DYNAMICSDYNAMICSPart 2Part 2

HOW DOES IT WORK??HOW DOES IT WORK??byby

Willis LouieWillis LouieJianfei LiaoJianfei Liao

Arcade Game - 1942Arcade Game - 1942

Presentation MilestonePresentation Milestone Presentation 1 What is a Physics Presentation 1 What is a Physics

Engine?Engine? Presentation 2 How Does It Presentation 2 How Does It

Work?Work? Presentation 3 IntegrationPresentation 3 Integration Presentation 4 Testing and Presentation 4 Testing and

DocumentationDocumentation

TABLE OF CONTENTTABLE OF CONTENT 1) Implementation1) Implementation 2) Timeline / Current Status2) Timeline / Current Status 3) Concepts3) Concepts

ObjectsObjects JointsJoints CollisionCollision

TABLE OF CONTENTTABLE OF CONTENT 1) 1) ImplementationImplementation 2) Timeline / Current Status2) Timeline / Current Status 3) Concepts3) Concepts

ObjectsObjects JointsJoints CollisionCollision

Question:Question: How to implement the How to implement the physics?physics?

Answer: Answer: Physics simulationPhysics simulation

Simulation ProcessSimulation Process 1) Create a dynamic world1) Create a dynamic world

2) Create dynamics bodies2) Create dynamics bodies

3) Initializations3) Initializations

4) Step forward in the world4) Step forward in the world

TABLE OF CONTENTTABLE OF CONTENT 1) Implementation1) Implementation 2) 2) Timeline / Current StatusTimeline / Current Status 3) Concepts3) Concepts

ObjectsObjects JointsJoints CollisionCollision

Our TimelineOur Timeline

TABLE OF CONTENTTABLE OF CONTENT 1) Implementation1) Implementation 2) Timeline / Current Status2) Timeline / Current Status 3) 3) ConceptsConcepts

ObjectsObjects JointsJoints CollisionCollision

Applying PhysicsApplying Physics In order to apply physics we need to In order to apply physics we need to

know the object properties and know the object properties and attributesattributes

ObjectsObjects JointsJoints Collision Collision

TABLE OF CONTENTTABLE OF CONTENT 1) Implementation1) Implementation 2) Timeline / Current Status2) Timeline / Current Status 3) 3) ConceptsConcepts

ObjectsObjects JointsJoints CollisionCollision

Object PropertiesObject Properties position vector(x,y,z) – shape,sizeposition vector(x,y,z) – shape,size linear velocity(vx,vy,vz) – movementlinear velocity(vx,vy,vz) – movement Orientation – rotation,directionOrientation – rotation,direction Total body massTotal body mass Center of mass(and inertia matrix)Center of mass(and inertia matrix)

Object PropertiesObject Properties

Geometry objects + Rigid body = simulated Geometry objects + Rigid body = simulated objectobjectShape, etc Shape, etc Mass, etc Mass, etc

TABLE OF CONTENTTABLE OF CONTENT 1) Implementation1) Implementation 2) Timeline / Current Status2) Timeline / Current Status 3) 3) ConceptsConcepts

ObjectsObjects JointsJoints CollisionCollision

Joints, Joints, Joints!!!Joints, Joints, Joints!!! Joints (relationship between bodies) Joints (relationship between bodies)

Can move or turn a certain way onlyCan move or turn a certain way only Different joints (human vs. robot) Different joints (human vs. robot)

Ball, socket, universal joints, etcBall, socket, universal joints, etc Joints must connect, if not they fly offJoints must connect, if not they fly off Constraint force mixing for soft Constraint force mixing for soft

materialmaterial

TABLE OF CONTENTTABLE OF CONTENT 1) Implementation1) Implementation 2) Timeline / Current Status2) Timeline / Current Status 3) 3) ConceptsConcepts

ObjectsObjects JointsJoints CollisionCollision

CollisionCollision

CollisionCollision

Why must we have it?Why must we have it?

PING’S LAWPING’S LAW

Object A crashing into object B = Object A crashing into object B = EXPLOSIONEXPLOSION

EXPLOSION = EXCITEMENTEXPLOSION = EXCITEMENT

Collision DetectionCollision Detection collision detection enginecollision detection engine collision detection function – collision detection function –

touching or not?touching or not? Checks for contact points Checks for contact points Each contact point creates a contact Each contact point creates a contact

jointjoint To see what reaction should occur, To see what reaction should occur, Hard or soft, explode or bounce offHard or soft, explode or bounce off

Collision DetectionCollision Detection Each contact point creates a contact Each contact point creates a contact

jointjoint To see what reaction should occur, To see what reaction should occur, Hard or soft, explode or bounce offHard or soft, explode or bounce off

Collision DetectionCollision Detection LoopLoop

Apply forcesApply forces Adjust jointsAdjust joints Collision detectionCollision detection Create contact jointsCreate contact joints Carry out actionCarry out action Remove all contact jointsRemove all contact joints

So…How does it work?So…How does it work? Create the worldCreate the world Using attributes to simulate objectsUsing attributes to simulate objects Using joints to built complex objectsUsing joints to built complex objects Check the collision detectionCheck the collision detection Check the contact jointsCheck the contact joints If hit blow it upIf hit blow it up