public static CompiledDrawing FromFace(FillFace face)
{
var fill = new CompiledDrawing();
// Simplify the face by subdividing overlapping curves
var newFace = face.SubdivideOverlapping();
// Build the fill polygons and triangulate them
fill.Triangles = Triangulator.YMonotone.Triangulate(newFace.Contours.Select(FillPolygon).ToArray());
// Collect all curve triangles
var curves = newFace.Contours.SelectMany(v => v.Where(c => c.Type != CurveType.Line)).ToArray();
var curveTriangles = new List <CurveTriangle>();
var doubleCurveTriangles = new List <DoubleCurveTriangle>();
if (curves.Length > 0)
{
// Check first if the last and first curve aren't joinable
bool lastFirstJoin = curves.Length > 1 && FillFace.AreCurvesFusable(curves[curves.Length - 1], curves[0]);
if (lastFirstJoin)
{
doubleCurveTriangles.AddRange(FuseCurveTriangles(curves[curves.Length - 1], curves[0]));
}
else
{
curveTriangles.AddRange(CurveVertex.MakeTriangleFan(curves[0].CurveVertices));
}
// Now, scan the curve list for pairs of scannable curves
var k = lastFirstJoin ? 1 : 0;
for (int i = k; i < curves.Length - k; i++)
{
if (i < curves.Length - 1 && FillFace.AreCurvesFusable(curves[i], curves[i + 1]))
{
doubleCurveTriangles.AddRange(FuseCurveTriangles(curves[i], curves[i + 1]));
i++;
}
else
{
curveTriangles.AddRange(CurveVertex.MakeTriangleFan(curves[i].CurveVertices));
}
}
}
fill.CurveTriangles = curveTriangles.ToArray();
fill.DoubleCurveTriangles = doubleCurveTriangles.ToArray();
return(fill);
}
private CurveVertex[] EllipticArc_CurveVertices()
{
// Apply the Loop-Blinn method to get the texture coordinates
// Available on https://www.microsoft.com/en-us/research/wp-content/uploads/2005/01/p1000-loop.pdf
// This case is not described in the paper, but it is easily derived
// The texture coordinates are actually, x/a, 1 - y/b, 1 + y/b in local space
var sign = IsConvex ? 1 : -1;
var localPoints = EllipticArc_EnclosingPolygonLocalSpace();
var vertices = new CurveVertex[localPoints.Length];
for (int i = 0; i < localPoints.Length; i++)
{
var p = localPoints[i];
var kx = p.X / Radii.X;
var ky = p.Y / Radii.Y;
// Apply the vertex
vertices[i] = new CurveVertex(LocalSpaceToGlobal(p), new Double4(kx, 1 - ky, 1 + ky, sign));
}
return(vertices);
}