Centroid class
Computes the centroid of a {@link Geometry} of any dimension.
If the geometry is nominally of higher dimension,
but has lower effective dimension
(i.e. contains only components
having zero length or area),
the centroid will be computed as for the equivalent lower-dimension geometry.
If the input geometry is empty, a
null Coordinate is returned.
Algorithm
- Dimension 2 - the centroid is computed
as the weighted sum of the centroids
of a decomposition of the area into (possibly overlapping) triangles.
Holes and multipolygons are handled correctly.
See
http://www.faqs.org/faqs/graphics/algorithms-faq/for further details of the basic approach. - Dimension 1 - Computes the average of the midpoints of all line segments weighted by the segment length. Zero-length lines are treated as points.
- Dimension 0 - Compute the average coordinate for all points. Repeated points are all included in the average.
@version 1.7
Constructors
Properties
- areaBasePt ↔ Coordinate?
-
getter/setter pair
- areasum2 ↔ double
-
getter/setter pair
- cg3 ↔ Coordinate
-
getter/setter pair
- hashCode → int
-
The hash code for this object.
no setterinherited
- lineCentSum ↔ Coordinate
-
getter/setter pair
- ptCentSum ↔ Coordinate
-
getter/setter pair
- ptCount ↔ int
-
getter/setter pair
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- totalLength ↔ double
-
getter/setter pair
- triangleCent3 ↔ Coordinate
-
getter/setter pair
Methods
-
add(
Geometry geom) → void - Adds a Geometry to the centroid total.
-
addHole(
List< Coordinate> pts) → void -
addLineSegments(
List< Coordinate> pts) → void - Adds the line segments defined by an array of coordinates to the linear centroid accumulators.
-
addPoint(
Coordinate pt) → void - Adds a point to the point centroid accumulator. @param pt a {@link Coordinate}
-
addPolygon(
Polygon poly) → void -
addShell(
List< Coordinate> pts) → void -
addTriangle(
Coordinate p0, Coordinate p1, Coordinate p2, bool isPositiveArea) → void -
getCentroid(
) → Coordinate? - Gets the computed centroid.
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
setAreaBasePoint(
Coordinate basePt) → void -
toString(
) → String -
A string representation of this object.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited
Static Methods
-
area2(
Coordinate p1, Coordinate p2, Coordinate p3) → double - Returns twice the signed area of the triangle p1-p2-p3. The area is positive if the triangle is oriented CCW, and negative if CW.
-
centroid3(
Coordinate p1, Coordinate p2, Coordinate p3, Coordinate c) → void - Computes three times the centroid of the triangle p1-p2-p3. The factor of 3 is left in to permit division to be avoided until later.
-
getCentroidStatic(
Geometry geom) → Coordinate? - Computes the centroid point of a geometry.