75 lines
2.4 KiB
C#
75 lines
2.4 KiB
C#
/*
|
|
* Farseer Physics Engine:
|
|
* Copyright (c) 2012 Ian Qvist
|
|
*/
|
|
|
|
using System.Collections.Generic;
|
|
using System.Diagnostics;
|
|
using FarseerPhysics.Common.Decomposition.CDT;
|
|
using FarseerPhysics.Common.Decomposition.CDT.Delaunay;
|
|
using FarseerPhysics.Common.Decomposition.CDT.Delaunay.Sweep;
|
|
using FarseerPhysics.Common.Decomposition.CDT.Polygon;
|
|
using Microsoft.Xna.Framework;
|
|
|
|
namespace FarseerPhysics.Common.Decomposition
|
|
{
|
|
/// <summary>
|
|
/// 2D constrained Delaunay triangulation algorithm.
|
|
/// Based on the paper "Sweep-line algorithm for constrained Delaunay triangulation" by V. Domiter and and B. Zalik
|
|
///
|
|
/// Properties:
|
|
/// - Creates triangles with a large interior angle.
|
|
/// - Supports holes
|
|
/// - Generate a lot of garbage due to incapsulation of the Poly2Tri library.
|
|
/// - Running time is O(n^2), n = number of vertices.
|
|
/// - Does not care about winding order.
|
|
///
|
|
/// Source: http://code.google.com/p/poly2tri/
|
|
/// </summary>
|
|
internal static class CDTDecomposer
|
|
{
|
|
/// <summary>
|
|
/// Decompose the polygon into several smaller non-concave polygon.
|
|
/// </summary>
|
|
public static List<Vertices> ConvexPartition(Vertices vertices)
|
|
{
|
|
Debug.Assert(vertices.Count > 3);
|
|
|
|
Polygon poly = new Polygon();
|
|
|
|
foreach (Vector2 vertex in vertices)
|
|
poly.Points.Add(new TriangulationPoint(vertex.X, vertex.Y));
|
|
|
|
if (vertices.Holes != null)
|
|
{
|
|
foreach (Vertices holeVertices in vertices.Holes)
|
|
{
|
|
Polygon hole = new Polygon();
|
|
|
|
foreach (Vector2 vertex in holeVertices)
|
|
hole.Points.Add(new TriangulationPoint(vertex.X, vertex.Y));
|
|
|
|
poly.AddHole(hole);
|
|
}
|
|
}
|
|
|
|
DTSweepContext tcx = new DTSweepContext();
|
|
tcx.PrepareTriangulation(poly);
|
|
DTSweep.Triangulate(tcx);
|
|
|
|
List<Vertices> results = new List<Vertices>();
|
|
|
|
foreach (DelaunayTriangle triangle in poly.Triangles)
|
|
{
|
|
Vertices v = new Vertices();
|
|
foreach (TriangulationPoint p in triangle.Points)
|
|
{
|
|
v.Add(new Vector2((float)p.X, (float)p.Y));
|
|
}
|
|
results.Add(v);
|
|
}
|
|
|
|
return results;
|
|
}
|
|
}
|
|
} |