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Deleted more unneeded logic in EarClipping.
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@MeltyPlayer
MeltyPlayer committed Jan 5, 2025
1 parent 609f22e commit 62bf129
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Showing 3 changed files with 2 additions and 451 deletions.
267 changes: 0 additions & 267 deletions FinModelUtility/Formats/Vrml/Vrml/src/util/EarClipping.cs
View file
Original file line number Diff line number Diff line change
@@ -1,14 +1,11 @@
using System.Diagnostics;

using PeterO.Numbers;

namespace vrml.util;

// Implementation of Triangulation by Ear Clipping
// by David Eberly
public class EarClipping {
private Polygon _mainPointList;
private List<Polygon> _holes;
private Vector3m Normal;
public List<Vector3m> Result { get; private set; }

Expand Down Expand Up @@ -82,9 +79,6 @@ Dictionary<Vector3m, Vector3m> pointsHashSet
public void Triangulate() {
if (Normal.Equals(Vector3m.Zero()))
throw new Exception("The input is not a valid polygon");
if (_holes != null && _holes.Count > 0) {
ProcessHoles();
}

List<ConnectionEdge> nonConvexPoints = FindNonConvexPoints(_mainPointList);

Expand Down Expand Up @@ -154,214 +148,6 @@ private bool IsConvex(ConnectionEdge curPoint) {
return orientation == 1;
}

private void ProcessHoles() {
for (int h = 0; h < _holes.Count; h++) {
List<Polygon> polygons = new List<Polygon>();
polygons.Add(_mainPointList);
polygons.AddRange(_holes);
ConnectionEdge M, P;
GetVisiblePoints(h + 1, polygons, out M, out P);
if (M.Origin.Equals(P.Origin))
throw new Exception();

var insertionEdge = P;
InsertNewEdges(insertionEdge, M);
_holes.RemoveAt(h);
h--;
}
}

private void InsertNewEdges(ConnectionEdge insertionEdge, ConnectionEdge m) {
insertionEdge.Polygon.PointCount += m.Polygon.PointCount;
var cur = m;
var forwardEdge
= new ConnectionEdge(insertionEdge.Origin, insertionEdge.Polygon);
forwardEdge.Prev = insertionEdge.Prev;
forwardEdge.Prev.Next = forwardEdge;
forwardEdge.Next = m;
forwardEdge.Next.Prev = forwardEdge;
var end = insertionEdge;
ConnectionEdge prev = null;
do {
cur.Polygon = insertionEdge.Polygon;
prev = cur;
cur = cur.Next;
} while (m != cur);

var backEdge = new ConnectionEdge(cur.Origin, insertionEdge.Polygon);
cur = prev;
cur.Next = backEdge;
backEdge.Prev = cur;
backEdge.Next = end;
end.Prev = backEdge;
}

private void GetVisiblePoints(int holeIndex,
List<Polygon> polygons,
out ConnectionEdge M,
out ConnectionEdge P) {
M = FindLargest(polygons[holeIndex]);

var direction
= (polygons[holeIndex].Start.Next.Origin -
polygons[holeIndex].Start.Origin).Cross(Normal);
var I = FindPointI(M, polygons, holeIndex, direction);

Vector3m res;
if (polygons[I.PolyIndex].Contains(I.I, out res)) {
var incidentEdges =
(List<ConnectionEdge>) res.DynamicProperties.GetValue(
PropertyConstants.IncidentEdges);
foreach (var connectionEdge in incidentEdges) {
if (Misc.IsBetween(connectionEdge.Origin,
connectionEdge.Next.Origin,
connectionEdge.Prev.Origin,
M.Origin,
Normal) ==
1) {
P = connectionEdge;
return;
}
}

throw new Exception();
} else {
P = FindVisiblePoint(I, polygons, M, direction);
}
}

private ConnectionEdge FindVisiblePoint(Candidate I,
List<Polygon> polygons,
ConnectionEdge M,
Vector3m direction) {
ConnectionEdge P = null;

if (I.Origin.Origin.Dot(direction)
.CompareTo(I.Origin.Next.Origin.Dot(direction)) >
0) {
P = I.Origin;
} else {
P = I.Origin.Next;
}

List<ConnectionEdge> nonConvexPoints
= FindNonConvexPoints(polygons[I.PolyIndex]);


nonConvexPoints.Remove(P);

var m = M.Origin;
var i = I.I;
var p = P.Origin;
List<ConnectionEdge> candidates = new List<ConnectionEdge>();

// invert i and p if triangle is oriented CW
if (Misc.GetOrientation(m, i, p, Normal) == -1) {
var tmp = i;
i = p;
p = tmp;
}

foreach (var nonConvexPoint in nonConvexPoints) {
if (Misc.PointInOrOnTriangle(m, i, p, nonConvexPoint.Origin, Normal)) {
candidates.Add(nonConvexPoint);
}
}

if (candidates.Count == 0)
return P;
return FindMinimumAngle(candidates, m, direction);
}

private ConnectionEdge FindMinimumAngle(List<ConnectionEdge> candidates,
Vector3m M,
Vector3m direction) {
ERational angle = -double.MaxValue;
ConnectionEdge result = null;
foreach (var R in candidates) {
var a = direction;
var b = R.Origin - M;
var num = a.Dot(b) * a.Dot(b);
var denom = b.Dot(b);
var res = num / denom;
if (res.CompareTo(angle) > 0) {
result = R;
angle = res;
}
}

return result;
}

private Candidate FindPointI(ConnectionEdge M,
List<Polygon> polygons,
int holeIndex,
Vector3m direction) {
Candidate candidate = new Candidate();
for (int i = 0; i < polygons.Count; i++) {
if (i == holeIndex) // Don't test the hole with itself
continue;
foreach (var connectionEdge in polygons[i].GetPolygonCirculator()) {
ERational rayDistanceSquared;
Vector3m intersectionPoint;

if (RaySegmentIntersection(out intersectionPoint,
out rayDistanceSquared,
M.Origin,
direction,
connectionEdge.Origin,
connectionEdge.Next.Origin,
direction)) {
if (rayDistanceSquared ==
candidate
.currentDistance) // if this is an M/I edge, then both edge and his twin have the same distance; we take the edge where the point is on the left side
{
if (Misc.GetOrientation(connectionEdge.Origin,
connectionEdge.Next.Origin,
M.Origin,
Normal) ==
1) {
candidate.currentDistance = rayDistanceSquared;
candidate.Origin = connectionEdge;
candidate.PolyIndex = i;
candidate.I = intersectionPoint;
}
} else if (rayDistanceSquared.CompareTo(candidate.currentDistance) <
0) {
candidate.currentDistance = rayDistanceSquared;
candidate.Origin = connectionEdge;
candidate.PolyIndex = i;
candidate.I = intersectionPoint;
}
}
}
}

return candidate;
}

private ConnectionEdge FindLargest(Polygon testHole) {
ERational maximum = 0;
ConnectionEdge maxEdge = null;
Vector3m v0 = testHole.Start.Origin;
Vector3m v1 = testHole.Start.Next.Origin;
foreach (var connectionEdge in testHole.GetPolygonCirculator()) {
// we take the first two points as a reference line

if (Misc.GetOrientation(v0, v1, connectionEdge.Origin, Normal) < 0) {
var r = Misc.PointLineDistance(v0, v1, connectionEdge.Origin);
if (r.CompareTo(maximum) > 0) {
maximum = r;
maxEdge = connectionEdge;
}
}
}

if (maxEdge == null)
return testHole.Start;
return maxEdge;
}

private bool IsPointInTriangle(Vector3m prevPoint,
Vector3m curPoint,
Vector3m nextPoint,
Expand Down Expand Up @@ -395,59 +181,6 @@ private List<ConnectionEdge> FindNonConvexPoints(Polygon p) {

return resultList;
}

public bool RaySegmentIntersection(out Vector3m intersection,
out ERational distanceSquared,
Vector3m linePoint1,
Vector3m lineVec1,
Vector3m linePoint3,
Vector3m linePoint4,
Vector3m direction) {
var lineVec2 = linePoint4 - linePoint3;
Vector3m lineVec3 = linePoint3 - linePoint1;
Vector3m crossVec1and2 = lineVec1.Cross(lineVec2);
Vector3m crossVec3and2 = lineVec3.Cross(lineVec2);

var res = Misc.PointLineDistance(linePoint3, linePoint4, linePoint1);
if (res.IsZero) // line and ray are collinear
{
var p = linePoint1 + lineVec1;
var res2 = Misc.PointLineDistance(linePoint3, linePoint4, p);
if (res2.IsZero) {
var s = linePoint3 - linePoint1;
if (s.X == direction.X && s.Y == direction.Y && s.Z == direction.Z) {
intersection = linePoint3;
distanceSquared = s.LengthSquared();
return true;
}
}
}

//is coplanar, and not parallel
if ( /*planarFactor == 0.0f && */crossVec1and2.LengthSquared().Sign > 0) {
var s = crossVec3and2.Dot(crossVec1and2) / crossVec1and2.LengthSquared();
if (s.Sign >= 0) {
intersection = linePoint1 + (lineVec1 * s);
distanceSquared = (lineVec1 * s).LengthSquared();
if (((intersection - linePoint3).LengthSquared() +
(intersection - linePoint4).LengthSquared())
.CompareTo(lineVec2.LengthSquared()) <=
0)
return true;
}
}

intersection = Vector3m.Zero();
distanceSquared = 0;
return false;
}
}

internal class Candidate {
internal ERational currentDistance = double.MaxValue;
internal Vector3m I;
internal ConnectionEdge Origin;
internal int PolyIndex;
}

internal class ConnectionEdge {
Expand Down
72 changes: 1 addition & 71 deletions FinModelUtility/Formats/Vrml/Vrml/src/util/Misc.cs
View file
Original file line number Diff line number Diff line change
@@ -1,6 +1,4 @@
using PeterO.Numbers;

namespace vrml.util;
namespace vrml.util;

class Misc {
public static int GetOrientation(Vector3m v0,
Expand All @@ -17,68 +15,6 @@ public static int GetOrientation(Vector3m v0,
return -1;
}

// Is testPoint between a and b in ccw order?
// > 0 if strictly yes
// < 0 if strictly no
// = 0 if testPoint lies either on a or on b
public static int IsBetween(Vector3m Origin,
Vector3m a,
Vector3m b,
Vector3m testPoint,
Vector3m normal) {
var psca = GetOrientation(Origin, a, testPoint, normal);
var pscb = GetOrientation(Origin, b, testPoint, normal);

// where does b in relation to a lie? Left, right or collinear?
var psb = GetOrientation(Origin, a, b, normal);
if (psb > 0) // left
{
// if left then testPoint lies between a and b iff testPoint left of a AND testPoint right of b
if (psca > 0 && pscb < 0)
return 1;
if (psca == 0) {
var t = a - Origin;
var t2 = testPoint - Origin;
if (t.X.Sign != t2.X.Sign || t.Y.Sign != t2.Y.Sign)
return -1;
return 0;
} else if (pscb == 0) {
var t = b - Origin;
var t2 = testPoint - Origin;
if (t.X.Sign != t2.X.Sign || t.Y.Sign != t2.Y.Sign)
return -1;
return 0;
}
} else if (psb < 0) // right
{
// if right then testPoint lies between a and b iff testPoint left of a OR testPoint right of b
if (psca > 0 || pscb < 0)
return 1;
if (psca == 0) {
var t = a - Origin;
var t2 = testPoint - Origin;
if (t.X.Sign != t2.X.Sign || t.Y.Sign != t2.Y.Sign)
return 1;
return 0;
} else if (pscb == 0) {
var t = b - Origin;
var t2 = testPoint - Origin;
if (t.X.Sign != t2.X.Sign || t.Y.Sign != t2.Y.Sign)
return 1;
return 0;
}
} else if (psb == 0) {
if (psca > 0)
return 1;
else if (psca < 0)
return -1;
else
return 0;
}

return -1;
}

public static bool PointInOrOnTriangle(Vector3m prevPoint,
Vector3m curPoint,
Vector3m nextPoint,
Expand All @@ -90,10 +26,4 @@ var res2
= Misc.GetOrientation(nextPoint, nonConvexPoint, prevPoint, normal);
return res0 != 1 && res1 != 1 && res2 != 1;
}

public static ERational PointLineDistance(Vector3m p1,
Vector3m p2,
Vector3m p3) {
return (p2 - p1).Cross(p3 - p1).LengthSquared();
}
}
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