Minkowski difference class of two shapes. More...

#include <coal/narrowphase/minkowski_difference.h>

Collaboration diagram for coal::details::MinkowskiDiff:

[legend]

Public Types
typedef Eigen::Array< Scalar, 1, 2 >	Array2

typedef void(*	GetSupportFunction) (const MinkowskiDiff &minkowskiDiff, const Vec3s &dir, Vec3s &support0, Vec3s &support1, support_func_guess_t &hint, ShapeSupportData data[2])

Public Member Functions
	MinkowskiDiff ()

template<int _SupportOptions = SupportOptions::NoSweptSphere>
void	set (const ShapeBase shape0, const ShapeBase shape1)
	Set the two shapes, assuming the relative transformation between them is identity. Consequently, all support points computed with the MinkowskiDiff will be expressed in the world frame. More...

template<int _SupportOptions = SupportOptions::NoSweptSphere>
void	set (const ShapeBase shape0, const ShapeBase shape1, const Transform3s &tf0, const Transform3s &tf1)
	Set the two shapes, with a relative transformation from shape0 to shape1. Consequently, all support points computed with the MinkowskiDiff will be expressed in the frame of shape0. More...

template<int _SupportOptions = SupportOptions::NoSweptSphere>
Vec3s	support0 (const Vec3s &dir, int &hint) const
	support function for shape0. The output vector is expressed in the local frame of shape0. More...

template<int _SupportOptions = SupportOptions::NoSweptSphere>
Vec3s	support1 (const Vec3s &dir, int &hint) const
	support function for shape1. The output vector is expressed in the local frame of shape0. This is mandatory because in the end we are interested in support points of the Minkowski difference; hence the supports of shape0 and shape1 must live in the same frame. More...

void	support (const Vec3s &dir, Vec3s &supp0, Vec3s &supp1, support_func_guess_t &hint) const
	Support function for the pair of shapes. This method assumes `set` has already been called. More...

Public Attributes
const ShapeBase *	shapes [2]
	points to two shapes More...

ShapeSupportData	data [2]
	Store temporary data for the computation of the support point for each shape. More...

Matrix3s	oR1
	rotation from shape1 to shape0 such that \( p_in_0 = oR1 * p_in_1 + ot1 \). More...

Vec3s	ot1
	translation from shape1 to shape0 such that \( p_in_0 = oR1 * p_in_1 + ot1 \). More...

Array2	swept_sphere_radius
	The radii of the sphere swepted around each shape of the Minkowski difference. The 2 values correspond to the swept-sphere radius of shape 0 and shape 1. More...

bool	normalize_support_direction
	Wether or not to use the normalize heuristic in the GJK Nesterov acceleration. This setting is only applied if the Nesterov acceleration in the GJK class is active. More...

GetSupportFunction	getSupportFunc

Detailed Description

Minkowski difference class of two shapes.

Note: The Minkowski difference is expressed in the frame of the first shape.

Member Typedef Documentation

◆ Array2

typedef Eigen::Array<Scalar, 1, 2> coal::details::MinkowskiDiff::Array2

◆ GetSupportFunction

typedef void(* coal::details::MinkowskiDiff::GetSupportFunction) (const MinkowskiDiff &minkowskiDiff, const Vec3s &dir, Vec3s &support0, Vec3s &support1, support_func_guess_t &hint, ShapeSupportData data[2])

Constructor & Destructor Documentation

◆ MinkowskiDiff()

coal::details::MinkowskiDiff::MinkowskiDiff ( )

inline

Member Function Documentation

◆ set() [1/2]

template<int _SupportOptions = SupportOptions::NoSweptSphere>

void coal::details::MinkowskiDiff::set	(	const ShapeBase *	shape0,
		const ShapeBase *	shape1
	)

Set the two shapes, assuming the relative transformation between them is identity. Consequently, all support points computed with the MinkowskiDiff will be expressed in the world frame.

Parameters

shape0	the first shape.
shape1	the second shape.

Template Parameters

_SupportOptions is a value of the SupportOptions enum. If set to WithSweptSphere, the support computation will take into account the swept sphere radius of the shapes. If set to NoSweptSphere, where this information is simply stored in the Minkowski's difference swept_sphere_radius array. This array is then used to correct the solution found when GJK or EPA have converged.

Note: In practice, there is no need to take into account the swept-sphere radius in the iterations of GJK/EPA. It is in fact detrimental to the convergence of both algos. This is because it makes corners and edges of shapes look strictly convex to the algorithms, which leads to poor convergence. This swept sphere template parameter is only here for debugging purposes and for specific uses cases where the swept sphere radius is needed in the support function. The rule is simple. When interacting with GJK/EPA, the SupportOptions template parameter should always be set to NoSweptSphere (except for debugging or testing purposes). When working directly with the shapes involved in the collision, and not relying on GJK/EPA, the SupportOptions template parameter should be set to WithSweptSphere. This is for example the case for specialized collision/distance functions.

◆ set() [2/2]

template<int _SupportOptions = SupportOptions::NoSweptSphere>

void coal::details::MinkowskiDiff::set	(	const ShapeBase *	shape0,
		const ShapeBase *	shape1,
		const Transform3s &	tf0,
		const Transform3s &	tf1
	)

Set the two shapes, with a relative transformation from shape0 to shape1. Consequently, all support points computed with the MinkowskiDiff will be expressed in the frame of shape0.

Parameters

shape0	the first shape.
shape1	the second shape.
tf0	the transformation of the first shape.
tf1	the transformation of the second shape.

Template Parameters

_SupportOptions see set(const ShapeBase*, const ShapeBase*) for more details.

◆ support()

void coal::details::MinkowskiDiff::support	(	const Vec3s &	dir,
		Vec3s &	supp0,
		Vec3s &	supp1,
		support_func_guess_t &	hint
	)		const

inline

Support function for the pair of shapes. This method assumes set has already been called.

Parameters

[in]	dir	the support direction.
[out]	supp0	support of shape0 in direction dir, expressed in the frame of shape0.
[out]	supp1	support of shape1 in direction -dir, expressed in the frame of shape0.
	[in/out]	hint used to initialize the search when shape is a ConvexBase object.

◆ support0()

template<int _SupportOptions = SupportOptions::NoSweptSphere>

Vec3s coal::details::MinkowskiDiff::support0	(	const Vec3s &	dir,
		int &	hint
	)		const

inline

support function for shape0. The output vector is expressed in the local frame of shape0.

Returns: a point which belongs to the set {argmax_{v in shape0} v.dot(dir)}, i.e a support of shape0 in direction dir.

Parameters

dir	support direction.
hint	used to initialize the search when shape is a ConvexBase object.

Template Parameters

_SupportOptions see set(const ShapeBase*, const ShapeBase*) for more details.

◆ support1()

template<int _SupportOptions = SupportOptions::NoSweptSphere>

Vec3s coal::details::MinkowskiDiff::support1	(	const Vec3s &	dir,
		int &	hint
	)		const

inline

support function for shape1. The output vector is expressed in the local frame of shape0. This is mandatory because in the end we are interested in support points of the Minkowski difference; hence the supports of shape0 and shape1 must live in the same frame.

Returns: a point which belongs to the set {tf * argmax_{v in shape1} v.dot(R^T * dir)}, i.e. the support of shape1 in direction dir (tf is the tranform from shape1 to shape0).

Parameters

dir	support direction.
hint	used to initialize the search when shape is a ConvexBase.

Template Parameters

_SupportOptions see set(const ShapeBase*, const ShapeBase*) for more details.

Member Data Documentation

◆ data

ShapeSupportData coal::details::MinkowskiDiff::data[2]

Store temporary data for the computation of the support point for each shape.

◆ getSupportFunc

GetSupportFunction coal::details::MinkowskiDiff::getSupportFunc

◆ normalize_support_direction

bool coal::details::MinkowskiDiff::normalize_support_direction

Wether or not to use the normalize heuristic in the GJK Nesterov acceleration. This setting is only applied if the Nesterov acceleration in the GJK class is active.

◆ oR1

Matrix3s coal::details::MinkowskiDiff::oR1

rotation from shape1 to shape0 such that \( p_in_0 = oR1 * p_in_1 + ot1 \).

◆ ot1

Vec3s coal::details::MinkowskiDiff::ot1

translation from shape1 to shape0 such that \( p_in_0 = oR1 * p_in_1 + ot1 \).

◆ shapes

const ShapeBase* coal::details::MinkowskiDiff::shapes[2]

points to two shapes

◆ swept_sphere_radius

Array2 coal::details::MinkowskiDiff::swept_sphere_radius

The radii of the sphere swepted around each shape of the Minkowski difference. The 2 values correspond to the swept-sphere radius of shape 0 and shape 1.

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

include/coal/narrowphase/minkowski_difference.h

Public Types

Public Member Functions

Public Attributes

Detailed Description

Member Typedef Documentation

◆ Array2

◆ GetSupportFunction

Constructor & Destructor Documentation

◆ MinkowskiDiff()

Member Function Documentation

◆ set() [1/2]

◆ set() [2/2]

◆ support()

◆ support0()

◆ support1()

Member Data Documentation

◆ data

◆ getSupportFunc

◆ normalize_support_direction

◆ oR1

◆ ot1

◆ shapes

◆ swept_sphere_radius