public static void ConvexHull(ref Surface surf)
{
if (surf.NumPoints < 4)
return;
//add the middle point to make a tetrahedron for some numerical stability
Point3D Middle = new Point3D();
for (int i = 0; i < surf.NumPoints; i++)
{
Middle += surf.Point(i);
}
Middle /= surf.NumPoints;
int mid = surf.AddPoint(Middle);
//clean out the faces, and add faces of a tetrahedron using the first 3 pts and the middle.
Point3D inside = (surf.Point(0) + surf.Point(1) + surf.Point(2) + surf.Point(mid)) / 4.0;
while (surf.NumFaces > 0)
surf.RemoveFace(0);
surf.AddFace(0, 1, 2, inside);
surf.AddFace(0, 1, mid, inside);
surf.AddFace(0, 2, mid, inside);
surf.AddFace(1, 2, mid, inside);
// add in points one at a time, remove and replace faces as necessary
for (int i = 3; i < surf.NumPoints; i++)
{
List<Edge> Edges = new List<Edge>();
//for the ith point...
//go through the each existing face,
for (int j = surf.NumFaces - 1; j >= 0; j--)
{
//if a triangle is facing our new point, remove the face, add its edges to a list.
double tmp = Point3D.Dot(surf.FaceNormal(j), surf.Point(i) - surf.Point(surf.Face(j).I));
if (Point3D.Dot(surf.FaceNormal(j), (surf.Point(i) - surf.Point(surf.Face(j).I)).Normalized) > -DMS.EPSILON)
{
Edges.Add(new Edge(surf.Face(j).I, surf.Face(j).J));
Edges.Add(new Edge(surf.Face(j).J, surf.Face(j).K));
Edges.Add(new Edge(surf.Face(j).K, surf.Face(j).I));
surf.RemoveFace(j);
}
}
//now add a triangle using any non duplicated edges together with our new point.
Edges.Sort(Edge.Comparison);
for (int j = 0; j < Edges.Count(); j++)
{
if (j != Edges.Count() - 1 && Edges[j] == Edges[j + 1])
{
//this edge is a duplicate, do nothing.
j++; //we'll skip the next one which is a duplicate too.
continue;
}
surf.AddFace(Edges[j].I, Edges[j].J, i, inside);
}
}
}
public static void PunchHole(ref Surface surf, Point3D center, Point3D direction, double Length, double Radius)
{
Surface HoleWall = new Surface();
List<int> HoleIdxs = new List<int>();
Point3D dir = direction.Normalized;
for (int i = 0; i < surf.NumPoints; i++)
{
if (!IsInCylinder(surf.Point(i), center, dir, Length, Radius))
continue;
for (int j = surf.NumFaces - 1; j >= 0; j--)
{
if (surf.Face(j).I == i ||
surf.Face(j).J == i ||
surf.Face(j).K == i)
{
if (!IsInCylinder(surf.Point(surf.Face(j).I), center, dir, Length, Radius)) HoleIdxs.Add(surf.Face(j).I);
if (!IsInCylinder(surf.Point(surf.Face(j).J), center, dir, Length, Radius)) HoleIdxs.Add(surf.Face(j).J);
if (!IsInCylinder(surf.Point(surf.Face(j).K), center, dir, Length, Radius)) HoleIdxs.Add(surf.Face(j).K);
surf.RemoveFace(j);
}
}
}
//make sure points in hole wall are unique
for (int j = HoleIdxs.Count() - 1; j >= 0; j--)
{
Point3D NewPt = surf.Point(HoleIdxs[j]);
//check that existing points in HoleWall surface don't match
int k;
for (k = 0; k < HoleWall.NumPoints; k++)
{
if (NewPt == HoleWall.Point(k))
break;
}
//add if we haven't found it.
if (k == HoleWall.NumPoints)
HoleWall.AddPoint(NewPt);
}
//get the convex hull faces, then either remove them if they're pointing in our direction, or reverse them
ConvexHull(ref HoleWall);
for (int i = HoleWall.NumFaces - 1; i >= 0; i--)
{
double IR = HoleWall.Point(HoleWall.Face(i).I).R;
double JR = HoleWall.Point(HoleWall.Face(i).J).R;
double KR = HoleWall.Point(HoleWall.Face(i).K).R;
if ( IR > center.R && JR > center.R && KR > center.R ||
IR < center.R && JR < center.R && KR < center.R )
{
HoleWall.RemoveFace(i);
}
else
{
HoleWall.Face(i).Reverse();
}
}
//add in the new hole wall
surf.AddSurface(HoleWall);
}