This ContactGeometry subclass represents an arbitrary shape described by a mesh of triangular faces. More...

#include <ContactGeometry.h>

Inheritance diagram for SimTK::ContactGeometry::TriangleMesh:

Classes
class	OBBTreeNode
	This class represents a node in the Oriented Bounding Box Tree for a TriangleMesh. More...
Public Member Functions
	TriangleMesh (const ArrayViewConst_< Vec3 > &vertices, const ArrayViewConst_< int > &faceIndices, bool smooth=false)
	Create a TriangleMesh.
	TriangleMesh (const PolygonalMesh &mesh, bool smooth=false)
	Create a TriangleMesh based on a PolygonalMesh object.
int	getNumEdges () const
	Get the number of edges in the mesh.
int	getNumFaces () const
	Get the number of faces in the mesh.
int	getNumVertices () const
	Get the number of vertices in the mesh.
const Vec3 &	getVertexPosition (int index) const
	Get the position of a vertex in the mesh.
int	getFaceEdge (int face, int edge) const
	Get the index of one of the edges of a face.
int	getFaceVertex (int face, int vertex) const
	Get the index of one of the vertices of a face.
int	getEdgeFace (int edge, int face) const
	Get the index of one of the faces shared by an edge.
int	getEdgeVertex (int edge, int vertex) const
	Get the index of one of the vertices shared by an edge.
void	findVertexEdges (int vertex, Array_< int > &edges) const
	Find all edges that intersect a vertex.
const UnitVec3 &	getFaceNormal (int face) const
	Get the normal vector for a face.
Real	getFaceArea (int face) const
	Get the area of a face.
Vec3	findPoint (int face, const Vec2 &uv) const
	Calculate the location of a point on the surface, in the local frame of the TriangleMesh.
Vec3	findCentroid (int face) const
	Calculate the location of a face's centroid, that is, the point uv=(1/3,1/3) which is the average of the three vertex locations.
UnitVec3	findNormalAtPoint (int face, const Vec2 &uv) const
	Calculate the normal vector at a point on the surface.
Vec3	findNearestPoint (const Vec3 &position, bool &inside, UnitVec3 &normal) const
	Given a point, find the nearest point on the surface of this object.
Vec3	findNearestPoint (const Vec3 &position, bool &inside, int &face, Vec2 &uv) const
	Given a point, find the nearest point on the surface of this object.
Vec3	findNearestPointToFace (const Vec3 &position, int face, Vec2 &uv) const
	Given a point and a face of this object, find the point of the face that is nearest the given point.
bool	intersectsRay (const Vec3 &origin, const UnitVec3 &direction, Real &distance, UnitVec3 &normal) const
	Determine whether this mesh intersects a ray, and if so, find the intersection point.
bool	intersectsRay (const Vec3 &origin, const UnitVec3 &direction, Real &distance, int &face, Vec2 &uv) const
	Determine whether this mesh intersects a ray, and if so, find what face it hit.
OBBTreeNode	getOBBTreeNode () const
	Get the OBBTreeNode which forms the root of this mesh's Oriented Bounding Box Tree.
PolygonalMesh	createPolygonalMesh () const
	Generate a PolygonalMesh from this TriangleMesh; useful mostly for debugging because you can create a DecorativeMesh from this and then look at it.
const Impl &	getImpl () const
Impl &	updImpl ()
	Internal use only.
Static Public Member Functions
static bool	isInstance (const ContactGeometry &geo)
	Return true if the supplied ContactGeometry object is a triangle mesh.
static const TriangleMesh &	getAs (const ContactGeometry &geo)
	Cast the supplied ContactGeometry object to a const triangle mesh.
static TriangleMesh &	updAs (ContactGeometry &geo)
	Cast the supplied ContactGeometry object to a writable triangle mesh.
static ContactGeometryTypeId	classTypeId ()
	Obtain the unique id for TriangleMesh contact geometry.

Detailed Description

This ContactGeometry subclass represents an arbitrary shape described by a mesh of triangular faces.

The mesh surface must satisfy the following requirements:

It must be closed, so that any point can unambiguously be classified as either inside or outside.
It may not intersect itself anywhere, even at a single point.
It must be an oriented manifold.
The vertices for each face must be ordered counter-clockwise when viewed from the outside. That is, if v0, v1, and v2 are the locations of the three vertices for a face, the cross product (v1-v0)%(v2-v0) must point outward.
The length of every edge must be non-zero.

It is your responsibility to ensure that any mesh you create meets these requirements. The constructor will detect many incorrect meshes and signal them by throwing an exception, but it is not guaranteed to detect all possible problems. If a mesh fails to satisfy any of these requirements, the results of calculations performed with it are undefined. For example, collisions involving it might fail to be detected, or contact forces on it might be calculated incorrectly.

Constructor & Destructor Documentation

SimTK::ContactGeometry::TriangleMesh::TriangleMesh	(	const ArrayViewConst_< Vec3 > &	vertices,
		const ArrayViewConst_< int > &	faceIndices,
		bool	smooth = `false`
	)

Create a TriangleMesh.

Parameters:

vertices	The positions of all vertices in the mesh.
faceIndices	The indices of the vertices that make up each face. The first three elements are the vertices in the first face, the next three elements are the vertices in the second face, etc.
smooth	If true, the mesh will be treated as a smooth surface, and normal vectors will be smoothly interpolated between vertices. If false, it will be treated as a faceted mesh with a constant normal vector over each face.

SimTK::ContactGeometry::TriangleMesh::TriangleMesh	(	const PolygonalMesh &	mesh,
		bool	smooth = `false`
	)		`[explicit]`

Create a TriangleMesh based on a PolygonalMesh object.

If any faces of the PolygonalMesh have more than three vertices, they are automatically triangulated.

Parameters:

mesh	The PolygonalMesh from which to construct a triangle mesh.
smooth	If true, the mesh will be treated as a smooth surface, and normal vectors will be smoothly interpolated between vertices. If false, it will be treated as a faceted mesh with a constant normal vector over each face.

Member Function Documentation

int SimTK::ContactGeometry::TriangleMesh::getNumEdges ( ) const

Get the number of edges in the mesh.

int SimTK::ContactGeometry::TriangleMesh::getNumFaces ( ) const

Get the number of faces in the mesh.

int SimTK::ContactGeometry::TriangleMesh::getNumVertices ( ) const

Get the number of vertices in the mesh.

const Vec3& SimTK::ContactGeometry::TriangleMesh::getVertexPosition ( int index ) const

Get the position of a vertex in the mesh.

Parameters:

index The index of the vertex to get.

Returns:: The position of the specified vertex.

int SimTK::ContactGeometry::TriangleMesh::getFaceEdge	(	int	face,
		int	edge
	)		const

Get the index of one of the edges of a face.

Edge 0 connects vertices 0 and 1. Edge 1 connects vertices 1 and 2. Edge 2 connects vertices 0 and 2.

Parameters:

face	The index of the face.
edge	The index of the edge within the face (0, 1, or 2).

Returns:: The index of the specified edge.

int SimTK::ContactGeometry::TriangleMesh::getFaceVertex	(	int	face,
		int	vertex
	)		const

Get the index of one of the vertices of a face.

Parameters:

face	The index of the face.
vertex	The index of the vertex within the face (0, 1, or 2).

Returns:: The index of the specified vertex.

int SimTK::ContactGeometry::TriangleMesh::getEdgeFace	(	int	edge,
		int	face
	)		const

Get the index of one of the faces shared by an edge.

Parameters:

edge	The index of the edge.
face	The index of the face within the edge (0 or 1).

Returns:: The index of the specified face.

int SimTK::ContactGeometry::TriangleMesh::getEdgeVertex	(	int	edge,
		int	vertex
	)		const

Get the index of one of the vertices shared by an edge.

Parameters:

edge	The index of the edge.
vertex	The index of the vertex within the edge (0 or 1).

Returns:: The index of the specified vertex.

void SimTK::ContactGeometry::TriangleMesh::findVertexEdges	(	int	vertex,
		Array_< int > &	edges
	)		const

Find all edges that intersect a vertex.

Parameters:

vertex	The index of the vertex.
edges	The indices of all edges intersecting the vertex will be added to this.

const UnitVec3& SimTK::ContactGeometry::TriangleMesh::getFaceNormal ( int face ) const

Get the normal vector for a face.

This points outward from the mesh.

Parameters:

face	The index of the face.

Real SimTK::ContactGeometry::TriangleMesh::getFaceArea ( int face ) const

Get the area of a face.

Parameters:

face	The index of the face.

Vec3 SimTK::ContactGeometry::TriangleMesh::findPoint	(	int	face,
		const Vec2 &	uv
	)		const

Calculate the location of a point on the surface, in the local frame of the TriangleMesh.

Cost is 11 flops.

Parameters:

face	The index of the face containing the point.
uv	The point within the face, specified by its barycentric uv coordinates.

Vec3 SimTK::ContactGeometry::TriangleMesh::findCentroid ( int face ) const

Calculate the location of a face's centroid, that is, the point uv=(1/3,1/3) which is the average of the three vertex locations.

This is a common special case of findPoint() that can be calculated more quickly (7 flops).

Parameters:

face	The index of the face whose centroid is of interest.

UnitVec3 SimTK::ContactGeometry::TriangleMesh::findNormalAtPoint	(	int	face,
		const Vec2 &	uv
	)		const

Calculate the normal vector at a point on the surface.

Parameters:

face	The index of the face containing the point.
uv	The point within the face, specified by its barycentric uv coordinates.

Vec3 SimTK::ContactGeometry::TriangleMesh::findNearestPoint	(	const Vec3 &	position,
		bool &	inside,
		UnitVec3 &	normal
	)		const

Given a point, find the nearest point on the surface of this object.

If multiple points on the surface are equally close to the specified point, this may return any of them.

Parameters:

position	The point in question.
inside	On exit, this is set to true if the specified point is inside this object, false otherwise.
normal	On exit, this contains the surface normal at the returned point.

Returns:: The point on the surface of the object which is closest to the specified point.

Reimplemented from SimTK::ContactGeometry.

Vec3 SimTK::ContactGeometry::TriangleMesh::findNearestPoint	(	const Vec3 &	position,
		bool &	inside,
		int &	face,
		Vec2 &	uv
	)		const

Given a point, find the nearest point on the surface of this object.

If multiple points on the surface are equally close to the specified point, this may return any of them.

Parameters:

position	The point in question.
inside	On exit, this is set to true if the specified point is inside this object, false otherwise.
face	On exit, this contains the index of the face containing the returned point.
uv	On exit, this contains the barycentric coordinates (u and v) of the returned point within its face.

Returns:: The point on the surface of the object which is closest to the specified point.

Vec3 SimTK::ContactGeometry::TriangleMesh::findNearestPointToFace	(	const Vec3 &	position,
		int	face,
		Vec2 &	uv
	)		const

Given a point and a face of this object, find the point of the face that is nearest the given point.

If multiple points on the face are equally close to the specified point, this may return any of them.

Parameters:

position	The point in question.
face	The face to be examined.
uv	On exit, this contains the barycentric coordinates (u and v) of the returned point within the face.

Returns:: The face point, in the surface's frame, that is closest to the specified point.

bool SimTK::ContactGeometry::TriangleMesh::intersectsRay	(	const Vec3 &	origin,
		const UnitVec3 &	direction,
		Real &	distance,
		UnitVec3 &	normal
	)		const

Determine whether this mesh intersects a ray, and if so, find the intersection point.

Parameters:

origin	The position at which the ray begins.
direction	The ray direction.
distance	If an intersection is found, the distance from the ray origin to the intersection point is stored in this. Otherwise, it is left unchanged.
normal	If an intersection is found, the surface normal of the intersection point is stored in this. Otherwise, it is left unchanged.

Returns:: true if an intersection is found, false otherwise.

Reimplemented from SimTK::ContactGeometry.

bool SimTK::ContactGeometry::TriangleMesh::intersectsRay	(	const Vec3 &	origin,
		const UnitVec3 &	direction,
		Real &	distance,
		int &	face,
		Vec2 &	uv
	)		const

Determine whether this mesh intersects a ray, and if so, find what face it hit.

Parameters:

origin	The position at which the ray begins.
direction	The ray direction.
distance	If an intersection is found, the distance from the ray origin to the intersection point is stored in this. Otherwise, it is left unchanged.
face	If an intersection is found, the index of the face hit by the ray is stored in this. Otherwise, it is left unchanged.
uv	If an intersection is found, the barycentric coordinates (u and v) of the intersection point within the hit face are stored in this. Otherwise, it is left unchanged.

Returns:: true if an intersection is found, false otherwise.

OBBTreeNode SimTK::ContactGeometry::TriangleMesh::getOBBTreeNode ( ) const

Get the OBBTreeNode which forms the root of this mesh's Oriented Bounding Box Tree.

PolygonalMesh SimTK::ContactGeometry::TriangleMesh::createPolygonalMesh ( ) const

Generate a PolygonalMesh from this TriangleMesh; useful mostly for debugging because you can create a DecorativeMesh from this and then look at it.

static bool SimTK::ContactGeometry::TriangleMesh::isInstance ( const ContactGeometry & geo ) [inline, static]

Return true if the supplied ContactGeometry object is a triangle mesh.

static const TriangleMesh& SimTK::ContactGeometry::TriangleMesh::getAs ( const ContactGeometry & geo ) [inline, static]

Cast the supplied ContactGeometry object to a const triangle mesh.

static TriangleMesh& SimTK::ContactGeometry::TriangleMesh::updAs ( ContactGeometry & geo ) [inline, static]

Cast the supplied ContactGeometry object to a writable triangle mesh.

static ContactGeometryTypeId SimTK::ContactGeometry::TriangleMesh::classTypeId ( ) [static]

Obtain the unique id for TriangleMesh contact geometry.

const Impl& SimTK::ContactGeometry::TriangleMesh::getImpl ( ) const

Internal use only.

Reimplemented from SimTK::ContactGeometry.

Impl& SimTK::ContactGeometry::TriangleMesh::updImpl ( )

Internal use only.

Reimplemented from SimTK::ContactGeometry.

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

ContactGeometry.h

Classes

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation