Implements basic computational geometry algorithms using extended precision float-point arithmetic.
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#include <CGAlgorithmsDD.h>
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| static int | orientationIndex (const geom::Coordinate &p1, const geom::Coordinate &p2, const geom::Coordinate &q) |
| | Returns the index of the direction of the point q relative to a vector specified by p1-p2. More...
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| static int | orientationIndex (double p1x, double p1y, double p2x, double p2y, double qx, double qy) |
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| static int | orientationIndexFilter (double pax, double pay, double pbx, double pby, double pcx, double pcy) |
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| static int | orientation (double x) |
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| static geom::Coordinate | intersection (const geom::Coordinate &p1, const geom::Coordinate &p2, const geom::Coordinate &q1, const geom::Coordinate &q2) |
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| static int | signOfDet2x2 (double dx1, double dy1, double dx2, double dy2) |
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| static DD | detDD (double x1, double y1, double x2, double y2) |
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| static DD | detDD (const DD &x1, const DD &y1, const DD &x2, const DD &y2) |
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| static geom::Coordinate | circumcentreDD (const geom::Coordinate &a, const geom::Coordinate &b, const geom::Coordinate &c) |
| | Computes the circumcentre of a triangle. More...
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Implements basic computational geometry algorithms using extended precision float-point arithmetic.
Definition at line 38 of file CGAlgorithmsDD.h.
| Enumerator |
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| CLOCKWISE |
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| COLLINEAR |
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| COUNTERCLOCKWISE |
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Definition at line 42 of file CGAlgorithmsDD.h.
Computes the circumcentre of a triangle.
The circumcentre is the centre of the circumcircle, the smallest circle which encloses the triangle. It is also the common intersection point of the perpendicular bisectors of the sides of the triangle, and is the only point which has equal distance to all three vertices of the triangle.
The circumcentre does not necessarily lie within the triangle. For example, the circumcentre of an obtuse isosceles triangle lies outside the triangle.
This method uses geos::math::DD extended-precision arithmetic to provide more accurate results than circumcentre(Coordinate, Coordinate, Coordinate).
- Parameters
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| a | a vertex of the triangle |
| b | a vertex of the triangle |
| c | a vertex of the triangle |
- Returns
- the circumcentre of the triangle
| static DD geos::algorithm::CGAlgorithmsDD::detDD |
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double |
x1, |
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double |
y1, |
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double |
x2, |
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double |
y2 |
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| static DD geos::algorithm::CGAlgorithmsDD::detDD |
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const DD & |
x1, |
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const DD & |
y1, |
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const DD & |
x2, |
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const DD & |
y2 |
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If the lines are parallel (either identical or separate) a null value is returned.
- Parameters
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| p1 | an endpoint of line segment 1 |
| p2 | an endpoint of line segment 1 |
| q1 | an endpoint of line segment 2 |
| q2 | an endpoint of line segment 2 |
- Returns
- an intersection point if one exists, or null if the lines are parallel
| static int geos::algorithm::CGAlgorithmsDD::orientation |
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double |
x | ) |
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inlinestatic |
Returns the index of the direction of the point q relative to a vector specified by p1-p2.
- Parameters
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| p1 | the origin point of the vector |
| p2 | the final point of the vector |
| q | the point to compute the direction to |
- Returns
- 1 if q is counter-clockwise (left) from p1-p2
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-1 if q is clockwise (right) from p1-p2
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0 if q is collinear with p1-p2
| static int geos::algorithm::CGAlgorithmsDD::orientationIndex |
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double |
p1x, |
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double |
p1y, |
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double |
p2x, |
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double |
p2y, |
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double |
qx, |
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double |
qy |
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| static int geos::algorithm::CGAlgorithmsDD::orientationIndexFilter |
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double |
pax, |
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double |
pay, |
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double |
pbx, |
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double |
pby, |
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double |
pcx, |
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double |
pcy |
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A filter for computing the orientation index of three coordinates.
If the orientation can be computed safely using standard DP arithmetic, this routine returns the orientation index. Otherwise, a value i > 1 is returned. In this case the orientation index must be computed using some other more robust method.
The filter is fast to compute, so can be used to avoid the use of slower robust methods except when they are really needed, thus providing better average performance.
Uses an approach due to Jonathan Shewchuk, which is in the public domain.
| static int geos::algorithm::CGAlgorithmsDD::signOfDet2x2 |
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double |
dx1, |
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double |
dy1, |
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double |
dx2, |
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double |
dy2 |
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| static int geos::algorithm::CGAlgorithmsDD::signOfDet2x2 |
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const DD & |
x1, |
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const DD & |
y1, |
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const DD & |
x2, |
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const DD & |
y2 |
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staticprotected |
The documentation for this class was generated from the following file:
