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Added "alpha" friction 

Alpha means that the friction is not tested and most likely needs
tweaking.
This commit is contained in:
Robin Engman 2013-12-19 08:34:16 +01:00 committed by Dander7BD
parent 09e55ddc30
commit 56dec6cf5d
1 changed files with 33 additions and 6 deletions
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39
Code/GamePhysics/Implementation/PhysicsAPI_Impl.cpp
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@ -38,12 +38,37 @@ namespace
deuterG_Magnitude = deuterG.Dot( normal ); deuterG_Magnitude = deuterG.Dot( normal );
// bounce // bounce
Float4 sumJ = normal * Formula::CollisionResponse::Impulse( deuterState.GetRestitutionCoeff(), Float impulse = Formula::CollisionResponse::Impulse( deuterState.GetRestitutionCoeff(),
deuterState.GetMass(), deuterG_Magnitude, deuterState.GetMass(), deuterG_Magnitude,
protoState.GetMass(), protoG_Magnitude ); protoState.GetMass(), protoG_Magnitude );;
Float4 sumJ = normal*impulse;
// @todo TODO: friction // FRICTION
// sumJ -= ; // Relative momentum after normal impulse
Float4 relativeMomentum = deuterState.GetLinearMomentum() - protoState.GetLinearMomentum();
Float4 tanFriction = relativeMomentum - relativeMomentum.Dot(normal)*normal;
tanFriction.Normalize();
Float magnitudeFriction = -relativeMomentum.Dot(tanFriction);
magnitudeFriction = magnitudeFriction/( 1/protoState.GetMass() + 1/deuterState.GetMass() );
float mu = 0.5f;
Float4 frictionImpulse;
if( abs(magnitudeFriction) < impulse*mu )
{
frictionImpulse = magnitudeFriction*tanFriction;
}
else
{
Float dynamicFriction = 0.5f;
frictionImpulse = -impulse*tanFriction*dynamicFriction;
}
// Apply
sumJ -= ( 1 / protoState.GetMass() )*frictionImpulse;
// FRICTION END
// calc from perspective of proto // calc from perspective of proto
proto->GetNormalAt( worldPointOfContact, normal ); proto->GetNormalAt( worldPointOfContact, normal );
@ -54,8 +79,10 @@ namespace
sumJ += normal * Formula::CollisionResponse::Impulse( protoState.GetRestitutionCoeff(), sumJ += normal * Formula::CollisionResponse::Impulse( protoState.GetRestitutionCoeff(),
protoState.GetMass(), protoG_Magnitude, protoState.GetMass(), protoG_Magnitude,
deuterState.GetMass(), deuterG_Magnitude ); deuterState.GetMass(), deuterG_Magnitude );
// @todo TODO: friction // FRICTION
// sumJ += ; // Apply
//sumJ += ( 1 / deuterState.GetMass() )*frictionImpulse;
// FRICTION END
protoState.ApplyImpulse( sumJ, worldPointOfContact, normal ); protoState.ApplyImpulse( sumJ, worldPointOfContact, normal );
proto->SetState( protoState ); proto->SetState( protoState );