openswmm::twoD::footprint Namespace Reference

Classes
struct	Point

Typedefs
using	Ring = std::vector<Point>

Functions
double	cross (Point a, Point b, Point c)
	Compute the oriented twice-area of a triangle in planar coordinates.
double	signedArea (const Ring &p)
	Sum a polygon ring's signed triangle-fan area.
double	tolerance (const Ring &p)
	Derive a scale-relative tolerance for ring cross products and areas.
bool	between (Point a, Point b, Point p, double eps)
	Test whether a point lies on a closed segment within a cross-product tolerance.
bool	intersects (Point a, Point b, Point c, Point d, double eps)
	Test closed planar segments for proper crossing or endpoint/collinear contact.
std::string	triangulate (Ring &p, std::vector< Ring > &triangles, const std::function< bool()> &running={})
	Validate a simple ring and triangulate it by counterclockwise ear clipping.
double	intersectionArea (Ring subject, const Ring &clip)
	Clip a polygon against a counterclockwise convex ring and return its area.

Typedef Documentation

Ring

using openswmm::twoD::footprint::Ring = std::vector<Point>

Function Documentation

between()

bool openswmm::twoD::footprint::between ( Point a, Point b, Point p, double eps )

inline

Test whether a point lies on a closed segment within a cross-product tolerance.

Parameters

[in]	a	First segment endpoint.
[in]	b	Second segment endpoint; equality with a is allowed.
[in]	p	Point tested against the segment.
[in]	eps	Nonnegative tolerance in squared coordinate units for collinearity only.

Returns

True when the cross-product magnitude is at most eps and both point coordinates are inside the exact endpoint bounds. Bounds are not expanded by eps; inputs are not validated.

Here is the call graph for this function:

Here is the caller graph for this function:

cross()

double openswmm::twoD::footprint::cross ( Point a, Point b, Point c )

inline

Compute the oriented twice-area of a triangle in planar coordinates.

Parameters

[in]	a	First point, serving as the subtraction origin.
[in]	b	Second point.
[in]	c	Third point.

Returns

Signed cross product (b-a) x (c-a), positive for counterclockwise order, in squared coordinate units (m2 for SI mesh coordinates). No finite-value or degeneracy checks are made.

Here is the caller graph for this function:

intersectionArea()

double openswmm::twoD::footprint::intersectionArea ( Ring subject, const Ring & clip )

inline

Clip a polygon against a counterclockwise convex ring and return its area.

Parameters

[in]	subject	Owned working copy of the subject polygon, implicitly closed. Caller data is unchanged; for general concave footprints, pass each triangle produced by triangulate().
[in]	clip	Stable counterclockwise convex clipping polygon in the same planar coordinate system, with at least three valid vertices for a meaningful polygon intersection.

Returns

Nonnegative clipped area in squared coordinate units. An empty clip performs no clipping and returns the subject area. Winding, convexity, finiteness and topology are unchecked.

Note

Uses exact half-plane sign tests without epsilon. Intermediate polygon allocation may throw; no references to either input survive the call.

Here is the call graph for this function:

intersects()

bool openswmm::twoD::footprint::intersects ( Point a, Point b, Point c, Point d, double eps )

inline

Test closed planar segments for proper crossing or endpoint/collinear contact.

Parameters

[in]	a	First endpoint of the first segment.
[in]	b	Second endpoint of the first segment.
[in]	c	First endpoint of the second segment.
[in]	d	Second endpoint of the second segment.
[in]	eps	Nonnegative cross-product tolerance in squared coordinate units.

Returns

True for opposite-sided crossings beyond eps or a between() contact; false otherwise. Finite coordinates are assumed. No allocation or mutation occurs.

Here is the call graph for this function:

signedArea()

double openswmm::twoD::footprint::signedArea ( const Ring & p )

inline

Sum a polygon ring's signed triangle-fan area.

Parameters

[in]

p

Stable planar vertices, implicitly closed; a repeated final vertex is permitted.

Returns

Signed area in squared coordinate units, positive for counterclockwise winding, or zero for fewer than three vertices. Self intersections and nonfinite coordinates are unchecked; simple-ring validation belongs to triangulate(). No allocation or input mutation occurs.

Here is the call graph for this function:

Here is the caller graph for this function:

tolerance()

double openswmm::twoD::footprint::tolerance ( const Ring & p )

inline

Derive a scale-relative tolerance for ring cross products and areas.

Parameters

[in]

p

Planar ring; coordinates should be finite. Extent is measured relative to its first vertex using the largest absolute coordinate offset.

Returns

128 machine epsilons times max(span squared, 1e-24), or zero for an empty ring, in squared coordinate units. The lower floor is absolute, so coordinate-unit changes affect it.

triangulate()

std::string openswmm::twoD::footprint::triangulate ( Ring & p, std::vector< Ring > & triangles, const std::function< bool()> & running = {} )

inline

Validate a simple ring and triangulate it by counterclockwise ear clipping.

Parameters

[in,out]	p	Finite planar polygon. An exact repeated closing vertex is removed, clockwise order is reversed and collinear boundary vertices may be erased. These changes can survive a later failure; holes and multipart rings are unsupported.
[out]	triangles	Cleared immediately, then populated with owned three-point rings in p's coordinate units. Cancellation or triangulation failure can leave a partial triangulation.
[in]	running	Optional synchronous continuation callback; false cancels validation or the ear loop. The callback is not retained; its exceptions propagate.

Returns

Empty string on success; otherwise a diagnostic for missing/nonfinite/duplicate, self-intersecting or degenerate geometry, cancellation or failure to find an ear.

Note

Allocation exceptions propagate. Output must not alias p through an element of triangles; the method supplies no rollback and requires exclusive access to both mutable containers.