void splitSurface(Plane P)
{
List <HE_Vertex> newVertices = new List <HE_Vertex> ();
List <HE_Face> newFaces = new List <HE_Face> ();
List <HE_HalfEdge> newHalfEdges = new List <HE_HalfEdge> ();
List <HE_Edge> newEdges = new List <HE_Edge> ();
// get all split edges
List <SplitEdge> splitEdges = retrieveSplitEdges(P);
//check if the plane cuts the mesh at all, at least one point should be on the other side of the plane.
//compared to the first point
float[] sides = new float[vertices.Count];
//bool cut=false;
for (int i = 0; i < vertices.Count; i++)
{
HE_Vertex v = vertices [i];
sides [i] = P.side(v);
//if(sides[0]*sides[i]<=0f) cut=true;
}
//loop through all faces.
for (int i = 0; i < faces.Count; i++)
{
HE_Face face = faces [i];
HE_HalfEdge halfEdge = face.halfEdge;
List <HE_Vertex> newFaceVertices1 = new List <HE_Vertex> ();
List <HE_Vertex> newFaceVertices2 = new List <HE_Vertex> ();
List <HE_Vertex> currentFace = newFaceVertices1;
//for each face, loop through all vertices and retain the vertices on the correct side. If the edge
//is cut, insert the new point in the appropriate place.
do
{
currentFace.Add(halfEdge.vert);
for (int j = 0; j < splitEdges.Count; j++) // loop through all split edges to check for the current edge.
{
SplitEdge se = (SplitEdge)splitEdges [j];
if (halfEdge.edge == se.edge)
{
newFaceVertices1.Add(se.splitVertex);
newFaceVertices2.Add(se.splitVertex);
if (currentFace == newFaceVertices1)
{
currentFace = newFaceVertices2;
}
else
{
currentFace = newFaceVertices1;
}
break;
}
}
halfEdge = halfEdge.next;
} while(halfEdge != face.halfEdge);
//Create a new face form the vertices we retained,ignore degenerate faces with less than 3 vertices.
//Add all face-related information to the data-structure.
HE_Face newFace = new HE_Face();
newFaces.Add(newFace);
List <HE_HalfEdge> faceEdges = new List <HE_HalfEdge> ();
for (int j = 0; j < newFaceVertices1.Count; j++)
{
HE_Vertex v = newFaceVertices1 [j];
if (!newVertices.Contains(v))
{
newVertices.Add(v);
}
HE_HalfEdge newHalfEdge = new HE_HalfEdge();
faceEdges.Add(newHalfEdge);
newHalfEdge.vert = v;
v.halfEdge = newHalfEdge;
newHalfEdge.face = newFace;
if (newFace.halfEdge == null)
{
newFace.halfEdge = newHalfEdge;
}
}
cycleHalfEdges(faceEdges, false);
newHalfEdges.AddRange(faceEdges);
if (newFaceVertices2.Count > 0)
{
newFace = new HE_Face();
newFaces.Add(newFace);
faceEdges = new List <HE_HalfEdge> ();
for (int j = 0; j < newFaceVertices2.Count; j++)
{
HE_Vertex v = newFaceVertices2 [j];
if (!newVertices.Contains(v))
{
newVertices.Add(v);
}
HE_HalfEdge newHalfEdge = new HE_HalfEdge();
faceEdges.Add(newHalfEdge);
newHalfEdge.vert = v;
v.halfEdge = newHalfEdge;
newHalfEdge.face = newFace;
if (newFace.halfEdge == null)
{
newFace.halfEdge = newHalfEdge;
}
}
cycleHalfEdges(faceEdges, false);
newHalfEdges.AddRange(faceEdges);
//}//test
}
//Add missing information to the datastructure
pairHalfEdges(newHalfEdges);
createEdges(newHalfEdges, newEdges);
}
// update the mesh
vertices = newVertices;
faces = newFaces;
halfEdges = newHalfEdges;
edges = newEdges;
reindex();
}
// Split the mesh in half, retain the part on the same side as the point "center".
// Works only on a convex mesh !!!
public void cutMesh(Plane P, PVector center)
{
float centerside = P.side(center);
if (centerside != 0) // if center is on the plane, we can't decide which part to keep, ignore.
{
List <HE_Vertex> newVertices = new List <HE_Vertex> ();
List <HE_Face> newFaces = new List <HE_Face> ();
List <HE_HalfEdge> newHalfEdges = new List <HE_HalfEdge> ();
List <HE_Edge> newEdges = new List <HE_Edge> ();
// get all split edges
List <SplitEdge> splitEdges = retrieveSplitEdges(P);
//check if the plane cuts the mesh at all, at least one point should be on the other side of the plane.
//compared to the first point
float[] sides = new float[vertices.Count];
//bool cut = false;// add inok
for (int i = 0; i < vertices.Count; i++)
{
HE_Vertex v = vertices [i];
sides [i] = P.side(v);
//if(sides[0]*sides[i]<=0f) cut=true;// add inok
}
//loop through all faces.
for (int i = 0; i < faces.Count; i++)
{
HE_Face face = faces [i];
HE_HalfEdge halfEdge = face.halfEdge;
List <HE_Vertex> newFaceVertices1 = new List <HE_Vertex> (); // vertices on the correct side.
List <HE_Vertex> newFaceVertices2 = new List <HE_Vertex> (); // vertices on the wrong side, not used right now.
//for each face, loop through all vertices and retain the vertices on the correct side. If the edge
//is cut, insert the new point in the appropriate place.
do
{
if (sides [halfEdge.vert.id] * centerside >= 0f)
{
newFaceVertices1.Add(halfEdge.vert);
}
if (sides [halfEdge.vert.id] * centerside <= 0f)
{
newFaceVertices2.Add(halfEdge.vert);
}
for (int j = 0; j < splitEdges.Count; j++) // loop through all split edges to check for the current edge.
{
SplitEdge se = splitEdges [j];
if (halfEdge.edge == se.edge)
{
newFaceVertices1.Add(se.splitVertex);
newFaceVertices2.Add(se.splitVertex);
break;
}
}
halfEdge = halfEdge.next;
} while(halfEdge != face.halfEdge);
//Create a new face form the vertices we retained,ignore degenerate faces with less than 3 vertices.
//Add all face-related information to the data-structure.
if (newFaceVertices1.Count > 2)
{
HE_Face newFace = new HE_Face();
newFaces.Add(newFace);
List <HE_HalfEdge> faceEdges = new List <HE_HalfEdge> ();
for (int j = 0; j < newFaceVertices1.Count; j++)
{
HE_Vertex v = newFaceVertices1 [j];
if (!newVertices.Contains(v))
{
newVertices.Add(v);
}
HE_HalfEdge newHalfEdge = new HE_HalfEdge();
faceEdges.Add(newHalfEdge);
newHalfEdge.vert = v;
v.halfEdge = newHalfEdge;
newHalfEdge.face = newFace;
if (newFace.halfEdge == null)
{
newFace.halfEdge = newHalfEdge;
}
}
cycleHalfEdges(faceEdges, false);
newHalfEdges.AddRange(faceEdges);
}
}
//Add missing information to the datastructure
int n = newHalfEdges.Count;
pairHalfEdges(newHalfEdges);
createEdges(newHalfEdges, newEdges);
//Cutting the mesh not only cuts the faces, it also creates one new planar face looping through all new cutpoints(in a convex mesh).
//This hole in the mesh is identified by unpaired halfedges remaining after the pairibg operation.
//This part needs to rethought to extend to concave meshes!!!
List <HE_HalfEdge> unpairedEdges = new List <HE_HalfEdge> ();
for (int i = 0; i < n; i++)
{
HE_HalfEdge he = newHalfEdges [i];
if (he.pair == null)
{
unpairedEdges.Add(he);
}
}
if (unpairedEdges.Count > 0)
{
//Create a closed loop out of the collection of unpaired halfedges and associate a new face with this.
//Easy to explain with a drawing, beyond my skill with words.
HE_Face cutFace = new HE_Face();
List <HE_HalfEdge> faceEdges = new List <HE_HalfEdge> ();
HE_HalfEdge he = unpairedEdges [0];
HE_HalfEdge hen = he;
do
{
HE_HalfEdge _hen = he.next;
HE_HalfEdge _hep = he.next.pair;
if (_hep != null) //add inok
{
hen = he.next.pair.next;
while (!unpairedEdges.Contains(hen))
{
hen = hen.pair.next;
}
}
else
{
hen = hen.next;
Debug.LogWarning("LogWarning: null");
}
HE_HalfEdge newhe = new HE_HalfEdge();
faceEdges.Add(newhe);
if (cutFace.halfEdge == null)
{
cutFace.halfEdge = newhe;
}
newhe.vert = hen.vert;
newhe.pair = he;
he.pair = newhe;
HE_Edge e = new HE_Edge();
e.halfEdge = newhe;
he.edge = e;
newhe.edge = e;
newEdges.Add(e);
newhe.face = cutFace;
he = hen;
} while(hen != unpairedEdges[0]);
cycleHalfEdges(faceEdges, true);
newHalfEdges.AddRange(faceEdges);
newFaces.Add(cutFace);
}
// update the mesh
vertices = newVertices;
faces = newFaces;
halfEdges = newHalfEdges;
edges = newEdges;
reindex();
}
}