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• Wireless Network Found, can't connect, repeated requests for authentication

  - by Herm Holland

  After trawling through the internet, on forums, support websites, and through dozens upon dozens of answered questions on this site, I've not found a solution to what seems like a fairly regular problem... I cannot connect to a wireless network, and am continually asked for the network password. I have tried countless suggested solutions on the different locations I've already referred to. None of them have worked. Details of my experience are as follows: I have just recently installed Ubuntu 12.04.1 (32-bit). Ubuntu installed on my system seemingly fine, and I even formatted my hard drive during the process. It's as if it were a new desktop computer. During the installation I was asked to connect to a Wireless Network. I have a USB Wireless Card connected which I have used to connect desktop PC's, laptops, and a Wii to the internet from approximately the same area of the house (thus the same distance from the Wireless Router). I chose my network, entered the correct password for it (I double checked; it's definitely the right password) and proceeded with the installation. Several times before the installation was complete, I was asked to authenticate the connection, and this seemed to do nothing each time. On the repeated screens the password was already entered in the appropriate box. When Ubuntu booted up the first thing I was faced with (other than something about Language settings, or something) was another request for authentication. Again, the password was already there, so I clicked connect. It did not connect. Instead, I was once again faced with repeated requests every few minutes. I went onto my laptop, which is connected to this network, checked the details of the network, and entered them manually into my Ubuntu PC (including the IPv4 and IPv6 information) but this didn't work either, so I set it back to finding the settings automatically. Note, also, that the "Connect automatically" and "Available to all users" boxes are checked, and have been unchecked & rechecked countless times. I have also tried having my User account connect automatically, and to need a password entered at the welcome screen. Whilst I've been writing this, it has gone through a spat of connecting successfully to the network for less than a minute, before coming offline again, only to repeat the process. But it has now returned to prompting me for a password every couple of minutes. This computer has already run on the Fedora OS, and had no trouble connecting to, and maintaining a connection. I also have a laptop running Windows 7 less than a metre away from this desktop PC, which is connected and has no trouble maintaining a connection at 50%-100% strength (fluctuating). Therefore: - I know it's not the wireless card - I know it's not the PC itself - I know it's not the access point - I know it's not the location of my PC or wireless card - It is solely because of Ubuntu Everything else has worked fine, but the moment Ubuntu was introduced into the equation, it has gone completely wrong. Honestly; I prefer Ubuntu as an OS to Fedora, but if I can't solve the problem it'll be straight back to Fedora that I'll have to go. Can anyone help me at all?

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• The WaitForAll Roadshow

  - by adweigert

  OK, so I took for granted some imaginative uses of WaitForAll but lacking that, here is how I am using. First, I have a nice little class called Parallel that allows me to spin together a list of tasks (actions) and then use WaitForAll, so here it is, WaitForAll's 15 minutes of fame ... First Parallel that allows me to spin together several Action delegates to execute, well in parallel.   public static class Parallel { public static ParallelQuery Task(Action action) { return new Action[] { action }.AsParallel(); } public static ParallelQuery> Task(Action action) { return new Action[] { action }.AsParallel(); } public static ParallelQuery Task(this ParallelQuery actions, Action action) { var list = new List(actions); list.Add(action); return list.AsParallel(); } public static ParallelQuery> Task(this ParallelQuery> actions, Action action) { var list = new List>(actions); list.Add(action); return list.AsParallel(); } }   Next, this is an example usage from an app I'm working on that just is rendering some basic computer information via WMI and performance counters. The WMI calls can be expensive given the distance and link speed of some of the computers it will be trying to communicate with. This is the actual MVC action from my controller to return the data for an individual computer.  public PartialViewResult Detail(string computerName) { var computer = this.Computers.Get(computerName); var perf = Factory.GetInstance(); var detail = new ComputerDetailViewModel() { Computer = computer }; try { var work = Parallel .Task(delegate { // Win32_ComputerSystem var key = computer.Name + "_Win32_ComputerSystem"; var system = this.Cache.Get(key); if (system == null) { using (var impersonation = computer.ImpersonateElevatedIdentity()) { system = computer.GetWmiContext().GetInstances().Single(); } this.Cache.Set(key, system); } detail.TotalMemory = system.TotalPhysicalMemory; detail.Manufacturer = system.Manufacturer; detail.Model = system.Model; detail.NumberOfProcessors = system.NumberOfProcessors; }) .Task(delegate { // Win32_OperatingSystem var key = computer.Name + "_Win32_OperatingSystem"; var os = this.Cache.Get(key); if (os == null) { using (var impersonation = computer.ImpersonateElevatedIdentity()) { os = computer.GetWmiContext().GetInstances().Single(); } this.Cache.Set(key, os); } detail.OperatingSystem = os.Caption; detail.OSVersion = os.Version; }) // Performance Counters .Task(delegate { using (var impersonation = computer.ImpersonateElevatedIdentity()) { detail.AvailableBytes = perf.GetSample(computer, "Memory", "Available Bytes"); } }) .Task(delegate { using (var impersonation = computer.ImpersonateElevatedIdentity()) { detail.TotalProcessorUtilization = perf.GetValue(computer, "Processor", "% Processor Time", "_Total"); } }).WithExecutionMode(ParallelExecutionMode.ForceParallelism); if (!work.WaitForAll(TimeSpan.FromSeconds(15), task => task())) { return PartialView("Timeout"); } } catch (Exception ex) { this.LogException(ex); return PartialView("Error.ascx"); } return PartialView(detail); }

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• Dark Sun Dispatch 001

  - by Chris Williams

  If you aren't into tabletop (aka pen & paper) RPGs, you might as well click to the next post now... Still here? Awesome. I've recently started running a new D&D 4.0 Dark Sun campaign. If you don't know anything about Dark Sun, here's a quick intro: The campaign take place on the world of Athas, formerly a lush green world that is now a desert wasteland. Forests are rare in the extreme, as is water and metal. Coins are made of ceramic and weapons are often made of hardened wood, bone or obsidian. The green age of Athas was centuries ago and the current state was brought about through the reckless use of sorcerous magic. (In this world, you can augment spells by drawing on the life force of the world & people around you. This is called defiling. Preserving magic draws upon the casters life force and does not damage the surrounding world, but it isn't as powerful.) Humans are pretty much unchanged, but the traditional fantasy races have changed quite a bit. Elves don't live in the forest, they are shifty and untrustworthy desert traders known for their ability to run long distances through the wastes. Halflings are not short, fat, pleasant little riverside people. Instead they are bloodthirsty feral cannibals that roam the few remaining forests and ride reptilians beasts akin to raptors. Gnomes are extinct, as are orcs. Dwarves are mostly farmers and gladiators, and live out in the sun instead of staying under the mountains. Goliaths are half-giants, not known for their intellect. Muls are a Dwarf & Human crossbreed that displays the best traits of both races (human height and dwarven stoutness.) Thri-Kreen are sentient mantis people that are extremely fast. Most of the same character classes are available, with a few new twists. There are no divine characters (such as Priests, Paladins, etc) because the gods are gone. Nobody alive today can remember a time when they were still around. Instead, some folks worship the elemental forces (although they don't give out spells.) The cities are all ruled by Sorcerer King tyrants (except one city: Tyr) who are hundreds of years old and still practice defiling magic whenever they please. Serving the Sorcerer Kings are the Templars, who are also defilers and psionicists. Crossing them is as bad, in many cases, as crossing the Kings themselves. Between the cities you have small towns and trading outposts, and mostly barren desert with sometimes 4-5 days on foot between towns and the nearest oasis. Being caught out in the desert without adequate supplies and protection from the elements is pretty much a death sentence for even the toughest heroes. When you add in the natural (and unnatural) predators that roam the wastes, often in packs, most people don't last long alone. In this campaign, the adventure begins in the (small) trading fortress of Altaruk, a couple weeks walking distance from the newly freed city of Tyr. A caravan carrying trade goods from Altaruk has not made it to Tyr and the local merchant house has dispatched the heroes to find out what happened and to retrieve the goods (and drivers) if possible. The unlikely heroes consist of a human shaman, a thri-kreen monk, a human wizard, a kenku assassin and a (void aspect) genasi swordmage. Gathering up supplies and a little liquid courage, they set out into the desert and manage to find the northbound tracks of the wagon. Shortly after finding the tracks, they are ambushed by a pack of silt-runners (small lizard people with very large teeth and poisoned pointy spears.) The party makes short work of the creatures, taking a few minor wounds in the process. Proceeding onward without resting, they find the remains of the wagon and manage to sneak up on a pack of Kruthiks picking through the rubble and spilled goods. Unfortunately, they failed to take advantage of the opportunity and had a hard fight ahead of them. The party defeated the kruthiks, but took heavy damage (and almost lost a couple of their own) in the process. Once the kruthiks were dispatched, they followed a set of tracks further north to a ruined tower...

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• Big Data – Operational Databases Supporting Big Data – Columnar, Graph and Spatial Database – Day 14 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the Key-Value Pair Databases and Document Databases in the Big Data Story. In this article we will understand the role of Columnar, Graph and Spatial Database supporting Big Data Story. Now we will see a few of the examples of the operational databases. Relational Databases (The day before yesterday’s post) NoSQL Databases (The day before yesterday’s post) Key-Value Pair Databases (Yesterday’s post) Document Databases (Yesterday’s post) Columnar Databases (Tomorrow’s post) Graph Databases (Today’s post) Spatial Databases (Today’s post) Columnar Databases  Relational Database is a row store database or a row oriented database. Columnar databases are column oriented or column store databases. As we discussed earlier in Big Data we have different kinds of data and we need to store different kinds of data in the database. When we have columnar database it is very easy to do so as we can just add a new column to the columnar database. HBase is one of the most popular columnar databases. It uses Hadoop file system and MapReduce for its core data storage. However, remember this is not a good solution for every application. This is particularly good for the database where there is high volume incremental data is gathered and processed. Graph Databases For a highly interconnected data it is suitable to use Graph Database. This database has node relationship structure. Nodes and relationships contain a Key Value Pair where data is stored. The major advantage of this database is that it supports faster navigation among various relationships. For example, Facebook uses a graph database to list and demonstrate various relationships between users. Neo4J is one of the most popular open source graph database. One of the major dis-advantage of the Graph Database is that it is not possible to self-reference (self joins in the RDBMS terms) and there might be real world scenarios where this might be required and graph database does not support it. Spatial Databases  We all use Foursquare, Google+ as well Facebook Check-ins for location aware check-ins. All the location aware applications figure out the position of the phone with the help of Global Positioning System (GPS). Think about it, so many different users at different location in the world and checking-in all together. Additionally, the applications now feature reach and users are demanding more and more information from them, for example like movies, coffee shop or places see. They are all running with the help of Spatial Databases. Spatial data are standardize by the Open Geospatial Consortium known as OGC. Spatial data helps answering many interesting questions like “Distance between two locations, area of interesting places etc.” When we think of it, it is very clear that handing spatial data and returning meaningful result is one big task when there are millions of users moving dynamically from one place to another place & requesting various spatial information. PostGIS/OpenGIS suite is very popular spatial database. It runs as a layer implementation on the RDBMS PostgreSQL. This makes it totally unique as it offers best from both the worlds. Courtesy: mushroom network Tomorrow In tomorrow’s blog post we will discuss about very important components of the Big Data Ecosystem – Hive. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Move a sphere along the swipe?

  - by gameOne

  I am trying to get a sphere curl based on the swipe. I know this has been asked many times, but still it's yearning to be answered. I have managed to add force on the direction of the swipe and it works near perfect. I also have all the swipe positions stored in a list. Now I would like to know how can the curl be achieved. I believe the the curve in the swipe can be calculated by the Vector dot product If theta is 0, then there is no need to add the swipe. If it is not, then add the curl. Maybe this condition is redundant if I managed to find how to curl the sphere along the swipe position The code that adds the force to sphere based on the swipe direction is as below: using UnityEngine; using System.Collections; using System.Collections.Generic; public class SwipeControl : MonoBehaviour { //First establish some variables private Vector3 fp; //First finger position private Vector3 lp; //Last finger position private Vector3 ip; //some intermediate finger position private float dragDistance; //Distance needed for a swipe to register public float power; private Vector3 footballPos; private bool canShoot = true; private float factor = 40f; private List<Vector3> touchPositions = new List<Vector3>(); void Start(){ dragDistance = Screen.height*20/100; Physics.gravity = new Vector3(0, -20, 0); footballPos = transform.position; } // Update is called once per frame void Update() { //Examine the touch inputs foreach (Touch touch in Input.touches) { /*if (touch.phase == TouchPhase.Began) { fp = touch.position; lp = touch.position; }*/ if (touch.phase == TouchPhase.Moved) { touchPositions.Add(touch.position); } if (touch.phase == TouchPhase.Ended) { fp = touchPositions[0]; lp = touchPositions[touchPositions.Count-1]; ip = touchPositions[touchPositions.Count/2]; //First check if it's actually a drag if (Mathf.Abs(lp.x - fp.x) > dragDistance || Mathf.Abs(lp.y - fp.y) > dragDistance) { //It's a drag //Now check what direction the drag was //First check which axis if (Mathf.Abs(lp.x - fp.x) > Mathf.Abs(lp.y - fp.y)) { //If the horizontal movement is greater than the vertical movement... if ((lp.x>fp.x) && canShoot) //If the movement was to the right) { //Right move float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,10,16))*power); Debug.Log("right "+(lp.x-fp.x));//MOVE RIGHT CODE HERE canShoot = false; //rigidbody.AddForce((new Vector3((lp.x-fp.x)/30,10,16))*power); StartCoroutine(ReturnBall()); } else { //Left move float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,10,16))*power); Debug.Log("left "+(lp.x-fp.x));//MOVE LEFT CODE HERE canShoot = false; //rigidbody.AddForce(new Vector3((lp.x-fp.x)/30,10,16)*power); StartCoroutine(ReturnBall()); } } else { //the vertical movement is greater than the horizontal movement if (lp.y>fp.y) //If the movement was up { //Up move float y = (lp.y-fp.y)/Screen.height*factor; float x = (lp.x - fp.x) / Screen.height * factor; rigidbody.AddForce((new Vector3(x,y,16))*power); Debug.Log("up "+(lp.x-fp.x));//MOVE UP CODE HERE canShoot = false; //rigidbody.AddForce(new Vector3((lp.x-fp.x)/30,10,16)*power); StartCoroutine(ReturnBall()); } else { //Down move Debug.Log("down "+lp+" "+fp);//MOVE DOWN CODE HERE } } } else { //It's a tap Debug.Log("none");//TAP CODE HERE } } } } IEnumerator ReturnBall() { yield return new WaitForSeconds(5.0f); rigidbody.velocity = Vector3.zero; rigidbody.angularVelocity = Vector3.zero; transform.position = footballPos; canShoot =true; isKicked = false; } }

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• Problems implementing a screen space shadow ray tracing shader

  - by Grieverheart

  Here I previously asked for the possibility of ray tracing shadows in screen space in a deferred shader. Several problems were pointed out. One of the most important problem is that only visible objects can cast shadows and objects between the camera and the shadow caster can interfere. Still I thought it'd be a fun experiment. The idea is to calculate the view coordinates of pixels and cast a ray to the light. The ray is then traced pixel by pixel to the light and its depth is compared with the depth at the pixel. If a pixel is in front of the ray, a shadow is casted at the original pixel. At first I thought that I could use the DDA algorithm in 2D to calculate the distance 't' (in p = o + t d, where o origin, d direction) to the next pixel and use it in the 3D ray equation to find the ray's z coordinate at that pixel's position. For the 2D ray, I would use the projected and biased 3D ray direction and origin. The idea was that 't' would be the same in both 2D and 3D equations. Unfortunately, this is not the case since the projection matrix is 4D. Thus, some tweak needs to be done to make this work this way. I would like to ask if someone knows of a way to do what I described above, i.e. from a 2D ray in texture coordinate space to get the 3D ray in screen space. I did implement a simple version of the idea which you can see in the following video: video here Shadows may seem a bit pixelated, but that's mostly because of the size of the step in 't' I chose. And here is the shader: #version 330 core uniform sampler2D DepthMap; uniform vec2 projAB; uniform mat4 projectionMatrix; const vec3 light_p = vec3(-30.0, 30.0, -10.0); noperspective in vec2 pass_TexCoord; smooth in vec3 viewRay; layout(location = 0) out float out_AO; vec3 CalcPosition(void){ float depth = texture(DepthMap, pass_TexCoord).r; float linearDepth = projAB.y / (depth - projAB.x); vec3 ray = normalize(viewRay); ray = ray / ray.z; return linearDepth * ray; } void main(void){ vec3 origin = CalcPosition(); if(origin.z < -60) discard; vec2 pixOrigin = pass_TexCoord; //tex coords vec3 dir = normalize(light_p - origin); vec2 texel_size = vec2(1.0 / 600.0); float t = 0.1; ivec2 pixIndex = ivec2(pixOrigin / texel_size); out_AO = 1.0; while(true){ vec3 ray = origin + t * dir; vec4 temp = projectionMatrix * vec4(ray, 1.0); vec2 texCoord = (temp.xy / temp.w) * 0.5 + 0.5; ivec2 newIndex = ivec2(texCoord / texel_size); if(newIndex != pixIndex){ float depth = texture(DepthMap, texCoord).r; float linearDepth = projAB.y / (depth - projAB.x); if(linearDepth > ray.z + 0.1){ out_AO = 0.2; break; } pixIndex = newIndex; } t += 0.5; if(texCoord.x < 0 || texCoord.x > 1.0 || texCoord.y < 0 || texCoord.y > 1.0) break; } } As you can see, here I just increment 't' by some arbitrary factor, calculate the 3D ray and project it to get the pixel coordinates, which is not really optimal. Hopefully, I would like to optimize the code as much as possible and compare it with shadow mapping and how it scales with the number of lights. PS: Keep in mind that I reconstruct position from depth by interpolating rays through a full screen quad.

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• How can I draw an arrow at the edge of the screen pointing to an object that is off screen?

  - by Adam Henderson

  I am wishing to do what is described in this topic: http://www.allegro.cc/forums/print-thread/283220 I have attempted a variety of the methods mentioned here. First I tried to use the method described by Carrus85: Just take the ratio of the two triangle hypontenuses (doesn't matter which triagle you use for the other, I suggest point 1 and point 2 as the distance you calculate). This will give you the aspect ratio percentage of the triangle in the corner from the larger triangle. Then you simply multiply deltax by that value to get the x-coordinate offset, and deltay by that value to get the y-coordinate offset. But I could not find a way to calculate how far the object is away from the edge of the screen. I then tried using ray casting (which I have never done before) suggested by 23yrold3yrold: Fire a ray from the center of the screen to the offscreen object. Calculate where on the rectangle the ray intersects. There's your coordinates. I first calculated the hypotenuse of the triangle formed by the difference in x and y positions of the two points. I used this to create a unit vector along that line. I looped through that vector until either the x coordinate or the y coordinate was off the screen. The two current x and y values then form the x and y of the arrow. Here is the code for my ray casting method (written in C++ and Allegro 5) void renderArrows(Object* i) { float x1 = i->getX() + (i->getWidth() / 2); float y1 = i->getY() + (i->getHeight() / 2); float x2 = screenCentreX; float y2 = ScreenCentreY; float dx = x2 - x1; float dy = y2 - y1; float hypotSquared = (dx * dx) + (dy * dy); float hypot = sqrt(hypotSquared); float unitX = dx / hypot; float unitY = dy / hypot; float rayX = x2 - view->getViewportX(); float rayY = y2 - view->getViewportY(); float arrowX = 0; float arrowY = 0; bool posFound = false; while(posFound == false) { rayX += unitX; rayY += unitY; if(rayX <= 0 || rayX >= screenWidth || rayY <= 0 || rayY >= screenHeight) { arrowX = rayX; arrowY = rayY; posFound = true; } } al_draw_bitmap(sprite, arrowX - spriteWidth, arrowY - spriteHeight, 0); } This was relatively successful. Arrows are displayed in the bottom right section of the screen when objects are located above and left of the screen as if the locations of the where the arrows are drawn have been rotated 180 degrees around the center of the screen. I assumed this was due to the fact that when I was calculating the hypotenuse of the triangle, it would always be positive regardless of whether or not the difference in x or difference in y is negative. Thinking about it, ray casting does not seem like a good way of solving the problem (due to the fact that it involves using sqrt() and a large for loop). Any help finding a suitable solution would be greatly appreciated, Thanks Adam

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• How does interpolation actually work to smooth out an object's movement?

  - by user22241

  I've asked a few similar questions over the past 8 months or so with no real joy, so I am going make the question more general. I have an Android game which is OpenGL ES 2.0. within it I have the following Game Loop: My loop works on a fixed time step principle (dt = 1 / ticksPerSecond) loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip){ updateLogic(dt); nextGameTick+=skipTicks; timeCorrection += (1000d/ticksPerSecond) % 1; nextGameTick+=timeCorrection; timeCorrection %=1; loops++; } render(); My intergration works like this: sprite.posX+=sprite.xVel*dt; sprite.posXDrawAt=sprite.posX*width; Now, everything works pretty much as I would like. I can specify that I would like an object to move across a certain distance (screen width say) in 2.5 seconds and it will do just that. Also because of the frame skipping that I allow in my game loop, I can do this on pretty much any device and it will always take 2.5 seconds. Problem However, the problem is that when a render frame skips, the graphic stutter. It's extremely annoying. If I remove the ability to skip frames, then everything is smooth as you like, but will run at different speeds on different devices. So it's not an option. I'm still not sure why the frame skips, but I would like to point out that this is Nothing to do with poor performance, I've taken the code right back to 1 tiny sprite and no logic (apart from the logic required to move the sprite) and I still get skipped frames. And this is on a Google Nexus 10 tablet (and as mentioned above, I need frame skipping to keep the speed consistent across devices anyway). So, the only other option I have is to use interpolation (or extrapolation), I've read every article there is out there but none have really helped me to understand how it works and all of my attempted implementations have failed. Using one method I was able to get things moving smoothly but it was unworkable because it messed up my collision. I can foresee the same issue with any similar method because the interpolation is passed to (and acted upon within) the rendering method - at render time. So if Collision corrects position (character now standing right next to wall), then the renderer can alter it's position and draw it in the wall. So I'm really confused. People have said that you should never alter an object's position from within the rendering method, but all of the examples online show this. So I'm asking for a push in the right direction, please do not link to the popular game loop articles (deWitters, Fix your timestep, etc) as I've read these multiple times. I'm not asking anyone to write my code for me. Just explain please in simple terms how Interpolation actually works with some examples. I will then go and try to integrate any ideas into my code and will ask more specific questions if need-be further down the line. (I'm sure this is a problem many people struggle with).

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• To SYNC or not to SYNC – Part 4

  - by AshishRay

  This is Part 4 of a multi-part blog article where we are discussing various aspects of setting up Data Guard synchronous redo transport (SYNC). In Part 1 of this article, I debunked the myth that Data Guard SYNC is similar to a two-phase commit operation. In Part 2, I discussed the various ways that network latency may or may not impact a Data Guard SYNC configuration. In Part 3, I talked in details regarding why Data Guard SYNC is a good thing, and the distance implications you have to keep in mind. In this final article of the series, I will talk about how you can nicely complement Data Guard SYNC with the ability to failover in seconds. Wait - Did I Say “Seconds”? Did I just say that some customers do Data Guard failover in seconds? Yes, Virginia, there is a Santa Claus. Data Guard has an automatic failover capability, aptly called Fast-Start Failover. Initially available with Oracle Database 10g Release 2 for Data Guard SYNC transport mode (and enhanced in Oracle Database 11g to support Data Guard ASYNC transport mode), this capability, managed by Data Guard Broker, lets your Data Guard configuration automatically failover to a designated standby database. Yes, this means no human intervention is required to do the failover. This process is controlled by a low footprint Data Guard Broker client called Observer, which makes sure that the primary database and the designated standby database are behaving like good kids. If something bad were to happen to the primary database, the Observer, after a configurable threshold period, tells that standby, “Your time has come, you are the chosen one!” The standby dutifully follows the Observer directives by assuming the role of the new primary database. The DBA or the Sys Admin doesn’t need to be involved. And - in case you are following this discussion very closely, and are wondering … “Hmmm … what if the old primary is not really dead, but just network isolated from the Observer or the standby - won’t this lead to a split-brain situation?” The answer is No - It Doesn’t. With respect to why-it-doesn’t, I am sure there are some smart DBAs in the audience who can explain the technical reasons. Otherwise - that will be the material for a future blog post. So - this combination of SYNC and Fast-Start Failover is the nirvana of lights-out, integrated HA and DR, as practiced by some of our advanced customers. They have observed failover times (with no data loss) ranging from single-digit seconds to tens of seconds. With this, they support operations in industry verticals such as manufacturing, retail, telecom, Internet, etc. that have the most demanding availability requirements. One of our leading customers with massive cloud deployment initiatives tells us that they know about server failures only after Data Guard has automatically completed the failover process and the app is back up and running! Needless to mention, Data Guard Broker has the integration hooks for interfaces such as JDBC and OCI, or even for custom apps, to ensure the application gets automatically rerouted to the new primary database after the database level failover completes. Net Net? To sum up this multi-part blog article, Data Guard with SYNC redo transport mode, plus Fast-Start Failover, gives you the ideal triple-combo - that is, it gives you the assurance that for critical outages, you can failover your Oracle databases: very fast without human intervention, and without losing any data. In short, it takes the element of risk out of critical IT operations. It does require you to be more careful with your network and systems planning, but as far as HA is concerned, the benefits outweigh the investment costs. So, this is what we in the MAA Development Team believe in. What do you think? How has your deployment experience been? We look forward to hearing from you!

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• The Evolution of Oracle Direct EMEA by John McGann

  - by user769227

  John is expanding his Dublin based team and is currently recruiting a Director with marketing and sales leadership experience: http://bit.ly/O8PyDF Should you wish to apply, please send your CV to [email protected] Hi, my name is John McGann and I am part of the Oracle Direct management team, based in Dublin.   Today I’m writing from the Oracle London City office, right in the heart of the financial district and up to very recently at the centre of a fantastic Olympic Games. The Olympics saw individuals and teams from across the globe competing to decide who is Citius, Altius, Fortius - “Faster, Higher, Stronger" There are lots of obvious parallels between the competitive world of the Olympics and the Business environments that many of us operate in, but there are also some interesting differences – especially in my area of responsibility within Oracle. We are of course constantly striving to be the best - the best solution on offer for our clients, bringing simplicity to their management, consumption and application of information technology, and the best provider when compared with our many niche competitors.   In Oracle and especially in Oracle Direct, a key aspect of how we achieve this is what sets us apart from the Olympians.  We have long ago eliminated geographic boundaries as a limitation to what we can achieve. We assemble the strongest individuals across multiple countries and bring them together in teams focussed on a single goal. One such team is the Oracle Direct Sales Programs team. In case you don’t know, Oracle Direct EMEA (Europe Middle East and Africa) is the inside sales division in Oracle and it is where I started my Oracle career.  I remember that my first role involved putting direct mail in envelopes.... things have moved on a bit since then – for me, for Oracle Direct and in how we interact with our customers. Today, the team of over 1000 people is located in the different Oracle Direct offices around Europe – the main ones are Malaga, Berlin, Prague and Dubai plus the headquarters in Dublin. We work in over 20 languages and are in constant contact with current and future Oracle customers, using the latest internet and telephone technologies to effectively communicate and collaborate with each other, our customers and prospects. One of my areas of responsibility within Oracle Direct is the Sales Programs team. This team of 25 people manages the planning and execution of demand generation, leading the process of finding new and incremental revenue within Oracle Direct. The Sales Programs Managers or ‘SPMs’ are embedded within each of the Oracle Direct sales teams, focussed on distinct geographies or product groups. The SPMs are virtual members of the regional sales management teams, and work closely with the sales and marketing teams to define and deliver demand generation activities. The customer contact elements of these activities are executed via the Oracle Direct Sales and Business Development/Lead Generation teams, to deliver the pipeline required to meet our revenue goals. Activities can range from pan-EMEA joint sales and marketing campaigns, to very localised niche campaigns. The campaigns might focus on particular segments of our existing customers, introducing elements of our evolving solution portfolio which customers may not be familiar with. The Sales Programs team also manages ‘Nurture’ activities to ensure that we develop potential business opportunities with contacts and organisations that do not have immediate requirements. Looking ahead, it is really important that we continue to evolve our ability to add value to our clients and reduce the physical limitations of our distance from them through the innovative application of technology. This enables us to enhance the customer buying experience and to enable the Inside Sales teams to manage ever more complex sales cycles from start to finish.  One of my expectations of my team is to actively drive innovation in how we leverage data to better understand our customers, and exploit emerging technologies to better communicate with them.   With the rate of innovation and acquisition within Oracle, we need to ensure that existing and potential customers are aware of all we have to offer that relates to their business goals.   We need to achieve this via a coherent communication and sales strategy to effectively target the right people using the most effective medium. This is another area where the Sales Programs team plays a key role.

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• Oracle MAA Part 1: When One Size Does Not Fit All

  - by JoeMeeks

  The good news is that Oracle Maximum Availability Architecture (MAA) best practices combined with Oracle Database 12c (see video) introduce first-in-the-industry database capabilities that truly make unplanned outages and planned maintenance transparent to users. The trouble with such good news is that Oracle’s enthusiasm in evangelizing its latest innovations may leave some to wonder if we’ve lost sight of the fact that not all database applications are created equal. Afterall, many databases don’t have the business requirements for high availability and data protection that require all of Oracle’s ‘stuff’. For many real world applications, a controlled amount of downtime and/or data loss is OK if it saves money and effort. Well, not to worry. Oracle knows that enterprises need solutions that address the full continuum of requirements for data protection and availability. Oracle MAA accomplishes this by defining four HA service level tiers: BRONZE, SILVER, GOLD and PLATINUM. The figure below shows the progression in service levels provided by each tier. Each tier uses a different MAA reference architecture to deploy the optimal set of Oracle HA capabilities that reliably achieve a given service level (SLA) at the lowest cost.  Each tier includes all of the capabilities of the previous tier and builds upon the architecture to handle an expanded fault domain. Bronze is appropriate for databases where simple restart or restore from backup is ‘HA enough’. Bronze is based upon a single instance Oracle Database with MAA best practices that use the many capabilities for data protection and HA included with every Oracle Enterprise Edition license. Oracle-optimized backups using Oracle Recovery Manager (RMAN) provide data protection and are used to restore availability should an outage prevent the database from being able to restart. Silver provides an additional level of HA for databases that require minimal or zero downtime in the event of database instance or server failure as well as many types of planned maintenance. Silver adds clustering technology - either Oracle RAC or RAC One Node. RMAN provides database-optimized backups to protect data and restore availability should an outage prevent the cluster from being able to restart. Gold raises the game substantially for business critical applications that can’t accept vulnerability to single points-of-failure. Gold adds database-aware replication technologies, Active Data Guard and Oracle GoldenGate, which synchronize one or more replicas of the production database to provide real time data protection and availability. Database-aware replication greatly increases HA and data protection beyond what is possible with storage replication technologies. It also reduces cost while improving return on investment by actively utilizing all replicas at all times. Platinum introduces all of the sexy new Oracle Database 12c capabilities that Oracle staff will gush over with great enthusiasm. These capabilities include Application Continuity for reliable replay of in-flight transactions that masks outages from users; Active Data Guard Far Sync for zero data loss protection at any distance; new Oracle GoldenGate enhancements for zero downtime upgrades and migrations; and Global Data Services for automated service management and workload balancing in replicated database environments. Each of these technologies requires additional effort to implement. But they deliver substantial value for your most critical applications where downtime and data loss are not an option. The MAA reference architectures are inherently designed to address conflicting realities. On one hand, not every application has the same objectives for availability and data protection – the Not One Size Fits All title of this blog post. On the other hand, standard infrastructure is an operational requirement and a business necessity in order to reduce complexity and cost. MAA reference architectures address both realities by providing a standard infrastructure optimized for Oracle Database that enables you to dial-in the level of HA appropriate for different service level requirements. This makes it simple to move a database from one HA tier to the next should business requirements change, or from one hardware platform to another – whether it’s your favorite non-Oracle vendor or an Oracle Engineered System. Please stay tuned for additional blog posts in this series that dive into the details of each MAA reference architecture. Meanwhile, more information on Oracle HA solutions and the Maximum Availability Architecture can be found at: Oracle Maximum Availability Architecture - Webcast Maximize Availability with Oracle Database 12c - Technical White Paper

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• Detect multitouch (two fingers touch) on a sprite to apply pinch zoom behaviour

  - by Tahreem

  I am using andengine, want to move, zoom and rotate multiple sprites individually on a scene. I have achieved "move" but for pinch zoom i am unable to get the event to two fingers' touch. Below is the code: public class Main extends SimpleBaseGameActivity { private Camera camera; private BitmapTextureAtlas mBitmapTextureAtlas; private ITextureRegion mFaceTextureRegion; private ITextureRegion mFaceTextureRegion2; Sprite face2; private static final int CAMERA_WIDTH = 800; private static final int CAMERA_HEIGHT = 480; @Override public EngineOptions onCreateEngineOptions() { camera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT); EngineOptions engineOptions = new EngineOptions(true, ScreenOrientation.LANDSCAPE_FIXED, new RatioResolutionPolicy( CAMERA_WIDTH, CAMERA_HEIGHT), camera); return engineOptions; } @Override protected void onCreateResources() { BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/"); this.mBitmapTextureAtlas = new BitmapTextureAtlas( this.getTextureManager(), 1024, 1600, TextureOptions.NEAREST); BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mBitmapTextureAtlas, // this, "ui_ball_1.png", 0, 0, 1, 1), // this.getVertexBufferObjectManager()); this.mFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory .createFromAsset(this.mBitmapTextureAtlas, this, "ui_ball_1.png", 0, 0); this.mFaceTextureRegion2 = BitmapTextureAtlasTextureRegionFactory .createFromAsset(this.mBitmapTextureAtlas, this, "ui_ball_1.png", 0, 0); this.mBitmapTextureAtlas.load(); this.mEngine.getTextureManager().loadTexture(this.mBitmapTextureAtlas); } @Override protected Scene onCreateScene() { this.mEngine.registerUpdateHandler(new FPSLogger()); final Scene scene = new Scene(); scene.setBackground(new Background(0.09804f, 0.6274f, 0.8784f)); final float centerX = (CAMERA_WIDTH - this.mFaceTextureRegion .getWidth()) / 2; final float centerY = (CAMERA_HEIGHT - this.mFaceTextureRegion .getHeight()) / 2; final Sprite face = new Sprite(centerX, centerY, this.mFaceTextureRegion, this.getVertexBufferObjectManager()) { @Override public boolean onAreaTouched(final TouchEvent pSceneTouchEvent, final float pTouchAreaLocalX, final float pTouchAreaLocalY) { this.setPosition(pSceneTouchEvent.getX() - this.getWidth() / 2, pSceneTouchEvent.getY() - this.getHeight() / 2); return true; } }; face.setScale(2); scene.attachChild(face); scene.registerTouchArea(face); face2 = new Sprite(200, 200, this.mFaceTextureRegion2, this.getVertexBufferObjectManager()) { @Override public boolean onAreaTouched(final TouchEvent pSceneTouchEvent, final float pTouchAreaLocalX, final float pTouchAreaLocalY) { switch(pSceneTouchEvent.getAction()){ case TouchEvent.ACTION_DOWN: int count = pSceneTouchEvent.getMotionEvent().getPointerCount() ; for(int i= 0; i <count; i++) { int id = pSceneTouchEvent.getMotionEvent().getPointerId(i); } break; case TouchEvent.ACTION_MOVE: this.setPosition(pSceneTouchEvent.getX() -this.getWidth() / 2, pSceneTouchEvent.getY()-this.getHeight() / 2); break; case TouchEvent.ACTION_UP: break; } return true; } }; face2.setScale(2); scene.attachChild(face2); scene.registerTouchArea(face2); scene.setTouchAreaBindingOnActionDownEnabled(true); return scene; } } This line int count = pSceneTouchEvent.getMotionEvent().getPointerCount() ; should set 2 to the count variable if i touch the sprite with to fingers, then i can apply zooming functionality (setScale method) on the sprite by getting the distance between the coordinates of two fingers. Can anyone help me? why it does not detect two fingers? and without this how can i zoom the sprite on pinch of two fingers? I am very new to game development, any help would be appreciated. Thanks in advance.

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• How to Draw Lines on the Screen

  - by Geertjan

  I've seen occasional questions on mailing lists about how to use the NetBeans Visual Library to draw lines, e.g., to make graphs or diagrams of various kinds by drawing on the screen. So, rather than drag/drop causing widgets to be added, you'd want widgets to be added on mouse clicks, and you'd want to be able to connect those widgets together somehow. Via the code below, you'll be able to click on the screen, which causes a dot to appear. When you have multiple dots, you can hold down the Ctrl key and connect them together. A guiding line appears to help you position the dots exactly in line with each other. When you go to File | Print, you'll be able to preview and print the diagram you've created. A picture that speaks 1000 words: Here's the code: public final class PlotterTopComponent extends TopComponent { private final Scene scene; private final LayerWidget baseLayer; private final LayerWidget connectionLayer; private final LayerWidget interactionLayer; public PlotterTopComponent() { initComponents(); setName(Bundle.CTL_PlotterTopComponent()); setToolTipText(Bundle.HINT_PlotterTopComponent()); setLayout(new BorderLayout()); this.scene = new Scene(); this.baseLayer = new LayerWidget(scene); this.interactionLayer = new LayerWidget(scene); this.connectionLayer = new LayerWidget(scene); scene.getActions().addAction(new SceneCreateAction()); scene.addChild(baseLayer); scene.addChild(interactionLayer); scene.addChild(connectionLayer); add(scene.createView(), BorderLayout.CENTER); putClientProperty("print.printable", true); } private class SceneCreateAction extends WidgetAction.Adapter { @Override public WidgetAction.State mousePressed(Widget widget, WidgetAction.WidgetMouseEvent event) { if (event.getClickCount() == 1) { if (event.getButton() == MouseEvent.BUTTON1 || event.getButton() == MouseEvent.BUTTON2) { baseLayer.addChild(new BlackDotWidget(scene, widget, event)); repaint(); return WidgetAction.State.CONSUMED; } } return WidgetAction.State.REJECTED; } } private class BlackDotWidget extends ImageWidget { public BlackDotWidget(Scene scene, Widget widget, WidgetAction.WidgetMouseEvent event) { super(scene); setImage(ImageUtilities.loadImage("org/netbeans/plotter/blackdot.gif")); setPreferredLocation(widget.convertLocalToScene(event.getPoint())); getActions().addAction( ActionFactory.createExtendedConnectAction( connectionLayer, new BlackDotConnectProvider())); getActions().addAction( ActionFactory.createAlignWithMoveAction( baseLayer, interactionLayer, ActionFactory.createDefaultAlignWithMoveDecorator())); } } private class BlackDotConnectProvider implements ConnectProvider { @Override public boolean isSourceWidget(Widget source) { return source instanceof BlackDotWidget && source != null ? true : false; } @Override public ConnectorState isTargetWidget(Widget src, Widget trg) { return src != trg && trg instanceof BlackDotWidget ? ConnectorState.ACCEPT : ConnectorState.REJECT; } @Override public boolean hasCustomTargetWidgetResolver(Scene arg0) { return false; } @Override public Widget resolveTargetWidget(Scene arg0, Point arg1) { return null; } @Override public void createConnection(Widget source, Widget target) { ConnectionWidget conn = new ConnectionWidget(scene); conn.setTargetAnchor(AnchorFactory.createCircularAnchor(target, 10)); conn.setSourceAnchor(AnchorFactory.createCircularAnchor(source, 10)); connectionLayer.addChild(conn); } } ... ... ... Note: The code above was written based on the Visual Library tutorials on the NetBeans Platform Learning Trail, in particular via the "ConnectScene" sample in the "test.connect" package, which is part of the very long list of Visual Library samples referred to in the Visual Library tutorials on the NetBeans Platform Learning Trail. The next steps are to add a reconnect action and an action to delete a dot by double-clicking on it. Would be interesting to change the connecting line so that the length of the line were to be shown, i.e., as you draw a line from one dot to another, you'd see a constantly changing number representing the current distance of the connecting line. Also, once lines are connected to form a rectangle, would be cool to be able to write something within that rectangle. Then one could really create diagrams, which would be pretty cool.

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• Consumer Oriented Search In Oracle Endeca Information Discovery – Part 1

  - by Bob Zurek

  Information Discovery, a core capability of Oracle Endeca Information Discovery, enables business users to rapidly search, discover and navigate through a wide variety of big data including structured, unstructured and semi-structured data. One of the key capabilities, among many, that differentiate our solution from others in the Information Discovery market is our deep support for search across this growing amount of varied big data. Our method and approach is very different than classic simple keyword search that is found in may information discovery solutions. In this first part of a series on the topic of search, I will walk you through many of the key capabilities that go beyond the simple search box that you might experience in products where search was clearly an afterthought or attempt to catch up to our core capabilities in this area. Lets explore. The core data management solution of Oracle Endeca Information Discovery is the Endeca Server, a hybrid search-analytical database that his highly scalable and column-oriented in nature. We will talk in more technical detail about the capabilities of the Endeca Server in future blog posts as this post is intended to give you a feel for the deep search capabilities that are an integral part of the Endeca Server. The Endeca Server provides best-of-breed search features aw well as a new class of features that are the first to be designed around the requirement to bridge structured, semi-structured and unstructured big data. Some of the key features of search include type a heads, automatic alphanumeric spell corrections, positional search, Booleans, wildcarding, natural language, and category search and query classification dialogs. This is just a subset of the advanced search capabilities found in Oracle Endeca Information Discovery. Search is an important feature that makes it possible for business users to explore on the diverse data sets the Endeca Server can hold at any one time. The search capabilities in the Endeca server differ from other Information Discovery products with simple “search boxes” in the following ways: The Endeca Server Supports Exploratory Search.  Enterprise data frequently requires the user to explore content through an ad hoc dialog, with guidance that helps them succeed. This has implications for how to design search features. Traditional search doesn’t assume a dialog, and so it uses relevance ranking to get its best guess to the top of the results list. It calculates many relevance factors for each query, like word frequency, distance, and meaning, and then reduces those many factors to a single score based on a proprietary “black box” formula. But how can a business users, searching, act on the information that the document is say only 38.1% relevant? In contrast, exploratory search gives users the opportunity to clarify what is relevant to them through refinements and summaries. This approach has received consumer endorsement through popular ecommerce sites where guided navigation across a broad range of products has helped consumers better discover choices that meet their, sometimes undetermined requirements. This same model exists in Oracle Endeca Information Discovery. In fact, the Endeca Server powers many of the most popular e-commerce sites in the world. The Endeca Server Supports Cascading Relevance. Traditional approaches of search reduce many relevance weights to a single score. This means that if a result with a good title match gets a similar score to one with an exact phrase match, they’ll appear next to each other in a list. But a user can’t deduce from their score why each got it’s ranking, even though that information could be valuable. Oracle Endeca Information Discovery takes a different approach. The Endeca Server stratifies results by a primary relevance strategy, and then breaks ties within a strata by ordering them with a secondary strategy, and so on. Application managers get the explicit means to compose these strategies based on their knowledge of their own domain. This approach gives both business users and managers a deterministic way to set and understand relevance. Now that you have an understanding of two of the core search capabilities in Oracle Endeca Information Discovery, our next blog post on this topic will discuss more advanced features including set search, second-order relevance as well as an understanding of faceted search mechanisms that include queries and filters.  

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• Arcball Problems with UDK

  - by opdude

  I'm trying to re-create an arcball example from a Nehe, where an object can be rotated in a more realistic way while floating in the air (in my game the object is attached to the player at a distance like for example the Physics Gun) however I'm having trouble getting this to work with UDK. I have created an LGArcBall which follows the example from Nehe and I've compared outputs from this with the example code. I think where my problem lies is what I do to the Quaternion that is returned from the LGArcBall. Currently I am taking the returned Quaternion converting it to a rotation matrix. Getting the product of the last rotation (set when the object is first clicked) and then returning that into a Rotator and setting that to the objects rotation. If you could point me in the right direction that would be great, my code can be found below. class LGArcBall extends Object; var Quat StartRotation; var Vector StartVector; var float AdjustWidth, AdjustHeight, Epsilon; function SetBounds(float NewWidth, float NewHeight) { AdjustWidth = 1.0f / ((NewWidth - 1.0f) * 0.5f); AdjustHeight = 1.0f / ((NewHeight - 1.0f) * 0.5f); } function StartDrag(Vector2D startPoint, Quat rotation) { StartVector = MapToSphere(startPoint); } function Quat Update(Vector2D currentPoint) { local Vector currentVector, perp; local Quat newRot; //Map the new point to the sphere currentVector = MapToSphere(currentPoint); //Compute the vector perpendicular to the start and current perp = startVector cross currentVector; //Make sure our length is larger than Epsilon if (VSize(perp) > Epsilon) { //Return the perpendicular vector as the transform newRot.X = perp.X; newRot.Y = perp.Y; newRot.Z = perp.Z; //In the quaternion values, w is cosine (theta / 2), where //theta is the rotation angle newRot.W = startVector dot currentVector; } else { //The two vectors coincide, so return an identity transform newRot.X = 0.0f; newRot.Y = 0.0f; newRot.Z = 0.0f; newRot.W = 0.0f; } return newRot; } function Vector MapToSphere(Vector2D point) { local float x, y, length, norm; local Vector result; //Transform the mouse coords to [-1..1] //and inverse the Y coord x = (point.X * AdjustWidth) - 1.0f; y = 1.0f - (point.Y * AdjustHeight); length = (x * x) + (y * y); //If the point is mapped outside of the sphere //( length > radius squared) if (length > 1.0f) { norm = 1.0f / Sqrt(length); //Return the "normalized" vector, a point on the sphere result.X = x * norm; result.Y = y * norm; result.Z = 0.0f; } else //It's inside of the sphere { //Return a vector to the point mapped inside the sphere //sqrt(radius squared - length) result.X = x; result.Y = y; result.Z = Sqrt(1.0f - length); } return result; } DefaultProperties { Epsilon = 0.000001f } I'm then attempting to rotate that object when the mouse is dragged, with the following update code in my PlayerController. //Get Mouse Position MousePosition.X = LGMouseInterfacePlayerInput(PlayerInput).MousePosition.X; MousePosition.Y = LGMouseInterfacePlayerInput(PlayerInput).MousePosition.Y; newQuat = ArcBall.Update(MousePosition); rotMatrix = MakeRotationMatrix(QuatToRotator(newQuat)); rotMatrix = rotMatrix * LastRot; LGMoveableActor(movingPawn.CurrentUseableObject).SetPhysics(EPhysics.PHYS_Rotating); LGMoveableActor(movingPawn.CurrentUseableObject).SetRotation(MatrixGetRotator(rotMatrix));

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• Omni-directional light shadow mapping with cubemaps in WebGL

  - by Winged

  First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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• Drawing random smooth lines contained in a square [migrated]

  - by Doug Mercer

  I'm trying to write a matlab function that creates random, smooth trajectories in a square of finite side length. Here is my current attempt at such a procedure: function [] = drawroutes( SideLength, v, t) %DRAWROUTES Summary of this function goes here % Detailed explanation goes here %Some parameters intended to help help keep the particles in the box RandAccel=.01; ConservAccel=0; speedlimit=.1; G=10^(-8); % %Initialize Matrices Ax=zeros(v,10*t); Ay=Ax; vx=Ax; vy=Ax; x=Ax; y=Ax; sx=zeros(v,1); sy=zeros(v,1); % %Define initial position in square x(:,1)=SideLength*.15*ones(v,1)+(SideLength*.7)*rand(v,1); y(:,1)=SideLength*.15*ones(v,1)+(SideLength*.7)*rand(v,1); % for i=2:10*t %Measure minimum particle distance component wise from boundary %for each vehicle BorderGravX=[abs(SideLength*ones(v,1)-x(:,i-1)),abs(x(:,i-1))]'; BorderGravY=[abs(SideLength*ones(v,1)-y(:,i-1)),abs(y(:,i-1))]'; rx=min(BorderGravX)'; ry=min(BorderGravY)'; % %Set the sign of the repulsive force for k=1:v if x(k,i)<.5*SideLength sx(k)=1; else sx(k)=-1; end if y(k,i)<.5*SideLength sy(k)=1; else sy(k)=-1; end end % %Calculate Acceleration w/ random "nudge" and repulive force Ax(:,i)=ConservAccel*Ax(:,i-1)+RandAccel*(rand(v,1)-.5*ones(v,1))+sx*G./rx.^2; Ay(:,i)=ConservAccel*Ay(:,i-1)+RandAccel*(rand(v,1)-.5*ones(v,1))+sy*G./ry.^2; % %Ad hoc method of trying to slow down particles from jumping outside of %feasible region for h=1:v if abs(vx(h,i-1)+Ax(h,i))<speedlimit vx(h,i)=vx(h,i-1)+Ax(h,i); elseif (vx(h,i-1)+Ax(h,i))<-speedlimit vx(h,i)=-speedlimit; else vx(h,i)=speedlimit; end end for h=1:v if abs(vy(h,i-1)+Ay(h,i))<speedlimit vy(h,i)=vy(h,i-1)+Ay(h,i); elseif (vy(h,i-1)+Ay(h,i))<-speedlimit vy(h,i)=-speedlimit; else vy(h,i)=speedlimit; end end % %Update position x(:,i)=x(:,i-1)+(vx(:,i-1)+vx(:,i))/2; y(:,i)=y(:,i-1)+(vy(:,i-1)+vy(:,1))/2; % end %Plot position clf; hold on; axis([-100,SideLength+100,-100,SideLength+100]); cc=hsv(v); for j=1:v plot(x(j,1),y(j,1),'ko') plot(x(j,:),y(j,:),'color',cc(j,:)) end hold off; % end My original plan was to place particles within a square, and move them around by allowing their acceleration in the x and y direction to be governed by a uniformly distributed random variable. To keep the particles within the square, I tried to create a repulsive force that would push the particles away from the boundaries of the square. In practice, the particles tend to leave the desired "feasible" region after a relatively small number of time steps (say, 1000)." I'd love to hear your suggestions on either modifying my existing code or considering the problem from another perspective. When reading the code, please don't feel the need to get hung up on any of the ad hoc parameters at the very beginning of the script. They seem to help, but I don't believe any beside the "G" constant should truly be necessary to make this system work. Here is an example of the current output: Many of the vehicles have found their way outside of the desired square region, [0,400] X [0,400].

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• Test your internet connection - Emtel Fixed Broadband

  Already at the begin of April, I had a phone conversation with my representative at Emtel Ltd. about some upcoming issues due to the ongoing construction work in my neighbourhood. Unfortunately, they finally raised the house two levels above ours, and of course this has to have a negative impact on the visibility between the WiMAX outdoor unit on the roof and the aimed access point at Medine. So, today I had a technical team here to do a site survey and to come up with potential solutions. Short version: It doesn't look good after all. The site survey Well, the two technicians did their work properly, even re-arranged the antenna to check the connection with another end point down at La Preneuse. But no improvements. Looks like we are out of luck since the construction next door hasn't finished yet and at the moment, it even looks like they are planning to put at least one more level on top. I really wonder about the sanity of the responsible bodies at the local district council. But that's another story. Anyway, the outdoor unit was once again pointed towards Medine and properly fixed with new cable guides (air from the sea and rust...). Both of them did a good job and fine-tuned the reception signal to a mere 3 over 9; compared to the original 7 over 9 I had before the daily terror started. The site survey has been done, and now it's up to Emtel to come up with (better) solutions. Well, I wouldn't mind to have an unlimited, symmetric 3G/UMTS or even LTE connection. Let's see what they can do... Testing the connection There are several online sites available which offer you to check certain aspects of your internet connection. Personally, I'm used to speedtest.net and it works very well. I think it is good and necessary to check your connection from time to time, and only a couple of days ago, I posted the following on Emtel's wall at Facebook (21.05.2013 - 14:06 hrs): Dear Emtel, could you eventually provide an answer on the miserable results of SpeedTest? I chose Rose Hill (Hosted by Emtel Ltd.) as testing endpoint... Sadly, no response to this. Seems that the marketing department is not willing to deal with customers on Facebook. Okay, over at speedtest.net you can use their Flash-based test suite to check your connection to quite a number of servers of different providers world-wide. It's actually very interesting to see the results for different end points and to compare them to each other. The results Following are the results of Rose Hill (hosted by Emtel) and respectively Frankfurt, Germany (hosted by Vodafone DE): Speedtest.net result of 30.05.2013 between Flic en Flac and Rose Hill, Mauritius (Emtel - Fixed Broadband) Speedtest.net result of 30.05.2013 between Flic en Flac and Frankfurt, Germany (Emtel - Fixed Broadband) Luckily, the results are quite similar in terms of connection speed; which is good. I'm currently on a WiMAX tariff called 'Classic Browsing 2', or Fixed Broadband as they call it now, which provides a symmetric line of 768 Kbps (or roughly 0.75 Mbps). In terms of downloads or uploads this means that I would be able to transfer files in either direction with approximately 96 KB/s. Frankly speaking, thanks to compression, my choice of browser and operating system I usually exceed this value and I have download rates up to 120 KB/s - not too bad after all. Only the ping times are a little bit of concern. Due to the difference in distance, or better said based on the number of hubs between the endpoints, they indicate the amount of time that it takes to send a package from your machine to the remote server and get a response back. A lower value is better, and usually the ping is less than 300 ms between Mauritius and Europe. The alternatives in Mauritius Not sure whether I should note this done because for my requirements there are no alternatives to Emtel WiMAX at the moment. It would be great to have your opinion on the situation of internet connectivity in Mauritius. Are there really alternatives? And if so, what are the conditions?

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• Basic collision direction detection on 2d objects

  - by Osso Buko

  I am trying to develop a platform game for Android by using ANdroid GL Engine (ANGLE). And I am having trouble with collision detection. I have two objects which is shaped as rectangular. And no change in rotation. Here is a scheme of attributes of objects. What i am trying to do is when objects collide they block each other's movement on that direction. Every object has 4 boolean (bTop, bBottom, bRight, bLeft). For example when bBottom is true object can't advance on that direction. I came up with a solution but it seems it only works on one dimensional. Bottom and top or right and left. public void collisionPlatform (MyObject a, MyObject b) { // first obj is player and second is a wall or a platform Vector p1 = a.mPosition; // p1 = middle point of first object Vector d1 = a.mPosition2; // width(mX) and height of first object Vector mSpeed1 = a.mSpeed; // speed vector of first object Vector p2 = b.mPosition; // p1 = middle point of second object Vector d2 = b.mPosition2; // width(mX) and height of second object Vector mSpeed2 = b.mSpeed; // speed vector of second object float xDist, yDist; // distant between middle of two object float width , height; // this is average of two objects measurements width=(width1+width2)/2 xDist=(p1.mX - p2.mX); // calculate distance // if positive first object is at the right yDist=(p1.mY - p2.mY); // if positive first object is below width = d1.mX + d2.mX; // average measurements calculate height = d1.mY + d2.mY; width/=2; height/=2; if (Math.abs(xDist) < width && Math.abs(yDist) < height) { // Two object is collided if(p1.mY>p2.mY) { // first object is below second one a.bTop = true; if(a.mSpeed.mY<0) a.mSpeed.mY=0; b.bBottom = true; if(b.mSpeed.mY>0) b.mSpeed.mY=0; } else { a.bBottom = true; if(a.mSpeed.mY>0) a.mSpeed.mY=0; b.bTop = true; if(b.mSpeed.mY<0) b.mSpeed.mY=0; } } As seen in my code it simply will not work. when object comes from right or left it doesn't work. I tried couple of ways other than this one but none worked. I am guessing right method will include mSpeed vector. But I have no idea how to do it. I really appreciate if you could help. Sorry for my bad english.

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• Generic Adjacency List Graph implementation

  - by DmainEvent

  I am trying to come up with a decent Adjacency List graph implementation so I can start tooling around with all kinds of graph problems and algorithms like traveling salesman and other problems... But I can't seem to come up with a decent implementation. This is probably because I am trying to dust the cobwebs off my data structures class. But what I have so far... and this is implemented in Java... is basically an edgeNode class that has a generic type and a weight-in the event the graph is indeed weighted. public class edgeNode<E> { private E y; private int weight; //... getters and setters as well as constructors... } I have a graph class that has a list of edges a value for the number of Vertices and and an int value for edges as well as a boolean value for whether or not it is directed. The brings up my first question, if the graph is indeed directed, shouldn't I have a value in my edgeNode class? Or would I just need to add another vertices to my LinkedList? That would imply that a directed graph is 2X as big as an undirected graph wouldn't it? public class graph { private List<edgeNode<?>> edges; private int nVertices; private int nEdges; private boolean directed; //... getters and setters as well as constructors... } Finally does anybody have a standard way of initializing there graph? I was thinking of reading in a pipe-delimited file but that is so 1997. public graph GenereateGraph(boolean directed, String file){ List<edgeNode<?>> edges; graph g; try{ int count = 0; String line; FileReader input = new FileReader("C:\\Users\\derekww\\Documents\\JavaEE Projects\\graphFile"); BufferedReader bufRead = new BufferedReader(input); line = bufRead.readLine(); count++; edges = new ArrayList<edgeNode<?>>(); while(line != null){ line = bufRead.readLine(); Object edgeInfo = line.split("|")[0]; int weight = Integer.parseInt(line.split("|")[1]); edgeNode<String> e = new edgeNode<String>((String) edges.add(e); } return g; } catch(Exception e){ return null; } } I guess when I am adding edges if boolean is true I would be adding a second edge. So far, this all depends on the file I write. So if I wrote a file with the following Vertices and weights... Buffalo | 18 br Pittsburgh | 20 br New York | 15 br D.C | 45 br I would obviously load them into my list of edges, but how can I represent one vertices connected to the other... so on... I would need the opposite vertices? Say I was representing Highways connected to each city weighted and un-directed (each edge is bi-directional with weights in some fictional distance unit)... Would my implementation be the best way to do that? I found this tutorial online Graph Tutorial that has a connector object. This appears to me be a collection of vertices pointing to each other. So you would have A and B each with there weights and so on, and you would add this to a list and this list of connectors to your graph... That strikes me as somewhat cumbersome and a little dismissive of the adjacency list concept? Am I wrong and that is a novel solution? This is all inspired by steve skiena's Algorithm Design Manual. Which I have to say is pretty good so far. Thanks for any help you can provide.

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• How to place rooms proceduraly (rule based) on in a game word

  - by gardian06

  I am trying to design the algorithm for my level generation which is a rule driven system. I have created all the rules for the system. I have taken care to insure that all rooms make sense in a grid type setup. for example: these rooms could make this configuration The logic flow code that I have so far Door{ Vector3 position; POD orient; // 5 possible values (up is not an option) bool Open; } Room{ String roomRule; Vector3 roomPos; Vector3 dimensions; POD roomOrient; // 4 possible values List doors<Door>; } LevelManager{ float scale = 18f; List usedRooms<Room>; List openDoors<Door> bool Grid[][][]; Room CreateRoom(String rule, Vector3 position, POD Orient){ place recieved values based on rule fill in other data } Vector3 getDimenstions(String rule){ return dimensions of the room } RotateRoom(POD rotateAmount){ rotate all items in the room } MoveRoom(Room toBeMoved, POD orientataion, float distance){ move the position of the room based on inputs } GenerateMap(Vector3 size, Vector3 start, Vector3 end){ Grid = array[size.y][size.x][size.z]; Room floatingRoom; floatingRoom = Room.CreateRoom(S01, start, rand(4)); usedRooms.Add(floatingRoom); for each Door in floatingRoom.doors{ openDoors.Add(door); } // fill used grid spaces floatingRoom = Room.CreateRoom(S02, end, rand(4); usedRooms.Add(floatingRoom); for each Door in floatingRoom.doors{ openDoors.Add(door); } Vector3 nRoomLocation; Door workingDoor; string workingRoom; // fill used grid spaces // pick random door on the openDoors list workingDoor = /*randomDoor*/ // get a random rule nRoomLocation = workingDoor.position; // then I'm lost } } I know that I have to make sure for convergence (namely the end is reachable), and to do this until there are no more doors on the openDoors list. right now I am simply trying to get this to work in 2D (there are rules that introduce 3D), but I am working on a presumption that a rigorous algorithm can be trivially extended to 3D. EDIT: my thought pattern so far is to take an existing open door and then pick a random room (restrictions can be put in later) place that room's center at the doors location move the room in the direction of the doors orientation half the rooms dimension w/respect to that axis then test against the 3D array to see if all the grid points are open, or have been used, or if there is even space to put the room (caseEdge) if caseEdge (which can also occur in between rooms) then put the door on a toBeClosed list, and remove it from the open list (placing a wall or something there). then to do some kind of test that both the start, and the goal are connected, and reachable from each other (each room has nodes for AI, but I don't want to "have" to pull those out to accomplish this). but this logic has the problem for say the U, or L shaped rooms in my example, and then I also have a problem conceptually if the room needs to be rotated.

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• Multidimensional multiple-choice knapsack problem: find a feasible solution

  - by Onheiron

  My assignment is to use local search heuristics to solve the Multidimensional multiple-choice knapsack problem, but to do so I first need to find a feasible solution to start with. Here is an example problem with what I tried so far. Problem R1 R2 R3 RESOUCES : 8 8 8 GROUPS: G1: 11.0 3 2 2 12.0 1 1 3 G2: 20.0 1 1 3 5.0 2 3 2 G3: 10.0 2 2 3 30.0 1 1 3 Sorting strategies To find a starting feasible solution for my local search I decided to ignore maximization of gains and just try to fit the resources requirements. I decided to sort the choices (strategies) in each group by comparing their "distance" from the multidimensional space origin, thus calculating SQRT(R1^2 + R2^2 + ... + RN^2). I felt like this was a keen solution as it somehow privileged those choices with resouce usages closer to each other (e.g. R1:2 R2:2 R3:2 < R1:1 R2:2 R3:3) even if the total sum is the same. Doing so and selecting the best choice from each group proved sufficent to find a feasible solution for many[30] different benchmark problems, but of course I knew it was just luck. So I came up with the problem presented above which sorts like this: R1 R2 R3 RESOUCES : 8 8 8 GROUPS: G1: 12.0 1 1 3 < select this 11.0 3 2 2 G2: 20.0 1 1 3 < select this 5.0 2 3 2 G3: 30.0 1 1 3 < select this 10.0 2 2 3 And it is not feasible because the resources consmption is R1:3, R2:3, R3:9. The easy solution is to pick one of the second best choices in group 1 or 2, so I'll need some kind of iteration (local search[?]) to find the starting feasible solution for my local search solution. Here are the options I came up with Option 1: iterate choices I tried to find a way to iterate all the choices with a specific order, something like G1 G2 G3 1 1 1 2 1 1 1 2 1 1 1 2 2 2 1 ... believeng that feasible solutions won't be that far away from the unfeasible one I start with and thus the number of iterations will keep quite low. Does this make any sense? If yes, how can I iterate the choices (grouped combinations) of each group keeping "as near as possibile" to the previous iteration? Option 2: Change the comparation term I tried to think how to find a better variable to sort the choices on. I thought at a measure of how "precious" a resource is based on supply and demand, so that an higer demand of a more precious resource will push you down the list, but this didn't help at all. Also I thought there probably isn't gonna be such a comparsion variable which assures me a feasible solution at first strike. I there such a variable? If not, is there a better sorting criteria anyways? Option 3: implement any known sub-optimal fast solving algorithm Unfortunately I could not find any of such algorithms online. Any suggestion?

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• Is my implementation of A* wrong?

  - by Bloodyaugust

  I've implemented the A* algorithm in my program. However, it would seem to be functioning incorrectly at times. Below is a screenshot of one such time. The obviously shorter line is to go immediately right at the second to last row. Instead, they move down, around the tower, and continue to their destination (bottom right from top left). Below is my actual code implementation: nodeMap.prototype.findPath = function(p1, p2) { var openList = []; var closedList = []; var nodes = this.nodes; for (var i = 0; i < nodes.length; i++) { //reset heuristics and parents for nodes var curNode = nodes[i]; curNode.f = 0; curNode.g = 0; curNode.h = 0; curNode.parent = null; if (curNode.pathable === false) { closedList.push(curNode); } } openList.push(this.getNode(p1)); while(openList.length > 0) { // Grab the lowest f(x) to process next var lowInd = 0; for(i=0; i<openList.length; i++) { if(openList[i].f < openList[lowInd].f) { lowInd = i; } } var currentNode = openList[lowInd]; if (currentNode === this.getNode(p2)) { var curr = currentNode; var ret = []; while(curr.parent) { ret.push(curr); curr = curr.parent; } return ret.reverse(); } closedList.push(currentNode); for (i = 0; i < openList.length; i++) { //remove currentNode from openList if (openList[i] === currentNode) { openList.splice(i, 1); break; } } for (i = 0; i < currentNode.neighbors.length; i++) { if(closedList.indexOf(currentNode.neighbors[i]) !== -1 ) { continue; } if (currentNode.neighbors[i].isPathable === false) { closedList.push(currentNode.neighbors[i]); continue; } var gScore = currentNode.g + 1; // 1 is the distance from a node to it's neighbor var gScoreIsBest = false; if (openList.indexOf(currentNode.neighbors[i]) === -1) { //save g, h, and f then save the current parent gScoreIsBest = true; currentNode.neighbors[i].h = currentNode.neighbors[i].heuristic(this.getNode(p2)); openList.push(currentNode.neighbors[i]); } else if (gScore < currentNode.neighbors[i].g) { //current g better than previous g gScoreIsBest = true; } if (gScoreIsBest) { currentNode.neighbors[i].parent = currentNode; currentNode.neighbors[i].g = gScore; currentNode.neighbors[i].f = currentNode.neighbors[i].g + currentNode.neighbors[i].h; } } } return false; } Towers block pathability. Is there perhaps something I am missing here, or does A* not always find the shortest path in a situation such as this? Thanks in advance for any help.

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• Reading graph inputs for a programming puzzle and then solving it

  - by Vrashabh

  I just took a programming competition question and I absolutely bombed it. I had trouble right at the beginning itself from reading the input set. The question was basically a variant of this puzzle http://codercharts.com/puzzle/evacuation-plan but also had an hour component in the first line(say 3 hours after start of evacuation). It reads like this This puzzle is a tribute to all the people who suffered from the earthquake in Japan. The goal of this puzzle is, given a network of road and locations, to determine the maximum number of people that can be evacuated. The people must be evacuated from evacuation points to rescue points. The list of road and the number of people they can carry per hour is provided. Input Specifications Your program must accept one and only one command line argument: the input file. The input file is formatted as follows: the first line contains 4 integers n r s t n is the number of locations (each location is given by a number from 0 to n-1) r is the number of roads s is the number of locations to be evacuated from (evacuation points) t is the number of locations where people must be evacuated to (rescue points) the second line contains s integers giving the locations of the evacuation points the third line contains t integers giving the locations of the rescue points the r following lines contain to the road definitions. Each road is defined by 3 integers l1 l2 width where l1 and l2 are the locations connected by the road (roads are one-way) and width is the number of people per hour that can fit on the road Now look at the sample input set 5 5 1 2 3 0 3 4 0 1 10 0 2 5 1 2 4 1 3 5 2 4 10 The 3 in the first line is the additional component and is defined as the number of hours since the resuce has started which is 3 in this case. Now my solution was to use Dijisktras algorithm to find the shortest path between each of the rescue and evac nodes. Now my problem started with how to read the input set. I read the first line in python and stored the values in variables. But then I did not know how to store the values of the distance between the nodes and what DS to use and how to input it to say a standard implementation of dijikstras algorithm. So my question is two fold 1.) How do I take the input of such problems? - I have faced this problem in quite a few competitions recently and I hope I can get a simple code snippet or an explanation in java or python to read the data input set in such a way that I can input it as a graph to graph algorithms like dijikstra and floyd/warshall. Also a solution to the above problem would also help. 2.) How to solve this puzzle? My algorithm was: Find shortest path between evac points (in the above example it is 14 from 0 to 3) Multiply it by number of hours to get maximal number of saves Also the answer given for the variant for the input set was 24 which I dont understand. Can someone explain that also. UPDATE: I get how the answer is 14 in the given problem link - it seems to be just the shortest path between node 0 and 3. But with the 3 hour component how is the answer 24 UPDATE I get how it is 24 - its a complete graph traversal at every hour and this is how I solve it Hour 1 Node 0 to Node 1 - 10 people Node 0 to Node 2- 5 people TotalRescueCount=0 Node 1=10 Node 2= 5 Hour 2 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5(Rescued) Node 0 to Node 1 = 10 Node 0 to Node 2 = 5 Node 1 to Node 2 = 4 TotalRescueCount = 10 Node 1 = 10 Node 2= 5+4 = 9 Hour 3 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5+4 = 9(Rescued) TotalRescueCount = 9+5+10 = 24 It hard enough for this case , for multiple evac and rescue points how in the world would I write a pgm for this ?

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• jerky animation using Core Animation

  - by Paul from Boston

  In my iPhone app, I am trying to get some red and white stripes that are scrolling across the screen to animate smoothly when the speed of the stripes gets high. In my app the user starts the animation and changes the scrolling speed by a finger swipe and changes the width of the stripes by a two finger pinch. Animation is stopped in response to a double tap. If the speed gets high or the stripes get narrow the animation is no longer smooth to the eye. The edges of the stripes seem to jump around. The animation is simple. I draw the stripes in a layer that's a bit larger than the screen. I then set up an animation that moves the layer position by exactly the distance from one red stripe to the next. The duration is set by the speed of the finger swipe and the repeat count is 1. When the animation stops the delegate checks a flag to see if the user wants to stop the scrolling. If not, the animation is restarted again for one cycle. Are there better ways of doing this so that the animation is smooth at high speeds or with narrow stripes? Thanks--

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