private IntersectionData?Intersection(Point3D a, Point3D b, double z)
{
if ((Equality.AreLessOrEqual(a.Z, z) && Equality.AreLessOrEqual(b.Z, z)) ||
(Equality.AreMoreOrEqual(a.Z, z) && Equality.AreMoreOrEqual(b.Z, z)))
{
return(null);
}
if (Equality.AreEqual(a.X, b.X) && Equality.AreEqual(a.Y, b.Y))
{
return(new IntersectionData(new Point3D(a.X, a.Y, z), a, b));
}
var x = (z - a.Z) * (b.X - a.X) / (b.Z - a.Z) + a.X;
var y = (z - a.Z) * (b.Y - a.Y) / (b.Z - a.Z) + a.Y;
if (Equality.AreEqual(a.X, b.X))
{
return(new IntersectionData(new Point3D(a.X, y, z), a, b));
}
if (Equality.AreEqual(a.Y, b.Y))
{
return(new IntersectionData(new Point3D(x, a.Y, z), a, b));
}
return(new IntersectionData(new Point3D(x, y, z), a, b));
}
public TriangulatedSurface GetModifiedSurface(TriangulatedSurface surface, IOptions options)
{
var cutOptions = (TriangulatedSurfaceCutterOptions)options;
List <Triangle3D> triangles = new List <Triangle3D>();
foreach (var triangle in surface.Triangles)
{
if (Equality.AreLessOrEqual(triangle.Points.Max(p => p.Z), cutOptions.CutDepth))
{
triangles.Add(triangle);
}
else if (Equality.AreMoreOrEqual(triangle.Points.Min(p => p.Z), cutOptions.CutDepth))
{
continue;
}
else
{
Point3D[] pointsToInclude = triangle.Points.Where(p => Equality.Less(p.Z, cutOptions.CutDepth)).ToArray();
List <IntersectionData> intersectionList = new List <IntersectionData>();
var intersect = Intersection(triangle.A, triangle.B, cutOptions.CutDepth);
if (intersect != null)
{
intersectionList.Add(intersect.Value);
}
intersect = Intersection(triangle.B, triangle.C, cutOptions.CutDepth);
if (intersect != null)
{
intersectionList.Add(intersect.Value);
}
intersect = Intersection(triangle.A, triangle.C, cutOptions.CutDepth);
if (intersect != null)
{
intersectionList.Add(intersect.Value);
}
var firstPoint = pointsToInclude[0];
triangles.Add(new Triangle3D(firstPoint, intersectionList[0].Intersection, intersectionList[1].Intersection));
if (pointsToInclude.Length == 2)
{
var secondPoint = pointsToInclude[1];
if (intersectionList[0].HasPoint(secondPoint))
{
triangles.Add(new Triangle3D(firstPoint, secondPoint, intersectionList[0].Intersection));
}
else if (intersectionList[1].HasPoint(secondPoint))
{
triangles.Add(new Triangle3D(firstPoint, secondPoint, intersectionList[1].Intersection));
}
else
{
throw new Exception("Unexpected program behavior.");
}
}
}
}
return(new TriangulatedSurface(triangles.ToArray()));
}