hpp::fcl::details::GJK Struct Reference

class for GJK algorithm More...

#include <hpp/fcl/narrowphase/gjk.h>

Collaboration diagram for hpp::fcl::details::GJK:

Classes
struct	Simplex
struct	SimplexV

Public Types
enum	Status { Valid, Inside, Failed, EarlyStopped }
	Status of the GJK algorithm: Valid: GJK converged and the shapes are not in collision. Inside: GJK converged and the shapes are in collision. Failed: GJK did not converge. More...
typedef unsigned char	vertex_id_t

Public Member Functions
	GJK (unsigned int max_iterations_, FCL_REAL tolerance_)
void	initialize ()
Status	evaluate (const MinkowskiDiff &shape, const Vec3f &guess, const support_func_guess_t &supportHint=support_func_guess_t::Zero())
	GJK algorithm, given the initial value guess. More...
void	getSupport (const Vec3f &d, bool dIsNormalized, SimplexV &sv, support_func_guess_t &hint) const
	apply the support function along a direction, the result is return in sv More...
bool	encloseOrigin ()
	whether the simplex enclose the origin More...
Simplex *	getSimplex () const
	get the underlying simplex using in GJK, can be used for cache in next iteration More...
bool	hasClosestPoints ()
	Tells whether the closest points are available. More...
bool	hasPenetrationInformation (const MinkowskiDiff &shape)
bool	getClosestPoints (const MinkowskiDiff &shape, Vec3f &w0, Vec3f &w1)
Vec3f	getGuessFromSimplex () const
	get the guess from current simplex More...
void	setDistanceEarlyBreak (const FCL_REAL &dup)
	Distance threshold for early break. GJK stops when it proved the distance is more than this threshold. More...
bool	checkConvergence (const Vec3f &w, const FCL_REAL &rl, FCL_REAL &alpha, const FCL_REAL &omega)
	Convergence check used to stop GJK when shapes are not in collision. More...
size_t	getIterations ()
	Get GJK number of iterations. More...
FCL_REAL	getTolerance ()
	Get GJK tolerance. More...

Public Attributes
MinkowskiDiff const *	shape
Vec3f	ray
GJKVariant	gjk_variant
GJKConvergenceCriterion	convergence_criterion
GJKConvergenceCriterionType	convergence_criterion_type
support_func_guess_t	support_hint
FCL_REAL	distance
Simplex	simplices [2]

Detailed Description

class for GJK algorithm

Note

The computations are performed in the frame of the first shape.

Member Typedef Documentation

vertex_id_t

typedef unsigned char hpp::fcl::details::GJK::vertex_id_t

Member Enumeration Documentation

Status

enum hpp::fcl::details::GJK::Status

Status of the GJK algorithm: Valid: GJK converged and the shapes are not in collision. Inside: GJK converged and the shapes are in collision. Failed: GJK did not converge.

Enumerator
Valid
Inside
Failed
EarlyStopped

Constructor & Destructor Documentation

GJK()

hpp::fcl::details::GJK::GJK ( unsigned int  max_iterations_, FCL_REAL  tolerance_  )

inline

Parameters

max_iterations_	number of iteration before GJK returns failure.
tolerance_	precision of the algorithm.

The tolerance argument is useful for continuous shapes and for polyhedron with some vertices closer than this threshold.

Suggested values are 100 iterations and a tolerance of 1e-6.

Member Function Documentation

checkConvergence()

bool hpp::fcl::details::GJK::checkConvergence	(	const Vec3f &	w,
		const FCL_REAL &	rl,
		FCL_REAL &	alpha,
		const FCL_REAL &	omega
	)

Convergence check used to stop GJK when shapes are not in collision.

encloseOrigin()

bool hpp::fcl::details::GJK::encloseOrigin

(

)

whether the simplex enclose the origin

evaluate()

Status hpp::fcl::details::GJK::evaluate	(	const MinkowskiDiff &	shape,
		const Vec3f &	guess,
		const support_func_guess_t &	supportHint = support_func_guess_t::Zero()
	)

GJK algorithm, given the initial value guess.

getClosestPoints()

bool hpp::fcl::details::GJK::getClosestPoints	(	const MinkowskiDiff &	shape,
		Vec3f &	w0,
		Vec3f &	w1
	)

Get the closest points on each object.

Returns

true on success

getGuessFromSimplex()

Vec3f hpp::fcl::details::GJK::getGuessFromSimplex

(

)

const

get the guess from current simplex

getIterations()

size_t hpp::fcl::details::GJK::getIterations ( )

inline

Get GJK number of iterations.

getSimplex()

Simplex* hpp::fcl::details::GJK::getSimplex ( ) const

inline

get the underlying simplex using in GJK, can be used for cache in next iteration

getSupport()

void hpp::fcl::details::GJK::getSupport ( const Vec3f &  d, bool  dIsNormalized, SimplexV &  sv, support_func_guess_t &  hint  ) const

inline

apply the support function along a direction, the result is return in sv

getTolerance()

FCL_REAL hpp::fcl::details::GJK::getTolerance ( )

inline

Get GJK tolerance.

hasClosestPoints()

bool hpp::fcl::details::GJK::hasClosestPoints ( )

inline

Tells whether the closest points are available.

hasPenetrationInformation()

bool hpp::fcl::details::GJK::hasPenetrationInformation ( const MinkowskiDiff &  shape )

inline

Tells whether the penetration information.

In such case, most indepth points and penetration depth can be retrieved from GJK. Calling EPA has an undefined behaviour.

initialize()

void hpp::fcl::details::GJK::initialize

(

)

setDistanceEarlyBreak()

void hpp::fcl::details::GJK::setDistanceEarlyBreak ( const FCL_REAL &  dup )

inline

Distance threshold for early break. GJK stops when it proved the distance is more than this threshold.

Note

The closest points will be erroneous in this case. If you want the closest points, set this to infinity (the default).

Member Data Documentation

convergence_criterion

GJKConvergenceCriterion hpp::fcl::details::GJK::convergence_criterion

convergence_criterion_type

GJKConvergenceCriterionType hpp::fcl::details::GJK::convergence_criterion_type

distance

FCL_REAL hpp::fcl::details::GJK::distance

The distance computed by GJK. The possible values are

• \( d = - R - 1 \) when a collision is detected and GJK cannot compute penetration informations.
• \( - R \le d \le 0 \) when a collision is detected and GJK can compute penetration informations.
• \( 0 < d \le d_{ub} \) when there is no collision and GJK can compute the closest points.
• \( d_{ub} < d \) when there is no collision and GJK cannot compute the closest points.

where \( d \) is the GJK::distance, \( R \) is the sum of the shape MinkowskiDiff::inflation and \( d_{ub} \) is the GJK::distance_upper_bound.

gjk_variant

GJKVariant hpp::fcl::details::GJK::gjk_variant

ray

Vec3f hpp::fcl::details::GJK::ray

shape

MinkowskiDiff const* hpp::fcl::details::GJK::shape

simplices

Simplex hpp::fcl::details::GJK::simplices[2]

support_hint

support_func_guess_t hpp::fcl::details::GJK::support_hint

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

• include/hpp/fcl/narrowphase/gjk.h