Module org.dyn4j

Package org.dyn4j.geometry.decompose

This package contains algorithms to decompose polygons into Convex pieces.

Three implementations of the Decomposer interface are provided: Bayazit, EarClipping, and SweepLine.

All three Decomposer algorithms are non-optimal, meaning they do not always produce a decomposition with the minimum number of convex pieces. Instead, they get close in exchange for performance.

NOTE: All three Decomposer algorithms operate on simple polygons without holes.

The EarClipping and SweepLine algorithms both triangulate the simple polygon first, then run Hertel-Mehlhorn to recombine triangles into convex pieces. Hertel-Mehlhorn is guarenteed to produce a convex decomposition with no more than 4 times the minimum number of convex pieces.

The EarClipping and SweepLine algorithms also implement the Triangulator interface to provide the ability to get a triangulation as well.

The Bayazit algorithm has O(nr) time-complexity.

The EarClipping algorithm has O(n²) time-complexity.

The SweepLine algorithm has O(n log n) time-complexity.

In general the algorithms will generate different decompositions. If used for pre-processing just choose the best result, for runtime generation, the Bayazit may be slower but will generally produce a better decomposition.

A "better" decomposition is one that contains fewer convex pieces and the convex pieces that are created are of better quality for simulation.

Since:

2.2.0

Version:

3.2.0

Author:

William Bittle

Interface Summary

Interface	Description
Decomposer	Represents an algorithm to decompose a given polygon (as a list of points) into Convex pieces.
Triangulator	Represents an algorithm to triangulate a given polygon (as a list of points) into Triangles.

Class Summary

Class	Description
AbstractDecomposer	Abstract implementation of the Decomposer interface.
Bayazit	Implementation of the Bayazit convex decomposition algorithm for simple polygons.
EarClipping	Implementation of the Ear Clipping convex decomposition algorithm for simple polygons.
SweepLine	Implementation of the Sweep convex decomposition algorithm for simple polygons.