/// <summary>
/// Finally, build the triangles
/// </summary>
/// <param name="collector">the triangle collector</param>
public void BuildTriangles(ITriangleCollector collector)
{
var splits = ScanSplitByTrapezoidation.BuildSplits(this.polygon);
var polygonWithMonotones = Polygon.Split(this.polygon, splits, collector);
foreach (var subPolygonId in polygonWithMonotones.SubPolygonIds)
{
var triangluator = new MonotonePolygonTriangulator(polygonWithMonotones, subPolygonId);
triangluator.Build(collector);
}
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="polygon">the original polygon</param>
/// <param name="splits">tuples of vertex ids, where to split</param>
public PolygonSplitter(Polygon polygon, IEnumerable <Tuple <int, int> > splits, ITriangleCollector triangleCollector)
{
this.allSplits = splits.ToArray();
this.originalPolygon = polygon;
this.polygonStartIndices = new List <int>(polygon.polygonStartIndices);
this.chainFreeIndex = polygon.chain.Length;
this.chain = new VertexChain[this.chainFreeIndex + this.allSplits.Length * 2];
Array.Copy(polygon.chain, this.chain, this.chainFreeIndex);
this.triangleCollector = triangleCollector;
}
/// <summary>
/// traverse the polygon and add triangles to the collector
/// </summary>
/// <param name="collector">collector for resulting triangles</param>
public void Build(ITriangleCollector collector)
{
var start = this.FindStartOfMonotonePolygon();
if (start >= 0)
{
this.TriangulateMonotonePolygon(start, collector);
}
else
{
var triangleVertices = this.polygon.SubPolygonVertices(this.subPolygonId).ToArray();
collector.AddTriangle(triangleVertices[0], triangleVertices[1], triangleVertices[2]);
}
}
/// <summary>
/// Create triangles for a monotone polygon
/// </summary>
/// <param name="polygon">the monotone polygon</param>
/// <param name="startPoint">the first point (clockwise) of the long edge.</param>
/// <param name="result">the collector for resulting triangles</param>
private void TriangulateMonotonePolygon(int startPoint, ITriangleCollector result)
{
this.PullFirstTriangle(startPoint);
while (true)
{
if (this.IsConvexCorner())
{
result.AddTriangle(this.current, this.third, this.second);
if (!this.PopOrPullNextVertex())
{
return;
}
}
else
{
this.PushAndPullNextVertex();
}
}
}
