Contains the parameters which describe how a buffer should be constructed.
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#include <BufferParameters.h>
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| static double | bufferDistanceError (int quadSegs) |
| | Computes the maximum distance error due to a given level of approximation to a true arc. More...
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Contains the parameters which describe how a buffer should be constructed.
◆ EndCapStyle
End cap styles.
| Enumerator |
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| CAP_ROUND | Specifies a round line buffer end cap style.
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| CAP_FLAT | Specifies a flat line buffer end cap style.
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| CAP_SQUARE | Specifies a square line buffer end cap style.
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◆ JoinStyle
Join styles.
| Enumerator |
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| JOIN_ROUND | Specifies a round join style.
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| JOIN_MITRE | Specifies a mitre join style.
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| JOIN_BEVEL | Specifies a bevel join style.
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◆ BufferParameters() [1/3]
| geos::operation::buffer::BufferParameters::BufferParameters |
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int |
quadrantSegments | ) |
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Creates a set of parameters with the given quadrantSegments value.
- Parameters
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| quadrantSegments | the number of quadrant segments to use |
◆ BufferParameters() [2/3]
| geos::operation::buffer::BufferParameters::BufferParameters |
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int |
quadrantSegments, |
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EndCapStyle |
endCapStyle |
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) |
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Creates a set of parameters with the given quadrantSegments and endCapStyle values.
- Parameters
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| quadrantSegments | the number of quadrant segments to use |
| endCapStyle | the end cap style to use |
◆ BufferParameters() [3/3]
| geos::operation::buffer::BufferParameters::BufferParameters |
( |
int |
quadrantSegments, |
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EndCapStyle |
endCapStyle, |
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JoinStyle |
joinStyle, |
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double |
mitreLimit |
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) |
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Creates a set of parameters with the given parameter values.
- Parameters
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| quadrantSegments | the number of quadrant segments to use |
| endCapStyle | the end cap style to use |
| joinStyle | the join style to use |
| mitreLimit | the mitre limit to use |
◆ bufferDistanceError()
| static double geos::operation::buffer::BufferParameters::bufferDistanceError |
( |
int |
quadSegs | ) |
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static |
Computes the maximum distance error due to a given level of approximation to a true arc.
- Parameters
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| quadSegs | the number of segments used to approximate a quarter-circle |
- Returns
- the error of approximation
◆ getEndCapStyle()
| EndCapStyle geos::operation::buffer::BufferParameters::getEndCapStyle |
( |
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const |
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inline |
Gets the end cap style.
- Returns
- the end cap style
◆ getJoinStyle()
| JoinStyle geos::operation::buffer::BufferParameters::getJoinStyle |
( |
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const |
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inline |
◆ getMitreLimit()
| double geos::operation::buffer::BufferParameters::getMitreLimit |
( |
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const |
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inline |
◆ getQuadrantSegments()
| int geos::operation::buffer::BufferParameters::getQuadrantSegments |
( |
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const |
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inline |
◆ isSingleSided()
| bool geos::operation::buffer::BufferParameters::isSingleSided |
( |
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const |
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inline |
Tests whether the buffer is to be generated on a single side only.
- Returns
- true if the generated buffer is to be single-sided
◆ setEndCapStyle()
| void geos::operation::buffer::BufferParameters::setEndCapStyle |
( |
EndCapStyle |
style | ) |
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inline |
◆ setJoinStyle()
| void geos::operation::buffer::BufferParameters::setJoinStyle |
( |
JoinStyle |
style | ) |
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inline |
Sets the join style for outside (reflex) corners between line segments.
Allowable values are JOIN_ROUND (which is the default), JOIN_MITRE and JOIN_BEVEL.
- Parameters
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| style | the code for the join style |
Referenced by geos::operation::buffer::OffsetCurve::OffsetCurve().
◆ setMitreLimit()
| void geos::operation::buffer::BufferParameters::setMitreLimit |
( |
double |
limit | ) |
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inline |
Sets the limit on the mitre ratio used for very sharp corners.
The mitre ratio is the ratio of the distance from the corner to the end of the mitred offset corner. When two line segments meet at a sharp angle, a miter join will extend far beyond the original geometry. (and in the extreme case will be infinitely far.) To prevent unreasonable geometry, the mitre limit allows controlling the maximum length of the join corner. Corners with a ratio which exceed the limit will be beveled.
- Parameters
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| limit | the mitre ratio limit |
Referenced by geos::operation::buffer::OffsetCurve::OffsetCurve().
◆ setQuadrantSegments()
| void geos::operation::buffer::BufferParameters::setQuadrantSegments |
( |
int |
quadSegs | ) |
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Sets the number of line segments used to approximate an angle fillet.
- If
quadSegs >= 1, joins are round, and quadSegs indicates the number of segments to use to approximate a quarter-circle.
- If
quadSegs = 0, joins are bevelled (flat)
- If
quadSegs < 0, joins are mitred, and the value of qs indicates the mitre ration limit as
mitreLimit = |quadSegs|
For round joins, quadSegs determines the maximum error in the approximation to the true buffer curve.
The default value of 8 gives less than 2% max error in the buffer distance.
For a max error of < 1%, use QS = 12. For a max error of < 0.1%, use QS = 18. The error is always less than the buffer distance (in other words, the computed buffer curve is always inside the true curve).
- Parameters
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| quadSegs | the number of segments in a fillet for a quadrant |
Referenced by geos::operation::buffer::OffsetCurve::OffsetCurve(), and geos::operation::buffer::BufferOp::setQuadrantSegments().
◆ setSingleSided()
| void geos::operation::buffer::BufferParameters::setSingleSided |
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bool |
p_isSingleSided | ) |
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inline |
Sets whether the computed buffer should be single-sided. A single-sided buffer is constructed on only one side of each input line.
The side used is determined by the sign of the buffer distance:
- a positive distance indicates the left-hand side
- a negative distance indicates the right-hand side
The single-sided buffer of point geometries is the same as the regular buffer.
The End Cap Style for single-sided buffers is always ignored, and forced to the equivalent of CAP_FLAT.
- Parameters
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| p_isSingleSided | true if a single-sided buffer should be constructed |
Referenced by geos::operation::buffer::BufferOp::setSingleSided().
◆ DEFAULT_MITRE_LIMIT
| const double geos::operation::buffer::BufferParameters::DEFAULT_MITRE_LIMIT |
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static |
The default mitre limit
Allows fairly pointy mitres.
◆ DEFAULT_QUADRANT_SEGMENTS
| const int geos::operation::buffer::BufferParameters::DEFAULT_QUADRANT_SEGMENTS = 8 |
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static |
The default number of facets into which to divide a fillet of 90 degrees.
A value of 8 gives less than 2% max error in the buffer distance. For a max error of < 1%, use QS = 12. For a max error of < 0.1%, use QS = 18.
The documentation for this class was generated from the following file:
