private void AddFirst(List<int> strip, StripTriangle tris)
{
int maxEdge = (tris.edges[0].Connections < tris.edges[1].Connections) ? 0 : 1;
if (tris.edges[maxEdge].Connections < tris.edges[2].Connections) maxEdge=2;
tris.used = true;
foreach (var i in tris.verts)
if (i!= tris.edges[maxEdge].v0 && i != tris.edges[maxEdge].v1)
AddTriangleFrom(strip, tris, i);
}
private static void AddEdge(StripEdge stripEdge, Dictionary<StripEdge, int> map, List<StripEdge> edges, StripTriangle t)
{
int i;
if (!map.TryGetValue(stripEdge, out i))
{
i = edges.Count;
stripEdge.tris = new List<StripTriangle>();
edges.Add(stripEdge);
map[stripEdge] = i;
}
else
{
stripEdge = edges[i];
}
stripEdge.tris.Add(t);
t.edges.Add(stripEdge);
}
private static void AddTriangleFrom(List<int> strip, StripTriangle tris, int startIndex)
{
if (startIndex == tris.verts[0])
{
strip.Add(tris.verts[0]);
strip.Add(tris.verts[1]);
strip.Add(tris.verts[2]);
}
else if (startIndex == tris.verts[1])
{
strip.Add(tris.verts[1]);
strip.Add(tris.verts[2]);
strip.Add(tris.verts[0]);
}
else if (startIndex == tris.verts[2])
{
strip.Add(tris.verts[2]);
strip.Add(tris.verts[0]);
strip.Add(tris.verts[1]);
}
}
private IList<int> BuildStrip(List<int> Indices)
{
var strip = new List<int>();
var tris = new List<StripTriangle>();
var edges = new List<StripEdge>();
var map = new Dictionary<StripEdge, int>();
for (int i = 0; i < Indices.Count; i += 3)
{
var t = new StripTriangle();
t.index = tris.Count;
t.verts = new int[] { Indices[i], Indices[i + 1], Indices[i + 2] };
tris.Add(t);
AddEdge(new StripEdge(Indices[i], Indices[i + 1]), map, edges, t);
AddEdge(new StripEdge(Indices[i + 1], Indices[i + 2]), map, edges, t);
AddEdge(new StripEdge(Indices[i + 2], Indices[i]), map, edges, t);
}
var sortedTris = tris.ToArray();
Array.Sort(sortedTris, new TrisConnectionsComparer());
foreach (var e in edges)
{
var t = e.tris.ToArray();
Array.Sort(t, new TrisConnectionsComparer());
e.tris.Clear();
e.tris.AddRange(t);
}
int left = sortedTris.Length - 1;
StripTriangle next = sortedTris[0];
AddFirst(strip, next);
while (left > 0)
{
int lastEdgeIndex;
if (!map.TryGetValue(new StripEdge(strip[strip.Count - 1], strip[strip.Count - 2]), out lastEdgeIndex))
if (!map.TryGetValue(new StripEdge(strip[strip.Count - 2], strip[strip.Count - 1]), out lastEdgeIndex))
{
throw new ApplicationException(String.Format("No edge of {0},{1}, last tris {2}", strip[strip.Count - 1], strip[strip.Count - 2], next));
}
var e = edges[lastEdgeIndex];
next = null;
foreach (var t in e.tris)
if (!t.used)
{
next = t;
break;
}
if (next != null)
{
next.used = true;
--left;
foreach (var nextE in next.edges)
if (nextE.v0 == strip[strip.Count - 1])
{
strip.Add(nextE.v1);
break;
}
continue;
}
int pos = 0;
while (sortedTris[pos].used) ++pos;
--left;
next = sortedTris[pos];
JumpTo(strip, next);
}
return strip;
}
private void JumpTo(List<int> strip, StripTriangle tris)
{
strip.Add(strip[strip.Count - 1]);
int maxEdge = (tris.edges[0].Connections < tris.edges[1].Connections) ? 0 : 1;
if (tris.edges[maxEdge].Connections < tris.edges[2].Connections) maxEdge = 2;
tris.used = true;
foreach (var i in tris.verts)
if (i != tris.edges[maxEdge].v0 && i != tris.edges[maxEdge].v1)
{
strip.Add(i);
AddTriangleFrom(strip, tris, i);
}
}