public static List <Vertices> ConvexPartition(Vertices vertices, TriangulationAlgorithm algorithm, bool discardAndFixInvalid = true, float tolerance = 0.001f)
{
if (vertices.Count <= 3)
{
return new List <Vertices> {
vertices
}
}
;
List <Vertices> results = null;
switch (algorithm)
{
case TriangulationAlgorithm.Earclip:
#pragma warning disable 162
// ReSharper disable three ConditionIsAlwaysTrueOrFalse
if (Settings.SkipSanityChecks)
{
Debug.Assert(!vertices.IsCounterClockWise(), "The Ear-clip algorithm expects the polygon to be clockwise.");
}
else
{
if (vertices.IsCounterClockWise())
{
Vertices temp = new Vertices(vertices);
temp.Reverse();
results = EarclipDecomposer.ConvexPartition(temp, tolerance);
}
else
{
results = EarclipDecomposer.ConvexPartition(vertices, tolerance);
}
}
break;
case TriangulationAlgorithm.Bayazit:
if (Settings.SkipSanityChecks)
{
Debug.Assert(vertices.IsCounterClockWise(), "The polygon is not counter clockwise. This is needed for Bayazit to work correctly.");
}
else
{
if (!vertices.IsCounterClockWise())
{
Vertices temp = new Vertices(vertices);
temp.Reverse();
results = BayazitDecomposer.ConvexPartition(temp);
}
else
{
results = BayazitDecomposer.ConvexPartition(vertices);
}
}
break;
case TriangulationAlgorithm.Flipcode:
if (Settings.SkipSanityChecks)
{
Debug.Assert(vertices.IsCounterClockWise(), "The polygon is not counter clockwise. This is needed for Bayazit to work correctly.");
}
#pragma warning restore 162
else
{
if (!vertices.IsCounterClockWise())
{
Vertices temp = new Vertices(vertices);
temp.Reverse();
results = FlipcodeDecomposer.ConvexPartition(temp);
}
else
{
results = FlipcodeDecomposer.ConvexPartition(vertices);
}
}
break;
case TriangulationAlgorithm.Seidel:
results = SeidelDecomposer.ConvexPartition(vertices, tolerance);
break;
case TriangulationAlgorithm.SeidelTrapezoids:
results = SeidelDecomposer.ConvexPartitionTrapezoid(vertices, tolerance);
break;
case TriangulationAlgorithm.Delauny:
results = CDTDecomposer.ConvexPartition(vertices);
break;
default:
throw new ArgumentOutOfRangeException(nameof(algorithm));
}
if (discardAndFixInvalid)
{
for (int i = results.Count - 1; i >= 0; i--)
{
Vertices polygon = results[i];
if (!ValidatePolygon(polygon))
{
results.RemoveAt(i);
}
}
}
return(results);
}
/// <summary>
/// Creates a mesh out of a polygon.
/// </summary>
/// <param name="vertices">Boundary vertices of the polygon.</param>
/// <param name="holes">Hole vertices of the polygon if any.</param>
/// <returns></returns>
public static Mesh CreatePolygonMesh(List <Vector2> vertices, List <List <Vector2> > holes = null)
{
// split the polygon into convex parts so we can use fan triangulation https://en.wikipedia.org/wiki/Fan_triangulation
List <List <Vector2> > convexPolygons = CDTDecomposer.ConvexPartition(vertices, holes);
//Debug.Log("Polygon is split into " + convexPolygons.Count + " parts");
// create mesh arrays
List <List <Vector3> > meshVerticesList = new List <List <Vector3> >();
List <List <Vector3> > meshNormalsList = new List <List <Vector3> >();
List <List <int> > meshTrianglesList = new List <List <int> >();
for (int i = 0; i < convexPolygons.Count; i++)
{
// map 2d vertices of the polygon to 3d on the 0-plane
List <Vector3> polygon3D = new List <Vector3>();
foreach (var vertex in convexPolygons[i])
{
polygon3D.Add(new Vector3(vertex.x, 0, vertex.y));
}
meshVerticesList.Add(polygon3D);
// fan triangulation
List <int> triangles = new List <int>();
for (int k = 1; k < polygon3D.Count - 1; k++)
{
triangles.Add(0);
triangles.Add(k);
triangles.Add(k + 1);
}
meshTrianglesList.Add(triangles);
}
// let all normals point up as this is only in 2D
foreach (var meshVertices in meshVerticesList)
{
meshNormalsList.Add(new List <Vector3>(new Vector3[meshVertices.Count]));
}
foreach (var meshNormalList in meshNormalsList)
{
for (int i = 0; i < meshNormalList.Count; i++)
{
meshNormalList[i] = Vector3.up;
}
}
CombineInstance[] combinedMeshes = new CombineInstance[convexPolygons.Count];
for (int i = 0; i < convexPolygons.Count; i++)
{
// create a mesh for each convex polygon
Mesh meshPart = new Mesh();
meshPart.vertices = meshVerticesList[i].ToArray();
meshPart.normals = meshNormalsList[i].ToArray();
meshPart.triangles = meshTrianglesList[i].ToArray();
combinedMeshes[i].mesh = meshPart;
combinedMeshes[i].transform = Matrix4x4.identity;
}
// combine the meshes to one mesh
Mesh mesh = new Mesh();
mesh.CombineMeshes(combinedMeshes);
mesh.RecalculateBounds();
mesh.RecalculateNormals();
return(mesh);
}
