1. DYNAMICS Part I Physics Engine By Willis (The Magnificent) Louie Fei (The Coyote) Liao

2. Flight Simulator RPG

3. Table of Contents 1) Introduction physics engine What is a “ physics engine ” ? 2) Advantage of physics engine Why we want a physics engine? 3) Advantages and Disadvantages of different physics engines 4) Our PICK – we like it hot

4. What is a physics engine?

5. What is a PHYSICS ENGINE? Pre-designed to do physics calculations. Pre-designed to do physics calculations. It uses physical variables such as MASS, FRICTION, VELOCITY, etc., to simulate the objects movements. It uses physical variables such as MASS, FRICTION, VELOCITY, etc., to simulate the objects movements.

6. What is a PHYSICS ENGINE? Real-time vs high precision Real-time vs high precision Scientist and animated graphics Scientist and animated graphics Video game use real-time for time sensitive Video game use real-time for time sensitive Rigid body dynamics VS soft body dynamics Rigid body dynamics VS soft body dynamics Liquid, clothes, etc Liquid, clothes, etc

7. Table of Contents 1) Introduction physics engine What is a “ physics engine ” ? 2) Advantage of physics engine Why we want a physics engine? 3) Advantages and Disadvantages of different physics engines 4) Our PICK – we like it hot

8. Why do we want a physics engine?

9. Advantages of Physics Engine Manual labor sucks Manual 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 errors doing calculations most humans make errors Cost efficient Cost efficient Wouldn ’ t make a whole lot of money working on that engine all day long. Wouldn ’ t make a whole lot of money working on that engine all day long.

10. Table of Contents 1) Introduction physics engine What is a “ physics engine ” ? 2) Advantage of physics engine Why we want a physics engine? 3) Advantages and Disadvantages of different physics engines 4) Our PICK – we like it hot

11. Physics Engine Comparison User Base - popularity User Base - popularity Reliability - well tested Reliability - well tested Documentation - run into problems, look it up Documentation - run into problems, look it up

12. Physics Engine Comparison ODEBulletPAL/OPAL Popular, more activity Fresh project API Used with Ogre 3D, well tested Not as established High level vs low level Well Documented Not well documented More than we need

13. Table of Contents 1) Introduction physics engine What is a “ physics engine ” ? 2) Advantage of physics engine Why we want a physics engine? 3) Advantages and Disadvantages of different physics engines 4) Our PICK – we like it hot

14. OUR PICK Most popular Most popular Well tested Well tested Well documented Well documented

15. Why Do We Choose ODE? Good for simulating articulated rigid body structure. Good for simulating articulated rigid body structure. An articulated structure is created when rigid bodies of various shapes are connected together with joints of various kinds. An articulated structure is created when rigid bodies of various shapes are connected together with joints of various kinds. Example: Example: Ground vehicles Ground vehicles Airplane Airplane Robots Robots

16. Why Do We Choose ODE? Designed to be used in the interactive or real-time simulation. Designed to be used in the interactive or real-time simulation. The user is able to change the structure of the system while the simulation is running. The user is able to change the structure of the system while the simulation is running. More accurate adjustments are available. More accurate adjustments are available.

17. 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 hard contact. Every collision has hard contact. ODE: use a special non-penetration constraint whenever two bodies collide. ODE: use a special non-penetration constraint whenever two bodies collide. More realistic. More realistic. Other engines: use virtual springs to represent contacts. Other engines: use virtual springs to represent contacts. Extremely error-prone & Difficult to do it correctly. Extremely error-prone & Difficult to do it correctly.

18. Why Do We Choose ODE? Has a native C interface. Has a native C interface. Has a C++ interface built on top of the C one. Has a C++ interface built on top of the C one. Platform specific optimization is available. Platform specific optimization is available. Detailed tutorials and documentation. Detailed tutorials and documentation. Beginner-friendly engine. Beginner-friendly engine.

19. A Simple Car Demo