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  • Need some help implementing VBO's with Frustum Culling

    - by Isracg
    i'm currently developing my first 3D game for a school project, the game world is completely inspired by minecraft (world completely made out of cubes). I'm currently seeking to improve the performance trying to implement vertex buffer objects but i'm stuck, i already have this methods implemented: Frustum culling, only drawing exposed faces and distance culling but i have the following doubts: I currently have about 2^24 cubes in my world, divided in 1024 chunks of 16*16*64 cubes, right now i'm doing immediate mode rendering, which works well with frustum culling, if i implement one VBO per chunk, do i have to update that VBO each time i move the camera (to update the frustum)? is there a performance hit with this? Can i dynamically change the size of each VBO? of do i have to make each one the biggest possible size (the chunk completely filled with objects)?. Would i have to keep each visited chunk in memory or could i efficiently remove that VBO and recreated it when needed?.

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  • Is there a way to force ContourPlot re-check all the points on the each stage of it's recursion algorithm?

    - by Alexey Popkov
    Hello, Thanks to this excellent analysis of the Plot algorithm by Yaroslav Bulatov, I now understand the reason why Plot3D and ContourPlot fail to draw smoothly functions with breaks and discontinuities. For example, in the following case ContourPlot fails to draw contour x^2 + y^2 = 1 at all: ContourPlot[Abs[x^2 + y^2 - 1], {x, -1, 1}, {y, -1, 1}, Contours -> {0}] It is because the algorithm does not go deeply into the region near x^2 + y^2 = 1. It "drops" this region on an initial stage and do not tries to investigate it further. Increasing MaxRecursion does nothing in this sense. And even undocumented option Method -> {Refinement -> {ControlValue -> .01 \[Degree]}} does not help (but makes Plot3D a little bit smoother). The above function is just a simple example. In real life I'm working with very complicated implicit functions that cannot be solved analytically. Is there a way to get ContourPlot to go deeply into such regions near breaks and discontinuities?

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  • How does the rsync algorithm correctly identify repeating blocks?

    - by Kai
    I'm on a personal quest to learn how the rsync algorithm works. After some reading and thinking, I've come up with a situation where I think the algorithm fails. I'm trying to figure out how this is resolved in an actual implementation. Consider this example, where A is the receiver and B is the sender. A = abcde1234512345fghij B = abcde12345fghij As you can see, the only change is that 12345 has been removed. Now, to make this example interesting, let's choose a block size of 5 bytes (chars). Hashing the values on the sender's side using the weak checksum gives the following values list. abcde|12345|fghij abcde -> 495 12345 -> 255 fghij -> 520 values = [495, 255, 520] Next we check to see if any hash values differ in A. If there's a matching block we can skip to the end of that block for the next check. If there's a non-matching block then we've found a difference. I'll step through this process. Hash the first block. Does this hash exist in the values list? abcde -> 495 (yes, so skip) Hash the second block. Does this hash exist in the values list? 12345 -> 255 (yes, so skip) Hash the third block. Does this hash exist in the values list? 12345 -> 255 (yes, so skip) Hash the fourth block. Does this hash exist in the values list? fghij -> 520 (yes, so skip) No more data, we're done. Since every hash was found in the values list, we conclude that A and B are the same. Which, in my humble opinion, isn't true. It seems to me this will happen whenever there is more than one block that share the same hash. What am I missing?

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  • What algorithm should I use for encrypting and embedding a password for an application?

    - by vfclists
    What algorithm should I use for encrypting and embedding a password for an application? It obviously is not bullet proof, but it should be good enough to thwart someone scanning the database with a hex editor, or make it hard for someone who has the skills to use a debugger to trace the code to work out, either by scanning for the encrypted password, or using a debugger to run through the decryption code. Object Pascal would be nice. /vfclists

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  • QuickGraph - is there algorithm for find all parents (up to root vertex's) of a set of vertex's

    - by Greg
    Hi, In QuickGraph - is there algorithm for find all parents (up to root vertex's) of a set of vertex's. In other words all vertex's which have somewhere under them (on the way to the leaf nodes) one or more of the vertexs input. So if the vertexs were Nodes, and the edges were a depends on relationship, find all nodes that would be impacted by a given set of nodes. If not how hard is it to write one's own algorithms?

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  • User-Defined Customer Events & their impact (FA Type Profile)

    - by Rajesh Sharma
    CC&B automatically creates field activities when a specific Customer Event takes place. This depends on the way you have setup your Field Activity Type Profiles, the templates within, and associated SP Condition(s) on the template. CC&B uses the service point type, its state and referenced customer event to determine which field activity type to generate.   Customer events available in the base product include: Cut for Non-payment (CNP) Disconnect Warning (DIWA) Reconnect for Payment (REPY) Reread (RERD) Stop Service (STOP) Start Service (STRT) Start/Stop (STSP)   Note the Field values/codes defined for each event.   CC&B comes with a flexibility to define new set of customer events. These can be defined in the Look Up - CUST_EVT_FLG. Values from the Look Up are used on the Field Activity Type Profile Template page.     So what's the use of having user-defined Customer Events? And how will the system detect such events in order to create field activity(s)?   Well, system can only detect such events when you reference a user-defined customer event on a Severance Event Type for an event type Create Field Activities.     This way you can create additional field activities of a specific field activity type for user-defined customer events.   One of our customers adopted this feature and created a user-defined customer event CNPW - Cut for Non-payment for Water Services. This event was then linked on a Field Activity Type Profile and referenced on a Severance Event - CUT FOR NON PAY-W. The associated Severance Process was configured to trigger a reconnection process if it was cancelled (done by defining a Post Cancel Algorithm). Whenever this Severance Event was executed, a specific type of Field Activity was generated for disconnection purposes. The Field Activity type was determined by the system from the Field Activity Type Profile referenced for the SP Type, SP's state and the referenced user-defined customer event. All was working well until the time when they realized that in spite of the Severance Process getting cancelled (when a payment was made); the Post Cancel Algorithm was not executed to start a Reconnection Severance Process for the purpose of generating a reconnection field activity and reconnecting the service.   Basically, the Post Cancel algorithm (if specified on a Severance Process Template) is triggered when a Severance Process gets cancelled because a credit transaction has affected/relieved a Service Agreement's debt.   So what exactly was happening? Now we come to actual question as to what is the impact in having a user-defined customer event.   System defined/base customer events are hard-coded across the entire system. There is an impact even if you remove any customer event entry from the Look Up. User-defined customer events are not recognized by the system anywhere else except in the severance process, as described above.   There are few programs which have routines to first validate the completion of disconnection field activities, which were raised as a result of customer event CNP - Cut for Non-payment in order to perform other associated actions. One such program is the Post Cancel Algorithm, referenced on a Severance Process Template, generally used to reconnect services which were disconnected from other Severance Event, specifically CNP - Cut for Non-Payment. Post cancel algorithm provided by the product - SEV POST CAN does the following (below is the algorithm's description):   This algorithm is called after a severance process has been cancelled (typically because the debt was paid and the SA is no longer eligible to be on the severance process). It checks to see if the process has a completed 'disconnect' event and, if so, starts a reconnect process using the Reconnect Severance Process Template defined in the parameter.    Notice the underlined text. This algorithm implicitly checks for Field Activities having completed status, which were generated from Severance Events as a result of CNP - Cut for Non-payment customer event.   Now if we look back to the customer's issue, we can relate that the Post Cancel algorithm was triggered, but was not able to find any 'Completed' CNP - Cut for Non-payment related field activity. And hence was not able to start a reconnection severance process. This was because a field activity was generated and completed for a customer event CNPW - Cut for Non-payment of Water Services instead.   To conclude, if you introduce new customer events that extend or simulate base customer events, the ones that are included in the base product, ensure that there is no other impact either direct or indirect to other business functions that the application has to offer.  

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  • Limitations of User-Defined Customer Events (FA Type Profile)

    - by Rajesh Sharma
    CC&B automatically creates field activities when a specific Customer Event takes place. This depends on the way you have setup your Field Activity Type Profiles, the templates within, and associated SP Condition(s) on the template. CC&B uses the service point type, its state and referenced customer event to determine which field activity type to generate.   Customer events available in the base product include: Cut for Non-payment (CNP) Disconnect Warning (DIWA) Reconnect for Payment (REPY) Reread (RERD) Stop Service (STOP) Start Service (STRT) Start/Stop (STSP)   Note the Field values/codes defined for each event.   CC&B comes with a flexibility to define new set of customer events. These can be defined in the Look Up - CUST_EVT_FLG. Values from the Look Up are used on the Field Activity Type Profile Template page.     So what's the use of having user-defined Customer Events? And how will the system detect such events in order to create field activity(s)?   Well, system can only detect such events when you reference a user-defined customer event on a Severance Event Type for an event type Create Field Activities.     This way you can create additional field activities of a specific field activity type for user-defined customer events.   One of our customers adopted this feature and created a user-defined customer event CNPW - Cut for Non-payment for Water Services. This event was then linked on a Field Activity Type Profile and referenced on a Severance Event - CUT FOR NON PAY-W. The associated Severance Process was configured to trigger a reconnection process if it was cancelled (done by defining a Post Cancel Algorithm). Whenever this Severance Event was executed, a specific type of Field Activity was generated for disconnection purposes. The Field Activity type was determined by the system from the Field Activity Type Profile referenced for the SP Type, SP's state and the referenced user-defined customer event. All was working well until the time when they realized that in spite of the Severance Process getting cancelled (when a payment was made); the Post Cancel Algorithm was not executed to start a Reconnection Severance Process for the purpose of generating a reconnection field activity and reconnecting the service.   Basically, the Post Cancel algorithm (if specified on a Severance Process Template) is triggered when a Severance Process gets cancelled because a credit transaction has affected/relieved a Service Agreement's debt.   So what exactly was happening? Now we come to actual question as to what are limitations in having user-defined customer event.   System defined/base customer events are hard-coded across the entire system. There is an impact even if you remove any customer event entry from the Look Up. User-defined customer events are not recognized by the system anywhere else except in the severance process, as described above.   There are few programs which have routines to first validate the completion of disconnection field activities, which were raised as a result of customer event CNP - Cut for Non-payment in order to perform other associated actions. One such program is the Post Cancel Algorithm, referenced on a Severance Process Template, generally used to reconnect services which were disconnected from other Severance Event, specifically CNP - Cut for Non-Payment. Post cancel algorithm provided by the product - SEV POST CAN does the following (below is the algorithm's description):   This algorithm is called after a severance process has been cancelled (typically because the debt was paid and the SA is no longer eligible to be on the severance process). It checks to see if the process has a completed 'disconnect' event and, if so, starts a reconnect process using the Reconnect Severance Process Template defined in the parameter.    Notice the underlined text. This algorithm implicitly checks for Field Activities having completed status, which were generated from Severance Events as a result of CNP - Cut for Non-payment customer event.   Now if we look back to the customer's issue, we can relate that the Post Cancel algorithm was triggered, but was not able to find any 'Completed' CNP - Cut for Non-payment related field activity. And hence was not able to start a reconnection severance process. This was because a field activity was generated and completed for a customer event CNPW - Cut for Non-payment of Water Services instead.   To conclude, if you introduce new customer events, you should be aware that you don't extend or simulate base customer events, the ones that are included in the base product, as they are further used to provide/validate additional business functions.  

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  • Checksum Transformation

    The Checksum Transformation computes a hash value, the checksum, across one or more columns, returning the result in the Checksum output column. The transformation provides functionality similar to the T-SQL CHECKSUM function, but is encapsulated within SQL Server Integration Services, for use within the pipeline without code or a SQL Server connection. As featured in The Microsoft Data Warehouse Toolkit by Joy Mundy and Warren Thornthwaite from the Kimbal Group. Have a look at the book samples especially Sample package for custom SCD handling. All input columns are passed through the transformation unaltered, those selected are used to generate the checksum which is passed out through a single output column, Checksum. This does not restrict the number of columns available downstream from the transformation, as columns will always flow through a transformation. The Checksum output column is in addition to all existing columns within the pipeline buffer. The Checksum Transformation uses an algorithm based on the .Net framework GetHashCode method, it is not consistent with the T-SQL CHECKSUM() or BINARY_CHECKSUM() functions. The transformation does not support the following Integration Services data types, DT_NTEXT, DT_IMAGE and DT_BYTES. ChecksumAlgorithm Property There ChecksumAlgorithm property is defined with an enumeration. It was first added in v1.3.0, when the FrameworkChecksum was added. All previous algorithms are still supported for backward compatibility as ChecksumAlgorithm.Original (0). Original - Orginal checksum function, with known issues around column separators and null columns. This was deprecated in the first SQL Server 2005 RTM release. FrameworkChecksum - The hash function is based on the .NET Framework GetHash method for object types. This is based on the .NET Object.GetHashCode() method, which unfortunately differs between x86 and x64 systems. For that reason we now default to the CRC32 option. CRC32 - Using a standard 32-bit cyclic redundancy check (CRC), this provides a more open implementation. The component is provided as an MSI file, however to complete the installation, you will have to add the transformation to the Visual Studio toolbox by hand. This process has been described in detail in the related FAQ entry for How do I install a task or transform component?, just select Checksum from the SSIS Data Flow Items list in the Choose Toolbox Items window. Downloads The Checksum Transformation is available for SQL Server 2005, SQL Server 2008 (includes R2) and SQL Server 2012. Please choose the version to match your SQL Server version, or you can install multiple versions and use them side by side if you have more than one version of SQL Server installed. Checksum Transformation for SQL Server 2005 Checksum Transformation for SQL Server 2008 Checksum Transformation for SQL Server 2012 Version History SQL Server 2012 Version 3.0.0.27 – SQL Server 2012 release. Includes upgrade support for both 2005 and 2008 packages to 2012. (5 Jun 2010) SQL Server 2008 Version 2.0.0.27 – Fix for CRC-32 algorithm that inadvertently made it sort dependent. Fix for race condition which sometimes lead to the error Item has already been added. Key in dictionary: '79764919' . Fix for upgrade mappings between 2005 and 2008. (19 Oct 2010) Version 2.0.0.24 - SQL Server 2008 release. Introduces the new CRC-32 algorithm, which is consistent across x86 and x64.. The default algorithm is now CRC32. (29 Oct 2008) Version 2.0.0.6 - SQL Server 2008 pre-release. This version was released by mistake as part of the site migration, and had known issues. (20 Oct 2008) SQL Server 2005 Version 1.5.0.43 – Fix for CRC-32 algorithm that inadvertently made it sort dependent. Fix for race condition which sometimes lead to the error Item has already been added. Key in dictionary: '79764919' . (19 Oct 2010) Version 1.5.0.16 - Introduces the new CRC-32 algorithm, which is consistent across x86 and x64. The default algorithm is now CRC32. (20 Oct 2008) Version 1.4.0.0 - Installer refresh only. (22 Dec 2007) Version 1.4.0.0 - Refresh for minor UI enhancements. (5 Mar 2006) Version 1.3.0.0 - SQL Server 2005 RTM. The checksum algorithm has changed to improve cardinality when calculating multiple column checksums. The original algorithm is still available for backward compatibility. Fixed custom UI bug with Output column name not persisting. (10 Nov 2005) Version 1.2.0.1 - SQL Server 2005 IDW 15 June CTP. A user interface is provided, as well as the ability to change the checksum output column name. (29 Aug 2005) Version 1.0.0 - Public Release (Beta). (30 Oct 2004) Screenshot

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  • Master Note for Generic Data Warehousing

    - by lajos.varady(at)oracle.com
    ++++++++++++++++++++++++++++++++++++++++++++++++++++ The complete and the most recent version of this article can be viewed from My Oracle Support Knowledge Section. Master Note for Generic Data Warehousing [ID 1269175.1] ++++++++++++++++++++++++++++++++++++++++++++++++++++In this Document   Purpose   Master Note for Generic Data Warehousing      Components covered      Oracle Database Data Warehousing specific documents for recent versions      Technology Network Product Homes      Master Notes available in My Oracle Support      White Papers      Technical Presentations Platforms: 1-914CU; This document is being delivered to you via Oracle Support's Rapid Visibility (RaV) process and therefore has not been subject to an independent technical review. Applies to: Oracle Server - Enterprise Edition - Version: 9.2.0.1 to 11.2.0.2 - Release: 9.2 to 11.2Information in this document applies to any platform. Purpose Provide navigation path Master Note for Generic Data Warehousing Components covered Read Only Materialized ViewsQuery RewriteDatabase Object PartitioningParallel Execution and Parallel QueryDatabase CompressionTransportable TablespacesOracle Online Analytical Processing (OLAP)Oracle Data MiningOracle Database Data Warehousing specific documents for recent versions 11g Release 2 (11.2)11g Release 1 (11.1)10g Release 2 (10.2)10g Release 1 (10.1)9i Release 2 (9.2)9i Release 1 (9.0)Technology Network Product HomesOracle Partitioning Advanced CompressionOracle Data MiningOracle OLAPMaster Notes available in My Oracle SupportThese technical articles have been written by Oracle Support Engineers to provide proactive and top level information and knowledge about the components of thedatabase we handle under the "Database Datawarehousing".Note 1166564.1 Master Note: Transportable Tablespaces (TTS) -- Common Questions and IssuesNote 1087507.1 Master Note for MVIEW 'ORA-' error diagnosis. For Materialized View CREATE or REFRESHNote 1102801.1 Master Note: How to Get a 10046 trace for a Parallel QueryNote 1097154.1 Master Note Parallel Execution Wait Events Note 1107593.1 Master Note for the Oracle OLAP OptionNote 1087643.1 Master Note for Oracle Data MiningNote 1215173.1 Master Note for Query RewriteNote 1223705.1 Master Note for OLTP Compression Note 1269175.1 Master Note for Generic Data WarehousingWhite Papers Transportable Tablespaces white papers Database Upgrade Using Transportable Tablespaces:Oracle Database 11g Release 1 (February 2009) Platform Migration Using Transportable Database Oracle Database 11g and 10g Release 2 (August 2008) Database Upgrade using Transportable Tablespaces: Oracle Database 10g Release 2 (April 2007) Platform Migration using Transportable Tablespaces: Oracle Database 10g Release 2 (April 2007)Parallel Execution and Parallel Query white papers Best Practices for Workload Management of a Data Warehouse on the Sun Oracle Database Machine (June 2010) Effective resource utilization by In-Memory Parallel Execution in Oracle Real Application Clusters 11g Release 2 (Feb 2010) Parallel Execution Fundamentals in Oracle Database 11g Release 2 (November 2009) Parallel Execution with Oracle Database 10g Release 2 (June 2005)Oracle Data Mining white paper Oracle Data Mining 11g Release 2 (March 2010)Partitioning white papers Partitioning with Oracle Database 11g Release 2 (September 2009) Partitioning in Oracle Database 11g (June 2007)Materialized Views and Query Rewrite white papers Oracle Materialized Views  and Query Rewrite (May 2005) Improving Performance using Query Rewrite in Oracle Database 10g (December 2003)Database Compression white papers Advanced Compression with Oracle Database 11g Release 2 (September 2009) Table Compression in Oracle Database 10g Release 2 (May 2005)Oracle OLAP white papers On-line Analytic Processing with Oracle Database 11g Release 2 (September 2009) Using Oracle Business Intelligence Enterprise Edition with the OLAP Option to Oracle Database 11g (July 2008)Generic white papers Enabling Pervasive BI through a Practical Data Warehouse Reference Architecture (February 2010) Optimizing and Protecting Storage with Oracle Database 11g Release 2 (November 2009) Oracle Database 11g for Data Warehousing and Business Intelligence (August 2009) Best practices for a Data Warehouse on Oracle Database 11g (September 2008)Technical PresentationsA selection of ObE - Oracle by Examples documents: Generic Using Basic Database Functionality for Data Warehousing (10g) Partitioning Manipulating Partitions in Oracle Database (11g Release 1) Using High-Speed Data Loading and Rolling Window Operations with Partitioning (11g Release 1) Using Partitioned Outer Join to Fill Gaps in Sparse Data (10g) Materialized View and Query Rewrite Using Materialized Views and Query Rewrite Capabilities (10g) Using the SQLAccess Advisor to Recommend Materialized Views and Indexes (10g) Oracle OLAP Using Microsoft Excel With Oracle 11g Cubes (how to analyze data in Oracle OLAP Cubes using Excel's native capabilities) Using Oracle OLAP 11g With Oracle BI Enterprise Edition (Creating OBIEE Metadata for OLAP 11g Cubes and querying those in BI Answers) Building OLAP 11g Cubes Querying OLAP 11g Cubes Creating Interactive APEX Reports Over OLAP 11g CubesSelection of presentations from the BIWA website:Extreme Data Warehousing With Exadata  by Hermann Baer (July 2010) (slides 2.5MB, recording 54MB)Data Mining Made Easy! Introducing Oracle Data Miner 11g Release 2 New "Work flow" GUI   by Charlie Berger (May 2010) (slides 4.8MB, recording 85MB )Best Practices for Deploying a Data Warehouse on Oracle Database 11g  by Maria Colgan (December 2009)  (slides 3MB, recording 18MB, white paper 3MB )

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  • Memory is full with vertex buffer

    - by Christian Frantz
    I'm having a pretty strange problem that I didn't think I'd run into. I was able to store a 50x50 grid in one vertex buffer finally, in hopes of better performance. Before I had each cube have an individual vertex buffer and with 4 50x50 grids, this slowed down my game tremendously. But it still ran. With 4 50x50 grids with my new code, that's only 4 vertex buffers. With the 4 vertex buffers, I get a memory error. When I load the game with 1 grid, it takes forever to load and with my previous version, it started up right away. So I don't know if I'm storing chunks wrong or what but it stumped me -.- for (int x = 0; x < 50; x++) { for (int z = 0; z < 50; z++) { for (int y = 0; y <= map[x, z]; y++) { SetUpVertices(); SetUpIndices(); cubes.Add(new Cube(device, new Vector3(x, map[x, z] - y, z), grass)); } } } vertexBuffer = new VertexBuffer(device, typeof(VertexPositionTexture), vertices.Count(), BufferUsage.WriteOnly); vertexBuffer.SetData<VertexPositionTexture>(vertices.ToArray()); indexBuffer = new IndexBuffer(device, typeof(short), indices.Count(), BufferUsage.WriteOnly); indexBuffer.SetData(indices.ToArray()); Thats how theyre stored. The array I'm reading from is a byte array which defines the coordinates of my map. Now with my old version, I used the same loading from an array so that hasn't changed. The only difference is the one vertex buffer instead of 2500 for a 50x50 grid. cubes is just a normal list that holds all my cubes for the vertex buffer. Another thing that just came to mind would be my draw calls. If I'm setting an effect for each cube in my cube list, that's probably going to take a lot of memory. How can I avoid doing this? I need the foreach method to set my cubes to the right position foreach (Cube block in cube.cubes) { effect.VertexColorEnabled = false; effect.TextureEnabled = true; Matrix center = Matrix.CreateTranslation(new Vector3(-0.5f, -0.5f, -0.5f)); Matrix scale = Matrix.CreateScale(1f); Matrix translate = Matrix.CreateTranslation(block.cubePosition); effect.World = center * scale * translate; effect.View = cam.view; effect.Projection = cam.proj; effect.FogEnabled = false; effect.FogColor = Color.CornflowerBlue.ToVector3(); effect.FogStart = 1.0f; effect.FogEnd = 50.0f; cube.Draw(effect); noc++; }

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  • Using DynamicVertexBuffer in XNA 4.0

    - by Bevin
    I read about DynamicVertexBuffer, and how it's supposed to be better for data that changes often. I have a world built up by cubes, and I need to store the cubes' vertices in this buffer to draw them to the screen. However, not all cubes have vertices (some are air, which is transparent) and not all faces of the cubes need to be drawn either (they are facing each other), so how do I keep track of what vertices are stored where in the buffer? Also, certain faces need to be drawn last, namely the ones with transparency in them (like glass or leaves), and these faces also need to be drawn in a back-to-front order to not mess up the alpha blending. If all of these vertices are stored arbitrarily in this buffer, how do I know what vertices are where? Also, the number of vertices can change, but the DynamicVertexBuffer doesn't seem very dynamic to me, since I can't change it's size at all. Do I have to recreate the buffer every time I need to add or remove faces?

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  • Implementing RSA-SHA1 signature algorithm in Java (creating a private key for use with OAuth RSA-SHA

    - by The Elite Gentleman
    Hi everyone, As you know, OAuth can support RSA-SHA1 Signature. I have an OAuthSignature interface that has the following method public String sign(String data, String consumerSecret, String tokenSecret) throws GeneralSecurityException; I successfully implemented and tested HMAC-SHA1 Signature (which OAuth Supports) as well as the PLAINTEXT "signature". I have searched google and I have to create a private key if I need to use SHA1withRSA signature: Sample code: /** * Signs the data with the given key and the provided algorithm. */ private static byte[] sign(PrivateKey key, String data) throws GeneralSecurityException { Signature signature = Signature.getInstance("SHA1withRSA"); signature.initSign(key); signature.update(data.getBytes()); return signature.sign(); } Now, How can I take the OAuth key (which is key = consumerSecret&tokenSecret) and create a PrivateKey to use with SHA1withRSA signature? Thanks

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  • What do the ddx and ddy values do in this AABB ray intersect algorithm?

    - by Paz
    Does anyone know what the ddx and ddy values do in the AABB ray intersect algorithm? Taken from the following site http://www.blitzbasic.com/codearcs/codearcs.php?code=1029 (show below). Local txmin#,txmax#,tymin#,tymax# // rox, rdx are the ray origin on the x axis, and ray delta on the x axis ... y-axis is roy and rdy Local ddx# =1.0/(rox-rdx) Local ddy# =1.0/(roy-rdy) If ddx >= 0 txmin = (bminx - rox) * ddx txmax = (bmaxx - rox) * ddx Else txmin = (bmaxx - rox) * ddx txmax = (bminx - rox) * ddx EndIf If ddy >= 0 tymin = (bminy - roy) * ddy tymax = (bmaxy - roy) * ddy Else tymin = (bmaxy - roy) * ddy tymax = (bminy - roy) * ddy EndIf If ( (txmin > tymax) Or (tymin > txmax) ) Return 0 If (tymin > txmin) txmin = tymin If (tymax < txmax) txmax = tymax Local tzmin#,tzmax# Local ddz# =1.0/(roz-rdz) If ddz >= 0 tzmin = (bminz - roz) * ddz tzmax = (bmaxz - roz) * ddz Else tzmin = (bmaxz - roz) * ddz tzmax = (bminz - roz) * ddz EndIf If (txmin > tzmax) Or (tzmin > txmax) Return 0 Return 1

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  • Please help, now I have a matrix, I want use Combination algorithm to generate a array for length 6

    - by user313429
    The first thanks a lot for your help , the following is my matrix, I want to implement combination algorithm between multiple arrays in LINQ for this matrix. int[,] cj = { { 10, 23, 16, 20 }, { 22, 13, 1, 33 }, { 7, 19, 31, 12 }, { 30, 14, 21, 4 }, { 2, 29, 32, 6 }, { 18, 26, 17, 8 }, { 25, 11, 5, 28 }, { 24, 3, 15, 27 } }; other: public static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> elements, int k) { return k == 0 ? new[] { new T[0] } : elements.SelectMany((e, i) => elements.Skip(i + 1).**Combinations**(k - 1).Select(c => (new[] { e }).Concat(c))); } The above method has a error in my project, System.Collections.Generic.IEnumerable' does not contain a definition for 'Combinations' and no extension method 'Combinations' accepting a first argument of type 'System.Collections.Generic.IEnumerable' could be found (are you missing a using directive or an assembly reference? I use .Net Framework3.5, what is the reason it?

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  • What programming language is used to design google algorithm?

    - by AKN
    It is known that google has best searching & indexing algorithm. The also have good relevancy. They are also quicker in getting down the latest results. All that's fine. What programming language (c, c++, java, etc...) & database (oracle, MySQL, etc...) they have used in achieving this. Since they have to manipulate with volume of data quickly and effectively. Though I'm not looking for their indepth architecture (if in case violates their company policies) an overview of all such things could be useful. Anybody please add you valuable suggestions and insight on this?

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