Game Development Tutorials – Game Physics – Networked Physcis. Introduction Hi, I’m Glenn Fiedler and welcome to the final article in my series on Game Physics. In the previous article we discussed how to use spring-like forces to model basic collision response, joints and motors. Now we’re going to discuss how to network a physics simulation. Networking a physics simulation is the holy grail of multiplayer gaming and the massive popularity of first person shooters on the PC is a testament to the just how immersive a networked physics simulation can be.
In this article I will show you how apply the key networking techniques from first person shooters to network your own physics simulation. First person shooters First person shooter physics is very simple. The problem then is how to allow each client to control his own character while displaying a reasonable approximation of the motion of the other players. In order to do this elegantly and simply, we structure the physics simulation as follows: Network fundamentals Number one. Two. Client side prediction. Game Development Tutorials – Game Physics – Spring Physics. Introduction Hi, I’m Glenn Fiedler and welcome to the fourth article in my series on Game Physics. In the previous article we discussed how to simulate the motion of rigid bodies in 3D. Now we’re going to discuss spring physics. The physics behind springs is simple but extremely versatile and useful.
The more physics programming you do, the more springs pop up. Spring and dampers The formula to use for simulating spring-like behavior is called Hooke’s Law. F = -kx Where x is the vector displacement of the end of the spring from it’s equilibrium position, and k is a constant describing the tightness of the spring. Newton’s third law says that every force has an equal and opposite force. Spring forces alone are not much use though. A spring-damper system can be modeled as follows: F = - kx - bv Where b is the coefficient of damping and v is the relative velocity between the two points connected by the spring. The importance of a good integrator This brings me to a very important point. F = -kx -bv. Game Development Tutorials – Game Physics – Physics in 3D.
Introduction Hi, I’m Glenn Fiedler and welcome to the third article in my series on Game Physics. In the previous article we discussed how to integrate our physics simulation forward at fixed delta time increments, regardless of display framerate. Now are going to simulate objects that move linearly and rotate in three dimensions. We will concentrate on a type of object called a rigid body. Rigid bodies cannot bend, compress or deform in any way. To simulate the motion of rigid bodies, we must study both rigid body kinematics and rigid body dynamics. Along the way I will show you how to integrate vector quantities, handle rotations in three dimensions and integrate to find the motion of your object as it moves and spins around the world.
Enjoy! Moving in the Third Dimension As long as we only have single floating point values for position and velocity our physics simulation is limited to motion in a single dimension, and a point moving from side to side on the screen is pretty boring! Game Programming Tutorials – Game Physics – Fix your Timestep! Introduction Hello, I’m Glenn Fiedler and welcome to the second article in my series on Game Physics.
In the previous article we discussed how to integrate the equations of motion using an RK4 integrator. Integration sounds complicated but really it’s just a way to advance the your physics simulation forward by some small amount of time called “delta time” (or dt for short). But how to choose this delta time value? This may seem like a trivial subject but in fact there are many different ways to do it, each with their own strengths and weaknesses – so read on! Fixed delta time The simplest way to step forward is with a fixed delta time, like 1/60th of a second: double t = 0.0; double dt = 1.0 / 60.0; while ( !
In many ways this code is ideal. But in the real world you may not know the display refresh rate ahead of time, VSYNC could be turned off, or perhaps you could be running on a slow computer which cannot update and render your frame fast enough to present it at 60fps. Variable delta time. Game Development Tutorials – Game Physics – Integration Basics. Introduction Hi, I’m Glenn Fiedler and welcome to the first article in my series on Game Physics. If you have ever wondered how the physics simulation in a computer game works then this series of articles will explain it for you. I assume you are proficient with C++ and have a basic grasp of physics and mathematics. Nothing else will be required if you pay attention and study the example source code.
A game physics simulation works by making many small predictions based on the laws of physics. These predictions are actually quite simple, and basically boil down to something like “given that the object is here, and is traveling this fast, in a short amount of time from now should be over there”. Exactly how to implement this integration is the subject of this article. Integrating the Equations of Motion You should remember from high school or university physics that force equals mass times acceleration.
F = ma a = f/m dv/dt = a = F/m dx/dt = v Numerical Integration Lets put this into code. Game Development Tutorials – Game Physics. Integration Basics Integration is used to determine the motion of an object over time. In this article I show how to correctly integrate the equations of motion using an RK4 integrator instead of starting off on the wrong foot with a stupid Euler integrator. Fix Your Timestep! Even an RK4 integrator is sensitive to the amount of time you step when integrating. Physics in 3D Leap ahead from integrating single values to integrating the entire physics state for a cube in three dimensions.
Spring Physics Explains the physics of springs and how to apply them to control physics simulations. Networked Physics How do network games synchronize physics over the network? OpenGL Extensions Viewer. Welcome to OpenGL Extensions Viewer A reliable software which displays useful information about the current OpenGL 3D accelerator. OpenGL Extensions Viewer is available for Windows 32bit and 64bit and MacOS X, iOS, and Android. This program displays the vendor name, the version implemented, the renderer name and the extensions of the current OpenGL 3D accelerator. OpenGL Extensions Viewer 4.0 available for OSX, Snow Leopard and superior. Learn more Available for OpenGL ES for Android (Android 2.2 or superior) Available for OpenGL ES for iPhone and iPad. And always available for Windows XP or superior for OpenGL 1.1 to 4.3 Choose one of the topics for more information : OpenGL extensions Rendering tests Report Database Cross platformLinks and press reviews.
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