public static void RenderTile(Mesh mesh, SCoord tileCenter, Icosphere hexSphere)
{
// Make a linked list of the coordinate's neighbors
LinkedList <SCoord> neighbors;
// hexes are not triangles
neighbors = new LinkedList <SCoord>(hexSphere.GetNeighbors(tileCenter));
// Make list of vertices
List <Vector3> vertices = new List <Vector3>(neighbors.Count + 1);
// Make list of normals for each vertex
List <Vector3> normals = new List <Vector3>(neighbors.Count + 1);
// Make list of UV coordinates for each vertex
List <Vector2> uvLocations = new List <Vector2>(neighbors.Count + 1);
// Setup lookup table for vertices
Dictionary <SCoord, int> keyLookup = new Dictionary <SCoord, int>();
keyLookup.Add(tileCenter, keyLookup.Count);
uvLocations.Add(new Vector2(0.5f, 0.5f));
vertices.Add(hexSphere.GetPoint(tileCenter));
normals.Add(tileCenter.ToEuclidian());
float radPerVertex = Mathf.PI * 2 / neighbors.Count;
SCoord startVertex = neighbors.First.Value;
SCoord source = startVertex;
neighbors.RemoveFirst();
// Get the order of neighbors (forward or backward just wrapping around center)
LinkedList <SCoord> orderedNeighbors = new LinkedList <SCoord>();
orderedNeighbors.AddLast(startVertex);
// Calculate the teselated edges of the hexagon/pentagon
while (neighbors.Count > 1)
{
// Find the next SCoord in the sequence of neighbors (neighbor to origin that is
// adjacent to the previous neighbor)
LinkedListNode <SCoord> nextVertex = neighbors.First;
while (!new List <SCoord>(hexSphere.GetNeighbors(nextVertex.Value)).Contains(source))
{
nextVertex = nextVertex.Next;
}
orderedNeighbors.AddLast(nextVertex.Value);
// Save current vertex as previous vertex
source = nextVertex.Value;
// Remove current vertex so it is not checked again
neighbors.Remove(nextVertex);
}
// Finish list of ordered neighbors
orderedNeighbors.AddLast(neighbors.First.Value);
foreach (SCoord n in orderedNeighbors)
{
keyLookup.Add(n, keyLookup.Count);
}
List <SCoord> neighborList = new List <SCoord>(orderedNeighbors);
List <int> triangleList = new List <int>();
for (int idx = 0; idx < neighborList.Count; idx++)
{
// Get the centroid of the three adjacent tiles
SCoord vert = SCoord.GetCentroid(tileCenter, neighborList[idx], neighborList[(idx + 1) % neighborList.Count]);
// Sort the coordinates in the correct order so the face is visible
SCoord[] triangleCoords = SCoord.SortClockwiseOrder(tileCenter,
neighborList[idx],
neighborList[(idx + 1) % neighborList.Count]);
// Add the vertex
vertices.Add(hexSphere.GetPoint(vert));
// Add the normal vector of the vertex
normals.Add(vert.ToEuclidian());
// Add UV coordinate for this vertex
Vector2 uv = new Vector2(0.5f + Mathf.Cos(radPerVertex * idx) * 0.5f,
0.5f + Mathf.Sin(radPerVertex * idx) * 0.5f);
uvLocations.Add(new Vector2(0.5f + Mathf.Cos(radPerVertex * idx) * 0.5f,
0.5f + Mathf.Sin(radPerVertex * idx) * 0.5f));
// Add the triangles (set of three vertices)
triangleList.Add(keyLookup[triangleCoords[2]]);
triangleList.Add(keyLookup[triangleCoords[1]]);
triangleList.Add(keyLookup[triangleCoords[0]]);
}
// Flatten out the center of the hex so it doesn't arch out
Vector3 flatCenter = Vector3.zero;
for (int i = 1; i < vertices.Count; i++)
{
flatCenter += vertices[i];
}
flatCenter /= (vertices.Count - 1);
vertices[0] = flatCenter;
// assign values to mesh
mesh.vertices = vertices.ToArray();
mesh.normals = normals.ToArray();
mesh.triangles = triangleList.ToArray();
mesh.uv = uvLocations.ToArray();
}
/// <summary>
/// Teselates an icosphere but cutting each traingular face into four smaller traingular faces.
/// </summary>
/// <returns></returns>
public Icosphere SubdivideSphere()
{
// List of all vertices currently in the icosphere
List <SCoord> keys = new List <SCoord>(this.vertices.GetPoints());
BiDirectionalEdgeComparator <SCoord> edgeComparator = new BiDirectionalEdgeComparator <SCoord>();
// Set of all edges in the sphere (set to avoid duplicates)
HashSet <Edge <SCoord> > edges = new HashSet <Edge <SCoord> >(edgeComparator);
// For each vertex in the original icosphere
foreach (SCoord point in vertices.GetPoints())
{
// For each edge that this point is connected to
foreach (SCoord endpt in vertices.GetConnected(point))
{
// Create a structure for the edge
Edge <SCoord> edge = new Edge <SCoord>(point, endpt);
// Add the ege to the list of edges (Set to avoid duplicates)
edges.Add(edge);
}
}
// The graph of the subdivided sphere
Graph <SCoord> subdivided = new Graph <SCoord>(vertices.GetPoints());
// List of all the points in the subdivided sphere
List <SCoord> cuts = new List <SCoord>(edges.Count);
List <Edge <SCoord> > edgeList = new List <Edge <SCoord> >(edges);
Dictionary <Edge <SCoord>, SCoord> cutLookup = new Dictionary <Edge <SCoord>, SCoord>(edgeComparator);
// For each edge in the sphere
foreach (Edge <SCoord> edge in edgeList)
{
// Get the endpoints of the edge
SCoord[] endpts = edge.GetPoints();
// Get the midpoint between the edge
SCoord midpoint = SCoord.GetCentroid(endpts[0], endpts[1]);
cutLookup.Add(edge, midpoint);
// Add the point to the list of cuts
cuts.Add(midpoint);
// Put the new cut in the new sphere
subdivided.AddPoint(midpoint);
// connect the subdivided point to the points it cut apart
subdivided.Connect(midpoint, endpts[0]);
subdivided.Connect(midpoint, endpts[1]);
}
// For each new point added, connect it to other new points added
for (int cutIdx = 0; cutIdx < cuts.Count; cutIdx++)
{
// Get the point and the edge it divides
SCoord cut = cuts[cutIdx];
Edge <SCoord> originalEdge = edgeList[cutIdx];
// Get the edpoints on the original edge
SCoord[] endpts = originalEdge.GetPoints();
// Find the other points in the graph that these two points have in common
HashSet <SCoord> common = new HashSet <SCoord>(vertices.GetConnected(endpts[0]));
common.IntersectWith(vertices.GetConnected(endpts[1]));
List <SCoord> faceEdges = new List <SCoord>(common);
// There should always be two of these points. This means for points that
// should make up the original four edges. These plus the original edge
// define the two faces that the four points share in common
Edge <SCoord>[] commonEdges =
{
new Edge <SCoord>(faceEdges[0], endpts[0]),
new Edge <SCoord>(faceEdges[0], endpts[1]),
new Edge <SCoord>(faceEdges[1], endpts[0]),
new Edge <SCoord>(faceEdges[1], endpts[1])
};
// Connect the subdivisions of these other edges to this cut
foreach (Edge <SCoord> connected in commonEdges)
{
subdivided.Connect(cut, cutLookup[connected]);
}
}
return(new Icosphere(center, radius, subdivided));
}
