public static bool SplitPolygonAtEdge(Polygon polygon, Edge edge, out Vertex newVertex)
{
newVertex = null;
List <Vertex> vertices = new List <Vertex>(polygon.Vertices);
for (int i = 0; i < polygon.Vertices.Length; i++)
{
Vector3 position1 = polygon.Vertices[i].Position;
Vector3 position2 = polygon.Vertices[(i + 1) % polygon.Vertices.Length].Position;
if ((edge.Vertex1.Position.EqualsWithEpsilon(position1) && edge.Vertex2.Position.EqualsWithEpsilon(position2)) ||
(edge.Vertex1.Position.EqualsWithEpsilon(position2) && edge.Vertex2.Position.EqualsWithEpsilon(position1)))
{
newVertex = Vertex.Lerp(polygon.Vertices[i], polygon.Vertices[(i + 1) % polygon.Vertices.Length], 0.5f);
vertices.Insert(i + 1, newVertex);
break;
}
}
if (vertices.Count == polygon.Vertices.Length)
{
// Could not add vertex to adjacent polygon
return(false);
}
polygon.SetVertices(vertices.ToArray());
return(true);
}
/// <summary>
/// Generates an ico-sphere of radius 2. Unlike a polar-sphere this has a more even distribution of vertices.
/// </summary>
/// <returns>Polygons to be supplied to a brush.</returns>
/// <param name="iterationCount">Number of times the surface is subdivided, values of 1 or 2 are recommended.</param>
public static Polygon[] GenerateIcoSphere(int iterationCount)
{
// Derived from http://blog.andreaskahler.com/2009/06/creating-icosphere-mesh-in-code.html
float longestDimension = (1 + Mathf.Sqrt(5f)) / 2f;
Vector3 sourceVector = new Vector3(0, 1, longestDimension);
// Make the longest dimension 1, so the icosphere fits in a 2,2,2 cube
sourceVector.Normalize();
Vertex[] vertices = new Vertex[]
{
new Vertex(new Vector3(-sourceVector.y, +sourceVector.z, sourceVector.x), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(sourceVector.y, +sourceVector.z, sourceVector.x), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(-sourceVector.y, -sourceVector.z, sourceVector.x), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(sourceVector.y, -sourceVector.z, sourceVector.x), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(sourceVector.x, -sourceVector.y, +sourceVector.z), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(sourceVector.x, +sourceVector.y, +sourceVector.z), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(sourceVector.x, -sourceVector.y, -sourceVector.z), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(sourceVector.x, +sourceVector.y, -sourceVector.z), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(+sourceVector.z, sourceVector.x, -sourceVector.y), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(+sourceVector.z, sourceVector.x, +sourceVector.y), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(-sourceVector.z, sourceVector.x, -sourceVector.y), Vector3.zero, Vector2.zero),
new Vertex(new Vector3(-sourceVector.z, sourceVector.x, +sourceVector.y), Vector3.zero, Vector2.zero),
};
Polygon[] polygons = new Polygon[]
{
new Polygon(new Vertex[] { vertices[0].DeepCopy(), vertices[1].DeepCopy(), vertices[7].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[0].DeepCopy(), vertices[5].DeepCopy(), vertices[1].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[0].DeepCopy(), vertices[7].DeepCopy(), vertices[10].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[0].DeepCopy(), vertices[10].DeepCopy(), vertices[11].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[0].DeepCopy(), vertices[11].DeepCopy(), vertices[5].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[7].DeepCopy(), vertices[1].DeepCopy(), vertices[8].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[1].DeepCopy(), vertices[5].DeepCopy(), vertices[9].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[10].DeepCopy(), vertices[7].DeepCopy(), vertices[6].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[11].DeepCopy(), vertices[10].DeepCopy(), vertices[2].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[5].DeepCopy(), vertices[11].DeepCopy(), vertices[4].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[3].DeepCopy(), vertices[2].DeepCopy(), vertices[6].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[3].DeepCopy(), vertices[4].DeepCopy(), vertices[2].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[3].DeepCopy(), vertices[6].DeepCopy(), vertices[8].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[3].DeepCopy(), vertices[8].DeepCopy(), vertices[9].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[3].DeepCopy(), vertices[9].DeepCopy(), vertices[4].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[6].DeepCopy(), vertices[2].DeepCopy(), vertices[10].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[2].DeepCopy(), vertices[4].DeepCopy(), vertices[11].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[8].DeepCopy(), vertices[6].DeepCopy(), vertices[7].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[9].DeepCopy(), vertices[8].DeepCopy(), vertices[1].DeepCopy() }, null, false, false),
new Polygon(new Vertex[] { vertices[4].DeepCopy(), vertices[9].DeepCopy(), vertices[5].DeepCopy() }, null, false, false),
};
// Refine
for (int i = 0; i < iterationCount; i++)
{
Polygon[] newPolygons = new Polygon[polygons.Length * 4];
for (int j = 0; j < polygons.Length; j++)
{
Vertex a = Vertex.Lerp(polygons[j].Vertices[0], polygons[j].Vertices[1], 0.5f);
Vertex b = Vertex.Lerp(polygons[j].Vertices[1], polygons[j].Vertices[2], 0.5f);
Vertex c = Vertex.Lerp(polygons[j].Vertices[2], polygons[j].Vertices[0], 0.5f);
a.Position = a.Position.normalized;
b.Position = b.Position.normalized;
c.Position = c.Position.normalized;
newPolygons[j * 4 + 0] = new Polygon(new Vertex[] { polygons[j].Vertices[0].DeepCopy(), a.DeepCopy(), c.DeepCopy() }, null, false, false);
newPolygons[j * 4 + 1] = new Polygon(new Vertex[] { polygons[j].Vertices[1].DeepCopy(), b.DeepCopy(), a.DeepCopy() }, null, false, false);
newPolygons[j * 4 + 2] = new Polygon(new Vertex[] { polygons[j].Vertices[2].DeepCopy(), c.DeepCopy(), b.DeepCopy() }, null, false, false);
newPolygons[j * 4 + 3] = new Polygon(new Vertex[] { a.DeepCopy(), b.DeepCopy(), c.DeepCopy() }, null, false, false);
}
polygons = newPolygons;
}
for (int i = 0; i < polygons.Length; i++)
{
bool anyAboveHalf = false;
for (int j = 0; j < polygons[i].Vertices.Length; j++)
{
Vector3 normal = polygons[i].Vertices[j].Position.normalized;
polygons[i].Vertices[j].Normal = normal;
float piReciprocal = 1f / Mathf.PI;
float u = 0.5f - 0.5f * Mathf.Atan2(normal.x, -normal.z) * piReciprocal;
float v = 1f - Mathf.Acos(normal.y) * piReciprocal;
if (Mathf.Abs(u) < 0.01f ||
Mathf.Abs(1 - Mathf.Abs(u)) < 0.01f)
{
if (polygons[i].Plane.normal.x > 0)
{
u = 0;
}
else
{
u = 1;
}
}
if (u > 0.75f)
{
anyAboveHalf = true;
}
//Debug.Log(u);
polygons[i].Vertices[j].UV = new Vector2(u, v);
//const float kOneOverPi = 1.0 / 3.14159265;
//float u = 0.5 - 0.5 * atan(N.x, -N.z) * kOneOverPi;
//float v = 1.0 - acos(N.y) * kOneOverPi;
}
if (anyAboveHalf)
{
for (int j = 0; j < polygons[i].Vertices.Length; j++)
{
Vector2 uv = polygons[i].Vertices[j].UV;
if (uv.x < 0.5f)
{
uv.x += 1;
}
polygons[i].Vertices[j].UV = uv;
}
}
}
return(polygons);
}
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);
}
