《Unity虚拟现实技术及其应用》 课件 Physics Engine in Unity

UnityPhysicsDongfengLiuSchoolofInformationEngineering,GDUTIntroductiontoUnityPhysicsBasicIssuesforPhysicsEngineIntegrationtodescribetheobject’sphysicalpropertiesinadatastructure,suchasmass,currentvelocity,currentposition,orientation,theexternalforces.CollisiondetectionInmostinteractivedevelopments,however,wedon’twanttheobjectstopassthrougheachother.Weneedtoknowthattwoobjectsarecolliding!Andweshouldcollectadditionalcollisioninformation.CollisionresolutionWhatwillhappenafterthecollision?Physicsengineshouldcoverthebasicsofallphysicscomponents.Everysimulationsuitableforinteractivedevelopmentwillhavethesecomponents.Built-inPhysicscomponentsinUnity3DUnity3Dembedsastate-of-the-artPhysicsengine,PhysX.Ode,TheRigidbodycomponentinUnity3Dismostlytargetedatrigidobjects.Byadjustingobject’sparametersettings,wecanmakePhysicsapproximationsinarealisticway.UnityhastwoseparatePhysicsengines:onefor3Dphysics,andonefor2Dphysics.RigidbodiesARigidbodycomponenttakesthemovementoftheobjecttowhichitisattached.weshouldn’ttrytomoveitbychangingthetransformpositionandrotationinascript.Instead,wecanapplyforcestopushtheobjectandletthePhysicsenginecalculatetheresults.KinematicmotionandRigidbodies.CollidersStaticcolliders,ColliderscanbeaddedtoanobjectwithoutaRigidbodycomponentinordertocreatefloors,walls,andsoon.Thesearereferredtoasstaticcolliders.DynamiccollidersPhysicMaterialsAsthecollidersinteract,weneedtosimulatethepropertiesofthematerialthattheyaresupposedtorepresent.WecanconfigurethefrictionandbounceusingPhysicMaterials.JointsWecanattachoneRigidbodyobjecttoanotherortoafixedpointinspaceusingajointcomponent.SpringJoint,HingeJoint,FixedJoint,CharacterJoint.CharacterControllerAcharacterinafirst-orthird-persongamewilloftenneedsomecollision-basedPhysicssothatcharacterdoesn’tfallonthefloororwalkoverthewalls.Unity3Dprovidesacomponenttocreatethisbehavior,whichiscalledCharacterController.ThiscomponentusesaCapsuleCollider.UsingCollidersPrimitivecollidersandtheirimplementationNonprimitivecollidersandtheirimplementationsUsesofTriggerCollidersEditingPolygonCollider2DPrimitivecolliders:BoxCollider3DSphereCollider3DCapsuleCollider3DMeshCollideraccurateshapedefinitionforcollision.thisisexpensiveintermsofperformance.WecanmarkConvexastrueifwewantthisgameobjecttocollidewithanotherMeshCollider.NonprimitivecollidersNonprimitivecolliders:WheelColliderCollisionMatrix3DTriggerMatrixPhysicsManagerEdit/projectsettings/Physics下面查看并修改PhysicsManagerLayer-basedcollisiondetectionLayer-basedcollisiondetectionisawaytomakeaGameObjectcollidewithanotherGameObjectthatissetuptoaspecificLayerorLayers.ObjectscollidingwiththeirownlayerJointsJointsareimportantcomponentsofUnity3Dandprovidedifferenttypesofjoints.JointTypesFixedjointThefixedjointisusedtogrouptwoRigidbodiestogetherintheirboundpositionConnectedBodyreferstotheotherRigidbodyonwhichF