments' offset Will give me the texture part replaying.

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  • The Excel Column Name assigment problem

    - by Peter Larsson
    Here is a generic algorithm to get the Excel column name according to it's position. By changing the @Base parameter, you can do this for any sequence according to same style as Excel. DECLARE @Value INT = 8839,         @Base TINYINT = 26   ;WITH cteSequence(Value, Delta, Quote, Base, Chr) AS (     SELECT  CAST(@Value AS INT) AS Value,             CAST(1 AS INT) AS Delta,             CAST(@Base AS INT) AS Quote,             CAST(@Base AS INT) AS Base,             CHAR(65 +(@Value - 1) % @Base) AS Chr       UNION ALL       SELECT  Value AS Value,             Quote AS Delta,             26 * Quote AS Quote,             Base AS Base,             CHAR(65 +((Value - Delta)/ Quote - 1) % Base) AS Chr     FROM    cteSequence     WHERE   CHAR(65 +((Value - Delta)/ Quote - 1) % Base) <> '@' ) SELECT  CAST(Msg AS VARCHAR(MAX)) FROM    (             SELECT        '' + Chr             FROM        cteSequence             ORDER BY    Delta DESC             FOR XML        PATH('')         ) AS x(Msg)

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  • Limit the amount a camera can pitch

    - by ChocoMan
    I'm having problems trying to limit the range my camera can pitch. Currently my camera can pitch around a model without restriction, but having a hard time trying to find the value of the degree/radian the camera is currently at after pitching. Here is what I got so far: // Moves camera with thumbstick Pitch = pController.ThumbSticks.Right.Y * MathHelper.ToRadians(speedAngleMAX); // Pitch Camera around model public void cameraPitch(float pitch) { pitchAngle = ModelLoad.camTarget - ModelLoad.CameraPos; axisPitch = Vector3.Cross(Vector3.Up, pitchAngle); // pitch constrained to model's orientation axisPitch.Normalize(); ModelLoad.CameraPos = Vector3.Transform(ModelLoad.CameraPos - ModelLoad.camTarget, Matrix.CreateFromAxisAngle(axisPitch, pitch)) + ModelLoad.camTarget; } I've tried restraining the Y-camera position of ModelLoad.CameraPos.Y, but doing so gave me some unwanted results.

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  • First time android game development [on hold]

    - by Dave
    My friend and i are developing a android game. This is my first time develop android game, so we don't know how to code The game is 2d game and we develop it without 3rd party engine / framework. Now we got a few questions, hope you can help us. In game play, using 'Surfaceview' only to achieve it. Is it best practice? On 'Surfaceview', a lot of difference button(Menu, pause, game object..etc) is on it, but I don't know how to code it? (actually, i have already done, but...so stupid way. Detect the user touch position (x, y) to identify where they touch[rect(x1,y1,x2,y2).contain(x,y)] Is it right? Teach me how to do if wrong. View / Surfaceview / OpenGL, which is suitable for us? (if like Tetris) Thank you for your help. Ps: My english is not good, hope you can understand what i mean.

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  • What exactly is UV and UVW Mapping?

    - by Michael Stum
    Trying to understand some basic 3D concepts, at the moment I'm trying to figure out how textures actually work. I know that UV and UVW mapping are techniques that map 2D Textures to 3D Objects - Wikipedia told me as much. I googled for explanations but only found tutorials that assumed that I already know what it is. From my understanding, each 3D Model is made out of Points, and several points create a face? Does each point or face have a secondary coordinate that maps to a x/y position in the 2D Texture? Or how does unwrapping manipulate the model? Also, what does the W in UVW really do, what does it offer over UV? As I understand it, W maps to the Z coordinate, but in what situation would I have different textures for the same X/Y and different Z, wouldn't the Z part be invisible? Or am I completely misunderstanding this?

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  • Faut-il être bon en math pour être un bon développeur ? Quelle place ont les maths dans votre parcou

    Faut-il être bon en math pour être un bon développeur ? Quelle place ont les maths dans votre métier et votre parcours ? Faut-il être bon en math pour être un bon développeur ? La question mérite d'être posée. Certes, l'informatique est à classer, dans le système universitaire, du coté des sciences "dures", par oppositions aux sciences sociales et humaines. L'enseignement des mathématiques et la rigueur qu'elles amènent paraissent donc indispensable. Pourtant, beaucoup, comme Alan Skorkin - qui vient d'aborder ce sujet sur son blog -, reconnaissent qu'ils n'ont jamais vraiment eu besoin des maths dans leur travail. La position de Alan Skorkin est c...

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  • Unity3d vector and matrix operations

    - by brandon
    I have the following three vectors: posA: (1,2,3) normal: (0,1,0) offset: (2,3,1) I want to get the vector representing the position which is offset in the direction of the normal from posA. I know how to do this by cheating (not using matrix operations): Vector3 result = new Vector3(posA.x + normal.x*offset.x posA.y + normal.y*offset.y, posA.z + normal.z*offset.z); I know how to do this mathematically Note: [] indicates a column vector, {} indicates a row vector result = [1,2,3] + {2,3,1}*{[0,0,0],[0,1,0],[0,0,0]} What I don't know is which is better to use and if it's the latter how do I do this in unity? I only know of 4x4 matrices in unity. I don't like the first option because you are instantiating a new vector instead of just modifying the original. Suggestions? Note: by asking which is better, I am asking for a quantifiable reason, not just a preference.

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  • Tool for creating Spritesheet? and Tips

    - by Spooks
    I am looking for a tool that I can use to create sprite sheet easily. Right now I am using Illustrator, but I can never get the center of the character in the exact position, so it looks like it is moving around(even though its always in one place), while being loop through the sprite sheet. Is there any better tools that I can be using? Also what kind of tips would you give for working with a sprite sheet? Should I create each part of the character in individual layers (left arm, right arm, body, etc.) or everything at once? any other tips would also be helpful! thank you

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  • Typical Applications of Linear System Solver in Game Developemnt

    - by craftsman.don
    I am going to write a custom solver for linear system. I would like to survey the typical problems involved the linear system solving in games. So that I can custom optimization on these problems based on the shape of the matrix. currently I am focus on these problems: B-Spline editing (I use a linear solve to resolve the C0, C1, C2 continuity) Constraint in Simulation (especially Position-Constraint, cloth) Both of them are Banded Matrix. I want to hear about some other applications of a linear system in games. Thank you.

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  • Professional Development – Difference Between Bio, CV and Resume

    - by Pinal Dave
    Applying for work can be very stressful – you want to put your best foot forward, and it can be very hard to sell yourself to a potential employer while highlighting your best characteristics and answering questions.  On top of that, some jobs require different application materials – a biography (or bio), a curriculum vitae (or CV), or a resume.  These things seem so interchangeable, so what is the difference? Let’s start with the one most of us have heard of – the resume.  A resume is a summary of your job and education history.  If you have ever applied for a job, you will have used a resume.  The ability to write a good resume that highlights your best characteristics and emphasizes your qualifications for a specific job is a skill that will take you a long way in the world.  For such an essential skill, unfortunately it is one that many people struggle with. RESUME So let’s discuss what makes a great resume.  First, make sure that your name and contact information are at the top, in large print (slightly larger font than the rest of the text, size 14 or 16 if the rest is size 12, for example).  You need to make sure that if you catch the recruiter’s attention and they know how to get a hold of you. As for qualifications, be quick and to the point.  Make your job title and the company the headline, and include your skills, accomplishments, and qualifications as bullet points.  Use good action verbs, like “finished,” “arranged,” “solved,” and “completed.”  Include hard numbers – don’t just say you “changed the filing system,” say that you “revolutionized the storage of over 250 files in less than five days.”  Doesn’t that sentence sound much more powerful? Curriculum Vitae (CV) Now let’s talk about curriculum vitae, or “CVs”.  A CV is more like an expanded resume.  The same rules are still true: put your name front and center, keep your contact info up to date, and summarize your skills with bullet points.  However, CVs are often required in more technical fields – like science, engineering, and computer science.  This means that you need to really highlight your education and technical skills. Difference between Resume and CV Resumes are expected to be one or two pages long – CVs can be as many pages as necessary.  If you are one of those people lucky enough to feel limited by the size constraint of resumes, a CV is for you!  On a CV you can expand on your projects, highlight really exciting accomplishments, and include more educational experience – including GPA and test scores from the GRE or MCAT (as applicable).  You can also include awards, associations, teaching and research experience, and certifications.  A CV is a place to really expand on all your experience and how great you will be in this particular position. Biography (Bio) Chances are, you already know what a bio is, and you have even read a few of them.  Think about the one or two paragraphs that every author includes in the back flap of a book.  Think about the sentences under a blogger’s photo on every “About Me” page.  That is a bio.  It is a way to quickly highlight your life experiences.  It is essentially the way you would introduce yourself at a party. Where a bio is required for a job, chances are they won’t want to know about where you were born and how many pets you have, though.  This is a way to summarize your entire job history in quick-to-read format – and sometimes during a job hunt, being able to get to the point and grab the recruiter’s interest is the best way to get your foot in the door.  Think of a bio as your entire resume put into words. Most bios have a standard format.  In paragraph one, talk about your most recent position and accomplishments there, specifically how they relate to the job you are applying for.  If you have teaching or research experience, training experience, certifications, or management experience, talk about them in paragraph two.  Paragraph three and four are for highlighting publications, education, certifications, associations, etc.  To wrap up your bio, provide your contact info and availability (dates and times). Where to use What? For most positions, you will know exactly what kind of application to use, because the job announcement will state what materials are needed – resume, CV, bio, cover letter, skill set, etc.  If there is any confusion, choose whatever the industry standard is (CV for technical fields, resume for everything else) or choose which of your documents is the strongest. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: About Me, PostADay, Professional Development, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • How to read BC4 texture in GLSL?

    - by Question
    I'm supposed to receive a texture in BC4 format. In OpenGL, i guess this format is called GL_COMPRESSED_RED_RGTC1. The texture is not really a "texture", more like a data to handle at fragment shader. Usually, to get colors from a texture within a fragment shader, i do : uniform sampler2D TextureUnit; void main() { vec4 TexColor = texture2D(TextureUnit, vec2(gl_TexCoord[0])); (...) the result of which is obviously a v4, for RGBA. But now, i'm supposed to receive a single float from the read. I'm struggling to understand how this is achieved. Should i still use a texture sampler, and expect the value to be in a specific position (for example, within TexColor.r ?), or should i use something else ?

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  • Colleague unwilling to use unit tests "as it's more to code"

    - by m.edmondson
    A colleague is unwilling to use unit tests and instead opting for a quick test, pass it to the users, and if all is well it is published live. Needless to say some bugs do get through. I mentioned we should think about using unit tests - but she was all against it once it was realised more code would have to be written. This leaves me in the position of modifying something and not being sure the output is the same, especially as her code is spaghetti and I try to refactor it when I get a chance. So whats the best way forward for me?

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  • Quadtree collapsing

    - by Caius Eugene
    Okay so i've spent a few days learning what a quadtree is and how to implement one. So far I have a quadtree that when I click inside a leaf it subdivides, I wondering how do I get the previous subdivisions to collapse back up, so that only one area is subdivided at a time? This is what mine looks like: (1. initial mouse click) (2. another mouse click) The aim to to eventually track the position of my mouse and subdivide the area it is in dynamically. THE OVERALL aim it to use this to create a terrain mesh and subdivide based on the camera. But I've gone right back to basics to get an understanding of how this will work. Any advice would be grand! - Caius

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  • Working with packed dates in SSIS

    - by Jim Giercyk
    One of the challenges recently thrown my way was to read an EBCDIC flat file, decode packed dates, and insert the dates into a SQL table.  For those unfamiliar with packed data, it is a way to store data at the nibble level (half a byte), and was often used by mainframe programmers to conserve storage space.  In the case of my input file, the dates were 2 bytes long and  represented the number of days that have past since 01/01/1950.  My first thought was, in the words of Scooby, Hmmmmph?  But, I love a good challenge, so I dove in. Reading in the flat file was rather simple.  The only difference between reading an EBCDIC and an ASCII file is the Code Page option in the connection manager.  In my case, I needed to use Code Page 1140 for EBCDIC (I could have also used Code Page 37).       Once the code page is set correctly, SSIS can understand what it is reading and it will convert the output to the default code page, 1252.  However, packed data is either unreadable or produces non-alphabetic characters, as we can see in the preview window.   Column 1 is actually the packed date, columns 0 and 2 are the values in the rest of the file.  We are only interested in Column 1, which is a 2 byte field representing a packed date.  We know that 2 bytes of packed data can be stored in 1 byte of character data, so we are working with 4 packed digits in 2 character bytes.  If you are confused, stay tuned….this will make sense in a minute.   Right-click on your Flat File Source shape and select “Show Advanced Editor”. Here is where the magic begins. By changing the properties of the output columns, we can access the packed digits from each byte. By default, the Output Column data type is DT_STR. Since we want to look at the bytes individually and not the entire string, change the data type to DT_BYTES. Next, and most important, set UseBinaryFormat to TRUE. This will write the HEX VALUES of the output string instead of writing the character values.  Now we are getting somewhere! Next, you will need to use a Data Conversion shape in your Data Flow to transform the 2 position byte stream to a 4 position Unicode string containing the packed data.  You need the string to be 4 bytes long because it will contain the 4 packed digits.  Here is what that should look like in the Data Conversion shape: Direct the output of your data flow to a test table or file to see the results.  In my case, I created a test table.  The results looked like this:     Hold on a second!  That doesn't look like a date at all.  No, of course not.  It is a hex number which represents the days which have passed between 01/01/1950 and the date.  We have to convert the Hex value to a decimal value, and use the DATEADD function to get a date value.  Luckily, I have created a function to convert Hex to Decimal:   -- ============================================= -- Author:        Jim Giercyk -- Create date: March, 2012 -- Description:    Converts a Hex string to a decimal value -- ============================================= CREATE FUNCTION [dbo].[ftn_HexToDec] (     @hexValue NVARCHAR(6) ) RETURNS DECIMAL AS BEGIN     -- Declare the return variable here DECLARE @decValue DECIMAL IF @hexValue LIKE '0x%' SET @hexValue = SUBSTRING(@hexValue,3,4) DECLARE @decTab TABLE ( decPos1 VARCHAR(2), decPos2 VARCHAR(2), decPos3 VARCHAR(2), decPos4 VARCHAR(2) ) DECLARE @pos1 VARCHAR(1) = SUBSTRING(@hexValue,1,1) DECLARE @pos2 VARCHAR(1) = SUBSTRING(@hexValue,2,1) DECLARE @pos3 VARCHAR(1) = SUBSTRING(@hexValue,3,1) DECLARE @pos4 VARCHAR(1) = SUBSTRING(@hexValue,4,1) INSERT @decTab VALUES (CASE               WHEN @pos1 = 'A' THEN '10'                 WHEN @pos1 = 'B' THEN '11'               WHEN @pos1 = 'C' THEN '12'               WHEN @pos1 = 'D' THEN '13'               WHEN @pos1 = 'E' THEN '14'               WHEN @pos1 = 'F' THEN '15'               ELSE @pos1              END, CASE               WHEN @pos2 = 'A' THEN '10'                 WHEN @pos2 = 'B' THEN '11'               WHEN @pos2 = 'C' THEN '12'               WHEN @pos2 = 'D' THEN '13'               WHEN @pos2 = 'E' THEN '14'               WHEN @pos2 = 'F' THEN '15'               ELSE @pos2              END, CASE               WHEN @pos3 = 'A' THEN '10'                 WHEN @pos3 = 'B' THEN '11'               WHEN @pos3 = 'C' THEN '12'               WHEN @pos3 = 'D' THEN '13'               WHEN @pos3 = 'E' THEN '14'               WHEN @pos3 = 'F' THEN '15'               ELSE @pos3              END, CASE               WHEN @pos4 = 'A' THEN '10'                 WHEN @pos4 = 'B' THEN '11'               WHEN @pos4 = 'C' THEN '12'               WHEN @pos4 = 'D' THEN '13'               WHEN @pos4 = 'E' THEN '14'               WHEN @pos4 = 'F' THEN '15'               ELSE @pos4              END) SET @decValue = (CONVERT(INT,(SELECT decPos4 FROM @decTab)))         +                 (CONVERT(INT,(SELECT decPos3 FROM @decTab))*16)      +                 (CONVERT(INT,(SELECT decPos2 FROM @decTab))*(16*16)) +                 (CONVERT(INT,(SELECT decPos1 FROM @decTab))*(16*16*16))     RETURN @decValue END GO     Making use of the function, I found the decimal conversion, added that number of days to 01/01/1950 and FINALLY arrived at my “unpacked relative date”.  Here is the query I used to retrieve the formatted date, and the result set which was returned: SELECT [packedDate] AS 'Hex Value',        dbo.ftn_HexToDec([packedDate]) AS 'Decimal Value',        CONVERT(DATE,DATEADD(day,dbo.ftn_HexToDec([packedDate]),'01/01/1950'),101) AS 'Relative String Date'   FROM [dbo].[Output Table]         This technique can be used any time you need to retrieve the hex value of a character string in SSIS.  The date example may be a bit difficult to understand at first, but with SSIS becoming the preferred tool for enterprise level integration for many companies, there is no doubt that developers will encounter these types of requirements with regularity in the future. Please feel free to contact me if you have any questions.

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  • C#/.NET Little Wonders: Static Char Methods

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Often times in our code we deal with the bigger classes and types in the BCL, and occasionally forgot that there are some nice methods on the primitive types as well.  Today we will discuss some of the handy static methods that exist on the char (the C# alias of System.Char) type. The Background I was examining a piece of code this week where I saw the following: 1: // need to get the 5th (offset 4) character in upper case 2: var type = symbol.Substring(4, 1).ToUpper(); 3:  4: // test to see if the type is P 5: if (type == "P") 6: { 7: // ... do something with P type... 8: } Is there really any error in this code?  No, but it still struck me wrong because it is allocating two very short-lived throw-away strings, just to store and manipulate a single char: The call to Substring() generates a new string of length 1 The call to ToUpper() generates a new upper-case version of the string from Step 1. In my mind this is similar to using ToUpper() to do a case-insensitive compare: it isn’t wrong, it’s just much heavier than it needs to be (for more info on case-insensitive compares, see #2 in 5 More Little Wonders). One of my favorite books is the C++ Coding Standards: 101 Rules, Guidelines, and Best Practices by Sutter and Alexandrescu.  True, it’s about C++ standards, but there’s also some great general programming advice in there, including two rules I love:         8. Don’t Optimize Prematurely         9. Don’t Pessimize Prematurely We all know what #8 means: don’t optimize when there is no immediate need, especially at the expense of readability and maintainability.  I firmly believe this and in the axiom: it’s easier to make correct code fast than to make fast code correct.  Optimizing code to the point that it becomes difficult to maintain often gains little and often gives you little bang for the buck. But what about #9?  Well, for that they state: “All other things being equal, notably code complexity and readability, certain efficient design patterns and coding idioms should just flow naturally from your fingertips and are no harder to write then the pessimized alternatives. This is not premature optimization; it is avoiding gratuitous pessimization.” Or, if I may paraphrase: “where it doesn’t increase the code complexity and readability, prefer the more efficient option”. The example code above was one of those times I feel where we are violating a tacit C# coding idiom: avoid creating unnecessary temporary strings.  The code creates temporary strings to hold one char, which is just unnecessary.  I think the original coder thought he had to do this because ToUpper() is an instance method on string but not on char.  What he didn’t know, however, is that ToUpper() does exist on char, it’s just a static method instead (though you could write an extension method to make it look instance-ish). This leads me (in a long-winded way) to my Little Wonders for the day… Static Methods of System.Char So let’s look at some of these handy, and often overlooked, static methods on the char type: IsDigit(), IsLetter(), IsLetterOrDigit(), IsPunctuation(), IsWhiteSpace() Methods to tell you whether a char (or position in a string) belongs to a category of characters. IsLower(), IsUpper() Methods that check if a char (or position in a string) is lower or upper case ToLower(), ToUpper() Methods that convert a single char to the lower or upper equivalent. For example, if you wanted to see if a string contained any lower case characters, you could do the following: 1: if (symbol.Any(c => char.IsLower(c))) 2: { 3: // ... 4: } Which, incidentally, we could use a method group to shorten the expression to: 1: if (symbol.Any(char.IsLower)) 2: { 3: // ... 4: } Or, if you wanted to verify that all of the characters in a string are digits: 1: if (symbol.All(char.IsDigit)) 2: { 3: // ... 4: } Also, for the IsXxx() methods, there are overloads that take either a char, or a string and an index, this means that these two calls are logically identical: 1: // check given a character 2: if (char.IsUpper(symbol[0])) { ... } 3:  4: // check given a string and index 5: if (char.IsUpper(symbol, 0)) { ... } Obviously, if you just have a char, then you’d just use the first form.  But if you have a string you can use either form equally well. As a side note, care should be taken when examining all the available static methods on the System.Char type, as some seem to be redundant but actually have very different purposes.  For example, there are IsDigit() and IsNumeric() methods, which sound the same on the surface, but give you different results. IsDigit() returns true if it is a base-10 digit character (‘0’, ‘1’, … ‘9’) where IsNumeric() returns true if it’s any numeric character including the characters for ½, ¼, etc. Summary To come full circle back to our opening example, I would have preferred the code be written like this: 1: // grab 5th char and take upper case version of it 2: var type = char.ToUpper(symbol[4]); 3:  4: if (type == 'P') 5: { 6: // ... do something with P type... 7: } Not only is it just as readable (if not more so), but it performs over 3x faster on my machine:    1,000,000 iterations of char method took: 30 ms, 0.000050 ms/item.    1,000,000 iterations of string method took: 101 ms, 0.000101 ms/item. It’s not only immediately faster because we don’t allocate temporary strings, but as an added bonus there less garbage to collect later as well.  To me this qualifies as a case where we are using a common C# performance idiom (don’t create unnecessary temporary strings) to make our code better. Technorati Tags: C#,CSharp,.NET,Little Wonders,char,string

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  • Raycasting mouse coordinates to rotated object?

    - by SPL
    I am trying to cast a ray from my mouse to a plane at a specified position with a known width and length and height. I know that you can use the NDC (Normalized Device Coordinates) to cast ray but I don't know how can I detect if the ray actually hit the plane and when it did. The plane is translated -100 on the Y and rotated 60 on the X then translated again -100. Can anyone please give me a good tutorial on this? For a complete noob! I am almost new to matrix and vector transformations.

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  • Why does Google Search Engine reject my title tag's change?

    - by Michal P.
    I made a simple webpage http://pundaquitboat.michaelspages.com/ giving it the the title tag "Boat – Pundaquit" and I have submitted it to Google bot by Google Webmaster Tools. Then I decided to change the title to "Anawangin trip" of the same page and I submited my webpage again in the same way to Google bot. The result was that the new title of my webpage coexisted with the old title of the same webpage in SERPs for maybe 2 days. After that the new title was rejected and if I enter site:pundaquitboat.michaelspages.com/ I can see that Google has my old copy of my webpage with old title in its database. This problem doesn't occur in Bing when I can enjoy high position of "Anawangin trip" phrase. (In Bing I haven't submitted the old version of title.)

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  • How do you go about training a replacement?

    - by SnOrfus
    I recently asked about leaving a position and got a lot of great answers. One of the common threads was that being around to train the new person would be expected and could go a long way. Now considering that (I think) most people don't stay at a company for a long time after they've given notice, and it will take time for the company to interview/hire one - that leaves for a short amount of time to get someone up to speed. I've also never trained anyone before. I did a bunch of tutoring in University and College, but teaching a language/technology is far different from training someone to replace you on your job. So the question is: how do you go about training someone to replace you in a, potentially, short amount of time?

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  • Do we set the bar too high by requiring that code tests not suffer from buffer overflow?

    - by brice
    We are currently recruiting for a Junior Developer position working mainly in C on Linux. As part of the process, we require candidates to complete a code test at their leisure in C. So far we have rejected two candidates on the basis that their code, although readable and in one case rather idiomatic, suffered from buffer overflow errors due to unbounded buffer writes. Are buffer overflows acceptable from a graduate developer? Are we setting the bar too high? What is the expected capability of graduate/Junior engineers? [Edit]: We explicitly ask for error-checked, production quality code. We provide a test & build framework for the candidates

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  • I can't get ubunutu installation to start

    - by tyler
    AZUS Sabertooth Motherboard, Intel I5 2500 CPU, Windows 7 installed I'm trying to install linux. I first attempted to install pin guy. I burned the ISO; booted from it; got the initial menu; attempting either run the live version from DVD, or install to system; the process stops at a blank screen with the blinking cursor in left corner. So I downloaded Ubuntu and got the same results. Then tried wubi, and ended up in the same position; blinking cursor in left corner.

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  • LWJGL glRotatef() without rotating axes?

    - by Brandon oubiub
    Okay so, I noticed when you rotate around an axis, say you do this: glRotatef(90.0f, 1.0f, 0.0f, 0.0f); That will rotate things 90 degrees around the x-axis. However, it also sort of rotates the y and z axes as well. So now the y-axis is pointing in and out of the screen, instead of up and down. So when I try to do stuff like this: glRotatef(90.0f, 1.0f, 0.0f, 0.0f); glRotatef(whatever, 0.0f, 1.0f, 0.0f); glRotatef(whatever2, 0.0f, 0.0f, 1.0f); The rotations around the y and z-axes end up not how I want them. I was wondering if there is any way I can sort of rotate just the axes back to their initial position after using glRotatef(), without rotating the object back. Or something like that, just so that when I rotate around the y-axis, it rotates around a vertical axis.

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