public override IEnumerator <Triangle> GetEnumerator()
{
PartClassification classes = Classify(this.Original, this.OriginalMesh2);
foreach (var tri in classes.BInsideA.Concat(classes.AInsideB))
{
yield return(tri);
}
}
// Classify parts of a solid as inside or outside another
protected static PartClassification Classify(IMesh a, IMesh b)
{
// 0. Initialize intersection list
List <List <Line3> > acuts = new List <List <Line3> >();
List <List <Line3> > bcuts = new List <List <Line3> >();
foreach (Triangle atri in a)
{
acuts.Add(new List <Line3>());
}
foreach (Triangle btri in b)
{
bcuts.Add(new List <Line3>());
}
// 1. Determine intersection lines O(N^2)
Line3 hit;
// Iterate over Solid A
int k = 0;
foreach (Triangle atri in a)
{
// Create cut list for this triangle in A
List <Line3> atriCuts = acuts[k++];
int j = 0;
// Iterate over Solid b
foreach (Triangle btri in b)
{
// Create cut list for this triangle in B
List <Line3> btriCuts = bcuts[j++];
// Check if A & B intersect at these triangles
if (atri.Intersection(btri, out hit))
{
// Add line as a cut line for both triangles
atriCuts.Add(hit);
btriCuts.Add(hit);
}
}
}
// 2. Split a mesh based on intersection lines O(2N)
List <Triangle> SplitA = new List <Triangle>();
List <Triangle> SplitB = new List <Triangle>();
int i = 0;
foreach (Triangle tri in a)
{
SplitA.AddRange(Cut(tri, acuts[i++]));
}
i = 0;
foreach (Triangle tri in b)
{
SplitB.AddRange(Cut(tri, bcuts[i++]));
}
// 3. Classify triangles as AInsideB, AOutsideB, BInsideA, BOutsideA O(2N)
// - you can use raycast (any dir) to determine if inside (odd hits) vs outside (even hits)
PartClassification parts = new PartClassification();
foreach (Triangle tri in SplitA)
{
Ray ray = new Ray(tri.Centre, tri.Normal);
if (ray.CastAll(b).Count % 2 == 0)
{
// Even - Outside
parts.AOutsideB.Add(tri);
}
else
{
// Odd - Inside
parts.AInsideB.Add(tri);
}
}
foreach (Triangle tri in SplitB)
{
Ray ray = new Ray(tri.Centre, tri.Normal);
if (ray.CastAll(a).Count % 2 == 0)
{
// Even - Outside
parts.BOutsideA.Add(tri);
}
else
{
// Odd - Inside
parts.BInsideA.Add(tri);
}
}
// 4. Return classifications
return(parts);
}
