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attempt to make hinge motor work better

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This commit is contained in:
Seth Alves 2017-04-22 16:22:00 -07:00
parent 17b83dd64c
commit 59950236d3
2 changed files with 144 additions and 9 deletions
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118
libraries/physics/src/ObjectConstraintHinge.cpp
View file

@ -48,6 +48,50 @@ QList<btRigidBody*> ObjectConstraintHinge::getRigidBodies() {
return result;
}
void ObjectConstraintHinge::prepareForPhysicsSimulation() {
// setting the motor velocity doesn't appear to work for anyone. constantly adjusting the
// target angle seems to work.
// https://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=7020
uint64_t now = usecTimestampNow();
withWriteLock([&]{
btHingeConstraint* constraint = static_cast<btHingeConstraint*>(_constraint);
if (!constraint) {
return;
}
if (_previousMotorTime == 0) {
_previousMotorTime = now;
return;
}
if (_motorVelocity != 0.0f) {
if (_startMotorTime == 0) {
_startMotorTime = now;
}
float dt = (float)(now - _previousMotorTime) / (float)USECS_PER_SECOND;
float t = (float)(now - _startMotorTime) / (float)USECS_PER_SECOND;
float motorTarget = _motorVelocity * t;
while (motorTarget > PI) {
motorTarget -= PI;
}
while (motorTarget < PI) {
motorTarget += PI;
}
if (!_motorEnabled) {
constraint->enableMotor(true);
_motorEnabled = true;
}
constraint->setMaxMotorImpulse(_maxImpulse);
constraint->setMotorTarget(motorTarget, dt);
} else if (_motorTargetTimeScale > 0.0f) {
// XXX
} else if (_motorEnabled) {
constraint->enableMotor(false);
_motorEnabled = false;
_startMotorTime = 0;
}
_previousMotorTime = now;
});
}
void ObjectConstraintHinge::updateHinge() {
btHingeConstraint* constraint { nullptr };
float low;
@ -56,28 +100,45 @@ void ObjectConstraintHinge::updateHinge() {
float biasFactor;
float relaxationFactor;
float motorVelocity;
float motorTarget;
float motorTargetTimeScale;
float maxImpulse;
withReadLock([&]{
constraint = static_cast<btHingeConstraint*>(_constraint);
low = _low;
high = _high;
softness = _softness;
maxImpulse = _maxImpulse;
biasFactor = _biasFactor;
relaxationFactor = _relaxationFactor;
// under the hood, motorTarget sets a veloctiy and must be called repeatedly to maintain
// a velocity. _motorTargetTimeScale of 0.0f means the target isn't set. motorVelocity is
// only considered when motorTarget isn't set.
motorVelocity = _motorVelocity;
motorTarget = _motorTarget;
motorTargetTimeScale = _motorTargetTimeScale;
softness = _softness;
});
if (!constraint) {
return;
}
constraint->setLimit(low, high, softness, biasFactor, relaxationFactor);
if (motorVelocity != 0.0f) {
constraint->setMotorTargetVelocity(motorVelocity);
constraint->enableMotor(true);
} else {
constraint->enableMotor(false);
}
// constraint->setLimit(low, high, softness, biasFactor, relaxationFactor);
// if (motorTargetTimeScale > 0.0f) {
// qDebug() << "--- setting motor target:" << motorTarget << motorTargetTimeScale;
// constraint->setMotorTarget(motorTarget, motorTargetTimeScale);
// constraint->enableMotor(true);
// withWriteLock([&]{
// _motorTargetTimeScale = 0.0f; // it's a one-shot.
// });
// } else if (motorVelocity != 0.0f) {
// // constraint->setMotorTargetVelocity(motorVelocity);
// // constraint->enableMotor(true);
// } else {
// constraint->enableMotor(false);
// }
}
@ -151,6 +212,9 @@ bool ObjectConstraintHinge::updateArguments(QVariantMap arguments) {
float biasFactor;
float relaxationFactor;
float motorVelocity;
float motorTarget;
float motorTargetTimeScale;
float maxImpulse;
bool needUpdate = false;
bool somethingChanged = ObjectDynamic::updateArguments(arguments);
@ -224,6 +288,27 @@ bool ObjectConstraintHinge::updateArguments(QVariantMap arguments) {
motorVelocity = _motorVelocity;
}
ok = true;
motorTarget = EntityDynamicInterface::extractFloatArgument("hinge constraint", arguments,
"motorTarget", ok, false);
if (!ok) {
motorTarget = _motorTarget;
}
ok = true;
motorTargetTimeScale = EntityDynamicInterface::extractFloatArgument("hinge constraint", arguments,
"motorTargetTimeScale", ok, false);
if (!ok) {
motorTargetTimeScale = _motorTargetTimeScale;
}
ok = true;
maxImpulse = EntityDynamicInterface::extractFloatArgument("hinge constraint", arguments, "maxImpulse", ok, false);
if (!ok) {
maxImpulse = _maxImpulse;
}
if (somethingChanged ||
pivotInA != _pivotInA ||
axisInA != _axisInA ||
@ -235,7 +320,10 @@ bool ObjectConstraintHinge::updateArguments(QVariantMap arguments) {
softness != _softness ||
biasFactor != _biasFactor ||
relaxationFactor != _relaxationFactor ||
motorVelocity != _motorVelocity) {
motorVelocity != _motorVelocity ||
motorTarget != _motorTarget ||
motorTargetTimeScale != _motorTargetTimeScale ||
maxImpulse != _maxImpulse) {
// something changed
needUpdate = true;
}
@ -254,6 +342,9 @@ bool ObjectConstraintHinge::updateArguments(QVariantMap arguments) {
_biasFactor = biasFactor;
_relaxationFactor = relaxationFactor;
_motorVelocity = motorVelocity;
_motorTarget = motorTarget;
_motorTargetTimeScale = motorTargetTimeScale;
_maxImpulse = maxImpulse;
_active = true;
@ -285,6 +376,9 @@ QVariantMap ObjectConstraintHinge::getArguments() {
arguments["biasFactor"] = _biasFactor;
arguments["relaxationFactor"] = _relaxationFactor;
arguments["motorVelocity"] = _motorVelocity;
arguments["motorTarget"] = _motorTarget;
arguments["motorTargetTimeScale"] = _motorTargetTimeScale;
arguments["maxImpulse"] = _maxImpulse;
arguments["angle"] = static_cast<btHingeConstraint*>(_constraint)->getHingeAngle(); // [-PI,PI]
}
});
@ -315,6 +409,9 @@ QByteArray ObjectConstraintHinge::serialize() const {
dataStream << _tag;
dataStream << _motorVelocity;
dataStream << _motorTarget;
dataStream << _motorTargetTimeScale;
dataStream << _maxImpulse;
});
return serializedConstraintArguments;
@ -357,6 +454,9 @@ void ObjectConstraintHinge::deserialize(QByteArray serializedArguments) {
dataStream >> _tag;
dataStream >> _motorVelocity;
dataStream >> _motorTarget;
dataStream >> _motorTargetTimeScale;
dataStream >> _maxImpulse;
_active = true;
});

35
libraries/physics/src/ObjectConstraintHinge.h
View file

@ -21,6 +21,8 @@ public:
ObjectConstraintHinge(const QUuid& id, EntityItemPointer ownerEntity);
virtual ~ObjectConstraintHinge();
virtual void prepareForPhysicsSimulation() override;
virtual bool updateArguments(QVariantMap arguments) override;
virtual QVariantMap getArguments() override;
@ -44,10 +46,43 @@ protected:
float _low { -2.0f * PI };
float _high { 2.0f * PI };
// https://gamedev.stackexchange.com/questions/71436/what-are-the-parameters-for-bthingeconstraintsetlimit
//
// softness: a negative measure of the friction that determines how much the hinge rotates for a given force. A high
// softness would make the hinge rotate easily like it's oiled then.
// biasFactor: an offset for the relaxed rotation of the hinge. It won't be right in the middle of the low and high angles
// anymore. 1.0f is the neural value.
// relaxationFactor: a measure of how much force is applied internally to bring the hinge in its central rotation.
// This is right in the middle of the low and high angles. For example, consider a western swing door. After
// walking through it will swing in both directions but at the end it stays right in the middle.
// http://javadoc.jmonkeyengine.org/com/jme3/bullet/joints/HingeJoint.html
//
// _softness - the factor at which the velocity error correction starts operating, i.e. a softness of 0.9 means that
// the vel. corr starts at 90% of the limit range.
// _biasFactor - the magnitude of the position correction. It tells you how strictly the position error (drift) is
// corrected.
// _relaxationFactor - the rate at which velocity errors are corrected. This can be seen as the strength of the
// limits. A low value will make the the limits more spongy.
float _maxImpulse { 1.0f };
float _softness { 0.9f };
float _biasFactor { 0.3f };
float _relaxationFactor { 1.0f };
float _motorVelocity { 0.0f };
float _motorTarget { 0.0f };
float _motorTargetTimeScale { 0.0f };
uint64_t _startMotorTime { 0 };
uint64_t _previousMotorTime { 0 };
bool _motorEnabled { false };
};
#endif // hifi_ObjectConstraintHinge_h