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DYNAMICSDYNAMICS Part IPart I
Physics EnginePhysics Engine
ByBy
Willis (The Magnificent) LouieWillis (The Magnificent) Louie
Fei (The Coyote) LiaoFei (The Coyote) Liao
Flight Simulator RPGFlight Simulator RPG
Table of ContentsTable of Contents
1) Introduction physics engine1) Introduction physics engine
What is a “physics engine”?What is a “physics engine”?
2) Advantage of physics engine2) Advantage of physics engine
Why we want a physics engine?Why we want a physics engine?
3)3) Advantages and Disadvantages Advantages and Disadvantages of different physics enginesof different physics engines
4) Our PICK – we like it hot4) Our PICK – we like it hot
What is a physics What is a physics engine?engine?
What is a PHYSICS ENGINE?What is a PHYSICS ENGINE?
Pre-designed to do physics Pre-designed to do physics calculations.calculations.
It uses physical variables such as It uses physical variables such as MASS, FRICTION, VELOCITY, etc., to MASS, FRICTION, VELOCITY, etc., to simulate the objects movements.simulate the objects movements.
What is a PHYSICS ENGINE?What is a PHYSICS ENGINE?
Real-time vs high precisionReal-time vs high precision Scientist and animated graphicsScientist and animated graphics Video game use real-time for time Video game use real-time for time
sensitivesensitive Rigid body dynamics VS soft body Rigid body dynamics VS soft body
dynamicsdynamics Liquid, clothes, etcLiquid, clothes, etc
Table of ContentsTable of Contents
1) Introduction physics engine1) Introduction physics engine
What is a “physics engine”?What is a “physics engine”?
2) Advantage of physics engine2) Advantage of physics engine
Why we want a physics engine?Why we want a physics engine?
3)3) Advantages and Disadvantages Advantages and Disadvantages of different physics enginesof different physics engines
4) Our PICK – we like it hot4) Our PICK – we like it hot
Why do we want a Why do we want a physics engine?physics engine?
Advantages of Physics EngineAdvantages of Physics Engine
Manual labor sucksManual labor sucks It does most of the work for us It does most of the work for us
Error prone Error prone doing calculations most humans make doing calculations most humans make
errorserrors Cost efficientCost efficient
Wouldn’t make a whole lot of money Wouldn’t make a whole lot of money working on that engine all day long.working on that engine all day long.
Table of ContentsTable of Contents
1) Introduction physics engine1) Introduction physics engine
What is a “physics engine”?What is a “physics engine”?
2) Advantage of physics engine2) Advantage of physics engine
Why we want a physics engine?Why we want a physics engine?
3)3) Advantages and Advantages and DisadvantagesDisadvantages of different physics of different physics enginesengines
4) Our PICK – we like it hot4) Our PICK – we like it hot
Physics Engine ComparisonPhysics Engine Comparison
User Base - popularityUser Base - popularity Reliability - well testedReliability - well tested Documentation - run into problems, Documentation - run into problems,
look it uplook it up
Physics Engine ComparisonPhysics Engine Comparison
ODEODE BulletBullet PAL/OPALPAL/OPAL
Popular, more Popular, more activityactivity
Fresh projectFresh project APIAPI
Used with Used with Ogre 3D, well Ogre 3D, well testedtested
Not as Not as establishedestablished
High level vs High level vs low levellow level
Well Well DocumentedDocumented
Not well Not well documenteddocumented
More than we More than we needneed
Table of ContentsTable of Contents
1) Introduction physics engine1) Introduction physics engine
What is a “physics engine”?What is a “physics engine”?
2) Advantage of physics engine2) Advantage of physics engine
Why we want a physics engine?Why we want a physics engine?
3)3) Advantages and Disadvantages Advantages and Disadvantages of different physics enginesof different physics engines
4) Our PICK4) Our PICK – we like it hot – we like it hot
OUR PICKOUR PICK
Most popularMost popular Well testedWell tested Well documentedWell documented
Why Do We Choose ODE?Why Do We Choose ODE?
Good for simulating articulated rigid Good for simulating articulated rigid body structure.body structure. An articulated structure is created when An articulated structure is created when
rigid bodies of various shapes are rigid bodies of various shapes are connected together with joints of connected together with joints of various kinds.various kinds.
Example:Example: Ground vehiclesGround vehicles AirplaneAirplane RobotsRobots
Why Do We Choose ODE?Why Do We Choose ODE?
Designed to be used in the Designed to be used in the interactive or real-time simulation.interactive or real-time simulation. The user is able to change the structure The user is able to change the structure
of the system while the simulation is of the system while the simulation is running.running.
More accurate adjustments are More accurate adjustments are available.available.
Why Do We Choose ODE?Why Do We Choose ODE?
Built-in collision detection system.Built-in collision detection system. Supports various primitives: Supports various primitives:
Sphere, box, cylinder, plane, triangular mesh, etc.Sphere, box, cylinder, plane, triangular mesh, etc. Every collision has Every collision has hard contacthard contact..
ODE: use a special non-penetration ODE: use a special non-penetration constraint whenever two bodies collide.constraint whenever two bodies collide.
More realistic. More realistic. Other engines: use virtual springs to Other engines: use virtual springs to
represent contacts.represent contacts. Extremely error-prone & Difficult to do it correctly Extremely error-prone & Difficult to do it correctly
..
Why Do We Choose ODE?Why Do We Choose ODE?
Has a native C interface.Has a native C interface. Has a C++ interface built on top of Has a C++ interface built on top of
the C one.the C one. Platform specific optimization is Platform specific optimization is
available.available. Detailed tutorials and Detailed tutorials and
documentation.documentation. Beginner-friendly engine.Beginner-friendly engine.
A Simple Car DemoA Simple Car Demo
