Package micycle.pgs

Class PGS_Hull

java.lang.Object
micycle.pgs.PGS_Hull
public class PGS_Hull extends Object
Generates various types of geomtric hulls (convex, concave, etc.) for polygons and point sets.

A hull is the smallest enclosing shape of some nature that contains all points in a set.

Since:
1.3.0
Author:
Michael Carleton

  • Method Summary

    Modifier and Type
    Method
    Description
    static processing.core.PShape
    boundingBox(processing.core.PShape shape)
    Calculates the bounding box (envelope) for the given PShape and returns it as a new PShape.
    static processing.core.PShape
    boundingBox(processing.core.PShape shape, double[] out)
    Computes the bounding box (envelope) of the given PShape and writes its coordinates to the provided array.
    static processing.core.PShape
    concaveHull(processing.core.PShape shapeSet, double concavity, boolean tight)
    Constructs a concave hull of a set of polygons, respecting the polygons as constraints (i.e. the hull is guaranteed to contain the polygons).
    static processing.core.PShape
    concaveHullBFS(List<processing.core.PVector> points, double edgeLengthRatio)
    Computes the concave hull of a point set using a breadth-first method.
    static processing.core.PShape
    concaveHullBFS2(List<processing.core.PVector> points, double threshold)
    Computes the concave hull of a point set using a different algorithm.
    static processing.core.PShape
    concaveHullDFS(List<processing.core.PVector> points, double concavity)
    Computes the concave hull of a point set using a depth-first method.
    static processing.core.PShape
    convexHull(Collection<processing.core.PVector> points)
    Computes the convex hull of a point set (the smallest convex polygon that contains all the points).
    static processing.core.PShape
    convexHull(processing.core.PShape shape)
    Computes the convex hull of the vertices from the input shape (the smallest convex polygon that contains all the shape's vertices).
    static processing.core.PShape
    snapHull(processing.core.PShape shape, double convexity)
    Computes a hull, having a variable level of convexity, of a shape.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • boundingBox

      public static processing.core.PShape boundingBox(processing.core.PShape shape)
      Calculates the bounding box (envelope) for the given PShape and returns it as a new PShape.

      The returned shape represents the axis-aligned bounding rectangle that contains the input shape.

      Parameters:
      shape - the input shape for which to compute the bounding box
      Returns:
      a PShape representing the bounding box of the input shape
      Since:
      2.1

    • boundingBox

      public static processing.core.PShape boundingBox(processing.core.PShape shape, double[] out)
      Computes the bounding box (envelope) of the given PShape and writes its coordinates to the provided array.

      The coordinates are written as: {minX, minY, maxX, maxY}.

      Parameters:
      shape - the shape for which to calculate the bounding box
      out - an array (length ≥ 4) that will hold the bounding box coordinates:
      • out[0] = minX
      • out[1] = minY
      • out[2] = maxX
      • out[3] = maxY
      Returns:
      a PShape representing the bounding box of the input shape
      Since:
      2.1

    • convexHull

      public static processing.core.PShape convexHull(Collection<processing.core.PVector> points)
      Computes the convex hull of a point set (the smallest convex polygon that contains all the points).
      Parameters:
      points - a collection of points
      Returns:
      the minimum-area convex polygon containing the points
      Since:
      1.3.0

    • convexHull

      public static processing.core.PShape convexHull(processing.core.PShape shape)
      Computes the convex hull of the vertices from the input shape (the smallest convex polygon that contains all the shape's vertices).
      Parameters:
      shape - a concave shape
      Returns:
      the minimum-area convex polygon containing the input's vertices
      Since:
      1.3.0

    • concaveHull

      public static processing.core.PShape concaveHull(processing.core.PShape shapeSet, double concavity, boolean tight)
      Constructs a concave hull of a set of polygons, respecting the polygons as constraints (i.e. the hull is guaranteed to contain the polygons).
      Parameters:
      shapeSet - a GROUP PShape, having multiple child PShapes, each of which is a polygon
      concavity - a factor value between 0 and 1, specifying how concave the output is.
      tight - sets whether the boundary of the hull polygon is kept tight to precisely the outer edges of the input polygons
      Returns:
      concave hull of the input shapes
      Since:
      1.3.0

    • concaveHullDFS

      public static processing.core.PShape concaveHullDFS(List<processing.core.PVector> points, double concavity)
      Computes the concave hull of a point set using a depth-first method. In contrast to the BFS method, the depth-first approach produces shapes that are more contiguous/less branching and spiral-like.
      Parameters:
      points -
      concavity - a factor value between 0 and 1, specifying how concave the output is (where 1 is maximal concavity)
      Returns:
      Since:
      1.1.0
      See Also:

    • concaveHullBFS

      public static processing.core.PShape concaveHullBFS(List<processing.core.PVector> points, double edgeLengthRatio)
      Computes the concave hull of a point set using a breadth-first method.
      Parameters:
      points -
      edgeLengthRatio - Sets the target maximum edge length ratio for the concave hull. The edge length ratio is a fraction of the difference between the longest and shortest edge lengths in the Delaunay Triangulation of the input points. It is a value in the range 0.0 to 1; at 0.0 it produces a concave hull of minimum area that is still connected; 1.0 produces the convex hull.
      Returns:
      Since:
      1.1.0
      See Also:

    • concaveHullBFS2

      public static processing.core.PShape concaveHullBFS2(List<processing.core.PVector> points, double threshold)
      Computes the concave hull of a point set using a different algorithm. This approach has a more "organic" structure compared to other concaveBFS method.
      Parameters:
      points -
      threshold - 0...1 (Normalized length parameter).
      • Setting threshold=1 means that no edges will be removed from the Delaunay triangulation, so the resulting polygon will be the convex hull.
      • Setting threshold=0 means that all edges that can be removed subject to the regularity constraint will be removed (however polygons that are eroded beyond the point where they provide a desirable characterization of the shape).
      • Although the optimal parameter value varies for different shapes and point distributions, values between 0.05–0.2 typically produce optimal or near-optimal shape characterization across a wide range of point distributions.
      Returns:
      See Also:

    • snapHull

      public static processing.core.PShape snapHull(processing.core.PShape shape, double convexity)
      Computes a hull, having a variable level of convexity, of a shape.

      When convexity=0, the original shape is reproduced (a pure concave hull); the hull tends towards a convex hull of the input as convexity goes to 1 (in other words, a hull with some level of "snapping" to the original shape).

      Parameters:
      shape -
      convexity - how convex the snap hull is, where 0 is the original shape (no convexity, fully concave) and 1 forms the convex hull of the shape's vertices
      Returns: