OMK::Iii::JointExtension Class Reference
[Joints]

Kinematic joint between two objects. More...

#include <OMKJointExtension.h>

Inheritance diagram for OMK::Iii::JointExtension:

[legend]Collaboration diagram for OMK::Iii::JointExtension:

[legend]List of all members.

Protected Member Functions
virtual bool	loadObjectParameters (const ConfigurationParameterDescriptor *node)
	Configuration parameters loader of Extension.
virtual bool	loadExtensionParameters (const ConfigurationParameterDescriptor *node)
	Configuration parameters loader of Extension.
virtual void	postComputeParameters ()
	Calculates the new position of the object.
Protected Attributes
IAttributeBaseT< OMK::Type::Transform > *	_objectPosition
	The position of the object.
AttributeT< OMK::Type::Transform >	_referencePosition
	The reference position.
AttributeT< OMK::Type::Transform >	_jointPosition
	The joint position.
bool	_connected
	The state of the joint.
JointInteractorExtension *	_interactor
	The retro-propagation interactor.
Joint *	_joint
	The joint.
Private Member Functions
	DECLARE_EXTENSION_FACTORY (JointExtension)
	Factory and constructor/destructor.
Friends
class	JointInteractorExtension
class	Joint

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Detailed Description

Kinematic joint between two objects.

Date:

2007-06-20

Author:

Benoît Chanclou

Module description :

To calculate the position of the object the joint extension use the following parameters:

• reference position
• joint position
• object position
• the offset to get the joint position from the reference position
• the offset to get the object position from the joint position

The two following formulas are the base for the others:

• (1)
• (2)

There is two states for the joint:

• The unconnected state does nothing
• The connected state calculates the position of the object.

  In this state, there are two cases:

  • The object hasn't moved, in this case the new object position is calculated with (1) then (2)
  • The object has moved, in that case the ideal reference position is calculated with the inverse formulas (5).
    • (2) (3)
    • (1) (4)
    • (3)+(4) (5)
    Then the new object position is calculated with (1) then (2).

The transitions between states are occured:

• When the link is made, the offsets are computed, based on the current positions of the three items.
  • (1)
  • (2)
  The inverse are also calculated for optimisation to calculate (5).
• When the link is destroyed, there nothing to do except updating the state flag.

If the joint gives some degrees of freedom to the object, like allowing sliding or rotating, it have to calculte the ideal reference position according to its degrees of freedom.

This calculation takes place in the (5) formula. The must be update according to the freedom of the joint. These calculation is made by the Joint class. By choosing the associated joint class the behavior can be choose.

See the introduction to the interaction protocols

Definition at line 107 of file OMKJointExtension.h.

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Member Function Documentation

OMK::Iii::JointExtension::DECLARE_EXTENSION_FACTORY

(

JointExtension

)

[private]

Factory and constructor/destructor.

See Extension feature

bool OMK::Iii::JointExtension::loadObjectParameters

(

const ConfigurationParameterDescriptor *

node

)

[protected, virtual]

Configuration parameters loader of Extension.

Parameters:

[in]

node

the root node of the configuration parameter.

Returns:

should return true if all the parameters are well retrieved.

Overwrite this method to initialise the extension. This method allows the extension to get parameters of the object.
Be careful, this method is called before loadExtensionParameters.
See How to configure an extension ? for details.

Reimplemented from OMK::Extension.

Definition at line 231 of file OMKJointExtension.cpp.

References _interactor, and OMK::Iii::JointInteractorExtension::loadObjectParameters().

{
  // Calls the interactor loader if neccessary
  return !_interactor || _interactor->loadObjectParameters( node ) ;
}

bool OMK::Iii::JointExtension::loadExtensionParameters

(

const ConfigurationParameterDescriptor *

node

)

[protected, virtual]

Configuration parameters loader of Extension.

It retrieves, in the extension configuration, the joint parameters and the name of the attribute to control.

Reimplemented from OMK::Extension.

Definition at line 238 of file OMKJointExtension.cpp.

References _interactor, _joint, _objectPosition, OMK::ExtensionT< SimulatedObjectType >::_owner, OMK::ParametersAccessor::get(), OMK::Iii::JointInteractorExtension::loadExtensionParameters(), and OMASSERTM.

{
  // Gets the name of the position attribute of the object
  Name attributeName( "Position" ) ; // by default "Position"
  ParametersAccessor::get( node, "PositionName", attributeName ) ;
  // Gets the attribute accessor
  _objectPosition = _owner->getBaseAttribute< OMK::Type::Transform >( attributeName ) ;
  bool ok = _objectPosition != 0 ;
  
  // Calls the interactor loader if neccessary
  ok = ok && ( !_interactor || _interactor->loadExtensionParameters( node ) ) ;
  
  // The joint
  std::string jointClass( "Lock" ) ;
  
  ok = ok && ParametersAccessor::get( node, "Joint", jointClass ) ;
  _joint = OMK::Iii::JointFactory::getInstance().create( jointClass )( this, node ) ;
  OMASSERTM( _joint, "Joint  [" << jointClass << "] cannot be created, may be not registered in the main !" ) ;
  
  return ok ;
}

void OMK::Iii::JointExtension::postComputeParameters

(

)

[protected, virtual]

Calculates the new position of the object.

Calculates the axe position by offsetting the reference position. Then calculates the joint constraintes and the new position of the object. If necessary the

Reimplemented from OMK::Extension.

Definition at line 261 of file OMKJointExtension.cpp.

References _connected, _interactor, _joint, _objectPosition, _referencePosition, OMK::Iii::Joint::currentJointPosition(), OMK::Iii::Joint::currentObjectPosition(), OMK::Iii::Joint::establishLink(), OMK::InputNT::getConnectedOutput(), OMK::IAttributeT< PrmType, ModelType, AccessorType >::getInput(), OMK::IAttribute::isUpdated(), OMASSERTM, OMMESSAGE, OMK::Iii::Joint::retroPropagation(), and OMK::Iii::JointInteractorExtension::stopRetroPropagation().

{
  OMASSERTM( _joint, "The joint must be created" ) ;
  // To be linked the joint must found the position, see if the reference position declares an input and if this one is connected
  bool updatedLinkstate = _objectPosition 
                       && _referencePosition.getInput() 
                       && _referencePosition.getInput()->getConnectedOutput() ;
  if( _connected )
  { 
    if( !updatedLinkstate )
    { // Change the state => no more connected
      _connected = false ;
      // Nothing else to do
      OMMESSAGE( "release" ) ;
    }
    else
    { // Connected and still connected
      // Calculates the new joint position based on the reference position
      _joint->currentJointPosition() ;
      // Does the object move ?
      
      // Retro propagation is activated
      // the object moves itself (by an interactor, its own behavior,...)
      // => calculates the the ideal position for the reference position
      if( _objectPosition->isUpdated() && _joint->retroPropagation() )
      { 
        // Starts retro-propagation
        if( _interactor ) _interactor->startRetroPropagation() ;
      }
      else
      {
        // The object doesn't move itself => it follows the reference, no more retro-propagation
        if( _interactor ) _interactor->stopRetroPropagation() ;
      }
      // Calculates the new joint position based on the joint position
      _joint->currentObjectPosition() ;
    }
  }
  else
  {
    if( updatedLinkstate )
    { // Change the state => The connection has just been connected
      OMMESSAGE( "linked" ) ;
      _connected = true ;
      _joint->establishLink() ;
    }
    // else unconnected and still unconnected => nothing to do
  }
}

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Friends And Related Function Documentation

friend class JointInteractorExtension [friend]

Definition at line 110 of file OMKJointExtension.h.

friend class Joint [friend]

Definition at line 111 of file OMKJointExtension.h.

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Member Data Documentation

IAttributeBaseT< OMK::Type::Transform >* OMK::Iii::JointExtension::_objectPosition [protected]

The position of the object.

The reference to the attribute which define the position of the object.

The name can be defined by the configuration parameter named Attribute, Attribute, if not defined the default is Position.

Definition at line 131 of file OMKJointExtension.h.

Referenced by loadExtensionParameters(), and postComputeParameters().

AttributeT< OMK::Type::Transform > OMK::Iii::JointExtension::_referencePosition [protected]

The reference position.

This attribute is used to retrieve the position of the reference object.

Definition at line 134 of file OMKJointExtension.h.

Referenced by OMK::Iii::JointInteractorExtension::loadExtensionParameters(), postComputeParameters(), OMK::Iii::JointInteractorExtension::startRetroPropagation(), and OMK::Iii::JointInteractorExtension::stopRetroPropagation().

AttributeT< OMK::Type::Transform > OMK::Iii::JointExtension::_jointPosition [protected]

The joint position.

This attribute defines the position of the joint. This position follows the reference position and it is calculated by offsetting this one.

Definition at line 139 of file OMKJointExtension.h.

bool OMK::Iii::JointExtension::_connected [protected]

The state of the joint.

true the connection is done. false the joint is free.

Definition at line 142 of file OMKJointExtension.h.

Referenced by postComputeParameters().

JointInteractorExtension* OMK::Iii::JointExtension::_interactor [protected]

The retro-propagation interactor.

Definition at line 144 of file OMKJointExtension.h.

Referenced by loadExtensionParameters(), loadObjectParameters(), and postComputeParameters().

Joint* OMK::Iii::JointExtension::_joint [protected]

The joint.

This joint calculates the ideal reference position according to the current position of the object and its characteristics.

Definition at line 147 of file OMKJointExtension.h.

Referenced by loadExtensionParameters(), and postComputeParameters().

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