2020. 1. 24. 00:17ㆍ카테고리 없음
- Box2dweb is a JavaScript port of Box2D Physics Engine (converted from Box2DFlash 2.1a in an automatic manner) wck (World Construction Kit ). A ActionScript 3 (using Alchemy) port of Box2D 2.10+ fbox2d, another ActionScript 3 port of Box2D 2.10+ revision 141.
- In this video, I attempt to answer the questions: (1) what are Physics Engines? And (2) why would you want to use them? I discuss some common physics engines and their various pros/cons - box2d.
These are four examples of a physics engine simulating an object falling onto a slope. The examples differ in accuracy of the simulation:. No physics., no collision detection. Gravity and, no rigid body dynamics.
Making a Simple 2D Physics Engine - Part 3. Content: Drawing objects and optimizing your engine. Physics Simulator game. Content: Multiple physics-handling methods in the same game, small 'playground' to test object collisions, in-game settings for variables and methods as shown in the tutorials; Tutorial snippets.
Gravity, collision detection and rotation calculationsA physics engine is that provides an approximate of certain, such as (including ), and, of use in the of,. Their main uses are in video games (typically as ), in which case the are in. The term is sometimes used more generally to describe any for simulating physical phenomena, such as.
Contents.Description There are generally two classes of physics: and high-precision. High-precision physics engines require more processing power to calculate very physics and are usually used by scientists and computer animated movies.
Real-time physics engines—as used in video games and other forms of interactive computing—use simplified calculations and decreased accuracy to compute in time for the game to respond at an appropriate rate for game play.Scientific engines. This section needs expansion. You can help.
( August 2010)One of the first general purpose computers, was used as a very simple type of physics engine. It was used to design ballistics tables to help the United States military estimate where shells of various mass would land when fired at varying angles and gunpowder charges, also accounting for drift caused by wind. The results were calculated a single time only, and were tabulated into printed tables handed out to the artillery commanders.Physics engines have been commonly used on supercomputers since the 1980s to perform modeling, where particles are assigned that are combined to show circulation. Due to the requirements of speed and high precision, special computer processors known as were developed to accelerate the calculations. The techniques can be used to model weather patterns in, wind tunnel data for designing air- and watercraft or motor vehicles including racecars, and thermal cooling of computer processors for improving. As with many calculation-laden processes in computing, the accuracy of the simulation is related to the resolution of the simulation and the precision of the calculations; not modeled in the simulation can drastically change the predicted results.Tire manufacturers use physics simulations to examine how new types will perform under wet and dry conditions, using new tire materials of varying flexibility and under different levels of weight loading.Game engines. Main articles: andIn most computer games, speed of the processors and are more important than accuracy of simulation.
This leads to designs for physics engines that produce results in real-time but that replicate real world physics only for simple cases and typically with some approximation. More often than not, the simulation is geared towards providing a 'perceptually correct' approximation rather than a real simulation. However some game engines, such as, use physics in puzzles or in combat situations. This requires more accurate physics so that, for example, the momentum of an object can knock over an obstacle or lift a sinking object.character animation in the past only used because they are faster and easier to calculate, but modern games and movies are starting to use. Soft body physics are also used for particle effects, liquids and cloth.
Some form of limited simulation is sometimes provided to simulate water and other liquids as well as the flow of fire and explosions through the air.Collision detection Objects in games interact with the player, the environment, and each other. Typically, most 3D objects in games are represented by two separate meshes or shapes. One of these meshes is the highly complex and detailed shape visible to the player in the game, such as a vase with elegant curved and looping handles. For purpose of speed, a second, simplified invisible mesh is used to represent the object to the physics engine so that the physics engine treats the example vase as a simple cylinder. It would thus be impossible to insert a rod or fire a projectile through the handle holes on the vase, because the physics engine model is based on the cylinder and is unaware of the handles. The simplified mesh used for physics processing is often referred to as the. This may be a, sphere,.
Engines that use bounding boxes or bounding spheres as the final shape for collision detection are considered extremely simple. Generally a bounding box is used for broad phase to narrow down the number of possible collisions before costly mesh on mesh collision detection is done in the narrow phase of collision detection.Another aspect of precision in involves the, or the number of moments in time per second when physics is calculated.
Each frame is treated as separate from all other frames, and the space between frames is not calculated. A low framerate and a small fast-moving object causes a situation where the object does not move smoothly through space but instead seems to teleport from one point in space to the next as each frame is calculated.
Projectiles moving at sufficiently high speeds will miss targets, if the target is small enough to fit in the gap between the calculated frames of the fast moving projectile. Various techniques are used to overcome this flaw, such as 's representation of projectiles as arrows with invisible trailing tails longer than the gap in frames to collide with any object that might fit between the calculated frames. By contrast, such as in or does not suffer this problem.Soft-body dynamics An alternative to using bounding box-based rigid body physics systems is to use a -based system. In such a system, a 3-dimensional, volumetric is created of the 3D object.
The tessellation results in a number of finite elements which represent aspects of the object's physical properties such as toughness, plasticity, and volume preservation. Once constructed, the finite elements are used by a to model the stress within the 3D object. The stress can be used to drive fracture, deformation and other physical effects with a high degree of realism and uniqueness. As the number of modeled elements is increased, the engine's ability to model physical behavior increases. The visual representation of the 3D object is altered by the finite element system through the use of a run on the CPU or GPU. Finite Element-based systems had been impractical for use in games due to the performance overhead and the lack of tools to create finite element representations out of 3D art objects. With higher performance processors and tools to rapidly create the volumetric tessellations, real-time finite element systems began to be used in games, beginning with that used for the deformation and destruction effects of wood, steel, flesh and plants using an algorithm developed by Dr.
James O'Brien as a part of his PhD thesis. Brownian motion In the real world, physics is always active.
There is a constant jitter to all particles in our universe as the forces push back and forth against each other. For a engine, such constant active precision is unnecessarily wasting the limited CPU power, which can cause problems such as decreased. Thus, games may put objects to 'sleep' by disabling the computation of physics on objects that have not moved a particular distance within a certain amount of time. For example, in the 3D, if an object is resting on the floor and the object does not move beyond a minimal distance in about two seconds, then the physics calculations are disabled for the object and it becomes frozen in place. The object remains frozen until physics processing reactivates for the object after collision occurs with some other active physical object. Paradigms Physics engines for video games typically have two core components, a / system, and the component responsible for solving the forces affecting the simulated objects. Modern physics engines may also contain, animation and tools.
There are three major paradigms for the physical simulation of solids:. Penalty methods, where interactions are commonly modelled as systems. This type of engine is popular for deformable, or. Constraint based methods, where are solved that estimate physical laws.
Impulse based methods, where are applied to object interactions.Finally, hybrid methods are possible that combine aspects of the above paradigms.Limitations A primary limit of physics engine is the of the numbers representing the positions of and forces acting upon objects. When precision is too low, affect results and not modeled in the simulation can drastically change the predicted results; simulated objects can behave unexpectedly or arrive at the wrong location.
The errors are compounded in situations where two free-moving objects are fit together with a precision that is greater than what the physics engine can calculate. This can lead to an unnatural buildup energy in the object due to the rounding errors that begins to violently shake and eventually blow the objects apart.
Any type of free-moving compound physics object can demonstrate this problem, but it is especially prone to affecting chain links under high tension and wheeled objects with actively physical bearing surfaces. Higher precision reduces the positional/force errors, but at the cost of greater CPU power needed for the calculations.Physics Processing Unit (PPU). Main article:A is a dedicated microprocessor designed to handle the calculations of physics, especially in the physics engine of.
Making A 2d Physics Engine For Kids
Examples of calculations involving a PPU might include, hair and clothing simulation, and fracturing of objects. The idea is that specialized processors offload time consuming tasks from a computer's CPU, much like how a performs graphics operations in the main CPU's place. The term was coined by 's marketing to describe their PhysX chip to consumers. Several other technologies in the CPU-GPU spectrum have some features in common with it, although Ageia's solution was the only complete one designed, marketed, supported, and placed within a system exclusively as a PPU.General Purpose processing on Graphics Processing Unit (GPGPU). Main article:Hardware acceleration for physics processing is now usually provided by graphics processing units that support more general computation, a concept known as. And provide support for rigid body dynamics computations on their latest graphics cards.supports a GPU-based Newtonian physics acceleration technology named Quantum Effects Technology. NVIDIA provides an SDK Toolkit for technology that offers both a low and high-level API to the GPU.
For their GPUs, offers a similar SDK, called (CTM), which provides a thin hardware interface.is an example of a physics engine that can use GPGPU based hardware acceleration when it is available.Engines Real-time physics engines.
Java 2d Physics Engine
Was written as a tutorial on how to write 2D physics engines. The site contains links to a lot of presentations on how the algorithms work and how to make it efficient.You might also want to look into this done by the Pixeljunk Shooter team, describing how they did 2D fluids.If you are interesed in 3D, read.For more cutting edge offline physics might be a good presentation. It describes how a new solver was developed for Maya, and I remember our physics programmer going nuts over it some years ago.