public void AddContour(ContourVertex[] vertices)
{
AddContour(vertices, ContourOrientation.Original);
}
public void AddContour(ContourVertex[] vertices, ContourOrientation forceOrientation)
{
if (_mesh == null)
{
_mesh = new Mesh();
}
bool reverse = false;
if (forceOrientation != ContourOrientation.Original)
{
float area = SignedArea(vertices);
reverse = (forceOrientation == ContourOrientation.Clockwise && area < 0.0f) || (forceOrientation == ContourOrientation.CounterClockwise && area > 0.0f);
}
MeshUtils.Edge e = null;
for (int i = 0; i < vertices.Length; ++i)
{
if (e == null)
{
e = _mesh.MakeEdge();
_mesh.Splice(e, e._Sym);
} else
{
// Create a new vertex and edge which immediately follow e
// in the ordering around the left face.
_mesh.SplitEdge(e);
e = e._Lnext;
}
int index = reverse ? vertices.Length - 1 - i : i;
// The new vertex is now e._Org.
e._Org._coords = vertices [index].Position;
e._Org._data = vertices [index].Data;
// The winding of an edge says how the winding number changes as we
// cross from the edge's right face to its left face. We add the
// vertices in such an order that a CCW contour will add +1 to
// the winding number of the region inside the contour.
e._winding = 1;
e._Sym._winding = -1;
}
}
private float SignedArea(ContourVertex[] vertices)
{
float area = 0.0f;
for (int i = 0; i < vertices.Length; i++)
{
var v0 = vertices [i];
var v1 = vertices [(i + 1) % vertices.Length];
area += v0.Position.X * v1.Position.Y;
area -= v0.Position.Y * v1.Position.X;
}
return area * 0.5f;
}
