Triangle Class Reference

Class that represents a single triangle together with associated metadata on the vertices (one float per vertex) More...

#include <CD_Triangle.H>

Inheritance diagram for Triangle:

Collaboration diagram for Triangle:

Public Types
using	Vec3 = EBGeometry::Vec3T< Real >
	Alias for always-3D vector type.

Public Member Functions
	Triangle () noexcept
	Default constructor.
	Triangle (const std::array< Vec3, 3 > &a_vertexPositions) noexcept
	Full constructor.
virtual	~Triangle () noexcept
	Destructor.
void	computeArea () noexcept
	Compute and store the triangle area in m_area.
void	setVertexPositions (const std::array< Vec3, 3 > &a_vertexPositions) noexcept
	Set vertex positions and recompute the triangle area.
void	setVertexData (const std::array< Real, 3 > &a_vertexData) noexcept
	Set meta-data on the vertices.
Vec3	projectToTrianglePlane (const Vec3 &a_point) const noexcept
	Project the input point to the triangle plane.
bool	isInside (const Vec3 &a_point) const noexcept
	Check if a point lies inside the triangle.
Real	interpolate (const Vec3 &a_point) const noexcept
	Interpolate vertex data at a point using barycentric coordinates or IDW fallback.

Protected Member Functions
Real	computeTriangleArea (const Vec3 a_x1, const Vec3 a_x2, const Vec3 a_x3) const noexcept
	Compute the area of a triangle defined by three vertices.

Protected Attributes
Real	m_area = Real(0)
	Triangle area.

Detailed Description

Class that represents a single triangle together with associated metadata on the vertices (one float per vertex)

Constructor & Destructor Documentation

Triangle() [1/2]

Triangle::Triangle ( )

noexcept

Default constructor.

Leaves vertex positions at their EBGeometry defaults and initializes vertex metadata to zero. The triangle area is zero-initialized. Vertex positions must be set before calling computeArea(), isInside(), or interpolate().

Triangle() [2/2]

Triangle::Triangle ( const std::array< Vec3, 3 > &  a_vertexPositions )

noexcept

Full constructor.

Sets vertex positions, computes the triangle normal and area, and zero-initializes vertex metadata.

Parameters

[in]

a_vertexPositions

Vertex positions, in CCW order when viewed from the normal direction.

Member Function Documentation

computeArea()

void Triangle::computeArea ( )

noexcept

Compute and store the triangle area in m_area.

Uses the cross-product formula: area = 0.5 * ||(v1-v0) x (v2-v0)||. This is called automatically by setVertexPositions(), so manual invocation is only needed if vertex positions were changed through the base class API directly.

computeTriangleArea()

Real Triangle::computeTriangleArea ( const Vec3  a_x1, const Vec3  a_x2, const Vec3  a_x3  ) const

inlineprotectednoexcept

Compute the area of a triangle defined by three vertices.

Parameters

[in]	a_x1	First vertex.
[in]	a_x2	Second vertex.
[in]	a_x3	Third vertex.

Returns

Triangle area: 0.5 * ||(a_x2 - a_x1) x (a_x3 - a_x1)||. Returns zero for degenerate (collinear or coincident) vertices.

interpolate()

Real Triangle::interpolate ( const Vec3 &  a_point ) const

noexcept

Interpolate vertex data at a point using barycentric coordinates or IDW fallback.

For points inside the triangle, barycentric weights are computed from area ratios and the weighted sum of the three vertex data values is returned. For points outside the triangle, inverse-distance weighting (IDW, Shepard power = 1) over the two nearest vertices is used instead: weights are w_i = d_j/(d_i+d_j) and w_j = d_i/(d_i+d_j), ensuring the interpolated value stays within the data range and is bounded. If both nearest distances are zero, equal weights of 0.5 are used. Returns zero for degenerate triangles (m_area == 0).

Parameters

[in]

a_point

Query point in 3D space.

Returns

Interpolated vertex data value at a_point.

isInside()

bool Triangle::isInside ( const Vec3 &  a_point ) const

noexcept

Check if a point lies inside the triangle.

Tests whether the projection of a_point onto the triangle plane falls within the triangle boundary. The test is based on the sign of the triple products of each edge direction with the triangle normal, so it is valid for arbitrary 3D points (not just coplanar ones). Points exactly on an edge are considered inside.

Parameters

[in]

a_point

Query point in 3D space.

Returns

True if the projection of a_point onto the triangle plane is inside the triangle, false otherwise.

Note

The user must first project the point to the triangle plane by using projectToTrianglePlane

projectToTrianglePlane()

EBGeometry::Vec3T< Real > Triangle::projectToTrianglePlane ( const Vec3 &  a_point ) const

noexcept

Project the input point to the triangle plane.

Parameters

[in]

a_point

Input point.

Returns

Returns a_point - dot(a_point, m_triangleNormal) * m_triangleNormal

setVertexData()

void Triangle::setVertexData ( const std::array< Real, 3 > &  a_vertexData )

noexcept

Set meta-data on the vertices.

Parameters

[in]

a_vertexData

Data on the vertices. Must be in the same order as the vertex positions.

setVertexPositions()

void Triangle::setVertexPositions ( const std::array< Vec3, 3 > &  a_vertexPositions )

noexcept

Set vertex positions and recompute the triangle area.

This shadows EBGeometry::Triangle::setVertexPositions to ensure that m_area is kept in sync whenever vertex positions change.

Parameters

[in]

a_vertexPositions

Vertex positions.

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

• Source/Utilities/CD_Triangle.H
• Source/Utilities/CD_Triangle.cpp