Class SimpleSnapRounder
- java.lang.Object
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- org.locationtech.jts.noding.snapround.SimpleSnapRounder
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- All Implemented Interfaces:
Noder
public class SimpleSnapRounder extends java.lang.Object implements Noder
Uses Snap Rounding to compute a rounded, fully noded arrangement from a set ofSegmentString
s. Implements the Snap Rounding technique described in the papers by Hobby, Guibas & Marimont, and Goodrich et al. Snap Rounding assumes that all vertices lie on a uniform grid; hence the precision model of the input must be fixed precision, and all the input vertices must be rounded to that precision.This implementation uses simple iteration over the line segments. This is not the most efficient approach for large sets of segments.
This implementation appears to be fully robust using an integer precision model. It will function with non-integer precision models, but the results are not 100% guaranteed to be correctly noded.
- Version:
- 1.7
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Field Summary
Fields Modifier and Type Field Description private LineIntersector
li
private java.util.Collection
nodedSegStrings
private PrecisionModel
pm
private double
scaleFactor
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Constructor Summary
Constructors Constructor Description SimpleSnapRounder(PrecisionModel pm)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private void
checkCorrectness(java.util.Collection inputSegmentStrings)
void
computeNodes(java.util.Collection inputSegmentStrings)
Computes the noding for a collection ofSegmentString
s.private void
computeSnaps(java.util.Collection segStrings, java.util.Collection snapPts)
Computes nodes introduced as a result of snapping segments to snap points (hot pixels)private void
computeSnaps(NodedSegmentString ss, java.util.Collection snapPts)
void
computeVertexSnaps(java.util.Collection edges)
Computes nodes introduced as a result of snapping segments to vertices of other segmentsprivate void
computeVertexSnaps(NodedSegmentString e0, NodedSegmentString e1)
Performs a brute-force comparison of every segment in eachSegmentString
.private java.util.List
findInteriorIntersections(java.util.Collection segStrings, LineIntersector li)
Computes all interior intersections in the collection ofSegmentString
s, and returns theirCoordinate
s.java.util.Collection
getNodedSubstrings()
Returns aCollection
of fully nodedSegmentString
s.private void
snapRound(java.util.Collection segStrings, LineIntersector li)
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Field Detail
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pm
private final PrecisionModel pm
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li
private LineIntersector li
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scaleFactor
private final double scaleFactor
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nodedSegStrings
private java.util.Collection nodedSegStrings
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Constructor Detail
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SimpleSnapRounder
public SimpleSnapRounder(PrecisionModel pm)
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Method Detail
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getNodedSubstrings
public java.util.Collection getNodedSubstrings()
Description copied from interface:Noder
Returns aCollection
of fully nodedSegmentString
s. The SegmentStrings have the same context as their parent.- Specified by:
getNodedSubstrings
in interfaceNoder
- Returns:
- a Collection of NodedSegmentStrings representing the substrings
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computeNodes
public void computeNodes(java.util.Collection inputSegmentStrings)
Description copied from interface:Noder
Computes the noding for a collection ofSegmentString
s. Some Noders may add all these nodes to the input SegmentStrings; others may only add some or none at all.- Specified by:
computeNodes
in interfaceNoder
- Parameters:
inputSegmentStrings
- a Collection of NodedSegmentStrings
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checkCorrectness
private void checkCorrectness(java.util.Collection inputSegmentStrings)
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snapRound
private void snapRound(java.util.Collection segStrings, LineIntersector li)
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findInteriorIntersections
private java.util.List findInteriorIntersections(java.util.Collection segStrings, LineIntersector li)
Computes all interior intersections in the collection ofSegmentString
s, and returns theirCoordinate
s. Does NOT node the segStrings.- Returns:
- a list of Coordinates for the intersections
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computeSnaps
private void computeSnaps(java.util.Collection segStrings, java.util.Collection snapPts)
Computes nodes introduced as a result of snapping segments to snap points (hot pixels)- Parameters:
li
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computeSnaps
private void computeSnaps(NodedSegmentString ss, java.util.Collection snapPts)
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computeVertexSnaps
public void computeVertexSnaps(java.util.Collection edges)
Computes nodes introduced as a result of snapping segments to vertices of other segments- Parameters:
edges
- the list of segment strings to snap together
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computeVertexSnaps
private void computeVertexSnaps(NodedSegmentString e0, NodedSegmentString e1)
Performs a brute-force comparison of every segment in eachSegmentString
. This has n^2 performance.
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