//Display a face which we know is a triangle with its normal at the center
public static void DebugDrawTriangle(HalfEdgeFace3 f, Color lineColor, Color normalColor, Normalizer3 normalizer = null)
{
MyVector3 p1 = f.edge.v.position;
MyVector3 p2 = f.edge.nextEdge.v.position;
MyVector3 p3 = f.edge.nextEdge.nextEdge.v.position;
if (normalizer != null)
{
p1 = normalizer.UnNormalize(p1);
p2 = normalizer.UnNormalize(p2);
p3 = normalizer.UnNormalize(p3);
}
Vector3 normal = f.edge.v.normal.ToVector3();
TestAlgorithmsHelpMethods.DebugDrawTriangle(p1.ToVector3(), p2.ToVector3(), p3.ToVector3(), normal * 0.5f, Color.white, Color.red);
//Debug.Log("Displayed Triangle");
//To test the the triangle is clock-wise
//TestAlgorithmsHelpMethods.DebugDrawCircle(p1_test, 0.1f, Color.red);
//TestAlgorithmsHelpMethods.DebugDrawCircle(p2_test, 0.2f, Color.blue);
}
//Needles. Triangle where the longest edge is much longer than the shortest one.
private static bool RemoveNeedle(HalfEdgeData3 meshData, Normalizer3 normalizer = null)
{
HashSet <HalfEdgeFace3> triangles = meshData.faces;
bool foundNeedle = false;
foreach (HalfEdgeFace3 triangle in triangles)
{
/*
* List<HalfEdge3> edges = triangle.GetEdges();
*
* //Sort the edges from shortest to longest
* List<HalfEdge3> edgesSorted = edges.OrderBy(e => e.Length()).ToList();
*
* //The ratio between the shortest and longest side
* float edgeLengthRatio = edgesSorted[0].Length() / edgesSorted[2].Length();
*/
//Instead of using a million lists, we know we have just three edges we have to sort, so we can do better
HalfEdge3 e1 = triangle.edge;
HalfEdge3 e2 = triangle.edge.nextEdge;
HalfEdge3 e3 = triangle.edge.nextEdge.nextEdge;
//We want e1 to be the shortest and e3 to be the longest
if (e1.SqrLength() > e3.SqrLength())
{
(e1, e3) = (e3, e1);
}
if (e1.SqrLength() > e2.SqrLength())
{
(e1, e2) = (e2, e1);
}
//e1 is now the shortest edge, so we just need to check the second and third
if (e2.SqrLength() > e3.SqrLength())
{
(e2, e3) = (e3, e2);
}
//The ratio between the shortest and longest edge
float edgeLengthRatio = e1.Length() / e3.Length();
//This is a needle
if (edgeLengthRatio < NEEDLE_RATIO)
{
//Debug.Log("We found a needle triangle");
TestAlgorithmsHelpMethods.DebugDrawTriangle(triangle, Color.blue, Color.red, normalizer);
//Remove the needle by merging the shortest edge
MyVector3 mergePosition = (e1.v.position + e1.prevEdge.v.position) * 0.5f;
meshData.ContractTriangleHalfEdge(e1, mergePosition);
foundNeedle = true;
//Now we have to restart because the triangulation has changed
break;
}
}
return(foundNeedle);
}
//Remove flat tetrahedrons (a vertex in a triangle)
private static bool RemoveFlatTetrahedrons(HalfEdgeData3 meshData, Normalizer3 normalizer = null)
{
HashSet <HalfEdgeVertex3> vertices = meshData.verts;
bool foundFlatTetrahedron = false;
foreach (HalfEdgeVertex3 vertex in vertices)
{
HashSet <HalfEdge3> edgesGoingToVertex = vertex.GetEdgesPointingToVertex(meshData);
if (edgesGoingToVertex.Count == 3)
{
//Find the vertices of the triangle covering this vertex clock-wise
HalfEdgeVertex3 v1 = vertex.edge.v;
HalfEdgeVertex3 v2 = vertex.edge.prevEdge.oppositeEdge.v;
HalfEdgeVertex3 v3 = vertex.edge.oppositeEdge.nextEdge.v;
//Build a plane
MyVector3 normal = MyVector3.Normalize(MyVector3.Cross(v3.position - v2.position, v1.position - v2.position));
Plane3 plane = new Plane3(v1.position, normal);
//Find the distance from the vertex to the plane
float distance = _Geometry.GetSignedDistanceFromPointToPlane(vertex.position, plane);
distance = Mathf.Abs(distance);
if (distance < FLAT_TETRAHEDRON_DISTANCE)
{
//Debug.Log("Found flat tetrahedron");
Vector3 p1 = normalizer.UnNormalize(v1.position).ToVector3();
Vector3 p2 = normalizer.UnNormalize(v2.position).ToVector3();
Vector3 p3 = normalizer.UnNormalize(v3.position).ToVector3();
TestAlgorithmsHelpMethods.DebugDrawTriangle(p1, p2, p3, normal.ToVector3(), Color.blue, Color.red);
foundFlatTetrahedron = true;
//Save the opposite edges
HashSet <HalfEdge3> oppositeEdges = new HashSet <HalfEdge3>();
oppositeEdges.Add(v1.edge.oppositeEdge);
oppositeEdges.Add(v2.edge.oppositeEdge);
oppositeEdges.Add(v3.edge.oppositeEdge);
//Remove the three triangles
foreach (HalfEdge3 e in edgesGoingToVertex)
{
meshData.DeleteFace(e.face);
}
//Add the new triangle (could maybe connect it ourselves)
HalfEdgeFace3 newTriangle = meshData.AddTriangle(v1.position, v2.position, v3.position, findOppositeEdge: false);
meshData.TryFindOppositeEdge(newTriangle.edge, oppositeEdges);
meshData.TryFindOppositeEdge(newTriangle.edge.nextEdge, oppositeEdges);
meshData.TryFindOppositeEdge(newTriangle.edge.nextEdge.nextEdge, oppositeEdges);
break;
}
}
}
return(foundFlatTetrahedron);
}