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  • Is there a technical way to speed up a general program above current PC speed limit?

    - by Maksee
    Let's imagine I developed a Windows console application implementing some algorithm calculating something. Let's say it doesn't use any threads, just straightforward linear approach with ifs, loops and so on. Is there any technical way to make if run it 100x times faster than on the most advanced current PC? For example one of the way would be to run it on a super computer that emulates i386 faster than any of the existing PCs. But in this case the question what computer and does it really have ability to emulate Windows. In other words, is there real examples of such approach? Although in general it looks useless, but if there is a way, one could develop some program on his general home computer and pay for running it much faster on some other hardware. I suppose that this question could be asked on superuser.com, but since there are possible specific with such things as assembler instructions or threads, I thought that stackoverflow.com is better

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  • How can I accelerate the generation of the an MD5 Checksum within vb.net?

    - by Richard
    I'm working with some very large files residing on P2 (Panasonic) cards. Part of the process we employ is to first generate a checksum of the file we are going to copy, then copy the file, then run a checksum on the file to confirm that it copied OK. The problem is, is that files are large (70 GB+) and take a long time to complete. It's an issue since we will eventually be dealing with thousands of these files. I would like to find a faster way to generate the checksum other than using the System.Security.Cryptography.MD5CryptoServiceProvider I don't care if this means using a specialized hardware card, provided it works and is not to ungodly expensive. I would prefer to have a method of encoding that provided some feedback as to how far the process has gone along so I can display it like I do now. The application is written in vb.net. I would prefer to be able to use it as component, library, reference within my application, but I'm willing to call an outside application if there is enough improvement in the speed of generating the checksum. Needless to say, the checksum must be consistent and correct. :-) Thank you in advance for your time and efforts, Richard

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  • What OpenGL functions are not GPU accelerated?

    - by Xavier Ho
    I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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  • Which OpenGL functions are not GPU-accelerated?

    - by Xavier Ho
    I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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  • Physics System ignores collision in some rare cases

    - by Gajoo
    I've been developing a simple physics engine for my game. since the game physics is very simple I've decided to increase accuracy a little bit. Instead of formal integration methods like fourier or RK4, I'm directly computing the results after delta time "dt". based on the very first laws of physics : dx = 0.5 * a * dt^2 + v0 * dt dv = a * dt where a is acceleration and v0 is object's previous velocity. Also to handle collisions I've used a method which is somehow different from those I've seen so far. I'm detecting all the collision in the given time frame, stepping the world forward to the nearest collision, resolving it and again check for possible collisions. As I said the world consist of very simple objects, so I'm not loosing any performance due to multiple collision checking. First I'm checking if the ball collides with any walls around it (which is working perfectly) and then I'm checking if it collides with the edges of the walls (yellow points in the picture). the algorithm seems to work without any problem except some rare cases, in which the collision with points are ignored. I've tested everything and all the variables seem to be what they should but after leaving the system work for a minute or two the system the ball passes through one of those points. Here is collision portion of my code, hopefully one of you guys can give me a hint where to look for a potential bug! void PhysicalWorld::checkForPointCollision(Vec2 acceleration, PhysicsComponent& ball, Vec2& collisionNormal, float& collisionTime, Vec2 target) { // this function checks if there will be any collision between a circle and a point // ball contains informations about the circle (it's current velocity, position and radius) // collisionNormal is an output variable // collisionTime is also an output varialbe // target is the point I want to check for collisions Vec2 V = ball.mVelocity; Vec2 A = acceleration; Vec2 P = ball.mPosition - target; float wallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; float r = ball.mRadius / (mMap->getWallWidth() + mMap->getHallWidth()); // r is ball radius scaled to match actual rendered object. if (A.any()) // todo : I need to first correctly solve the collisions in case there is no acceleration return; if (V.any()) // if object is not moving there will be no collisions! { float D = P.x * V.y - P.y * V.x; float Delta = r*r*V.length2() - D*D; if(Delta < eps) return; Delta = sqrt(Delta); float sgnvy = V.y > 0 ? 1: (V.y < 0?-1:0); Vec2 c1(( D*V.y+sgnvy*V.x*Delta) / V.length2(), (-D*V.x+fabs(V.y)*Delta) / V.length2()); Vec2 c2(( D*V.y-sgnvy*V.x*Delta) / V.length2(), (-D*V.x-fabs(V.y)*Delta) / V.length2()); float t1 = (c1.x - P.x) / V.x; float t2 = (c2.x - P.x) / V.x; if(t1 > eps && t1 <= collisionTime) { collisionTime = t1; collisionNormal = c1; } if(t2 > eps && t2 <= collisionTime) { collisionTime = t2; collisionNormal = c2; } } } // this function should step the world forward by dt. it doesn't check for collision of any two balls (components) // it just checks if there is a collision between the current component and 4 points forming a rectangle around it. void PhysicalWorld::step(float dt) { for (unsigned i=0;i<mObjects.size();i++) { PhysicsComponent &current = *mObjects[i]; Vec2 acceleration = current.mForces * current.mInvMass; float rt=dt; // stores how much more the world should advance while(rt > eps) { float collisionTime = rt; Vec2 collisionNormal = Vec2(0,0); float halfWallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; // we check if there is any collision with any of those 4 points around the ball // if there is a collision both collisionNormal and collisionTime variables will change // after these functions collisionTime will be exactly the value of nearest collision (if any) // and if there was, collisionNormal will report in which direction the ball should return. checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); // either if there is a collision or if there is not we step the forward since we are sure there will be no collision before collisionTime current.mPosition += collisionTime * (collisionTime * acceleration * 0.5 + current.mVelocity); current.mVelocity += collisionTime * acceleration; // if the ball collided with anything collisionNormal should be at least none zero in one of it's axis if (collisionNormal.any()) { collisionNormal *= Dot(collisionNormal, current.mVelocity) / collisionNormal.length2(); current.mVelocity -= 2 * collisionNormal; // simply reverse velocity along collision normal direction } rt -= collisionTime; } // reset all forces for current object so it'll be ready for later game event current.mForces.zero(); } }

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  • Should Windows Multipoint Server stations on individual video cards support hardware video acceleration?

    - by villares
    I've set up a test machine with multiple PCI-e nVidia GF440 Video cards and installed Windows Multipoint Server 2011. I use the same kind of hardware set up with a BeTwin multiseat solution to create a class lab for Google SketchUp teaching (highly OpenGL dependent) and it works ok. On the Multipoint Windows test machine the drivers seem to be installed OK but I don´t seem to get any hardware video acceleration. Is this a intrinsic limitation of this solution or am I doing something wrong?

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  • How do I know if DirectX is using hardware acceleration or software rendering?

    - by JohnIdol
    Is there any DirectX diagnostcs tool which will allow me to understand if Graphics acceleration from my GPU is actually working or software rendering is kicking-in instead? I ask this because If I go properties (right click on desktop) -- settings -- I get an error saying my drivers are not working for my Intel Embedded GPU (Intel Embedded Graphics Driver - IEGD) and the system is defaulting to standard VGA drivers. I am on WinXP Professional.

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  • On Linux, can I get 3D acceleration with a Nvidia card w/o X?

    - by anon
    I like Linux. I like OpenGL. I don't like X. On Linux, is there anyway to get 3D acceleration from my Nvidia card without X? Ideally, I'd have the kernel boot, get to a console, then somehow get into a "graphics mode", where my entire monitor is just a single OpenGL screen ... and I draw stuff to it with OpenGL. Without X. Is this possible? Thanks!

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  • Checking if Intel VT-x acceleration is enabled from inside a VMware virtual machine?

    - by user269950
    My (Fortune 500) company just rolled out new VMs and everyone is complaining they are dog slow. Is there any way I could verify, from inside a VM, whether Intel virtualization (VT-x) acceleration has been properly enabled? The processor claims to be a Xeon E7-2830 but the experience has been more like a first-gen Atom. I'd ask IT directly but I get the impression they're unlikely to respond to any suggestion that they are, in fact, drooling imbeciles.

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  • Configure one IIS site to handle two separate SSL certificates using external Load Balancing or SSL Acceleration Servers

    - by bmccleary
    I have one web application on our server that needs to be referenced by two different domain names, both of which have their own SSL certificates. The application is exactly the same for both domains, but we have to keep the two domain names for legal reasons. The problem is that, since both domains need to have their own SSL certificate, that inside of our IIS 7.5 configuration we have to have two separate IIS applications (both pointing to the same physical location) with their own unique IP address and SSL certificate installed. Now, I know that, due to the nature of SSL communications, that this is by design and that you can't assign more than one SSL certificate per IP address and domain name. My question is… is there any way around this limitation and keep one web application in IIS and have it service two SSL certificates based on host name? I know that with the basic IIS configuration that this is not possible, but I was thinking that with some sort of combination of external load balancing and/or SSL acceleration servers/services that we could have these servers process the SSL request and leave IIS clean to have one single application. I am not familiar at all with these technologies, hence the reason I am asking if it is theoretically possible. If not, does anyone else know how to achieve this?

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  • Win32: Is there a replacement GDI32.dll that uses hardware acceleration?

    - by Ian Boyd
    Has anyone out there created a version of GDI32.dll that takes advantage of hardware acceleration available on the machine? gdiplus.dll? Starting with Windows Vista, GDI is no longer hardware accelerated. (GDI+ was never hardware accelerated). Without Microsoft fixing GDI (and GDI+) to be able to run well on the computer: native applications (C++ MFC, Delphi, etc), and managed WinForms applications, will continue to run poorly forever. While i could use Direct2D for business applications, i cannot control the fact that the development environment still creates controls, with decades of library support code, that assumes the presence of GDI.

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  • browser without gpu support

    - by manuzhang
    Google has an Easter egg that draws 3D graph but when I tried it out on chrome it complained about no WebGL support. I've also tested it on Firefox whose WebGL support was enabled but ended up with the same problem. Thus, I suspect it's an issue of my GPU. Some googling led me to chrome://gpu and here's what I got Graphics Feature Status Canvas: Software only, hardware acceleration unavailable HTML Rendering: Software only, hardware acceleration unavailable 3D CSS: Unavailable. Hardware acceleration unavailable WebGL: Unavailable. Hardware acceleration unavailable WebGL multisampling: Unavailable. Hardware acceleration unavailable Problems Detected GPU process was unable to boot. Access to GPU disallowed. GL driver is software rendered. Accelerated compositing is disabled.: 59302 Mesa drivers in linux older than 7.11 are assumed to be buggy. Accelerated 2d canvas is unstable in Linux at the moment. Version Information Data exported Tue Apr 10 2012 18:35:57 GMT+0800 (CST) Chrome version 18.0.1025.151 (Official Build 130497) Operating system Linux 3.0.0-0300-generic Software rendering list version 1.27 ANGLE revision 988 2D graphics backend Skia I wonder what each of the problem implies and How I may properly deal with it? I'm using Ubuntu 11.04

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  • Cocos2d shake/accelerometer issue.

    - by Ryan Poolos
    So I a little backstory. I wanted to implement a particle effect and sound effect that both last about 3 sec or so when the user shakes their iDevice. But first issue arrived when the build in UIEvent for shakes refused to work. So I took the advice of a few Cocos veterans to just use some script to get "violent" accelerometer inputs as shakes. Worked great until now. The problem is that if you keep shaking it just stacks the particle and sounds over and over. Now this wouldn't be that big of a deal except it happens even if you are careful to try and not do so. So what I am hoping to do is disable the accelerometer when the particle effect/sound effect start and then reenable it as soon as they finish. Now I don't know if I should do this by schedule, NStimer, or some other function. I am open to ALL suggestions. here is my current "shake" code. - (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { const float violence = 1; static BOOL beenhere; BOOL shake = FALSE; if (beenhere) return; beenhere = TRUE; if (acceleration.x > violence * 1.5 || acceleration.x < (-1.5* violence)) shake = TRUE; if (acceleration.y > violence * 2 || acceleration.y < (-2 * violence)) shake = TRUE; if (acceleration.z > violence * 3 || acceleration.z < (-3 * violence)) shake = TRUE; if (shake) { id particleSystem = [CCParticleSystemQuad particleWithFile:@"particle.plist"]; [self addChild: particleSystem]; // Super simple Audio playback for sound effects! [[SimpleAudioEngine sharedEngine] playEffect:@"Sound.mp3"]; shake = FALSE; } beenhere = FALSE; }

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  • RK4 Bouncing a Ball

    - by Jonathan Dickinson
    I am trying to wrap my head around RK4. I decided to do the most basic 'ball with gravity that bounces' simulation. I have implemented the following integrator given Glenn Fiedler's tutorial: /// <summary> /// Represents physics state. /// </summary> public struct State { // Also used internally as derivative. // S: Position // D: Velocity. /// <summary> /// Gets or sets the Position. /// </summary> public Vector2 X; // S: Position // D: Acceleration. /// <summary> /// Gets or sets the Velocity. /// </summary> public Vector2 V; } /// <summary> /// Calculates the force given the specified state. /// </summary> /// <param name="state">The state.</param> /// <param name="t">The time.</param> /// <param name="acceleration">The value that should be updated with the acceleration.</param> public delegate void EulerIntegrator(ref State state, float t, ref Vector2 acceleration); /// <summary> /// Represents the RK4 Integrator. /// </summary> public static class RK4 { private const float OneSixth = 1.0f / 6.0f; private static void Evaluate(EulerIntegrator integrator, ref State initial, float t, float dt, ref State derivative, ref State output) { var state = new State(); // These are a premature optimization. I like premature optimization. // So let's not concentrate on that. state.X.X = initial.X.X + derivative.X.X * dt; state.X.Y = initial.X.Y + derivative.X.Y * dt; state.V.X = initial.V.X + derivative.V.X * dt; state.V.Y = initial.V.Y + derivative.V.Y * dt; output = new State(); output.X.X = state.V.X; output.X.Y = state.V.Y; integrator(ref state, t + dt, ref output.V); } /// <summary> /// Performs RK4 integration over the specified state. /// </summary> /// <param name="eulerIntegrator">The euler integrator.</param> /// <param name="state">The state.</param> /// <param name="t">The t.</param> /// <param name="dt">The dt.</param> public static void Integrate(EulerIntegrator eulerIntegrator, ref State state, float t, float dt) { var a = new State(); var b = new State(); var c = new State(); var d = new State(); Evaluate(eulerIntegrator, ref state, t, 0.0f, ref a, ref a); Evaluate(eulerIntegrator, ref state, t + dt * 0.5f, dt * 0.5f, ref a, ref b); Evaluate(eulerIntegrator, ref state, t + dt * 0.5f, dt * 0.5f, ref b, ref c); Evaluate(eulerIntegrator, ref state, t + dt, dt, ref c, ref d); a.X.X = OneSixth * (a.X.X + 2.0f * (b.X.X + c.X.X) + d.X.X); a.X.Y = OneSixth * (a.X.Y + 2.0f * (b.X.Y + c.X.Y) + d.X.Y); a.V.X = OneSixth * (a.V.X + 2.0f * (b.V.X + c.V.X) + d.V.X); a.V.Y = OneSixth * (a.V.Y + 2.0f * (b.V.Y + c.V.Y) + d.V.Y); state.X.X = state.X.X + a.X.X * dt; state.X.Y = state.X.Y + a.X.Y * dt; state.V.X = state.V.X + a.V.X * dt; state.V.Y = state.V.Y + a.V.Y * dt; } } After reading over the tutorial I noticed a few things that just seemed 'out' to me. Notably how the entire simulation revolves around t at 0 and state at 0 - considering that we are working out a curve over the duration it seems logical that RK4 wouldn't be able to handle this simple scenario. Never-the-less I forged on and wrote a very simple Euler integrator: static void Integrator(ref State state, float t, ref Vector2 acceleration) { if (state.X.Y > 100 && state.V.Y > 0) { // Bounce vertically. acceleration.Y = -state.V.Y * t; } else { acceleration.Y = 9.8f; } } I then ran the code against a simple fixed-time step loop and this is what I got: 0.05 0.20 0.44 0.78 1.23 1.76 ... 74.53 78.40 82.37 86.44 90.60 94.86 99.23 103.05 105.45 106.94 107.86 108.42 108.76 108.96 109.08 109.15 109.19 109.21 109.23 109.23 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 ... As I said, I was expecting it to break - however I am unsure of how to fix it. I am currently looking into keeping the previous state and time, and working from that - although at the same time I assume that will defeat the purpose of RK4. How would I get this simulation to print the expected results?

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  • How to set default xrandr settings?

    - by echo-flow
    I'm trying to enable dual monitors in Ubuntu. This is working fine, but every time I do it, desktop effects is disabled. I think I've found the reason why, though: https://wiki.ubuntu.com/X/Config/Multihead/ As with the GNOME XRandR configuration method, setting Virtual to too large a value may result in a loss of hardware acceleration, and thus an inability to use Compiz and its desktop effects. When I use the GNOME monitor applet, or the Monitors configuration in the System menu, the default xrandr settings puts the second monitor to the right of the first, and, as I found with this bug, for most monitors this creates a virtual desktop larger than the maximum 2048 horizontal resolution needed for hardware acceleration on my netbook hardware. So, it seems like if I can modify xrandr's default settings so that it places the new desktop above or below (north or south of) the main LVDS display, then hardware acceleration, and therefore compiz will continue to work. Can anyone tell me, what is the easiest way to achieve this? UPDATE: I have confirmed that multihead support with desktop effects and hardware acceleration works when I move the external monitor display north of the main LVDS display. Right now this involves the following process: plugging in the external monitor, starting the Monitors configuration menu, desktop effects are disabled automatically (and all of the windows on my workspaces are moved to the first workspace), repositioning the external display so that it is north of LVDS display and clicking apply, and then navigating to the Appearance menu and telling it to reenable desktop effects. Is there a simpler way do this? UPDATE 2: OK, so I thought that perhaps the GNOME Monitors configuration screen was trying to be clever, and might be disbling desktop effects. So, I just tried using the xrandr command-line client instead, as follows: xrandr --output VGA1 --above LVDS1 When I do that, desktop effects are still disabled, and I need to manually reenable them. This, despite the fact that hardware acceleration works, and there is never a point where hardware acceleration stops working because the horizontal dimension of the virtual display is too large. So what program is trying to be clever, and is turning off desktop effects when it doesn't need to? And how do I make it stop? If there were a way to re-enable desktop effects from the command line, which I could then put into a script along with the proper xrandr invocation, I would accept that as a workaround. UPDATE 3: OK, here's my script to enable a second monitor with desktop effects. It might be evil, I'm not sure: second-monitor.sh xrandr --output VGA1 --above LVDS1 sleep 3 compiz --replace & The sleep statement might not be necessary. If there's a better way to do this, please let me know. UPDATE 4: This is a Dell Mini Inspiron 1012. Here are my system specifications: lspci -vv 00:02.0 VGA compatible controller: Intel Corporation N10 Family Integrated Graphics Controller Subsystem: Dell Device 041a Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 Interrupt: pin A routed to IRQ 29 Region 0: Memory at f0b00000 (32-bit, non-prefetchable) [size=512K] Region 1: I/O ports at 18d0 [size=8] Region 2: Memory at d0000000 (32-bit, prefetchable) [size=256M] Region 3: Memory at f0900000 (32-bit, non-prefetchable) [size=1M] Capabilities: <access denied> Kernel driver in use: i915 Kernel modules: i915 00:02.1 Display controller: Intel Corporation N10 Family Integrated Graphics Controller Subsystem: Dell Device 041a Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 0 Region 0: Memory at f0b80000 (32-bit, non-prefetchable) [size=512K] Capabilities: <access denied> lsmod | grep i915 i915 287458 2 drm_kms_helper 29329 1 i915 drm 162409 3 i915,drm_kms_helper intel_agp 24375 2 i915 i2c_algo_bit 5028 1 i915 video 17375 1 i915

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  • Simple thruster like behaviour when rotating sprite

    - by ensamgud
    I'm prototyping some 2D game concepts with XNA and have added some basic keyboard inputs to control a triangle sprite. When I press key up the sprite accelerates in it's current facing direction, when I release the key it brakes down. For rotation, when I press left/right keys I rotate the sprite. Currently the sprite immedately changes direction when I rotate it. What I want is for it to keep moving in the same direction when I rotate, until I hit key up, adding thrust in whatever direction the sprite is pointing at. This would simulate thrusters on a classic space shooter like Asteroids. I'm adding an image to describe the behaviour I'm after and some code samples of how I'm doing things at the moment. This is my player struct, holding information of the sprite. public struct PlayerData { public Vector2 Position; // where to draw the sprite public Vector2 Direction; // travel direction of sprite public float Angle; // rotation of sprite public float Velocity; public float Acceleration; public float Decelleration; public float RotationAcceleration; public float RotationDecceleration; public float TopSpeed; public float Scale; } This is how I'm currently handling thrusting / braking (when pressing/releasing key up) (simplified, removed some bounds checking etc): player.Velocity += player.Acceleration * 0.1f; player.Velocity -= player.Acceleration * 0.1f; And when I rotate the sprite left and right: player.Angle -= player.RotationAcceleration * 0.1f; player.Angle += player.RotationAcceleration * 0.1f; This runs in the update loop, keeps the direction updated and updates the position: Vector2 up = new Vector2(0f, -1f); Matrix rotMatrix = Matrix.CreateRotationZ(player.Angle); player.Direction = Vector2.Transform(up, rotMatrix); player.Direction *= player.Velocity; player.Position += player.Direction; I am following along various beginner tutorials and haven't found any describing this, but I have tried some on my own without success. Do I need to change my velocity and acceleration fields to Vectors instead of floats to accomplish this type of movement? I realise my Angle and the Direction vector is currently tied together and I need to disconnect these somehow to be able to rotate freely without changing the direction of the movement, but I can't quite figure out how to do this while keeping the acceleration/decceleration functional. Would appreciate an explanation rather than pure code samples. Thanks,

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  • Rotation based on x coordinate and x velocity?

    - by Lewis
    -(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { float deceleration = 0.3f, sensitivity = 8.0f, maxVelocity = 150; // adjust velocity based on current accelerometer acceleration playerVelocity.x = playerVelocity.x * deceleration + acceleration.x * sensitivity; // we must limit the maximum velocity of the player sprite, in both directions (positive & negative values) playerVelocity.x = fmaxf(fminf(playerVelocity.x, maxVelocity), -maxVelocity); } Hi, I want to rotate my sprite based on the velocity and accelerometer input. My sprite can move along the X axis like so: <--------- sprite ----------- But it always faces forwards, if it is moving left I want it to point slightly to the left, the degree of how far it is pointing to be judged from the velocity. This should also work for the right. I tried using atan but as the y velocity and position is always the same the function returns 0, which doesn't rotate it at all. Any ideas? Regards, Lewis.

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  • Opposite Force to Apply to a Collided Rigid Body?

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

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  • Appropriate level of granularity for component-based architecture

    - by Jon Purdy
    I'm working on a game with a component-based architecture. An Entity owns a set of Component instances, each of which has a set of Slot instances with which to store, send, and receive values. Factory functions such as Player produce entities with the required components and slot connections. I'm trying to determine the best level of granularity for components. For example, right now Position, Velocity, and Acceleration are all separate components, connected in series. Velocity and Acceleration could easily be rewritten into a uniform Delta component, or Position, Velocity, and Acceleration could be combined alongside such components as Friction and Gravity into a monolithic Physics component. Should a component have the smallest responsibility possible (at the cost of lots of interconnectivity) or should related components be combined into monolithic ones (at the cost of flexibility)? I'm leaning toward the former, but I could use a second opinion.

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  • How can I limit CD drive speed while on the live CD to avoid drive noise?

    - by iugamarian
    I sometimes disconect my harddisks for the weeks while only using the internet and I use the Ubuntu Live CD. But every time it needs something while in live desktop it accelerates and makes a lot of noise, also the acceleration takes too long. I want lower drive speed than acceleration lags, because acceleration lags stop me completly exactly when I need something. How can I lower the CD drive speed, say to maximum 16x, without restarting? I can't restart because I only use the CD drive, no harddisks, no flash disks, no network disks. Edit: No USB drives. Setcd does not work for the live session.

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  • nVidia GT 220 not working properly with Ubuntu 12.10

    - by Glaedr
    I used to enable proprietary nVidia drivers on every previous Ubuntu release to get it working properly (elseway I was forced to a very low resolution and no graphic acceleration), and everything worked fine then. In particular, I noticed - still I don't know why - that the GPU fan on every OS gets noisy until the video drivers are loaded (runlevel 5, it seems, in Linux), and then slows down to a normal speed. Today I installed 12.10. Running the Live CD, surprisingly, everything was working fine: full resolution, acceleration, silent fan, and so on. The running driver was nvidia-current (GT 216). After installing and booting I found that the fan was overrunning. The installed driver is nouveau. I tried installing nvidia-current, or any other proprietary driver, even installing the kernel headers & source and then the drivers (as suggested here), but all I'm getting with proprietary drivers is, the irony, low resolution, noisy fan and no acceleration (thus obviously unity and compiz refusing to start). Does anybody know a way out?

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  • does the accelerometer work for the iphone/ipad simulator?

    - by Mark
    From what I can tell, my app should be firing accelerometer events while Im using the iPad simulator in XCode, but its not. I have googled around and it somewhat seems that the accelerometer is not implemented in the simulator, is this correct? If so, why on earth would they have a "Hardware-Shake Gesture" menu option? My code is as follows: .h file: @interface MyViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate, UIAccelerometerDelegate>{ UIAccelerometer *accelerometer; //...other stuff } @property (nonatomic, retain) UIAccelerometer *accelerometer; @end then the .m file: @implementation MyViewController @synthesize accelerometer; - (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { NSLog(@"%@", [NSString stringWithFormat:@"%@%f", @"X: ", acceleration.x]); NSLog(@"%@", [NSString stringWithFormat:@"%@%f", @"Y: ", acceleration.y]); NSLog(@"%@", [NSString stringWithFormat:@"%@%f", @"Z: ", acceleration.z]); } - (void)viewDidLoad { [super viewDidLoad]; self.accelerometer = [UIAccelerometer sharedAccelerometer]; self.accelerometer.updateInterval = .1; self.accelerometer.delegate = self; } @end Does this look right?

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  • UIAcceleration filtering

    - by Ilya
    Hi, I found the following piece of code in apple guidelines: - (void)accelerometer:(UIAccelerometer*)accelerometer didAccelerate:(UIAcceleration*)acceleration { //Use a basic low-pass filter to only keep the gravity in the accelerometer values accel[0] = acceleration.x * kFilteringFactor + accel[0] * (1.0 - kFilteringFactor); accel[1] = acceleration.y * kFilteringFactor + accel[1] * (1.0 - kFilteringFactor); accel[2] = acceleration.z * kFilteringFactor + accel[2] * (1.0 - kFilteringFactor); } What does it exactly do? What is this low-pass filter? Why do I have to apply it? Thank you in advance.

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