DigitalSpaces::DIPhysicsJoint Struct Reference
[Physics]

#include <Physics_Joint.h>

Inherits DigitalSpaces::DIObjectBase.

---

Detailed Description

Interface for interacting with a physics simulated joint.

Physics joints are used to link together two bodies, and limit the ways in which the bodies can move in relation to each other. The joint types (as specified to DIPhysicsBase::BeginSetup(const char*) ) are:

• ball (See http://opende.sourceforge.net/wiki/index.php/Manual_(Joint_Types_and_Functions)Ball_and_Socket )
• hinge (See http://opende.sourceforge.net/wiki/index.php/Manual_(Joint_Types_and_Functions)Hinge )
• hinge2 (See http://opende.sourceforge.net/wiki/index.php/Manual_(Joint_Types_and_Functions)Hinge-2 )
• slider (See http://opende.sourceforge.net/wiki/index.php/Manual_(Joint_Types_and_Functions)Slider )

See also http://www.digitalspaces.net/wiki/index.php/Scene_File_Format#joint .

Not all the functions included in this interface are appropriate for all joint types. When not appropriate, the function should just be silently ignored.

The joint types and the values that are accepted through the Set functions (name, type, default value):

• ball
  • position - vector - 0,0,0
  • collision - bool - false
• hinge
  • position - vector - 0,0,0
  • axis - vector - 0,1,0
  • collision - bool - false
  • orientation - quaternion - 1,0,0,0
  • stopERP - float - 1.0
  • stopCFM - float - stopCFM
  • CFM - float - 0.0
  • bounce - float - 0.0
• hinge2
  • position - vector - 0,0,0
  • axis - vector - 0,1,0
  • axis2 - vector - 1,0,0
  • collision - bool - false
  • orientation - quaternion - 1,0,0,0
  • stopERP - float - 1.0
  • stopCFM - float - 0.0
  • suspensionERP - float - 1.0
  • suspensionCFM - float - 0.0
  • CFM - float - 0.0
  • bounce - float - 0.0
• slider
  • position - vector - 0,0,0
  • axis - vector - 1,0,0
  • collision - bool - false
  • orientation - quaternion - 1,0,0,0
  • stopERP - float - 1.0
  • stopCFM - float - 0.0
  • CFM - float - 0.0
  • bounce - float - 0.0
  • springSpeed - float - 0.0
  • springMinForce - float - 0.0
  • springMaxForce - float - 0.0
  • fudge - float - 1.0

Public Member Functions
void	SetAngularLimits (float fLow, float fHigh, unsigned char cAxis)
	Limit the degree of motion around the specified axis of the joint.
void	SetLinearLimits (float fLow, float fHigh, unsigned char cAxis)
	Limit the range of motion along the specified axis of the joint.
float	GetAngularLowLimit (unsigned char axis)
	Retreive the lower angular limit.
float	GetAngularHighLimit (unsigned char axis)
	Retreive the higher angular limit.
float	GetLinearLowLimit (unsigned char axis)
	Retreive the lower linear limit.
float	GetLinearHighLimit (unsigned char axis)
	Retreive the higher linear limit.
float	GetAngle (unsigned char cAxis)
	Return the joints rotation, around the specified axis.
float	GetPosition (unsigned char cAxis)
	Returns the joints position, along the spcified axis.
float	GetAngularVelocity (unsigned char cAxis)
	Returns the joints rotational velocity (change in orientation) around the specified axis.
float	GetLinearVelocity (unsigned char cAxis)
	Returns the joints linear velocity (change in position) along the specified axis.
void	SetMotorParameters (float fVelocity, float fForce, unsigned int motor)
	Set the target speed and maximum force to be used by the physics simulation, to simulate a motorized joint.
float	GetMotorVelocity (unsigned int motor)
	Return the motor velocity setting, as set via SetMotorParameters.
float	GetMotorForce (unsigned int motor)
	Return the motor force setting, as set via SetMotorParameters.
void	ApplyForce (float fForce, unsigned char cAxis)
	Apply a linear force along the specified axis of the joint.
void	ApplyTorque (float fTorque, unsigned char cAxis)
	Apply a rotational force around the specified axis of the joint.
DIPhysicsBody *	GetBody ()
	Returns one of the bodies this joint is attached to.
DIPhysicsBody *	GetOtherBody ()
	Returns the other body this joint is attached to.

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Member Function Documentation

void DigitalSpaces::DIPhysicsJoint::SetAngularLimits	(	float	fLow,
		float	fHigh,
		unsigned char	cAxis
	)

Limit the degree of motion around the specified axis of the joint.

Note:

fLow must be less then fHigh, otherwise no limit is applied at all. This can be used to remove a limit, if desired.

Setting fLow equal to fHigh will result in a limit being placed, however it is often not stable.

Applicable joint types:

• hinge
• hinge2 - While a multi acis joint, implementation does not allow limitation around second axis

Parameters:

	fLow	The lower limit, between pi and -pi, measured in radians from the joints default position.
	fHigh	The upper limit, between pi and -pi, measured in radians from the joints default position.
	cAxis	Zero based index of which axis to limit, used for multi-axis joints.

void DigitalSpaces::DIPhysicsJoint::SetLinearLimits	(	float	fLow,
		float	fHigh,
		unsigned char	cAxis
	)

Limit the range of motion along the specified axis of the joint.

Note:

fLow must be less then fHigh, otherwise no limit is applied at all. This can be used to remove a limit, if desired.

Setting fLow equal to fHigh will result in a limit being placed, however it is often not stable.

Applicable joint types:

• slider

Parameters:

	fLow	The lower limit, measured in meters from the joints default position.
	fHigh	The upper limit, measured in meters from the joints default position.
	cAxis	Zero based index of which axis to limit, used for multi-axis joints.

float DigitalSpaces::DIPhysicsJoint::GetAngularLowLimit

(

unsigned char

axis

)

Retreive the lower angular limit.

Returns:

Low limit, or 0 if not appropriate.

Applicable joint types:

• hinge
• hinge2 - While a multi acis joint, implementation does not allow limitation around second axis

Parameters:

axis

Zero based index of which axis to limit, used for multi-axis joints.

Note:

The default value by the implementation docs is -infinity, not sure how this will extract as. Should return this as "not appropriate" error condition as well.

float DigitalSpaces::DIPhysicsJoint::GetAngularHighLimit

(

unsigned char

axis

)

Retreive the higher angular limit.

Returns:

High limit, or 0 if not appropriate.

Applicable joint types:

• hinge
• hinge2 - While a multi acis joint, implementation does not allow limitation around second axis

Parameters:

axis

Zero based index of which axis to limit, used for multi-axis joints.

Note:

The default value by the implementation docs is infinity, not sure how this will extract as. Should return this as "not appropriate" error condition as well.

float DigitalSpaces::DIPhysicsJoint::GetLinearLowLimit

(

unsigned char

axis

)

Retreive the lower linear limit.

Returns:

Low limit, or 0 if not appropriate.

Applicable joint types:

• slider

Parameters:

axis

Zero based index of which axis to limit, used for multi-axis joints.

Note:

The default value by the implementation docs is -infinity, not sure how this will extract as. Should return this as "not appropriate" error condition as well.

float DigitalSpaces::DIPhysicsJoint::GetLinearHighLimit

(

unsigned char

axis

)

Retreive the higher linear limit.

Returns:

High limit, or 0 if not appropriate.

Applicable joint types:

• slider

Parameters:

axis

Zero based index of which axis to limit, used for multi-axis joints.

Note:

The default value by the implementation docs is -infinity, not sure how this will extract as. Should return this as "not appropriate" error condition as well.

float DigitalSpaces::DIPhysicsJoint::GetAngle

(

unsigned char

cAxis

)

Return the joints rotation, around the specified axis.

Returns:

Angle measured in radians, between -pi and pi, or 0 if not applicable

Applicable joint types:

• hinge
• hinge2 - Implementation returns angle around 0th axis, regardless of value of cAxis?

Parameters:

cAxis

Zero based index of which axis to limit, used for multi-axis joints.

float DigitalSpaces::DIPhysicsJoint::GetPosition

(

unsigned char

cAxis

)

Returns the joints position, along the spcified axis.

Returns:

Distance measured in meters, or 0 if not applicable.

Applicable joint types:

• slider

Parameters:

cAxis

Zero based index of which axis to limit, used for multi-axis joints.

float DigitalSpaces::DIPhysicsJoint::GetAngularVelocity

(

unsigned char

cAxis

)

Returns the joints rotational velocity (change in orientation) around the specified axis.

Returns:

Change in angle, measured in radians per second, or 0 if not applicable.

Applicable joint types:

• hinge
• hinge2

Parameters:

cAxis

Zero based index of which axis to return value for.

float DigitalSpaces::DIPhysicsJoint::GetLinearVelocity

(

unsigned char

cAxis

)

Returns the joints linear velocity (change in position) along the specified axis.

Returns:

Speed measured in meters per second, or 0 if not applicable.

Applicable joint types:

• Slider

Parameters:

cAxis

Zero based index of which axis to return value for.

void DigitalSpaces::DIPhysicsJoint::SetMotorParameters	(	float	fVelocity,
		float	fForce,
		unsigned int	motor
	)

Set the target speed and maximum force to be used by the physics simulation, to simulate a motorized joint.

Parameters:

	fVelocity	Target velocity of the joint. Depending on the joint type, this is measured in radians per second (hinge, hinge2) or meters per second (slider).
	fForce	Maximum for usable by the simulation to accelerate the joint to the specified velocity, and to keep it there. Setting this to zero disables the motor.
	motor	Specifies which axis of a multi axis joint should be motorized. This is only applicable for hinge2, where 0 motorizes the "wheel" joint, and 1 motorizes the "steering" joint.

Applicable joint types:

• hinge
• hinge2
• Slider

float DigitalSpaces::DIPhysicsJoint::GetMotorVelocity

(

unsigned int

motor

)

Return the motor velocity setting, as set via SetMotorParameters.

Parameters:

motor

Specifies which axis of a multi axis joint to return the value for.

Returns:

0 If not applicable.

Applicable joint types:

• hinge
• hinge2
• Slider

float DigitalSpaces::DIPhysicsJoint::GetMotorForce

(

unsigned int

motor

)

Return the motor force setting, as set via SetMotorParameters.

Parameters:

motor

Specifies which axis of a multi axis joint to return the value for.

Returns:

0 If not applicable.

Applicable joint types:

• hinge
• hinge2
• Slider

void DigitalSpaces::DIPhysicsJoint::ApplyForce	(	float	fForce,
		unsigned char	cAxis
	)

Apply a linear force along the specified axis of the joint.

This will effectively apply the force to each of the jointed bodies, in opposite directions.

Parameters:

	fForce	Force to apply, measured in newtons (I think).
	cAxis	Zero based index of which axis to apply the force along.

Applicable joint types:

• slider

void DigitalSpaces::DIPhysicsJoint::ApplyTorque	(	float	fTorque,
		unsigned char	cAxis
	)

Apply a rotational force around the specified axis of the joint.

This will effectively apply the torque to each of the jointed bodies, in opposite directions.

Parameters:

	fTorque	Torque to apply, measured in newtonmeters (I think).
	cAxis	Zero based index of which axis to apply the torque around.

Applicable joint types:

• hinge
• hinge2

DIPhysicsBody* DigitalSpaces::DIPhysicsJoint::GetBody

(

)

Returns one of the bodies this joint is attached to.

Returns:

Interface to a body, or NULL if the joint is not attached to any bodies.

DIPhysicsBody* DigitalSpaces::DIPhysicsJoint::GetOtherBody

(

)

Returns the other body this joint is attached to.

Returns:

Interface to a body, or NULL if the joint is attached to one or no bodies.

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The documentation for this struct was generated from the following file:

• PhysicsInterfaces/Physics_Joint.h