private static IEnumerable <DoubleCurveTriangle> FuseCurveTriangles(Curve c1, Curve c2)
{
// Extract the curve vertices
var t1 = c1.CurveVertices;
var t2 = c2.CurveVertices;
// Pick their extrapolators
var ext1 = CoordExtrapolator(t1);
var ext2 = CoordExtrapolator(t2);
// Now, we are going to pick the convex hull of the polygon
var hull = GeometricUtils.ConvexHull(t1.Concat(t2).Select(v => v.Position).ToArray());
// Finally, calculate the new texture coordinates
var vertices = hull.Select(p => new DoubleCurveVertex(p, ext1(p), ext2(p)));
// And return the triangle
return(DoubleCurveVertex.MakeTriangleFan(vertices.ToArray()));
}
private static Double2[] FillPolygon(Curve[] contour)
{
// "Guess" a capacity for the list, add the first point
var list = new List <Double2>((int)(1.4 * contour.Length));
// Check first if the last and first curve aren't joinable
bool lastFirstJoin = FillFace.AreCurvesFusable(contour[contour.Length - 1], contour[0]);
if (lastFirstJoin)
{
list.Add(contour[0].At(1));
}
// Now, scan the curve list for pairs of scannable curves
var k = lastFirstJoin ? 1 : 0;
for (int i = k; i < contour.Length - k; i++)
{
if (i < contour.Length - 1 && FillFace.AreCurvesFusable(contour[i], contour[i + 1]))
{
// If they describe a positive winding on the plane, add only its endpoint
var endp0 = contour[i].At(0);
var endp1 = contour[i + 1].At(1);
var pth = (endp0 + endp1) / 2;
if (contour[i].WindingRelativeTo(pth) + contour[i + 1].WindingRelativeTo(pth) > 0)
{
list.Add(endp1);
}
else
{
// Else, compute the convex hull and add the correct point sequence
var points = contour[i].EnclosingPolygon.Concat(contour[i + 1].EnclosingPolygon).ToArray();
var hull = GeometricUtils.ConvexHull(points);
var hl = hull.Length;
// We have to go through the hull clockwise. Find the first point
int ik;
for (ik = 0; ik < hl; ik++)
{
if (hull[ik] == endp0)
{
break;
}
}
// And run through it
for (int i0 = ik; i0 != (ik + 1) % hl; i0 = (i0 + hl - 1) % hl)
{
list.Add(hull[i0]);
}
}
i++;
}
else if (contour[i].Type == CurveType.Line || contour[i].IsConvex)
{
list.Add(contour[i].At(1));
}
else
{
list.AddRange(contour[i].EnclosingPolygon.Skip(1));
}
}
// Sanitize the list; identical vertices
var indices = new List <int>();
for (int i = 0; i < list.Count; i++)
{
if (DoubleUtils.RoughlyEquals(list[i], list[(i + 1) % list.Count]))
{
indices.Add(i);
}
}
list.ExtractIndices(indices.ToArray());
return(list.ToArray());
}
