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  • Using Live Data in Database Development Work

    - by Phil Factor
    Guest Editorial for Simple-Talk Newsletter... in which Phil Factor reacts with some exasperation when coming across a report that a majority of companies were still using financial and personal data for both developing and testing database applications. If you routinely test your development work using real production data that contains personal or financial information, you are probably being irresponsible, and at worst, risking a heavy financial penalty for your company. Surprisingly, over 80% of financial companies still do this. Plenty of data breaches and fraud have happened from the use of real data for testing, and a data breach is a nightmare for any organisation that suffers one. The cost of each data breach averages out at around $7.2 million in the US in notification, escalation, credit monitoring, fines, litigation, legal costs, and lost business due to customer churn, £1.9 million in the UK. 70% of data breaches are done from within the organisation. Real data can be exploited in a number of ways for malicious or criminal purposes. It isn't just the obvious use of items such as name and address, date of birth, social security number, and credit card and bank account numbers: Data can be exploited in many subtle ways, so there are excellent reasons to ensure that a high priority is given to the detection and prevention of any data breaches. You'll never successfully guess all the ways that real data can be exploited maliciously, or the ease with which it can be accessed. It would be silly to argue that developers never need access to a copy of the database containing live data. Developers sometimes need to track a bug that can only be replicated on the data from the live database. However, it has to be done in a very restrictive harness. The law makes no distinction between development and production databases when a data breach occurs, so the data has to be held with all appropriate security measures in place. In Europe, the use of personal data for testing requires the explicit consent of the people whose data is being held. There are federal standards such as GLBA, PCI DSS and HIPAA, and most US States have privacy legislation. The task of ensuring compliance and tight security in such circumstances is an expensive and time-consuming overhead. The developer is likely to suffer investigation if a data breach occurs, even if the company manages to stay in business. Ironically, the use of copies of live data isn't usually the most effective way to develop or test your data. Data is usually time-specific and isn't usually current by the time it is used for testing, Existing data doesn't help much for new functionality, and every time the data is refreshed from production, any test data is likely to be overwritten. Also, it is not always going to test all the 'edge' conditions that are likely to flush out bugs. You still have the task of simulating the dynamics of actual usage of the database, and here you have no alternative to creating 'spoofed' data. Because of the complexities of relational data, It used to be that there was no realistic alternative to developing and testing with live data. However, this is no longer the case. Real data can be obfuscated, or it can be created entirely from scratch. The latter process used to be impractical, now that there are plenty of third-party tools to choose from. The process of obfuscation isn't risk free. The process must access the live data, and the success of the obfuscation process has to be carefully monitored. Database data security isn't an exciting topic to you or I, but to a hacker it can be an all-consuming obsession, especially if there is financial or political gain involved. This is not the sort of adversary one would wish for and it is far better to accept, and work with, security restrictions that exist for using live data in database development work, especially when the tools exist to create large realistic database test data that can be better for several aspects of testing.

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  • Sprite animation in openGL - Some frames are being skipped

    - by Sid
    Earlier, I was facing problems on implementing sprite animation in openGL ES. Now its being sorted up. But the problem that i am facing now is that some of my frames are being skipped when a bullet(a circle) strikes on it. What I need : A sprite animation should stop at the last frame without skipping any frame. What I did : Collision Detection function and working properly. PS : Everything is working fine but i want to implement the animation in OPENGL ONLY. Canvas won't work in my case. ------------------------ EDIT----------------------- My sprite sheet. Consider the animation from Left to right and then from top to bottom Here is an image for a better understanding. My spritesheet ... class FragileSquare{ FloatBuffer fVertexBuffer, mTextureBuffer; ByteBuffer mColorBuff; ByteBuffer mIndexBuff; int[] textures = new int[1]; public boolean beingHitFromBall = false; int numberSprites = 20; int columnInt = 4; //number of columns as int float columnFloat = 4.0f; //number of columns as float float rowFloat = 5.0f; int oldIdx; public FragileSquare() { // TODO Auto-generated constructor stub float vertices [] = {-1.0f,1.0f, //byte index 0 1.0f, 1.0f, //byte index 1 //byte index 2 -1.0f, -1.0f, 1.0f,-1.0f}; //byte index 3 float textureCoord[] = { 0.0f,0.0f, 0.25f,0.0f, 0.0f,0.20f, 0.25f,0.20f }; byte indices[] = {0, 1, 2, 1, 2, 3 }; ByteBuffer byteBuffer = ByteBuffer.allocateDirect(4*2 * 4); // 4 vertices, 2 co-ordinates(x,y) 4 for converting in float byteBuffer.order(ByteOrder.nativeOrder()); fVertexBuffer = byteBuffer.asFloatBuffer(); fVertexBuffer.put(vertices); fVertexBuffer.position(0); ByteBuffer byteBuffer2 = ByteBuffer.allocateDirect(textureCoord.length * 4); byteBuffer2.order(ByteOrder.nativeOrder()); mTextureBuffer = byteBuffer2.asFloatBuffer(); mTextureBuffer.put(textureCoord); mTextureBuffer.position(0); } public void draw(GL10 gl){ gl.glFrontFace(GL11.GL_CW); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glVertexPointer(1,GL10.GL_FLOAT, 0, fVertexBuffer); gl.glEnable(GL10.GL_TEXTURE_2D); if(MyRender.flag2==1){ /** Collision has taken place*/ int idx = oldIdx==(numberSprites-1) ? (numberSprites-1) : (int)((System.currentTimeMillis()%(200*numberSprites))/200); gl.glMatrixMode(GL10.GL_TEXTURE); gl.glTranslatef((idx%columnInt)/columnFloat, (idx/columnInt)/rowFloat, 0); gl.glMatrixMode(GL10.GL_MODELVIEW); oldIdx = idx; } gl.glEnable(GL10.GL_BLEND); gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA); gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]); //4 gl.glTexCoordPointer(2, GL10.GL_FLOAT,0, mTextureBuffer); //5 gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4); //7 gl.glFrontFace(GL11.GL_CCW); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glMatrixMode(GL10.GL_TEXTURE); gl.glLoadIdentity(); gl.glMatrixMode(GL10.GL_MODELVIEW); } public void loadFragileTexture(GL10 gl, Context context, int resource) { Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resource); gl.glGenTextures(1, textures, 0); gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_REPEAT); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_REPEAT); GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); bitmap.recycle(); }

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  • Oracle EMEA News Digest - May 2014

    - by Steve Walker
    Systems Oracle introduced a technology preview of an OpenStack® distribution that allows Oracle Linux and Oracle VM users to work with the open source cloud software. This provides customers with additional choices and interoperability while taking advantage of the efficiency, performance, scalability, and security of Oracle Linux and Oracle VM. The distribution is delivered as part of the Oracle Linux and Oracle VM Premier Support offerings, at no additional cost. Oracle plans to work further with the OpenStack community to develop and enhance its enterprise-class capabilities to meet customer demands. Also in the Open Source arena, Oracle announced the general availability of MySQL Fabric. MySQL Fabric provides an integrated system that makes it simpler to manage groups of MySQL databases. It delivers both high availability - via failure detection and failover - and scalability through automated data sharding. Oracle Database, Middleware and Technology The company made two announcements for Oracle Tuxedo, the #1 application server for C, C++, COBOL and Java deployments in private cloud or traditional data center environments. With enhanced management and monitoring features and tighter integration with Oracle technologies, the latest release of Oracle Tuxedo 12c enables organizations to dramatically increase application throughput, while reducing total cost of ownership and time to market for new application development and deployment. Oracle also introduced the latest release of its mainframe application rehosting platform, Oracle Tuxedo ART 12c, to help organizations speed up migration projects and accelerate the adoption of the new environment by current IT staff. It enables organizations to accelerate the rehosting of IBM mainframe applications and greatly enhance management and supportability of the rehosted applications while reducing costs and risk. Applications According to new Oracle studies, B2B and B2C commerce professionals find integrated, omni-channel customer experiences increasingly valuable to their organizations, and are continuing to invest in technologies and digital content strategies to facilitate them. The studies—one for B2B and one for B2C—surveyed e-commerce professionals in business and technology departments from around the world. Although the priorities, success metrics, and technology investments differed between the two groups, customer acquisition and retention emerged as common themes across B2B and B2C. Growing market share and enhancing customer experience are cited as top investment areas for all e-commerce professionals. In product news, Oracle announced the latest release of Oracle Business Intelligence (BI) Applications (version 11.1.1.8.1, in case anyone asks). It includes prebuilt connectors between Oracle Procurement and Spend Analytics and Oracle’s JD Edwards. Additionally, a new Oracle Human Resources Analytics module for developing and maintaining a skilled workforce has been introduced. In use at more than 4,000 companies worldwide, Oracle BI Applications support leading enterprise applications, including Oracle E-Business Suite, Oracle’s PeopleSoft, Oracle's Siebel CRM, Oracle’s JD Edwards EnterpriseOne offering high-performing analytics at a lower cost. Industries For the Communications Industry, Oracle has launched a new release of the Oracle Communications Core Session Manager. This gives CSPs a new way to design, deploy and manage complex networking services and embrace next-generation technology, It provides them with an immediate entry point for  network function virtualization (NFV) efforts, allowing them to realize immediate benefits associated with network virtualization – including increased service agility and improved network resource sharing. And for the Utilities Industry, Oracle is releasing solutions with new business features and enhanced technical architecture that help position utilities for success now and into the future. Oracle has provided new releases for its customer information system,  meter data management system, customer self-service solution and mobile workforce management solution.

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  • New R Interface to Oracle Data Mining Available for Download

    - by charlie.berger
      The R Interface to Oracle Data Mining ( R-ODM) allows R users to access the power of Oracle Data Mining's in-database functions using the familiar R syntax. R-ODM provides a powerful environment for prototyping data analysis and data mining methodologies. R-ODM is especially useful for: Quick prototyping of vertical or domain-based applications where the Oracle Database supports the application Scripting of "production" data mining methodologies Customizing graphics of ODM data mining results (examples: classification, regression, anomaly detection) The R-ODM interface allows R users to mine data using Oracle Data Mining from the R programming environment. It consists of a set of function wrappers written in source R language that pass data and parameters from the R environment to the Oracle RDBMS enterprise edition as standard user PL/SQL queries via an ODBC interface. The R-ODM interface code is a thin layer of logic and SQL that calls through an ODBC interface. R-ODM does not use or expose any Oracle product code as it is completely an external interface and not part of any Oracle product. R-ODM is similar to the example scripts (e.g., the PL/SQL demo code) that illustrates the use of Oracle Data Mining, for example, how to create Data Mining models, pass arguments, retrieve results etc. R-ODM is packaged as a standard R source package and is distributed freely as part of the R environment's Comprehensive R Archive Network (CRAN). For information about the R environment, R packages and CRAN, see www.r-project.org. R-ODM is particularly intended for data analysts and statisticians familiar with R but not necessarily familiar with the Oracle database environment or PL/SQL. It is a convenient environment to rapidly experiment and prototype Data Mining models and applications. Data Mining models prototyped in the R environment can easily be deployed in their final form in the database environment, just like any other standard Oracle Data Mining model. What is R? R is a system for statistical computation and graphics. It consists of a language plus a run-time environment with graphics, a debugger, access to certain system functions, and the ability to run programs stored in script files. The design of R has been heavily influenced by two existing languages: Becker, Chambers & Wilks' S and Sussman's Scheme. Whereas the resulting language is very similar in appearance to S, the underlying implementation and semantics are derived from Scheme. R was initially written by Ross Ihaka and Robert Gentleman at the Department of Statistics of the University of Auckland in Auckland, New Zealand. Since mid-1997 there has been a core group (the "R Core Team") who can modify the R source code archive. Besides this core group many R users have contributed application code as represented in the near 1,500 publicly-available packages in the CRAN archive (which has shown exponential growth since 2001; R News Volume 8/2, October 2008). Today the R community is a vibrant and growing group of dozens of thousands of users worldwide. It is free software distributed under a GNU-style copyleft, and an official part of the GNU project ("GNU S"). Resources: R website / CRAN R-ODM

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  • GoldenGate 12c - MySQL Active-Active Replication Setup

    - by Jinyu Wang-Oracle
    Active-active  (also called Master-Master or Bi-Directional) replication captures data changes from two or more systems and replicat the changes to synchronize the data.  Active-Active replication is often needed for high availability, load balancing and scaling out purposes.   Oracle GoldenGate is known to be one of the first and the best replication tool handling active-active replications. As of Oracle GoldenGate 12c, it provides (Refer to Oracle GoldenGate 12.1.2 Documentation - Configuring Oracle GoldenGate for Active-Active High Availability for more information) the followings: Robust loop-back prevention Comprehensive conflict resolution and detection support Heterogeneous support across different database versions and operation systems.  Oracle GoldenGate supports active-active configurations for DB2 on z/OS, LUW, and IBM i, MySQL, Oracle, SQL/MX,SQL Server, Sybase, and Teradata. However, the setup is different from database to database. In this example, I will show you how to setup an active-active data replication between two MySQL database instances. The example setup below is to have active-active replication between MySQL 5.5 and MySQL 5.6 instances and is shown as follows: MySQL 5.5 (Manager Port: 15105)  Extract EXTRACT demoex01 SETENV (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.5.38/data/mysql.sock') DBOPTIONS CONNECTIONPORT 3305 DBOPTIONS HOST oraclelinux6.localdomain SOURCEDB test USERID root, PASSWORD mysql EXTTRAIL ./dirdat/extract/de TRANLOGOPTIONS ALTLOGDEST "/home/oracle/software/mysql_5.5.38/data/binlog/bin-log.index" FILTERTABLE test.checkpoint_tbl REPORTROLLOVER AT 05:30 ON saturday TABLE test.TCUSTMER; TABLE test.TCUSTORD; Pump EXTRACT demopm01 RMTHOST localhost, MGRPORT 15106, COMPRESS, TIMEOUT 30 RMTTRAIL ./dirdat/replicat/ps PASSTHRU TABLE test.TCUSTMER; TABLE test.TCUSTORD; Replicat replicat demorp01 setenv (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.5.38/data/mysql.sock') dboptions host oraclelinux6.localdomain, connectionport 3305 targetdb test, userid root, password mysql sourcedefs ./dirdat/replicat/democust.def discardfile ./dirrpt/demprp01.dsc, purge REPERROR (DEFAULT, ABEND) REPERROR(1062, IGNORE) map test.TCUSTMER, target test.TCUSTMER,colmap(usedefaults, region_code="region code"); map test.TCUSTORD, target test.TCUSTORD; MySQL 5.6 (Manager Port: 15106) Replicat replicat demorp01 setenv (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.6.19/data/mysql.sock') dboptions host oraclelinux6.localdomain, connectionport 3306 targetdb test, userid root, password mysql --assumetargetdefs sourcedefs ./dirdat/replicat/democust.def discardfile ./dirrpt/demprp01.dsc, purge map test.TCUSTMER, target test.TCUSTMER, colmap(usedefaults, "region code"=region_code); map test.TCUSTORD, target test.TCUSTORD; Extract EXTRACT demoex01 SETENV (MYSQL_UNIX_PORT='/home/oracle/software/mysql_5.6.19/data/mysql.sock') DBOPTIONS CONNECTIONPORT 3306 DBOPTIONS HOST oraclelinux6.localdomain SOURCEDB test USERID root, USERID mysql EXTTRAIL ./dirdat/extract/de TRANLOGOPTIONS ALTLOGDEST "/usr/local/mysql56/data/binlog/bin-log.index" FILTERTABLE test.checkpoint_tbl TABLE test.TCUSTMER; TABLE test.TCUSTORD; Pump EXTRACT demopm01 RMTHOST localhost, MGRPORT 15105, COMPRESS, TIMEOUT 30 RMTTRAIL ./dirdat/replicat/ps PASSTHRU TABLE test.TCUSTMER; TABLE test.TCUSTORD; The setup parameters are quite self-explanatory. The key setup is to avoid the replication data  looping. Oracle GoldenGate for MySQL uses the information in the replication checkpoint table to identify the transaction applied by replicats and thus avoid extracting those transactions by Oracle GoldenGate extracts. The example setup in the extract in MySQL 5.5 instance is shown as follows.  TRANLOGOPTIONS ALTLOGDEST "/home/oracle/software/mysql_5.5.38/data/binlog/bin-log.index" FILTERTABLE test.checkpoint_tbl Setting up an active-active replication is often more complicated than this and requires the following additional considerations. I would elaborate on this in the follow-up discussions. 

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  • Protecting Consolidated Data on Engineered Systems

    - by Steve Enevold
    In this time of reduced budgets and cost cutting measures in Federal, State and Local governments, the requirement to provide services continues to grow. Many agencies are looking at consolidating their infrastructure to reduce cost and meet budget goals. Oracle's engineered systems are ideal platforms for accomplishing these goals. These systems provide unparalleled performance that is ideal for running applications and databases that traditionally run on separate dedicated environments. However, putting multiple critical applications and databases in a single architecture makes security more critical. You are putting a concentrated set of sensitive data on a single system, making it a more tempting target.  The environments were previously separated by iron so now you need to provide assurance that one group, department, or application's information is not visible to other personnel or applications resident in the Exadata system. Administration of the environments requires formal separation of duties so an administrator of one application environment cannot view or negatively impact others. Also, these systems need to be in protected environments just like other critical production servers. They should be in a data center protected by physical controls, network firewalls, intrusion detection and prevention, etc Exadata also provides unique security benefits, including a reducing attack surface by minimizing packages and services to only those required. In addition to reducing the possible system areas someone may attempt to infiltrate, Exadata has the following features: 1.    Infiniband, which functions as a secure private backplane 2.    IPTables  to perform stateful packet inspection for all nodes               Cellwall implements firewall services on each cell using IPTables 3.    Hardware accelerated encryption for data at rest on storage cells Oracle is uniquely positioned to provide the security necessary for implementing Exadata because security has been a core focus since the company's beginning. In addition to the security capabilities inherent in Exadata, Oracle security products are all certified to run in an Exadata environment. Database Vault Oracle Database Vault helps organizations increase the security of existing applications and address regulatory mandates that call for separation-of-duties, least privilege and other preventive controls to ensure data integrity and data privacy. Oracle Database Vault proactively protects application data stored in the Oracle database from being accessed by privileged database users. A unique feature of Database Vault is the ability to segregate administrative tasks including when a command can be executed, or that the DBA can manage the health of the database and objects, but may not see the data Advanced Security  helps organizations comply with privacy and regulatory mandates by transparently encrypting all application data or specific sensitive columns, such as credit cards, social security numbers, or personally identifiable information (PII). By encrypting data at rest and whenever it leaves the database over the network or via backups, Oracle Advanced Security provides the most cost-effective solution for comprehensive data protection. Label Security  is a powerful and easy-to-use tool for classifying data and mediating access to data based on its classification. Designed to meet public-sector requirements for multi-level security and mandatory access control, Oracle Label Security provides a flexible framework that both government and commercial entities worldwide can use to manage access to data on a "need to know" basis in order to protect data privacy and achieve regulatory compliance  Data Masking reduces the threat of someone in the development org taking data that has been copied from production to the development environment for testing, upgrades, etc by irreversibly replacing the original sensitive data with fictitious data so that production data can be shared safely with IT developers or offshore business partners  Audit Vault and Database Firewall Oracle Audit Vault and Database Firewall serves as a critical detective and preventive control across multiple operating systems and database platforms to protect against the abuse of legitimate access to databases responsible for almost all data breaches and cyber attacks.  Consolidation, cost-savings, and performance can now be achieved without sacrificing security. The combination of built in protection and Oracle’s industry-leading data protection solutions make Exadata an ideal platform for Federal, State, and local governments and agencies.

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  • Opposite Force to Apply to a Collided Rigid Body?

    - by Milo
    I'm working on the physics for my GTA2-like game so I can learn more about game physics. The collision detection and resolution are working great. I'm now just unsure how to compute the force to apply to a body after it collides with a wall. My rigid body looks like this: /our simulation object class RigidBody extends Entity { //linear private Vector2D velocity = new Vector2D(); private Vector2D forces = new Vector2D(); private float mass; private Vector2D v = new Vector2D(); //angular private float angularVelocity; private float torque; private float inertia; //graphical private Vector2D halfSize = new Vector2D(); private Bitmap image; private Matrix mat = new Matrix(); private float[] Vector2Ds = new float[2]; private Vector2D tangent = new Vector2D(); private static Vector2D worldRelVec = new Vector2D(); private static Vector2D relWorldVec = new Vector2D(); private static Vector2D pointVelVec = new Vector2D(); private static Vector2D acceleration = new Vector2D(); public RigidBody() { //set these defaults so we don't get divide by zeros mass = 1.0f; inertia = 1.0f; setLayer(LAYER_OBJECTS); } protected void rectChanged() { if(getWorld() != null) { getWorld().updateDynamic(this); } } //intialize out parameters public void initialize(Vector2D halfSize, float mass, Bitmap bitmap) { //store physical parameters this.halfSize = halfSize; this.mass = mass; image = bitmap; inertia = (1.0f / 20.0f) * (halfSize.x * halfSize.x) * (halfSize.y * halfSize.y) * mass; RectF rect = new RectF(); float scalar = 10.0f; rect.left = (int)-halfSize.x * scalar; rect.top = (int)-halfSize.y * scalar; rect.right = rect.left + (int)(halfSize.x * 2.0f * scalar); rect.bottom = rect.top + (int)(halfSize.y * 2.0f * scalar); setRect(rect); } public void setLocation(Vector2D position, float angle) { getRect().set(position.x,position.y, getWidth(), getHeight(), angle); rectChanged(); } public Vector2D getPosition() { return getRect().getCenter(); } @Override public void update(float timeStep) { doUpdate(timeStep); } public void doUpdate(float timeStep) { //integrate physics //linear acceleration.x = forces.x / mass; acceleration.y = forces.y / mass; velocity.x += (acceleration.x * timeStep); velocity.y += (acceleration.y * timeStep); //velocity = Vector2D.add(velocity, Vector2D.scalarMultiply(acceleration, timeStep)); Vector2D c = getRect().getCenter(); v.x = getRect().getCenter().getX() + (velocity.x * timeStep); v.y = getRect().getCenter().getY() + (velocity.y * timeStep); setCenter(v.x, v.y); forces.x = 0; //clear forces forces.y = 0; //angular float angAcc = torque / inertia; angularVelocity += angAcc * timeStep; setAngle(getAngle() + angularVelocity * timeStep); torque = 0; //clear torque } //take a relative Vector2D and make it a world Vector2D public Vector2D relativeToWorld(Vector2D relative) { mat.reset(); Vector2Ds[0] = relative.x; Vector2Ds[1] = relative.y; mat.postRotate(JMath.radToDeg(getAngle())); mat.mapVectors(Vector2Ds); relWorldVec.x = Vector2Ds[0]; relWorldVec.y = Vector2Ds[1]; return relWorldVec; } //take a world Vector2D and make it a relative Vector2D public Vector2D worldToRelative(Vector2D world) { mat.reset(); Vector2Ds[0] = world.x; Vector2Ds[1] = world.y; mat.postRotate(JMath.radToDeg(-getAngle())); mat.mapVectors(Vector2Ds); worldRelVec.x = Vector2Ds[0]; worldRelVec.y = Vector2Ds[1]; return worldRelVec; } //velocity of a point on body public Vector2D pointVelocity(Vector2D worldOffset) { tangent.x = -worldOffset.y; tangent.y = worldOffset.x; pointVelVec.x = (tangent.x * angularVelocity) + velocity.x; pointVelVec.y = (tangent.y * angularVelocity) + velocity.y; return pointVelVec; } public void applyForce(Vector2D worldForce, Vector2D worldOffset) { //add linear force forces.x += worldForce.x; forces.y += worldForce.y; //add associated torque torque += Vector2D.cross(worldOffset, worldForce); } @Override public void draw( GraphicsContext c) { c.drawRotatedScaledBitmap(image, getPosition().x, getPosition().y, getWidth(), getHeight(), getAngle()); } public Vector2D getVelocity() { return velocity; } public void setVelocity(Vector2D velocity) { this.velocity = velocity; } } The way it is given force is by the applyForce method, this method considers angular torque. I'm just not sure how to come up with the vectors in the case where: RigidBody hits static entity RigidBody hits other RigidBody that may or may not be in motion. Would anyone know a way (without too complex math) that I could figure out the opposite force I need to apply to the car? I know the normal it is colliding with and how deep it collided. My main goal is so that say I hit a building from the side, well the car should not just stay there, it should slowly rotate out of it if I'm more than 45 degrees. Right now when I hit a wall I only change the velocity directly which does not consider angular force. Thanks!

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  • Loading XML file containing leading zeros with SSIS preserving the zeros

    - by Compudicted
    Visiting the MSDN SQL Server Integration Services Forum oftentimes I could see that people would pop up asking this question: “why I am not able to load an element from an XML file that contains zeros so the leading/trailing zeros would remain intact?”. I started to suspect that such a trivial and often-required operation perhaps is being misunderstood by the developer community. I would also like to add that the whole state of affairs surrounding the XML today is probably also going to be increasingly affected by a motion of people who dislike XML in general and many aspects of it as XSD and XSLT invoke a negative reaction at best. Nevertheless, XML is in wide use today and its importance as a bridge between diverse systems is ever increasing. Therefore, I deiced to write up an example of loading an arbitrary XML file that contains leading zeros in one of its elements using SSIS so the leading zeros would be preserved keeping in mind the goal on simplicity into a table in SQL Server database. To start off bring up your BIDS (running as admin) and add a new Data Flow Task (DFT). This DFT will serve as container to adding our XML processing elements (besides, the XML Source is not available anywhere else other than from within the DFT). Double-click your DFT and drag and drop the XMS Source component from the Tool Box’s Data Flow Sources. Now, let the fun begin! Being inspired by the upcoming Christmas I created a simple XML file with one set of data that contains an imaginary SSN number of Rudolph containing several leading zeros like 0000003. This file can be viewed here. To configure the XML Source of course it is quite intuitive to point it to our XML file, next what the XML source needs is either an embedded schema (XSD) or it can generate one for us. In lack of the one I opted to auto-generate it for me and I ended up with an XSD that looked like: <?xml version="1.0"?> <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="XMasEvent"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="CaseInfo"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="ID" type="xs:unsignedByte" /> <xs:element minOccurs="0" name="CreatedDate" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="LastName" type="xs:string" /> <xs:element minOccurs="0" name="FirstName" type="xs:string" /> <xs:element minOccurs="0" name="SSN" type="xs:unsignedByte" /> <!-- Becomes string -- > <xs:element minOccurs="0" name="DOB" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="Event" type="xs:string" /> <xs:element minOccurs="0" name="ClosedDate" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> As an aside on the XML file: if your XML file does not contain the outer node (<XMasEvent>) then you may end up in a situation where you see just one field in the output. Now please note that the SSN element’s data type was chosen to be of unsignedByte (and this is for a reason). The reason is stemming from the fact all our figures in the element are digits, this is good, but this is not exactly what we need, because if we will attempt to load the data with this XSD then we are going to either get errors on the destination or most typically lose the leading zeros. So the next intuitive choice is to change the data type to string. Besides, if a SSIS package was already created based on this XSD and the data type change was done thereafter, one should re-set the metadata by right-clicking the XML Source and choosing “Advanced Editor” in which there is a refresh button at the bottom left which will do the trick. So far so good, we are ready to load our XML file, well actually yes, and no, in my experience typically some data conversion may be required. So depending on your data destination you may need to tweak the data types targeted. Let’s add a Data Conversion Task to our DFT. Your package should look like: To make the story short I only will cover the SSN field, so in my data source the target SQL Table has it as nchar(10) and we chose string in our XSD (yes, this is a big difference), under such circumstances the SSIS will complain. So will go and manipulate on the data type of SSN by making it Unicode String (DT_WSTR), World String per se. The conversion should look like: The peek at the Metadata: We are almost there, now all we need is to configure the destination. For simplicity I chose SQL Server Destination. The mapping is a breeze, F5 and I am able to insert my data into SQL Server now! Checking the zeros – they are all intact!

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  • Reducing Deadlocks - not a DBA issue ?

    - by steveh99999
     As a DBA, I'm involved on an almost daily basis troubleshooting 'SQL Server' performance issues. Often, this troubleshooting soon veers away from a 'its a SQL Server issue' to instead become a wider application/database design/coding issue.One common perception with SQL Server is that deadlocking is an application design issue - and is fixed by recoding...  I see this reinforced by MCP-type questions/scenarios where the answer to prevent deadlocking is simply to change the order in code in which tables are accessed....Whilst this is correct, I do think this has led to a situation where many 'operational' or 'production support' DBAs, when faced with a deadlock, are happy to throw the issue over to developers without analysing the issue further....A couple of 'war stories' on deadlocks which I think are interesting :- Case One , I had an issue recently on a third-party application that I support on SQL 2008.  This particular third-party application has an unusual support agreement where the customer is allowed to change the index design on the third-party provided database.  However, we are not allowed to alter application code or modify table structure..This third-party application is also known to encounter occasional deadlocks – indeed, I have documentation from the vendor that up to 50 deadlocks per day is not unusual !So, as a DBA I have to support an application which in my opinion has too many deadlocks - but, I cannot influence the design of the tables or stored procedures for the application. This should be the classic - blame the third-party developers scenario, and hope this issue gets addressed in a future application release - ie we could wait years for this to be resolved and implemented in our production environment...But, as DBAs  can change the index layout, is there anything I could do still to reduce the deadlocks in the application ?I initially used SQL traceflag 1222 to write deadlock detection output to the SQL Errorlog – using this I was able to identify one table heavily involved in the deadlocks.When I examined the table definition, I was surprised to see it was a heap – ie no clustered index existed on the table.Using SQL profiler to see locking behaviour and plan for the query involved in the deadlock, I was able to confirm a table scan was being performed.By creating an appropriate clustered index - it was possible to produce a more efficient plan and locking behaviour.So, less locks, held for less time = less possibility of deadlocks. I'm still unhappy about the overall number of deadlocks on this system - but that's something to be discussed further with the vendor.Case Two,  a system which hadn't changed for months suddenly started seeing deadlocks on a regular basis. I love the 'nothing's changed' scenario, as it gives me the opportunity to appear wise and say 'nothings changed on this system, except the data'.. This particular deadlock occurred on a table which had been growing rapidly. By using DBCC SHOW_STATISTICS - the DBA team were able to see that the deadlocks seemed to be occurring shortly after auto-update stats had regenerated the table statistics using it's default sampling behaviour.As a quick fix, we were able to schedule a nightly UPDATE STATISTICS WITH FULLSCAN on the table involved in the deadlock - thus, greatly reducing the potential for stats to be updated via auto_update_stats, consequently reducing the potential for a bad plan to be generated based on an unrepresentative sample of the data. This reduced the possibility of a deadlock occurring.  Not a perfect solution by any means, but quick, easy to implement, and needed no application code changes. This fix gave us some 'breathing space'  to properly fix the code during the next scheduled application release.   The moral of this post - don't dismiss deadlocks as issues that can only be fixed by developers...

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  • How do I cap rendering of tiles in a 2D game with SDL?

    - by farmdve
    I have some boilerplate code working, I basically have a tile based map composed of just 3 colors, and some walls and render with SDL. The tiles are in a bmp file, but each tile inside it corresponds to an internal number of the type of tile(color, or wall). I have pretty basic collision detection and it works, I can also detetc continuous presses, which allows me to move pretty much anywhere I want. I also have a moving camera, which follows the object. The problem is that, the tile based map is bigger than the resolution, thus not all of the map can be displayed on the screen, but it's still rendered. I would like to cap it, but since this is new to me, I pretty much have no idea. Although I cannot post all the code, as even though I am a newbie and the code pretty basic, it's already quite a few lines, I can post what I tried to do void set_camera() { //Center the camera over the dot camera.x = ( player.box.x + DOT_WIDTH / 2 ) - SCREEN_WIDTH / 2; camera.y = ( player.box.y + DOT_HEIGHT / 2 ) - SCREEN_HEIGHT / 2; //Keep the camera in bounds. if(camera.x < 0 ) { camera.x = 0; } if(camera.y < 0 ) { camera.y = 0; } if(camera.x > LEVEL_WIDTH - camera.w ) { camera.x = LEVEL_WIDTH - camera.w; } if(camera.y > LEVEL_HEIGHT - camera.h ) { camera.y = LEVEL_HEIGHT - camera.h; } } set_camera() is the function which calculates the camera position based on the player's positions. I won't pretend I know much about it. Rectangle box = {0,0,0,0}; for(int t = 0; t < TOTAL_TILES; t++) { if(box.x < (camera.x - TILE_WIDTH) || box.y > (camera.y - TILE_HEIGHT)) apply_surface(box.x - camera.x, box.y - camera.y, surface, screen, &clips[tiles[t]]); box.x += TILE_WIDTH; //If we've gone too far if(box.x >= LEVEL_WIDTH) { //Move back box.x = 0; //Move to the next row box.y += TILE_HEIGHT; } } This is basically my render code. The for loop loops over 192 tiles stored in an int array, each with their own unique value describing the tile type(wall or one of three possible colored tiles). box is an SDL_Rect containing the current position of the tile, which is calculated on render. TILE_HEIGHT and TILE_WIDTH are of value 80. So the cap is determined by if(box.x < (camera.x - TILE_WIDTH) || box.y > (camera.y - TILE_HEIGHT)) However, this is just me playing with the values and see what doesn't break it. I pretty much have no idea how to calculate it. My screen resolution is 1024/768, and the tile map is of size 1280/960.

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  • Android Bitmap : collision Detecting [on hold]

    - by user2505374
    I am writing an Android game right now and I would need some help in the collision of the wall on screen. When I drag the ball in the top and right it able to collide in wall but when I drag it faster it was able to overlap in the wall. public boolean onTouchEvent(MotionEvent event) { int x = (int) event.getX(); int y = (int) event.getY(); switch (event.getAction()) { // if the player moves case MotionEvent.ACTION_MOVE: { if (playerTouchRect.contains(x, y)) { boolean left = false; boolean right = false; boolean up = false; boolean down = false; boolean canMove = false; boolean foundFinish = false; if (x != pLastXPos) { if (x < pLastXPos) { left = true; } else { right = true; } pLastXPos = x; } if (y != pLastYPos) { if (y < pLastYPos) { up = true; } else { down = true; } pLastYPos = y; } plCellRect = getRectFromPos(x, y); newplRect.set(playerRect); newplRect.left = x - (int) (playerRect.width() / 2); newplRect.right = x + (int) (playerRect.width() / 2); newplRect.top = y - (int) (playerRect.height() / 2); newplRect.bottom = y + (int) (playerRect.height() / 2); int currentRow = 0; int currentCol = 0; currentRow = getRowFromYPos(newplRect.top); currentCol = getColFromXPos(newplRect.right); if(!canMove){ canMove = mapManager.getCurrentTile().pMaze[currentRow][currentCol] == Cell.wall; canMove =true; } finishTest = mapManager.getCurrentTile().pMaze[currentRow][currentCol]; foundA = finishTest == Cell.valueOf(letterNotGet + ""); canMove = mapManager.getCurrentTile().pMaze[currentRow][currentCol] != Cell.wall; canMove = (finishTest == Cell.floor || finishTest == Cell.pl) && canMove; if (canMove) { invalidate(); setTitle(); } if (foundA) { mapManager.getCurrentTile().pMaze[currentRow][currentCol] = Cell.floor; // finishTest letterGotten.add(letterNotGet); playCurrentLetter(); /*sounds.play(sExplosion, 1.0f, 1.0f, 0, 0, 1.5f);*/ foundS = letterNotGet == 's'; letterNotGet++; }if(foundS){ AlertDialog.Builder builder = new AlertDialog.Builder(mainActivity); builder.setTitle(mainActivity.getText(R.string.finished_title)); LayoutInflater inflater = mainActivity.getLayoutInflater(); View view = inflater.inflate(R.layout.finish, null); builder.setView(view); View closeButton =view.findViewById(R.id.closeGame); closeButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View clicked) { if(clicked.getId() == R.id.closeGame) { mainActivity.finish(); } } }); AlertDialog finishDialog = builder.create(); finishDialog.show(); } else { Log.d(TAG, "INFO: updated player position"); playerRect.set(newplRect); setTouchZone(); updatePlayerCell(); } } // end of (CASE) if playerTouch break; } // end of (SWITCH) Case motion }//end of Switch return true; }//end of TouchEvent private void finish() { // TODO Auto-generated method stub } public int getColFromXPos(int xPos) { val = xPos / (pvWidth / mapManager.getCurrentTile().pCols); if (val == mapManager.getCurrentTile().pCols) { val = mapManager.getCurrentTile().pCols - 1; } return val; } /** * Given a y pixel position, return the row of the cell it is in This is * used when determining the type of adjacent Cells. * * @param yPos * y position in pixels * @return The cell this position is in */ public int getRowFromYPos(int yPos) { val = yPos / (pvHeight / mapManager.getCurrentTile().pRows); if (val == mapManager.getCurrentTile().pRows) { val = mapManager.getCurrentTile().pRows - 1; } return val; } /** * When preserving the position we need to know which cell the player is in, * so calculate it from the centre on its Rect */ public void updatePlayerCell() { plCell.x = (playerRect.left + (playerRect.width() / 2)) / (pvWidth / mapManager.getCurrentTile().pCols); plCell.y = (playerRect.top + (playerRect.height() / 2)) / (pvHeight / mapManager.getCurrentTile().pRows); if (mapManager.getCurrentTile().pMaze[plCell.y][plCell.x] == Cell.floor) { for (int row = 0; row < mapManager.getCurrentTile().pRows; row++) { for (int col = 0; col < mapManager.getCurrentTile().pCols; col++) { if (mapManager.getCurrentTile().pMaze[row][col] == Cell.pl) { mapManager.getCurrentTile().pMaze[row][col] = Cell.floor; break; } } } mapManager.getCurrentTile().pMaze[plCell.y][plCell.x] = Cell.pl; } } public Rect getRectFromPos(int x, int y) { calcCell.left = ((x / cellWidth) + 0) * cellWidth; calcCell.right = calcCell.left + cellWidth; calcCell.top = ((y / cellHeight) + 0) * cellHeight; calcCell.bottom = calcCell.top + cellHeight; Log.d(TAG, "Rect: " + calcCell + " Player: " + playerRect); return calcCell; } public void setPlayerRect(Rect newplRect) { playerRect.set(newplRect); } private void setTouchZone() { playerTouchRect.set( playerRect.left - playerRect.width() / TOUCH_ZONE, playerRect.top - playerRect.height() / TOUCH_ZONE, playerRect.right + playerRect.width() / TOUCH_ZONE, playerRect.bottom + playerRect.height() / TOUCH_ZONE); } public Rect getPlayerRect() { return playerRect; } public Point getPlayerCell() { return plCell; } public void setPlayerCell(Point cell) { plCell = cell; }

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  • Why googling by keycaptcha gives results on reCAPTCHA? [closed]

    - by vgv8
    EDIT: I'd like to change this title to: How to STOP Google's manipulation of Google search engine presented to general public? I am frequently googling and more and more frequently bump when searching by one software product I am given instead the results on Google's own products. For ex., if I google by keyword keycaptcha for the "Past 24 hours" (after clicking on "Show search tools" -- "Past 24 hours" on the left sidebar of a browser) I am getting the Google's search results show only results on reCAPTCHA. Image uploaded later: Though, if confine keycaptcha in quotes the results are "correct" (well, kind of since they are still distorted in comparison with other search engines). I checked this during few months from different domains at different ISPs, different operating systems and from a dozen of browsers. The results are the same. Why is it and how can it be possibly corrected? My related posts: "How Gmail spam filter works?" IP adresses blacklisting Update: It is impossible for me to directly start using google.com as I am always redirected to google.ru (from google.com) by my ip-address "auto-detect location" google's "convenience". The google's help tells that it is impossible to switch off my location auto-detection because it is very helpful feature. There is a work-around to use google.com/ncr (to get google.com) (?anybody know what does it mean) to prevent redirection from google.com but even. But all results are exactly the same OK, I can search by quoted "keycaptcha", I am already accustomed to these google's quirks, but the question arises why the heck to burn time promoting someone's product if GOOGLE uses other product brands for showing its own interests/brands (reCAPTCHA) instead and what can be done with it? The general user will not understand that he was cheated and just will pick up the first (wrong) results Update2: Note that this googling behaviour: is independent on whether I am logged-in (or log-out-ed of) a google account, which account, on browser (I tried Opera, Chrome, FireFox, IE of different versions, Safari), OS or even domain; there are many such cases but I just targeted one concrete restricted example speciffically to to prevent wandering between unrelated details and peculiarities; @Michael, first it is not true and this text contains 2 links for real and significant results.. I also wrote that this is just one concrete example from many and based on many-month exp. These distortions happen upon clicking on: Past 24 hours, Past week, Past month, Past year in many other keywords, occasions/configurations of searches, etc. Second, the absence of the results is the result and there is no point to sneakingly substitute it by another unsolicited one. It is the definition of spam and scam. 3d, the question is not abt workarounds like how to write search queries or use another searching engines. The question is how to straighten the googling's results in order to stop disorienting general public about. Update: I could not understand: nobody reproduces the described by me behavior (i.e. when I click "Past 24 hours" link in google search searching for keycaptcha, the presented results are only on reCAPTCHA presented)? Update: And for the "Past week":

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  • What common interface would be appropriate for these game object classes?

    - by Jefffrey
    Question A component based system's goal is to solve the problems that derives from inheritance: for example the fact that some parts of the code (that are called components) are reused by very different classes that, hypothetically, would lie in a very different branch of the inheritance tree. That's a very nice concept, but I've found out that CBS is often hard to accomplish without using ugly hacks. Implementations of this system are often far from clean. But I don't want to discuss this any further. My question is: how can I solve the same problems a CBS try to solve with a very clean interface? (possibly with examples, there are a lot of abstract talks about the "perfect" design already). Context Here's an example I was going for before realizing I was just reinventing inheritance again: class Human { public: Position position; Movement movement; Sprite sprite; // other human specific components }; class Zombie { Position position; Movement movement; Sprite sprite; // other zombie specific components }; After writing that I realized I needed an interface, otherwise I would have needed N containers for N different types of objects (or to use boost::variant to gather them all together). So I've thought of polymorphism (move what systems do in a CBS design into class specific functions): class Entity { public: virtual void on_event(Event) {} // not pure virtual on purpose virtual void on_update(World) {} virtual void on_draw(Window) {} }; class Human : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; class Zombie : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; Which was nice, except for the fact that now the outside world would not even be able to know where a Human is positioned (it does not have access to its position member). That would be useful to track the player position for collision detection or if on_update the Zombie would want to track down its nearest human to move towards him. So I added const Position& get_position() const; to both the Zombie and Human classes. And then I realized that both functionality were shared, so it should have gone to the common base class: Entity. Do you notice anything? Yes, with that methodology I would have a god Entity class full of common functionality (which is the thing I was trying to avoid in the first place). Meaning of "hacks" in the implementation I'm referring to I'm talking about the implementations that defines Entities as simple IDs to which components are dynamically attached. Their implementation can vary from C-stylish: int last_id; Position* positions[MAX_ENTITIES]; Movement* movements[MAX_ENTITIES]; Where positions[i], movements[i], component[i], ... make up the entity. Or to more C++-style: int last_id; std::map<int, Position> positions; std::map<int, Movement> movements; From which systems can detect if an entity/id can have attached components.

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  • Application Logging needs work

    Application Logging Application logging is the act of logging events that occur within an application much like how a court report documents what happens in court case. Application logs can be useful for several reasons, but the most common use for logs is to recreate steps to find the root cause of applications errors. Other uses can include the detection of Fraud, verification of user activity, or provide audits on user/data interactions. “Logs can contain different kinds of data. The selection of the data used is normally affected by the motivation leading to the logging. “ (OWASP, 2009) OWASP also stats that logging include applicable debugging information like the event date time, responsible process, and a description of the event. “There are many reasons why a logging system is a necessary part of delivering a distributed application. One of the most important is the ability to track exactly how many users are using the application during different time periods.” (Hatton, 2000) Hatton also states that application logging helps system designers determine whether parts of an application aren't being used as designed. He implies that low usage can be used to identify if users like or do not like aspects of a system based on user usage of the application. This enables application designers to extract why users don't like aspects of an application so that changes can be made to increase its usefulness and effectiveness. “Logging memory usage can also assist you in tuning up the internals of your application. If you're experiencing a randomly occurring problem, being able to match activities performed with the memory status at the time may enable you to discover the cause of the problem. It also gives you a good indication of the health of the distributed server machine at the time any activity is performed. “ (Hatton, 2000) Commonly Logged Application Events (Defined by OWASP) Access of Data Creation of Data Modification of Data in any form Administrative Functions  Configuration Changes Debugging Information(Application Events)  Authorization Attempts  Data Deletion Network Communication  Authentication Events  Errors/Exceptions Application Error Logging The functionality associated with application error logging is actually the combination of proper error handling and applications logging.  If we look back at Figure 4 and Figure 5, these code examples allow developers to handle various types of errors that occur within the life cycle of an application’s execution. Application logging can be applied within the Catch section of the TryCatch statement allowing for the errors to be logged when they occur. By placing the logging within the Catch section specific error details can be accessed that help identify the source of the error, the path to the error, what caused the error and definition of the error that occurred. This can then be logged and reviewed at a later date in order recreate the error that was received based data found in the application log. By allowing applications to log errors developers IT staff can use them to recreate errors that are encountered by end-users or other dependent systems.

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  • How to make a stack stable? Need help for an explicit resting contact scheme (2-dimensional)

    - by Register Sole
    Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based method with Projected-Gauss-Seidel (PGS) iterative solver as described by Erin Catto (mentioned in the reference of the paper as [Catt05]). So here's how it currently is: The simulation handles 2-dimensional rotating convex polygons. Detection is using separating-axis test, with a SKIN, meaning closest points between two polygons is detected and determined if their distance is less than SKIN. To resolve collision, simultaneous impulse-based method is used. It is solved using iterative solver (PGS-solver) as in Erin Catto's paper. Error-correction is implemented using Baumgarte's stabilization (you can refer to either paper for this) using J V = beta/dt*overlap, J is the Jacobian for the constraints, V the matrix containing the velocities of the bodies, beta an error-correction parameter that is better be < 1, dt the time-step taken by the engine, and overlap, the overlap between the bodies (true overlap, so SKIN is ignored). However, it is still less stable than I expected :s I tried to stack hexagons (or squares, doesn't really matter), and even with only 4 to 5 of them, they would swing! Also note that I am not looking for a sleeping scheme. But I would settle if you have any explicit scheme to handle resting contacts. That said, I would be more than happy if you have a way of treating it generally (as continuous collision, instead of explicitly as a special state). Ideas I have tried: Using simultaneous position based error correction as described in the paper in section 5.3.2, turned out to be worse than the current scheme. If you want to know the parameters I used: Hexagons, side 50 (pixels) gravity 2400 (pixels/sec^2) time-step 1/60 (sec) beta 0.1 restitution 0 to 0.2 coeff. of friction 0.2 PGS iteration 10 initial separation 10 (pixels) mass 1 (unit is irrelevant for now, i modified velocity directly<-impulse method) inertia 1/1000 Thanks in advance! I really appreciate any help from you guys!! :) EDIT In response to Cholesky's comment about warm starting the solver and Baumgarte: Oh right, I forgot to mention! I do save the contact history and the impulse determined in this time step to be used as initial guess in the next time step. As for the Baumgarte, here's what actually happens in the code. Collision is detected when the bodies' closest distance is less than SKIN, meaning they are actually still separated. If at this moment, I used the PGS solver without Baumgarte, restitution of 0 alone would be able to stop the bodies, separated by a distance of ~SKIN, in mid-air! So this isn't right, I want to have the bodies touching each other. So I turn on the Baumgarte, where its role is actually to pull the bodies together! Weird I know, a scheme intended to push the body apart becomes useful for the reverse. Also, I found that if I increase the number of iteration to 100, stacks become much more stable, though the program becomes so slow. UPDATE Since the stack swings left and right, could it be something is wrong with my friction model? Current friction constraint: relative_tangential_velocity = 0

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  • WPF: Draw a grid on a Canvas?

    - by stefan.at.wpf
    Hello community, I'm currently trying to add gridlines to a canvas. I need an exact free space between them, where I'd like to place something for hit detection per cell, maybe simply a transparent border or such a thing. While I thought this would be an easy thing, I'm facing problems like antialiasing and that lines in WPF aren't very "calculate" / exact drawing friendly - e.g. if I draw a line on x=20 with a thickness of 10, the line's width goes from x=15 to x=25 (maybe not exactly, just some kind like that), so it takes the given position as middle point - if it would draw from 20 to 30 it would be easier in my case. Besides that making things more complex, how does WPF handle e.g. a thickness of 5? Draw thickness 3 left from the given point and the remaining 2 right from it? Or maybe just the opposite way? Well, just wanted to show you which problems I have, though this all maybe just seems simple to be done. Just wondering if anyone has ever done this before. Currently I find a Border without content and just 2 sites set to a thickness greater than 0 as line seems to work the best in my tests, seems like it's clear where they are drawn and they somehow don't seem to make any antialiasing problems. Just wondering if there's a more intuitive / better way of doing this? I don't want to lay a Canvas over a Grid, I think this maybe makes some things more complex in the end (by the way: how would I place a Canvas on top of a Grid?). Thanks for any hint!

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  • Detect blocked popup in Chrome

    - by Andrew
    I am aware of javascript techniques to detect whether a popup is blocked in other browsers (as described in the answer to this question). Here's the basic test: var newWin = window.open(url); if(!newWin || newWin.closed || typeof newWin.closed=='undefined') { //POPUP BLOCKED } But this does not work in Chrome. The "POPUP BLOCKED" section is never reached when the popup is blocked. Of course, the test is working to an extent since Chrome doesn't actually block the popup, but opens it in a tiny minimized window at the lower right corner which lists "blocked" popups. What I would like to do is be able to tell if the popup was blocked by Chrome's popup blocker. I try to avoid browser sniffing in favor of feature detection. Is there a way to do this without browser sniffing? Edit: I have now tried making use of newWin.outerHeight, newWin.left, and other similar properties to accomplish this. Google Chrome returns all position and height values as 0 when the popup is blocked. Unfortunately, it also returns the same values even if the popup is actually opened for an unknown amount of time. After some magical period (a couple of seconds in my testing), the location and size information is returned as the correct values. In other words, I'm still no closer to figuring this out. Any help would be appreciated.

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  • How to do proper Unicode and ANSI output redirection on cmd.exe?

    - by Sorin Sbarnea
    If you are doing automation on windows and you are redirecting the output of different commands (internal cmd.exe or external, you'll discover that your log files contains combined Unicode and ANSI output (meaning that they are invalid and will not load well in viewers/editors). Is it is possible to make cmd.exe work with UTF-8? This question is not about display, s about stdin/stdout/stderr redirection and Unicode. I am looking for a solution that would allow you to: redirect the output of the internal commands to a file using UTF-8 redirect output of external commands supporting Unicode to the files but encoded as UTF-8. If it is impossible to obtain this kind of consistence using batch files, is there another way of solving this problem, like using python scripting for this? In this case, I would like to know if it is possible to do the Unicode detection alone (user using the scripting should not remember if the called tools will output Unicode or not, it will just expect to convert the output to UTF-8. For simplicity we'll assume that if the tool output is not-Unicode it will be considered as UTF-8 (no codepage conversion).

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  • QT- QImage and multi-threading problem.

    - by umanga
    Greetings all, Please refer to image at : http://i48.tinypic.com/316qb78.jpg We are developing an application to extract cell edges from MRC images from electron microscope. MRC file format stores volumetric pixel data (http://en.wikipedia.org/wiki/Voxel) and we simply use 3D char array(char***) to load and store data (gray scale values) from a MRC file. As shown in the image,there are 3 viewers to display XY,YZ and ZX planes respectively. Scrollbars on the top of the viewers use to change the image slice along an axis. Here is the steps we do when user changes the scrollbar position. 1) get the new scrollbar value.(this is the selected slice) 2) for the relavant plane (YZ,XY or ZX), generate (char* slice;) array for the selected slice by reading 3D char array (char***) 3) Create a new QImage* (Format_RGB888) and set pixel values by reading 'slice' (using img-setPixel(x,y,c);) 4) This new QImage* is painted in the paintEvent() method. We are going to execute "edge-detection" process in a seperate thread since it is an intensive process.During this process we need to draw detected curve (set of pixels) on top of above QImage*.(as a layer).This means we need to call drawPoint() methods outside the QT thread. Is it the best wayto use QImage for this case? What is the best way to execute QT drawing methods from another thread? thanks in advance,

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  • Simple first-child js?

    - by Glister
    Searching for a simple first-child detection via javascript (no framework). It should add some class for the first child of the element. Like a css-hacks for ie, but in javascript and for a html file. Must work similar to :first-child When I say no framework, I mean some code like this: <script type="text/javascript">document.documentElement.id = "js"</script> For example: <div class="terms"> <dl> <dt>Term 1 name</dt> <dd>Term 1 description</dd> </dl> <dl> <dt>Term 2 name</dt> <dd>Term 2 description</dd> </dl> <dl> <dt>Term 3 name</dt> <dd>Term 3 description</dd> </dl> </div> Three <dl>, the first one includes Term 1. This css won't work in IE6, thats why I'm searching for a javascript solution. CSS-hacks are not allowed. .terms dl:first-child { float: right; }

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  • H.264 / FLV best practices for HTML

    - by Steve Murch
    I run a website with about 700 videos (And no, it's not porn -- get your mind out of the gutter :-) ). The videos are currently in FLV format. We use the JWPlayer to render those videos. IIS6 hosted. Everything works just fine. As I understand it, H.264 (not FLV and likely not OGG) is the emerging preferred HTML5 video standard. Today, the iPad really only respects H.264 or YouTube. Presumably, soon many more important browsers will follow Apple's lead and respect only the HTML5 tag. OK, so I think I can figure out how to convert my existing videos into the proper H.264 format. There are various tools available, including ffmpeg.exe. I haven't tried it yet, but I don't think that's going to be a problem after fiddling with the codec settings. My question is more about the container itself -- that is, planning graceful transition for all users. What's the best-practice recommendation for rendering these videos? If I just use the HTML5 tag, then presumably any browser that doesn't yet support HTML5 won't see the videos. And if I render them in Flash format via the JWPlayer or some other player, then they won't be playable on the iPad. Do I have to do ugly UserAgent detection here to figure out what to render? I know the JWPlayer supports H.264 media, but isn't the player itself a Flash component and therefore not playable on the iPad? Sorry if I'm not being clear, but I'm scratching my head on a graceful transition plan that will work for current browsers, the iPad and the upcoming HTML5 wave. I'm not a video expert, so any advice would be most welcome, thanks.

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  • How can I improve my real-time behavior in multi-threaded app using pthreads and condition variables

    - by WilliamKF
    I have a multi-threaded application that is using pthreads. I have a mutex() lock and condition variables(). There are two threads, one thread is producing data for the second thread, a worker, which is trying to process the produced data in a real time fashion such that one chuck is processed as close to the elapsing of a fixed time period as possible. This works pretty well, however, occasionally when the producer thread releases the condition upon which the worker is waiting, a delay of up to almost a whole second is seen before the worker thread gets control and executes again. I know this because right before the producer releases the condition upon which the worker is waiting, it does a chuck of processing for the worker if it is time to process another chuck, then immediately upon receiving the condition in the worker thread, it also does a chuck of processing if it is time to process another chuck. In this later case, I am seeing that I am late processing the chuck many times. I'd like to eliminate this lost efficiency and do what I can to keep the chucks ticking away as close to possible to the desired frequency. Is there anything I can do to reduce the delay between the release condition from the producer and the detection that that condition is released such that the worker resumes processing? For example, would it help for the producer to call something to force itself to be context switched out? Bottom line is the worker has to wait each time it asks the producer to create work for itself so that the producer can muck with the worker's data structures before telling the worker it is ready to run in parallel again. This period of exclusive access by the producer is meant to be short, but during this period, I am also checking for real-time work to be done by the producer on behalf of the worker while the producer has exclusive access. Somehow my hand off back to running in parallel again results in significant delay occasionally that I would like to avoid. Please suggest how this might be best accomplished.

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  • detecting pauses in a spoken word audio file using pymad, pcm, vad, etc

    - by james
    First I am going to broadly state what I'm trying to do and ask for advice. Then I will explain my current approach and ask for answers to my current problems. Problem I have an MP3 file of a person speaking. I'd like to split it up into segments roughly corresponding to a sentence or phrase. (I'd do it manually, but we are talking hours of data.) If you have advice on how to do this programatically or for some existing utilities, I'd love to hear it. (I'm aware of voice activity detection and I've looked into it a bit, but I didn't see any freely available utilities.) Current Approach I thought the simplest thing would be to scan the MP3 at certain intervals and identify places where the average volume was below some threshold. Then I would use some existing utility to cut up the mp3 at those locations. I've been playing around with pymad and I believe that I've successfully extracted the PCM (pulse code modulation) data for each frame of the mp3. Now I am stuck because I can't really seem to wrap my head around how the PCM data translates to relative volume. I'm also aware of other complicating factors like multiple channels, big endian vs little, etc. Advice on how to map a group of pcm samples to relative volume would be key. Thanks!

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  • Java Playing Cards Game Framework

    - by isme
    My friends and I at uni love playing Shithead into the wee hours. But soon we graduate and will leave town, so probably won't get together for a game for a while. I want to develop a Java app we can use to play Shithead and our other favorites over a network. An app like this already exists, but is ugly, buggy and does not support our house rules. The source is available, but is such a mess that I would really rather start from scratch than try to refactor it! Building my game using some standard playing card api or framework, if such a thing exists, would be better than starting from scratch. The answer to a similar SO question was to use the JPC-API, which allegedly provides basic playing card services and rendering. But this Sourceforge project currently makes available no files or source code! Is there an alternative, or somewhere else to find this framework? Soon I will need help with the following as well: Lobby services (finding other players) Gaming network protocol (to communicate moves between players) Gaming theory (to write the computer opponent) Winning condition detection Game UI development

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  • Visual Studio 2005 to VS 2008

    - by Adi
    hi all, I am a newbie in working on VS IDE and have not much experience in how the different libraries and files are linked in it. I have to build a OpenCV project which was made in VS2005 by one of my colleagues into VS2008. The project is for blob detection. Following is what he has to say in readme : Steps to use the library (using MSVC++ sp 5): 1 - open the project of the library and build it 2 - in the project where the library should be used, add: 2.1 In "Project/Settings/C++/Preprocessor/Additional Include directories" add the directory where the blob library is stored 2.2 In "Project/Settings/Link/Input/Additional library path" add the directory where the blob library is stored and in "Object/Library modules" add the cvblobslib.lib file 3- Include the file "BlobResult.h" where you want to use blob variables. 4- To see an example on using the blob library, see the file example.txt inside the zip file. NOTE: Verify that in the project where the cvblobslib.lib is used, the MFC Runtime Libraries are not mixed: Check in "Project-Settings-C/C++-Code Generation-Use run-time library" of your project and set it to Debug Multithreaded DLL (debug version ) or to Multithreaded DLL ( release version ). 2 Check in "Project-Settings-General" how it uses the MFC. It should be "Use MFC in a shared DLL". NOTE: The library can be compiled and used in .NET using this steps, but the menu options may differ a little NOTE2: In the .NET version, the character sets must be equal in the .lib and in the project. [OpenCV yahoo group: Msg 35500] Can anyone explain me , how to go about in doing this in VS2008. I would also appreciate if someone can explain me how the different libraries are linked , what is Debug, What is Release and all in a Visual Studio project folder we have.\ Thanks in advance Aditya

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