public static bool PlanePolygonIntersection(Polygon polygon, out Vector3 position1, out Vector3 position2, UnityEngine.Plane testPlane)
{
position1 = Vector3.zero;
position2 = Vector3.zero;
bool position1Set = false;
bool position2Set = false;
for (int i = 0; i < polygon.vertices.Length; i++)
{
int previousIndex = i - 1;
if (previousIndex < 0)
{
previousIndex = polygon.vertices.Length - 1;
}
Vertex currentVertex = polygon.vertices[i];
Vertex previousVertex = polygon.vertices[previousIndex];
PointPlaneRelation currentRelation = ComparePointToPlane(currentVertex.Position, testPlane);
PointPlaneRelation previousRelation = ComparePointToPlane(previousVertex.Position, testPlane);
if (previousRelation == PointPlaneRelation.InFront && currentRelation == PointPlaneRelation.InFront)
{
}
else if (previousRelation == PointPlaneRelation.Behind && currentRelation == PointPlaneRelation.InFront)
{
float interpolant = Edge.IntersectsPlane(testPlane, previousVertex.Position, currentVertex.Position);
position2 = Vector3.Lerp(previousVertex.Position, currentVertex.Position, interpolant);
position2Set = true;
}
else if (previousRelation == PointPlaneRelation.InFront && currentRelation == PointPlaneRelation.Behind)
{
// Reverse order here so that clipping remains consistent for either CW or CCW testing
float interpolant = Edge.IntersectsPlane(testPlane, currentVertex.Position, previousVertex.Position);
position1 = Vector3.Lerp(currentVertex.Position, previousVertex.Position, interpolant);
position1Set = true;
}
else if (previousRelation == PointPlaneRelation.Behind && currentRelation == PointPlaneRelation.Behind)
{
}
else if (currentRelation == PointPlaneRelation.On)
{
if (previousRelation == PointPlaneRelation.InFront)
{
position1 = currentVertex.Position;
position1Set = true;
}
else if (previousRelation == PointPlaneRelation.Behind)
{
position2 = currentVertex.Position;
position2Set = true;
}
else
{
// throw new System.Exception("Unhandled polygon configuration");
}
}
else if (currentRelation == PointPlaneRelation.Behind)
{
}
else if (currentRelation == PointPlaneRelation.InFront)
{
}
else
{
}
}
return(position1Set && position2Set);
}
public static bool SplitPolygon(Polygon polygon, out Polygon frontPolygon, out Polygon backPolygon, out Vertex newVertex1, out Vertex newVertex2, UnityEngine.Plane clipPlane)
{
newVertex1 = null;
newVertex2 = null;
List <Vertex> frontVertices = new List <Vertex>();
List <Vertex> backVertices = new List <Vertex>();
for (int i = 0; i < polygon.vertices.Length; i++)
{
int previousIndex = i - 1;
if (previousIndex < 0)
{
previousIndex = polygon.vertices.Length - 1;
}
Vertex currentVertex = polygon.vertices[i];
Vertex previousVertex = polygon.vertices[previousIndex];
PointPlaneRelation currentRelation = ComparePointToPlane(currentVertex.Position, clipPlane);
PointPlaneRelation previousRelation = ComparePointToPlane(previousVertex.Position, clipPlane);
if (previousRelation == PointPlaneRelation.InFront && currentRelation == PointPlaneRelation.InFront)
{
// Front add current
frontVertices.Add(currentVertex);
}
else if (previousRelation == PointPlaneRelation.Behind && currentRelation == PointPlaneRelation.InFront)
{
float interpolant = Edge.IntersectsPlane(clipPlane, previousVertex.Position, currentVertex.Position);
Vertex intersection = Vertex.Lerp(previousVertex, currentVertex, interpolant);
// Front add intersection, add current
frontVertices.Add(intersection);
frontVertices.Add(currentVertex);
// Back add intersection
backVertices.Add(intersection.DeepCopy());
newVertex2 = intersection;
}
else if (previousRelation == PointPlaneRelation.InFront && currentRelation == PointPlaneRelation.Behind)
{
// Reverse order here so that clipping remains consistent for either CW or CCW testing
float interpolant = Edge.IntersectsPlane(clipPlane, currentVertex.Position, previousVertex.Position);
Vertex intersection = Vertex.Lerp(currentVertex, previousVertex, interpolant);
// Front add intersection
frontVertices.Add(intersection);
// Back add intersection, current
backVertices.Add(intersection.DeepCopy());
backVertices.Add(currentVertex);
newVertex1 = intersection;
}
else if (previousRelation == PointPlaneRelation.Behind && currentRelation == PointPlaneRelation.Behind)
{
// Back add current
backVertices.Add(currentVertex);
}
else if (currentRelation == PointPlaneRelation.On)
{
// Front add current
frontVertices.Add(currentVertex);
// Back add current
backVertices.Add(currentVertex.DeepCopy());
if (previousRelation == PointPlaneRelation.InFront)
{
newVertex1 = currentVertex;
}
else if (previousRelation == PointPlaneRelation.Behind)
{
newVertex2 = currentVertex;
}
else
{
// throw new System.Exception("Unhandled polygon configuration");
}
}
else if (currentRelation == PointPlaneRelation.Behind)
{
backVertices.Add(currentVertex);
}
else if (currentRelation == PointPlaneRelation.InFront)
{
frontVertices.Add(currentVertex);
}
else
{
throw new System.Exception("Unhandled polygon configuration");
}
}
// Debug.Log("done");
frontPolygon = new Polygon(frontVertices.ToArray(), polygon.Material, polygon.ExcludeFromFinal, polygon.UserExcludeFromFinal, polygon.uniqueIndex);
backPolygon = new Polygon(backVertices.ToArray(), polygon.Material, polygon.ExcludeFromFinal, polygon.UserExcludeFromFinal, polygon.uniqueIndex);
// Because of some floating point issues and some edge cases relating to splitting the tip of a very thin
// polygon we can't reliable test that the polygon intersects a plane and will produce two valid pieces
// so after splitting we need to do an additional test to check that each polygon is valid. If it isn't
// then we mark that polygon as null and return false to indicate the split wasn't entirely successful
bool splitNecessary = true;
if (frontPolygon.vertices.Length < 3 || frontPolygon.Plane.normal == Vector3.zero)
{
frontPolygon = null;
splitNecessary = false;
}
if (backPolygon.vertices.Length < 3 || backPolygon.Plane.normal == Vector3.zero)
{
backPolygon = null;
splitNecessary = false;
}
return(splitNecessary);
}
