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  • Simulating smooth movement along a line after calculating a collision containing a restitution of zero in 2D

    - by Casey
    [for tl;dr see after listing] //...Code to determine shapes types involved in collision here... //...Rectangle-Line collision detected. if(_rbTest->GetCollisionShape()->Intersects(*_ground->GetCollisionShape())) { //Convert incoming shape to a line. a2de::Line l(*dynamic_cast<a2de::Line*>(_ground->GetCollisionShape())); //Get line's normal. a2de::Vector2D normal_vector(l.GetSlope().GetY(), -l.GetSlope().GetX()); a2de::Vector2D::Normalize(normal_vector); //Accumulate forces involved. a2de::Vector2D intermediate_forces; a2de::Vector2D normal_force = normal_vector * _rbTest->GetMass() * _world->GetGravityHandler()->GetGravityValue(); intermediate_forces += normal_force; //Calculate final velocity: See [1] double Ma = _rbTest->GetMass(); a2de::Vector2D Ua = _rbTest->GetVelocity(); double Mb = _ground->GetMass(); a2de::Vector2D Ub = _ground->GetVelocity(); double mCr = Mb * _ground->GetRestitution(); a2de::Vector2D collision_velocity( ((Ma * Ua) + (Mb * Ub) + ((mCr * Ub) - (mCr * Ua))) / (Ma + Mb)); //Calculate reflection vector: See [2] a2de::Vector2D reflect_velocity( -collision_velocity + 2 * (a2de::Vector2D::DotProduct(collision_velocity, normal_vector)) * normal_vector ); //Affect velocity to account for restitution of colliding bodies. reflect_velocity *= (_ground->GetRestitution() * _rbTest->GetRestitution()); _rbTest->SetVelocity(reflect_velocity); //THE ULTIMATE ISSUE STEMS FROM THE FOLLOWING LINE: //Move object away from collision one pixel to prevent constant collision. _rbTest->SetPosition(_rbTest->GetPosition() + normal_vector); _rbTest->ApplyImpulse(intermediate_forces); } Sources: (1) Wikipedia: Coefficient of Restitution: Speeds after impact (2) Wikipedia: Specular Reflection: Direction of reflection First, I have a system in place to account for friction (that is, a coefficient of friction) but is not used right now (in addition, it is zero, which should not affect the math anyway). I'll deal with that after I get this working. Anyway, when the restitution of either object involved in the collision is zero the object stops as required, but if movement along the same direction (again, irrespective of the friction value that isn't used) as the line is attempted the object moves as if slogging through knee deep snow. If I remove the line of code in question and the object is not push away one pixel the object barely moves at all. All because the object collides, is stopped, is pushed up, collides, is stopped...etc. OR collides, is stopped, collides, is stopped, etc... TL;DR How do I only account for a collision ONCE for restitution purposes (BONUS: but CONTINUALLY for frictional purposes, to be implemented later)

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  • Council for the Development of a jumping game!

    - by Esteban Quintero
    I want to create platforms on the stage, where a sprite is jumping on them. something like this http://itunes.apple.com/es/app/doodle-jump-cuidado-extremadamente/id307727765?mt=8 I would like some guidance to do so. 1) what is the best way to simulate the jump? (Velocity or EnityModifier) 2) as platforms rabdom I can generate, with no overlap? 3) should move the camera or the sprites of the stage?

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  • What different ways are there to model restitution in a physics engine?

    - by Mikael Högström
    In my physics engine I give a body a value for restitution between 0 and 1. When two bodies collide there seems to be different views on how the restitution of the collision should be calculated. To me the most intuitive seems to be to take the average of the two but some seem to take only the largest one. Are there other ways to do it? Also, could the closing velocity or some other parameter come into effect?

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  • How to implement smooth flocking

    - by Craig
    I'm working on a simple survival game, avoid the big guy and chase the the small guys to stay alive for as long as possible. I have taken the chase and evade example from MSDN create and drawn 20 mice on the screen. I want the small guys to flock when they arent evading. They are doing this, but it isnt as smooth as I would like it to be. How do i make the movement smoother? Its very jittery.# Below is what I have going at the moment, flocking code is within the IF statement, when it isnt set to evading. Any help would be greatly appreciated! :) namespace ChaseAndEvade { class MouseSprite { public enum MouseAiState { // evading the cat Evading, // the mouse can't see the "cat", and it's wandering around. Wander } // how fast can the mouse move? public float MaxMouseSpeed = 4.5f; // and how fast can it turn? public float MouseTurnSpeed = 0.20f; // MouseEvadeDistance controls the distance at which the mouse will flee from // cat. If the mouse is further than "MouseEvadeDistance" pixels away, he will // consider himself safe. public float MouseEvadeDistance = 100.0f; // this constant is similar to TankHysteresis. The value is larger than the // tank's hysteresis value because the mouse is faster than the tank: with a // higher velocity, small fluctuations are much more visible. public float MouseHysteresis = 60.0f; public Texture2D mouseTexture; public Vector2 mouseTextureCenter; public Vector2 mousePosition; public MouseAiState mouseState = MouseAiState.Wander; public float mouseOrientation; public Vector2 mouseWanderDirection; int separationImpact = 4; int cohesionImpact = 6; int alignmentImpact = 2; int sensorDistance = 50; public void UpdateMouse(Vector2 position, MouseSprite [] mice, int numberMice, int index) { Vector2 catPosition = position; int enemies = numberMice; // first, calculate how far away the mouse is from the cat, and use that // information to decide how to behave. If they are too close, the mouse // will switch to "active" mode - fleeing. if they are far apart, the mouse // will switch to "idle" mode, where it roams around the screen. // we use a hysteresis constant in the decision making process, as described // in the accompanying doc file. float distanceFromCat = Vector2.Distance(mousePosition, catPosition); // the cat is a safe distance away, so the mouse should idle: if (distanceFromCat > MouseEvadeDistance + MouseHysteresis) { mouseState = MouseAiState.Wander; } // the cat is too close; the mouse should run: else if (distanceFromCat < MouseEvadeDistance - MouseHysteresis) { mouseState = MouseAiState.Evading; } // if neither of those if blocks hit, we are in the "hysteresis" range, // and the mouse will continue doing whatever it is doing now. // the mouse will move at a different speed depending on what state it // is in. when idle it won't move at full speed, but when actively evading // it will move as fast as it can. this variable is used to track which // speed the mouse should be moving. float currentMouseSpeed; // the second step of the Update is to change the mouse's orientation based // on its current state. if (mouseState == MouseAiState.Evading) { // If the mouse is "active," it is trying to evade the cat. The evasion // behavior is accomplished by using the TurnToFace function to turn // towards a point on a straight line facing away from the cat. In other // words, if the cat is point A, and the mouse is point B, the "seek // point" is C. // C // B // A Vector2 seekPosition = 2 * mousePosition - catPosition; // Use the TurnToFace function, which we introduced in the AI Series 1: // Aiming sample, to turn the mouse towards the seekPosition. Now when // the mouse moves forward, it'll be trying to move in a straight line // away from the cat. mouseOrientation = ChaseAndEvadeGame.TurnToFace(mousePosition, seekPosition, mouseOrientation, MouseTurnSpeed); // set currentMouseSpeed to MaxMouseSpeed - the mouse should run as fast // as it can. currentMouseSpeed = MaxMouseSpeed; } else { // if the mouse isn't trying to evade the cat, it should just meander // around the screen. we'll use the Wander function, which the mouse and // tank share, to accomplish this. mouseWanderDirection and // mouseOrientation are passed by ref so that the wander function can // modify them. for more information on ref parameters, see // http://msdn2.microsoft.com/en-us/library/14akc2c7(VS.80).aspx ChaseAndEvadeGame.Wander(mousePosition, ref mouseWanderDirection, ref mouseOrientation, MouseTurnSpeed); // if the mouse is wandering, it should only move at 25% of its maximum // speed. currentMouseSpeed = .25f * MaxMouseSpeed; Vector2 separate = Vector2.Zero; Vector2 moveCloser = Vector2.Zero; Vector2 moveAligned = Vector2.Zero; // What the AI does when it sees other AIs for (int j = 0; j < enemies; j++) { if (index != j) { // Calculate a vector towards another AI Vector2 separation = mice[index].mousePosition - mice[j].mousePosition; // Only react if other AI is within a certain distance if ((separation.Length() < this.sensorDistance) & (separation.Length()> 0) ) { moveAligned += mice[j].mouseWanderDirection; float distance = Math.Abs(separation.Length()); if (distance == 0) distance = 1; moveCloser += mice[j].mousePosition; separation.Normalize(); separate += separation / distance; } } } if (moveAligned.LengthSquared() != 0) { moveAligned.Normalize(); } if (moveCloser.LengthSquared() != 0) { moveCloser.Normalize(); } moveCloser /= enemies; mice[index].mousePosition += (separate * separationImpact) + (moveCloser * cohesionImpact) + (moveAligned * alignmentImpact); } // The final step is to move the mouse forward based on its current // orientation. First, we construct a "heading" vector from the orientation // angle. To do this, we'll use Cosine and Sine to tell us the x and y // components of the heading vector. See the accompanying doc for more // information. Vector2 heading = new Vector2( (float)Math.Cos(mouseOrientation), (float)Math.Sin(mouseOrientation)); // by multiplying the heading and speed, we can get a velocity vector. the // velocity vector is then added to the mouse's current position, moving him // forward. mousePosition += heading * currentMouseSpeed; } } }

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  • The only metric with any value

    - by Malcolm Anderson
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} There's a lot of talk in the Scrum world about metrics. What's the velocity? How big is a story point?  How many story points is that team producing per man hour?   People are sadly missing the whole point.  Take your measurements up a level or two.  When you get down to it, the only metric that makes any difference, is ROI.   The problem is that often times, the developers work in a dark hole, far removed from the realities of how exactly they get paid.  A bigger problem is that mid-level managers tend to be further removed from the realities of ROI.  A lot of times mid-level managers get tasked with tracking their teams "productivity" using things like, "lines of code", or "completeness of the productivity reports."   Monetize your projects and then track your velocity against business value (real dollars).    When your development teams can say, "Last year, our team cost the business 2 million dollars and we know that because of our efforts, the company saved 2 million dollars in waste and increased revenues by another 4 million dollars." At that point you have just moved your development team from a cost center, to a profit center.  You might have to give them a raise, but they have demonstrated that they have earned it.

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  • Diminishing Returns on Additional Developers

    - by smp7d
    Is there a term to describe the point at which adding more developers to a software project will provide diminishing returns? I realize that at a high level, it is more complicated that just a number of developers at which the project will be at productive capacity (ex/ state of the project, quality of the added developer), but I am trying to come up with a way to relate this to non-technical management through repetition. I'm basically looking for a term which invokes a strong image like "terminal velocity", except for Brook's Law.

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  • 12 days to go for Messenger!

    - by TATWORTH
    In just over twelve days from now, the Messenger space probe will go into orbit around our innermost planet, Mercury. See http://messenger.jhuapl.edu/index.php for latest mission timings. After 2405 days in space and 15+ circuits of the sun (see http://messenger.jhuapl.edu/whereis/index.php), it about to go into orbit around Mercury. It has flown by Earth, Venus and Mercury in order to change velocity sufficiently to be able to go into orbit without requiring a massive amount of propellant.

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  • Mozilla développe un moteur DOM multi-thread, première application pratique du langage concurrentiel "Rust" créé par la fondation

    Mozilla développe un moteur DOM multi-thread Première application pratique du langage concurrentiel "Rust" créé par la fondation Durant la conférence « Velocity » clôturée hier à Santa Clara, la fondation Mozilla a affiché ses ambitions de créer un moteur DOM multithread, permettant à plusieurs coeurs du processeur de participer au rendu des pages Web. L'open source évangéliste Chris Blizzard croit fort en tout cas à ce projet, affirmant durant sa présentation qu'il s'agit là d'un domaine de recherche actif auquel il convie tous les développeurs. Le projet n'en est qu'à ses balbutiements et sera l'une des premières applications sérieuses

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  • Using NumPy arrays as 2D mathematical vectors?

    - by CorundumGames
    Right now I'm using lists as position, velocity, and acceleration vectors in my game. Is that a better option than using NumPy's arrays (not the standard library's) as vectors (with float data types)? I'm frequently adding vectors and changing their values directly, then placing the values in these vectors into a Pygame Rect. The vector is used for position (because Rects can't hold floats, so we can't go "between" pixels), and the Rect is used for rendering (because Pygame will only take in Rects for rendering positions).

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  • Fast Data Executive Round Table FY14 event kit

    - by JuergenKress
    We are very interested to run joint marketing events jointly with you as our partners! At our SOA Community Workspace (SOA Community membership required) you can find a new Fast Data Executive Round Table FY14 event kit. This event is designed at senior IT and executives level for the purposes of education, awareness, and thought leadership around the subject of big data; and a specific flavor of big data - Fast Data - that has begun to spark the imagination of many Oracle customers. Fast Data is not new. It’s a term that was invented initially by Ovum’s Tony Baer as a way to represent the collection of ‘high velocity’ solutions with respect to the big data. For Oracle, the Fast Data campaign in FY13 began as a way to tie a broader set of solutions together (SOA/Business Process Management, Data Integration and Business Analytics) under a set of use cases focused on real-time, high velocity data. It has helped to give Oracle a leap-frog advantage over many of the niche integration vendors (i.e. Informatica, Pega, Tibco, Software AG, Terracotta) who haven’t been able to address these types of end-to-end use cases which rely on the combination of filtering, in-memory data processing, correlation, real-time data movement and transformation, end-to-end analytics, and business process management. Only Oracle can address all the dimensions of fast data, and only Oracle can provide a set of engineered solutions to address this space. This event is designed to continue that thought leadership momentum and raise the awareness about what Oracle Fast Data solutions are designed to solve. It’s designed to highlight real customer solutions and articulate the business benefits that fast data can address. This is not an event that gets into the esoteric technical standards of Hadoop, NoSQL, and in-memory data grids. This is an event that instead gets into the heart of business problems that big data has left un-addressed and charts the path for next steps in fast data. Get the Fast Data Executive Round Table FY14 event kit here. Support marketing campaigns We can support such events by: Oracle speakers - contact your partner manager Marketing budget - contact your A&C marketing manager Event location - free use of Oracle Customer Visitor Centers conference rooms Promote your event at events.oracle.com: http://tinyurl.com/eventspecialized E-Blast: invite customers to your event – contact your A&C marketing manager For additional marketing kits e.g for Business Process Managementplease visit our SOA Community Workspace. SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags:

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  • Common Misconceptions in Physics [Video]

    - by Jason Fitzpatrick
    Take a tour of common misconceptions in physics–such as the nature of gravity and velocity–with this brief and simply animated video courtesy of MinutePhysics. Common Physics Misconceptions [via Neatorama] How to Factory Reset Your Android Phone or Tablet When It Won’t Boot Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode

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  • Point line collision reaction

    - by user4523
    I am trying to program point line segment collision detection and reaction. I am doing this for fun and to learn. The point moves (it has a velocity, and can be controlled by the user), whilst the lines are strait and stationary. The lines are not axis aligned. Everything is in 2D. It is quite straight forward to work out if a collision has occurred. For each frame, the point moves from A to B. AB is a line, and if it crosses the line segment, a collision has occurred (or will occur) and I am able to work out the point of intersection (poi). The problem I am having is with the reaction. Ideally I would like the point to be prevented from moving across the line. In one frame, I can move the point back to the poi (or only alow it to move as far as the poi), and alter the velocity. The problem I am having with this approach (I think) is that, next frame the user may try to cross the line again. Although the point is on the poi, the point may not be exactly on the line. Since it is not axis aligned, I think there is always some subtle rounding issue (A float representation of a point on a line might be rounded to a point that is slightly on one side or the other). Because of this, next frame the path might not intersect the line (because it can start on the other side and move away from it) and the point is effectively allowed to cross the line. Firstly, does the analysis sound correct? Having accepted (maybe) that I cannot always exactly position the point on the line, I tried to move the point away from the line slightly (either along the normal to the line, or along the path vector). I then get a problem at edges. Attempting to fix one collision by moving the point away from the line (even slightly) can cause it to cross another line (one shape I am dealing with is a star, with sharp corners). This can mean that the solution to one collision inadvertently creates another collision, which is ignored. Again, does this sound correct? Anyway, whatever I try, I am having difficulty with edges, and the point is occasionally able to penetrate the polygons and cross lines, which is undesirable. Whilst I can find a lot of information about collision detection on the web (and on this site) I can find precious little information on collision reaction. Does any one know of any good point line collision reaction tutorials? Or is my approach too flawed/over complicated?

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  • Chapter 5: From 2005 to 2010: Business Logic and Data

    After reading this chapter, you will be able to Use the Entity Framework (EF) to build a data access layer using an existing database or with the Model-First approach .Generate entity types from the Entity Data Model (EDM) Designer using the ADO.NET Entity Framework POCO templates. Get data from Web services Learn about data caching using the Microsoft Windows Server AppFabric (formerly known by the codename “Velocity”)

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  • Andengine. Put bullet to pool, when it leaves screen

    - by Ashot
    i'm creating a bullet with physics body. Bullet class (extends Sprite class) has die() method, which unregister physics connector, hide sprite and put it in pool public void die() { Log.d("bulletDie", "See you in hell!"); if (this.isVisible()) { this.setVisible(false); mPhysicsWorld.unregisterPhysicsConnector(physicsConnector); physicsConnector.setUpdatePosition(false); body.setActive(false); this.setIgnoreUpdate(true); bulletsPool.recyclePoolItem(this); } } in onUpdate method of PhysicsConnector i executes die method, when sprite leaves screen physicsConnector = new PhysicsConnector(this,body,true,false) { @Override public void onUpdate(final float pSecondsElapsed) { super.onUpdate(pSecondsElapsed); if (!camera.isRectangularShapeVisible(_bullet)) { Log.d("bulletDie","Dead?"); _bullet.die(); } } }; it works as i expected, but _bullet.die() executes TWICE. what i`m doing wrong and is it right way to hide sprites? here is full code of Bullet class (it is inner class of class that represents player) private class Bullet extends Sprite implements PhysicsConstants { private final Body body; private final PhysicsConnector physicsConnector; private final Bullet _bullet; private int id; public Bullet(float x, float y, ITextureRegion texture, VertexBufferObjectManager vertexBufferObjectManager) { super(x,y,texture,vertexBufferObjectManager); _bullet = this; id = bulletId++; body = PhysicsFactory.createCircleBody(mPhysicsWorld, this, BodyDef.BodyType.DynamicBody, bulletFixture); physicsConnector = new PhysicsConnector(this,body,true,false) { @Override public void onUpdate(final float pSecondsElapsed) { super.onUpdate(pSecondsElapsed); if (!camera.isRectangularShapeVisible(_bullet)) { Log.d("bulletDie","Dead?"); Log.d("bulletDie",id+""); _bullet.die(); } } }; mPhysicsWorld.registerPhysicsConnector(physicsConnector); $this.getParent().attachChild(this); } public void reset() { final float angle = canon.getRotation(); final float x = (float) ((Math.cos(MathUtils.degToRad(angle))*radius) + centerX) / PIXEL_TO_METER_RATIO_DEFAULT; final float y = (float) ((Math.sin(MathUtils.degToRad(angle))*radius) + centerY) / PIXEL_TO_METER_RATIO_DEFAULT; this.setVisible(true); this.setIgnoreUpdate(false); body.setActive(true); mPhysicsWorld.registerPhysicsConnector(physicsConnector); body.setTransform(new Vector2(x,y),0); } public Body getBody() { return body; } public void setLinearVelocity(Vector2 velocity) { body.setLinearVelocity(velocity); } public void die() { Log.d("bulletDie", "See you in hell!"); if (this.isVisible()) { this.setVisible(false); mPhysicsWorld.unregisterPhysicsConnector(physicsConnector); physicsConnector.setUpdatePosition(false); body.setActive(false); this.setIgnoreUpdate(true); bulletsPool.recyclePoolItem(this); } } }

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  • Physics Engine [Collision Response, 2-dimensional] experts, help!! My stack is unstable!

    - 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 hardly stand still! 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: I would try adding a damping term (proportional to velocity) to the Baumgarte. Is this a good idea in general? If not I would not want to waste my time trying to tune the parameter hoping it magically works. 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!! :)

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  • Google sort Page Visibilty API, l'outil détermine l'état d'un site pour réduire son activité lorsqu'il est en cache ou en arrière-plan

    Google sort Page Visibilty API Une API permettant de déterminer l'état d'un site Web pour réduire son activité La famille des API de Google vient de s'enrichir d'une nouvelle API expérimentale. Présentée lors de la conférence O'Reilly's Velocity qui s'est tenue en Californie, Page Visibility permet aux sites Web de détecter s'ils sont affichés dans un onglet en cours de consultation par l'utilisateur ou dans un onglet en arrière plan. Elle peut également être utilisée pour savoir quand une page est mise en cache par un moteur de recherche comme Google avec sa nouvelle fonctionnalité d'affichage instantané .

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  • How do I get a collision event from a KActor subclass?

    - by Almo
    I have a subclass of KActor, and I want an event when it collides with things. event RigidBodyCollision seems to be what I want according to this http://wiki.beyondunreal.com/UE3:Actor_events_%28UDK%29#RigidBodyCollision Called when a PrimitiveComponent this Actor owns has: -bNotifyRigidBodyCollision set to true -ScriptRigidBodyCollisionThreshold greater than 0 -it is involved in a physics collision where the relative velocity exceeds ScriptRigidBodyCollisionThreshold As far as I can tell, I have these set up, and the event is not called for any collisions (KActor-KActor, KActor-world geometry, etc). Is there something else I need to do?

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  • Big GRC: Turning Data into Actionable GRC Intelligence

    - by Jenna Danko
    While it’s no longer headline news that Governments have carried out large scale data-mining programmes aimed at terrorism detection and identifying other patterns of interest across a wide range of digital data sources, the debate over the ethics and justification over this action, will clearly continue for some time to come. What is becoming clear is that these programmes are a framework for the collation and aggregation of massive amounts of unstructured data and from this, the creation of actionable intelligence from analyses that allowed the analysts to explore and extract a variety of patterns and then direct resources. This data included audio and video chats, phone calls, photographs, e-mails, documents, internet searches, social media posts and mobile phone logs and connections. Although Governance, Risk and Compliance (GRC) professionals are not looking at the implementation of such programmes, there are many similar GRC “Big data” challenges to be faced and potential lessons to be learned from these high profile government programmes that can be applied a lot closer to home. For example, how can GRC professionals collect, manage and analyze an enormous and disparate volume of data to create and manage their own actionable intelligence covering hidden signs and patterns of criminal activity, the early or retrospective, violation of regulations/laws/corporate policies and procedures, emerging risks and weakening controls etc. Not exactly the stuff of James Bond to be sure, but it is certainly more applicable to most GRC professional’s day to day challenges. So what is Big Data and how can it benefit the GRC process? Although it often varies, the definition of Big Data largely refers to the following types of data: Traditional Enterprise Data – includes customer information from CRM systems, transactional ERP data, web store transactions, and general ledger data. Machine-Generated /Sensor Data – includes Call Detail Records (“CDR”), weblogs and trading systems data. Social Data – includes customer feedback streams, micro-blogging sites like Twitter, and social media platforms like Facebook. The McKinsey Global Institute estimates that data volume is growing 40% per year, and will grow 44x between 2009 and 2020. But while it’s often the most visible parameter, volume of data is not the only characteristic that matters. In fact, according to sources such as Forrester there are four key characteristics that define big data: Volume. Machine-generated data is produced in much larger quantities than non-traditional data. This is all the data generated by IT systems that power the enterprise. This includes live data from packaged and custom applications – for example, app servers, Web servers, databases, networks, virtual machines, telecom equipment, and much more. Velocity. Social media data streams – while not as massive as machine-generated data – produce a large influx of opinions and relationships valuable to customer relationship management as well as offering early insight into potential reputational risk issues. Even at 140 characters per tweet, the high velocity (or frequency) of Twitter data ensures large volumes (over 8 TB per day) need to be managed. Variety. Traditional data formats tend to be relatively well defined by a data schema and change slowly. In contrast, non-traditional data formats exhibit a dizzying rate of change. Without question, all GRC professionals work in a dynamic environment and as new services, new products, new business lines are added or new marketing campaigns executed for example, new data types are needed to capture the resultant information.  Value. The economic value of data varies significantly. Typically, there is good information hidden amongst a larger body of non-traditional data that GRC professionals can use to add real value to the organisation; the greater challenge is identifying what is valuable and then transforming and extracting that data for analysis and action. For example, customer service calls and emails have millions of useful data points and have long been a source of information to GRC professionals. Those calls and emails are critical in helping GRC professionals better identify hidden patterns and implement new policies that can reduce the amount of customer complaints.   Now on a scale and depth far beyond those in place today, all that unstructured call and email data can be captured, stored and analyzed to reveal the reasons for the contact, perhaps with the aggregated customer results cross referenced against what is being said about the organization or a similar peer organization on social media. The organization can then take positive actions, communicating to the market in advance of issues reaching the press, strengthening controls, adjusting risk profiles, changing policy and procedures and completely minimizing, if not eliminating, complaints and compensation for that specific reason in the future. In this one example of many similar ones, the GRC team(s) has demonstrated real and tangible business value. Big Challenges - Big Opportunities As pointed out by recent Forrester research, high performing companies (those that are growing 15% or more year-on-year compared to their peers) are taking a selective approach to investing in Big Data.  "Tomorrow's winners understand this, and they are making selective investments aimed at specific opportunities with tangible benefits where big data offers a more economical solution to meet a need." (Forrsights Strategy Spotlight: Business Intelligence and Big Data, Q4 2012) As pointed out earlier, with the ever increasing volume of regulatory demands and fines for getting it wrong, limited resource availability and out of date or inadequate GRC systems all contributing to a higher cost of compliance and/or higher risk profile than desired – a big data investment in GRC clearly falls into this category. However, to make the most of big data organizations must evolve both their business and IT procedures, processes, people and infrastructures to handle these new high-volume, high-velocity, high-variety sources of data and be able integrate them with the pre-existing company data to be analyzed. GRC big data clearly allows the organization access to and management over a huge amount of often very sensitive information that although can help create a more risk intelligent organization, also presents numerous data governance challenges, including regulatory compliance and information security. In addition to client and regulatory demands over better information security and data protection the sheer amount of information organizations deal with the need to quickly access, classify, protect and manage that information can quickly become a key issue  from a legal, as well as technical or operational standpoint. However, by making information governance processes a bigger part of everyday operations, organizations can make sure data remains readily available and protected. The Right GRC & Big Data Partnership Becomes Key  The "getting it right first time" mantra used in so many companies remains essential for any GRC team that is sponsoring, helping kick start, or even overseeing a big data project. To make a big data GRC initiative work and get the desired value, partnerships with companies, who have a long history of success in delivering successful GRC solutions as well as being at the very forefront of technology innovation, becomes key. Clearly solutions can be built in-house more cheaply than through vendor, but as has been proven time and time again, when it comes to self built solutions covering AML and Fraud for example, few have able to scale or adapt appropriately to meet the changing regulations or challenges that the GRC teams face on a daily basis. This has led to the creation of GRC silo’s that are causing so many headaches today. The solutions that stand out and should be explored are the ones that can seamlessly merge the traditional world of well-known data, analytics and visualization with the new world of seemingly innumerable data sources, utilizing Big Data technologies to generate new GRC insights right across the enterprise.Ultimately, Big Data is here to stay, and organizations that embrace its potential and outline a viable strategy, as well as understand and build a solid analytical foundation, will be the ones that are well positioned to make the most of it. A Blueprint and Roadmap Service for Big Data Big data adoption is first and foremost a business decision. As such it is essential that your partner can align your strategies, goals, and objectives with an architecture vision and roadmap to accelerate adoption of big data for your environment, as well as establish practical, effective governance that will maintain a well managed environment going forward. Key Activities: While your initiatives will clearly vary, there are some generic starting points the team and organization will need to complete: Clearly define your drivers, strategies, goals, objectives and requirements as it relates to big data Conduct a big data readiness and Information Architecture maturity assessment Develop future state big data architecture, including views across all relevant architecture domains; business, applications, information, and technology Provide initial guidance on big data candidate selection for migrations or implementation Develop a strategic roadmap and implementation plan that reflects a prioritization of initiatives based on business impact and technology dependency, and an incremental integration approach for evolving your current state to the target future state in a manner that represents the least amount of risk and impact of change on the business Provide recommendations for practical, effective Data Governance, Data Quality Management, and Information Lifecycle Management to maintain a well-managed environment Conduct an executive workshop with recommendations and next steps There is little debate that managing risk and data are the two biggest obstacles encountered by financial institutions.  Big data is here to stay and risk management certainly is not going anywhere, and ultimately financial services industry organizations that embrace its potential and outline a viable strategy, as well as understand and build a solid analytical foundation, will be best positioned to make the most of it. Matthew Long is a Financial Crime Specialist for Oracle Financial Services. He can be reached at matthew.long AT oracle.com.

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  • ViewPager and Fragment Pager adapter implementation

    - by Rohit Deshmukh
    So I am trying to implement sliding views/fragments using viewpager and fragment pager adapter. convert_home is my main xml file that has android.support.v4.view.PagerTitleStrip and temperature.xml and velocity.xml are my two other views. I have no clue where I am going wrong. package app.converto; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.view.LayoutInflater; import android.view.Menu; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; public class ConverTo extends FragmentActivity { SectionsPagerAdapter mSectionsPagerAdapter; ViewPager mViewPager; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager()); mViewPager.setAdapter(mSectionsPagerAdapter); setContentView(R.layout.converto_home); mViewPager = (ViewPager) findViewById(R.id.pager); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.converto_home, menu); return true; } public class SectionsPagerAdapter extends FragmentPagerAdapter { public SectionsPagerAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int i) { switch(i){ case 0: Fragment1 fragment = new Fragment1(); return fragment; case 1: Fragment2 fragment2 = new Fragment2(); return fragment2; } defaultFragment fragment3 = new defaultFragment(); return fragment3; } @Override public int getCount() { return 2; } // // @Override // public CharSequence getPageTitle(int position) { // switch (position) { // case 0: return getString(R.string.velocity); // case 1: return getString(R.string.temperature); // case 2: return getString(R.string.distance); // } // return null; // } } public static class Fragment1 extends Fragment{ public Fragment1(){ } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { //return inflater.inflate(R.layout.temperature, container, false); View view = inflater.inflate(R.layout.temperature, container, false); TextView textView = (TextView) view.findViewById(R.id.sample); textView.setText(getArguments().getString("title")); return view; } } public static class Fragment2 extends Fragment{ public Fragment2(){ } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { //return inflater.inflate(R.layout.velocity, container, false); View view = inflater.inflate(R.layout.temperature, container, false); TextView textView = (TextView) view.findViewById(R.id.sample); textView.setText(getArguments().getString("title")); return view; } } public static class defaultFragment extends Fragment{ public defaultFragment(){ }//end constructor @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // return inflater.inflate(R.layout.temperature, container, false); View view = inflater.inflate(R.layout.temperature, container, false); TextView textView = (TextView) view.findViewById(R.id.sample); textView.setText(getArguments().getString("title")); return view; }//end oncreate }//end default fragment }

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  • How can I change mouse keymapping

    - by zuberuber
    I have Razer DeathAdder(left handed edition) and A4Tech wireless mouse. My problem is I don't know how to change wireless mouse keymapping(swaping left/right click). Can somebody guide me how to do such thing? List of my devices: ? Virtual core pointer id=2 [master pointer (3)] ? ? Virtual core XTEST pointer id=4 [slave pointer (2)] ? ? Logitech Unifying Device. Wireless PID:4004 id=8 [slave pointer (2)] ? ? Razer Razer DeathAdder id=11 [slave pointer (2)] ? ? A4TECH USB Device id=12 [slave pointer (2)] ? ? A4TECH USB Device id=13 [slave pointer (2)] ? Virtual core keyboard id=3 [master keyboard (2)] ? Virtual core XTEST keyboard id=5 [slave keyboard (3)] ? Power Button id=6 [slave keyboard (3)] ? Power Button id=7 [slave keyboard (3)] ? Logitech USB Keyboard id=9 [slave keyboard (3)] ? Logitech USB Keyboard id=10 [slave keyboard (3)] This is my Razer xinput: Device 'Razer Razer DeathAdder': Device Enabled (121): 1 Coordinate Transformation Matrix (123): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000 Device Accel Profile (246): 0 Device Accel Constant Deceleration (247): 5.000000 Device Accel Adaptive Deceleration (248): 1.000000 Device Accel Velocity Scaling (249): 10.000000 Device Product ID (240): 5426, 22 Device Node (241): "/dev/input/event4" Evdev Axis Inversion (250): 0, 0 Evdev Axes Swap (252): 0 Axis Labels (253): "Rel X" (131), "Rel Y" (132), "Rel Vert Wheel" (274) Button Labels (254): "Button Left" (124), "Button Middle" (125), "Button Right" (126), "Button Wheel Up" (127), "Button Wheel Down" (128), "Button Horiz Wheel Left" (129), "Button Horiz Wheel Right" (130), "Button Side" (269), "Button Extra" (270), "Button Forward" (271), "Button Back" (272), "Button Task" (273), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243) Evdev Middle Button Emulation (255): 0 Evdev Middle Button Timeout (256): 50 Evdev Third Button Emulation (257): 0 Evdev Third Button Emulation Timeout (258): 1000 Evdev Third Button Emulation Button (259): 3 Evdev Third Button Emulation Threshold (260): 20 Evdev Wheel Emulation (261): 0 Evdev Wheel Emulation Axes (262): 0, 0, 4, 5 Evdev Wheel Emulation Inertia (263): 10 Evdev Wheel Emulation Timeout (264): 200 Evdev Wheel Emulation Button (265): 4 Evdev Drag Lock Buttons (266): 0 And this is my wireless mouse xinput: Device 'A4TECH USB Device': Device Enabled (121): 1 Coordinate Transformation Matrix (123): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000 Device Accel Profile (246): 0 Device Accel Constant Deceleration (247): 1.000000 Device Accel Adaptive Deceleration (248): 1.000000 Device Accel Velocity Scaling (249): 10.000000 Device Product ID (240): 2522, 1359 Device Node (241): "/dev/input/event16" Evdev Axis Inversion (250): 0, 0 Evdev Axes Swap (252): 0 Axis Labels (253): "Rel X" (131), "Rel Y" (132), "Rel Horiz Wheel" (245), "Rel Vert Wheel" (274) Button Labels (254): "Button Left" (124), "Button Middle" (125), "Button Right" (126), "Button Wheel Up" (127), "Button Wheel Down" (128), "Button Horiz Wheel Left" (129), "Button Horiz Wheel Right" (130), "Button Side" (269), "Button Extra" (270), "Button Forward" (271), "Button Back" (272), "Button Task" (273), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243) Evdev Middle Button Emulation (255): 0 Evdev Middle Button Timeout (256): 50 Evdev Third Button Emulation (257): 0 Evdev Third Button Emulation Timeout (258): 1000 Evdev Third Button Emulation Button (259): 3 Evdev Third Button Emulation Threshold (260): 20 Evdev Wheel Emulation (261): 0 Evdev Wheel Emulation Axes (262): 0, 0, 4, 5 Evdev Wheel Emulation Inertia (263): 10 Evdev Wheel Emulation Timeout (264): 200 Evdev Wheel Emulation Button (265): 4 Evdev Drag Lock Buttons (266): 0

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  • Algorithm to Find the Aggregate Mass of "Granola Bar"-Like Structures?

    - by Stuart Robbins
    I'm a planetary science researcher and one project I'm working on is N-body simulations of Saturn's rings. The goal of this particular study is to watch as particles clump together under their own self-gravity and measure the aggregate mass of the clumps versus the mean velocity of all particles in the cell. We're trying to figure out if this can explain some observations made by the Cassini spacecraft during the Saturnian summer solstice when large structures were seen casting shadows on the nearly edge-on rings. Below is a screenshot of what any given timestep looks like. (Each particle is 2 m in diameter and the simulation cell itself is around 700 m across.) The code I'm using already spits out the mean velocity at every timestep. What I need to do is figure out a way to determine the mass of particles in the clumps and NOT the stray particles between them. I know every particle's position, mass, size, etc., but I don't know easily that, say, particles 30,000-40,000 along with 102,000-105,000 make up one strand that to the human eye is obvious. So, the algorithm I need to write would need to be a code with as few user-entered parameters as possible (for replicability and objectivity) that would go through all the particle positions, figure out what particles belong to clumps, and then calculate the mass. It would be great if it could do it for "each" clump/strand as opposed to everything over the cell, but I don't think I actually need it to separate them out. The only thing I was thinking of was doing some sort of N2 distance calculation where I'd calculate the distance between every particle and if, say, the closest 100 particles were within a certain distance, then that particle would be considered part of a cluster. But that seems pretty sloppy and I was hoping that you CS folks and programmers might know of a more elegant solution? Edited with My Solution: What I did was to take a sort of nearest-neighbor / cluster approach and do the quick-n-dirty N2 implementation first. So, take every particle, calculate distance to all other particles, and the threshold for in a cluster or not was whether there were N particles within d distance (two parameters that have to be set a priori, unfortunately, but as was said by some responses/comments, I wasn't going to get away with not having some of those). I then sped it up by not sorting distances but simply doing an order N search and increment a counter for the particles within d, and that sped stuff up by a factor of 6. Then I added a "stupid programmer's tree" (because I know next to nothing about tree codes). I divide up the simulation cell into a set number of grids (best results when grid size ˜7 d) where the main grid lines up with the cell, one grid is offset by half in x and y, and the other two are offset by 1/4 in ±x and ±y. The code then divides particles into the grids, then each particle N only has to have distances calculated to the other particles in that cell. Theoretically, if this were a real tree, I should get order N*log(N) as opposed to N2 speeds. I got somewhere between the two, where for a 50,000-particle sub-set I got a 17x increase in speed, and for a 150,000-particle cell, I got a 38x increase in speed. 12 seconds for the first, 53 seconds for the second, 460 seconds for a 500,000-particle cell. Those are comparable speeds to how long the code takes to run the simulation 1 timestep forward, so that's reasonable at this point. Oh -- and it's fully threaded, so it'll take as many processors as I can throw at it.

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  • Difficulties with rotation of a sprite

    - by Johnny
    I want to program a dolphin that jumps and rotates like a real dolphin. Jumping is not the problem, but I don't know how to make the rotation. At the moment, my dolphin rotates a little weird. But I want that it rotates like a real dolphin does. How can I improve the rotation? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { rotation = 0; flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { rotation = 0; flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { rotation += 0.01f; VelocityY += 40f; } else { rotation -= 0.01f; VelocityY += 40f; } } } else { if (flip == SpriteEffects.None) { rotation -= 0.01f; VelocityY += -10f; } else { rotation += 0.01f; VelocityY += -10f; } } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, rotation, new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } }

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  • My 2D collision code does not work as expected. How do I fix it?

    - by farmdve
    I have a simple 2D game with a tile-based map. I am new to game development, I followed the LazyFoo tutorials on 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). The game is simple, but the code is a lot so I can only post snippets. // Player moved out of the map if((player.box.x < 0)) player.box.x += GetVelocity(player, 0); if((player.box.y < 0)) player.box.y += GetVelocity(player, 1); if((player.box.x > (LEVEL_WIDTH - DOT_WIDTH))) player.box.x -= GetVelocity(player, 0); if((player.box.y > (LEVEL_HEIGHT - DOT_HEIGHT))) player.box.y -= GetVelocity(player, 1); // Now that we are here, we check for collisions if(touches_wall(player.box)) { if(player.box.x < player.prev_x) { player.box.x += GetVelocity(player, 0); } if(player.box.x > player.prev_x) { player.box.x -= GetVelocity(player, 0); } if(player.box.y < player.prev_y) { player.box.y += GetVelocity(player, 1); } if(player.box.y > player.prev_y) { player.box.y -= GetVelocity(player, 1); } } player.prev_x = player.box.x; player.prev_y = player.box.y; Let me explain, player is a structure with the following contents typedef struct { Rectangle box; //Player position on a map(tile or whatever). int prev_x, prev_y; // Previous positions int key_press[3]; // Stores which key was pressed/released. Limited to three keys. E.g Left,right and perhaps jump if possible in 2D int velX, velY; // Velocity for X and Y coordinate. //Health int health; bool main_character; uint32_t jump_ticks; } Player; And Rectangle is just a typedef of SDL_Rect. GetVelocity is a function that according to the second argument, returns the velocity for the X or Y axis. This code I have basically works, however inside the if(touches_wall(player.box)) if statement, I have 4 more. These 4 if statements are responsible for detecting collision on all 4 sides(up,down,left,right). However, they also act as a block for any other movement. Example: I move down the object and collide with the wall, as I continue to move down and still collide with the wall, I wish to move left or right, which is indeed possible(not to mention in 3D games), but remember the 4 if statements? They are preventing me from moving anywhere. The original code on the LazyFoo Productions website has no problems, but it was written in C++, so I had to rewrite most of it to work, which is probably where the problem comes from. I also use a different method of moving, than the one in the examples. Of course, that was just an example. I wish to be able to move no matter at which wall I collide. Before this bit of code, I had another one that had more logic in there, but it was flawed.

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  • Resolving collisions between dynamic game objects

    - by TheBroodian
    I've been building a 2D platformer for some time now, I'm getting to the point where I am adding dynamic objects to the stage for testing. This has prompted me to consider how I would like my character and other objects to behave when they collide. A typical staple in many 2D platformer type games is that the player takes damage upon touching an enemy, and then essentially becomes able to pass through enemies during a period of invulnerability, and at the same time, enemies are able to pass through eachother freely. I personally don't want to take this approach, it feels strange to me that the player should receive arbitrary damage for harmless contact to an enemy, despite whether the enemy is attacking or not, and I would like my enemies' interactions between each other (and my player) to be a little more organic, so to speak. In my head I sort of have this idea where a game object (player, or non player) would be able to push other game objects around by manner of 'pushing' each other out of one anothers' bounding boxes if there is an intersection, and maybe correlate the repelling force to how much their bounding boxes are intersecting. The problem I'm experiencing is I have no idea what the math might look like for something like this? I'll show what work I've done so far, it sort of works, but it's jittery, and generally not quite what I would pass in a functional game: //Clears the anti-duplicate buffer collisionRecord.Clear(); //pick a thing foreach (GameObject entity in entities) { //pick another thing foreach (GameObject subject in entities) { //check to make sure both things aren't the same thing if (!ReferenceEquals(entity, subject)) { //check to see if thing2 is in semi-near proximity to thing1 if (entity.WideProximityArea.Intersects(subject.CollisionRectangle) || entity.WideProximityArea.Contains(subject.CollisionRectangle)) { //check to see if thing2 and thing1 are colliding. if (entity.CollisionRectangle.Intersects(subject.CollisionRectangle) || entity.CollisionRectangle.Contains(subject.CollisionRectangle) || subject.CollisionRectangle.Contains(entity.CollisionRectangle)) { //check if we've already resolved their collision or not. if (!collisionRecord.ContainsKey(entity.GetHashCode())) { //more duplicate resolution checking. if (!collisionRecord.ContainsKey(subject.GetHashCode())) { //if thing1 is traveling right... if (entity.Velocity.X > 0) { //if it isn't too far to the right... if (subject.CollisionRectangle.Contains(new Microsoft.Xna.Framework.Rectangle(entity.CollisionRectangle.Right, entity.CollisionRectangle.Y, 1, entity.CollisionRectangle.Height)) || subject.CollisionRectangle.Intersects(new Microsoft.Xna.Framework.Rectangle(entity.CollisionRectangle.Right, entity.CollisionRectangle.Y, 1, entity.CollisionRectangle.Height))) { //Find how deep thing1 is intersecting thing2's collision box; float offset = entity.CollisionRectangle.Right - subject.CollisionRectangle.Left; //Move both things in opposite directions half the length of the intersection, pushing thing1 to the left, and thing2 to the right. entity.Velocities.Add(new Vector2(-(((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); subject.Velocities.Add(new Vector2((((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); } } //if thing1 is traveling left... if (entity.Velocity.X < 0) { //if thing1 isn't too far left... if (entity.CollisionRectangle.Contains(new Microsoft.Xna.Framework.Rectangle(subject.CollisionRectangle.Right, subject.CollisionRectangle.Y, 1, subject.CollisionRectangle.Height)) || entity.CollisionRectangle.Intersects(new Microsoft.Xna.Framework.Rectangle(subject.CollisionRectangle.Right, subject.CollisionRectangle.Y, 1, subject.CollisionRectangle.Height))) { //Find how deep thing1 is intersecting thing2's collision box; float offset = subject.CollisionRectangle.Right - entity.CollisionRectangle.Left; //Move both things in opposite directions half the length of the intersection, pushing thing1 to the right, and thing2 to the left. entity.Velocities.Add(new Vector2((((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); subject.Velocities.Add(new Vector2(-(((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); } } //Make record that thing1 and thing2 have interacted and the collision has been solved, so that if thing2 is picked next in the foreach loop, it isn't checked against thing1 a second time before the next update. collisionRecord.Add(entity.GetHashCode(), subject.GetHashCode()); } } } } } } } } One of the biggest issues with my code aside from the jitteriness is that if one character were to land on top of another character, it very suddenly and abruptly resolves the collision, whereas I would like a more subtle and gradual resolution. Any thoughts or ideas are incredibly welcome and helpful.

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  • Difficulties with rotation of a sprite

    - by Andy
    I want to program a dolphin that jumps and rotates like a real dolphin. Jumping is not the problem, but I don't know how to make the rotation. My dolphin always rests in the same angle while it jumps. But I want that it changes the rotation during the jump, like a real dolphin does. How can I improve the rotation? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { rotation = 0; flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { rotation = 0; flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { rotation = 45; VelocityY += 40f; } else { rotation = -45; VelocityY += 40f; } } } else { VelocityY += -10f; } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, MathHelper.ToRadians(rotation), new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } }

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