SignedDistanceToPoint< T > Struct Template Reference

Detailed Description

template<typename T>
struct drake::geometry::SignedDistanceToPoint< T >

The data for reporting the signed distance from a query point to a geometry.

Reports the result of a signed distance query between a query point Q and geometry G. This includes G's id, the signed distance, the nearest point N on the surface of G, and the gradient of the signed distance with respect to the position of Q. Generally, the gradient of the signed distance function is not defined everywhere. The value reported in this struct depends on the query function returning it. Refer to the query function's documentation for what value it will report for otherwise undefined gradient values.

Template Parameters

T	The underlying scalar type. Must be a valid Eigen scalar.

#include <drake/geometry/query_results/signed_distance_to_point.h>

Public Member Functions
	SignedDistanceToPoint ()=default
	SignedDistanceToPoint (GeometryId id_G_in, const Vector3< T > &p_GN_in, T distance_in, const Vector3< T > &grad_W_in)
	Constructs SignedDistanceToPoint struct from calculated results. More...
Implements CopyConstructible, CopyAssignable, MoveConstructible, MoveAssignable
	SignedDistanceToPoint (const SignedDistanceToPoint &)=default
SignedDistanceToPoint &	operator= (const SignedDistanceToPoint &)=default
	SignedDistanceToPoint (SignedDistanceToPoint &&)=default
SignedDistanceToPoint &	operator= (SignedDistanceToPoint &&)=default

Public Attributes
GeometryId	id_G
	The id of the geometry G to which we measure distance from the query point Q. More...
Vector3< T >	p_GN
	The position of the nearest point N on G's surface from the query point Q, expressed in G's frame. More...
T	distance {}
	The signed distance from the query point Q to the nearest point N on the surface of geometry G. More...
Vector3< T >	grad_W
	The gradient vector of the distance function with respect to the query point Q, expressed in world frame W. More...

Constructor & Destructor Documentation

SignedDistanceToPoint() [1/4]

SignedDistanceToPoint ( const SignedDistanceToPoint< T > &  )

default

SignedDistanceToPoint() [2/4]

SignedDistanceToPoint ( SignedDistanceToPoint< T > &&  )

default

SignedDistanceToPoint() [3/4]

SignedDistanceToPoint ( )

default

SignedDistanceToPoint() [4/4]

SignedDistanceToPoint	(	GeometryId	id_G_in,
		const Vector3< T > &	p_GN_in,
		T	distance_in,
		const Vector3< T > &	grad_W_in
	)

Constructs SignedDistanceToPoint struct from calculated results.

Parameters

id_G_in	The id of the geometry G to which we measure distance from the query point Q.
p_GN_in	The position of the nearest point N on G's surface from the query point Q, expressed in G's frame.
distance_in	The signed distance from the query point Q to the nearest point N on the surface of geometry G. It is positive if Q is outside G. It is negative if Q is inside G. It is zero if Q is on the boundary of G.
grad_W_in	The gradient vector of the distance function with respect to the query point Q, expressed in world frame W.

Note

grad_W is not well defined everywhere. For example, when computing the distance from a point to a sphere, and the point coincides with the center of the sphere, grad_W is not well defined (as it can be computed as p_GQ / |p_GQ|, but the denominator is 0). When grad_W is not well defined, and we instantiate SignedDistanceToPoint<T> with T being an AutoDiffScalar (like AutoDiffXd), the gradient of the query result is not well defined either, so the user should use the gradient in p_GN, distance and grad_W with caution.

Precondition

grad_W_in must not contain NaN.

Member Function Documentation

operator=() [1/2]

SignedDistanceToPoint& operator= ( const SignedDistanceToPoint< T > &  )

default

operator=() [2/2]

SignedDistanceToPoint& operator= ( SignedDistanceToPoint< T > &&  )

default

Member Data Documentation

distance

T distance {}

The signed distance from the query point Q to the nearest point N on the surface of geometry G.

It is positive if Q is outside G. It is negative if Q is inside G. It is zero if Q is on the boundary of G.

grad_W

Vector3<T> grad_W

The gradient vector of the distance function with respect to the query point Q, expressed in world frame W.

id_G

GeometryId id_G

The id of the geometry G to which we measure distance from the query point Q.

p_GN

Vector3<T> p_GN

The position of the nearest point N on G's surface from the query point Q, expressed in G's frame.

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

• drake/geometry/query_results/signed_distance_to_point.h