// Update triangle connections and edge error after a edge is collapsed
void Update_triangles(int i0, ref Vertex v, ref ListHelper <int> deleted, ref int deleted_triangles)
{
Vector3 p = new Vector3();
for (int k = 0; k < v.tcount; k++)
{
Ref r = refs[v.tstart + k];
Triangle t = triangles[r.tid];
if (t.deleted != 0)
{
continue;
}
if (deleted[k] != 0)
{
t.deleted = 1;
deleted_triangles++;
continue;
}
t.v[r.tvertex] = i0;
t.dirty = 1;
t.err[0] = Calculate_error(t.v[0], t.v[1], ref p);
t.err[1] = Calculate_error(t.v[1], t.v[2], ref p);
t.err[2] = Calculate_error(t.v[2], t.v[0], ref p);
t.err[3] = Math.Min(t.err[0], Math.Min(t.err[1], t.err[2]));
refs.Add(r);
triangles[r.tid] = t;
}
}
// compact triangles, compute edge error and build reference list
void Update_mesh(int iteration)
{
if (iteration > 0) // compact triangles
{
int dst = 0;
for (int i = 0; i < triangles.Count; i++)
{
if (triangles[i].deleted == 0)
{
triangles[dst++] = triangles[i];
}
}
}
//
// Init Quadrics by Plane & Edge Errors
//
// required at the beginning ( iteration == 0 )
// recomputing during the simplification is not required,
// but mostly improves the result for closed meshes
//
if (iteration == 0)
{
for (int i = 0; i < vertices.Count; i++)
{
Vertex v = vertices[i];
v.q = new SymetricMatrix(0.0);
vertices[i] = v;
}
for (int i = 0; i < triangles.Count; i++)
{
Triangle t = triangles[i];
Vector3 n = new Vector3();
Vector3[] p = new Vector3[3];
for (int j = 0; j < 3; j++)
{
p[j] = vertices[t.v[j]].p;
}
n = Vector3.Cross(p[1] - p[0], p[2] - p[0]);
n.Normalize();
t.n = n;
for (int j = 0; j < 3; j++)
{
Vertex v = vertices[t.v[j]];
v.q = vertices[t.v[j]].q + new SymetricMatrix(n.X, n.Y, n.Z, -Vector3.Dot(n, p[0]));
vertices[t.v[j]] = v;
}
triangles[i] = t;
}
for (int i = 0; i < triangles.Count; i++)
{
// Calc Edge Error
Triangle t = triangles[i];
Vector3 p = new Vector3();
for (int j = 0; j < 3; j++)
{
t.err[j] = Calculate_error(t.v[j], t.v[(j + 1) % 3], ref p);
}
t.err[3] = Math.Min(t.err[0], Math.Min(t.err[1], t.err[2]));
triangles[i] = t;
}
}
// Init Reference ID list
for (int i = 0; i < vertices.Count; i++)
{
Vertex v = vertices[i];
v.tstart = 0;
v.tcount = 0;
vertices[i] = v;
}
for (int i = 0; i < triangles.Count; i++)
{
Triangle t = triangles[i];
for (int j = 0; j < 3; i++)
{
Vertex v = vertices[t.v[j]];
v.tcount++;
vertices[t.v[j]] = v;
}
}
int tstart = 0;
for (int i = 0; i < vertices.Count; i++)
{
Vertex v = vertices[i];
v.tstart = tstart;
tstart += v.tcount;
v.tcount = 0;
vertices[i] = v;
}
// Write References
for (int i = 0; i < triangles.Count; i++)
{
Triangle t = triangles[i];
for (int j = 0; j < 3; j++)
{
Vertex v = vertices[t.v[j]];
Ref r = refs[v.tstart + v.tcount];
r.tid = i;
r.tvertex = j;
refs[v.tstart + v.tcount] = r;
v.tcount++;
vertices[t.v[j]] = v;
}
triangles[i] = t;
}
// Identify boundary : vertices[].border=0,1
if (iteration == 0)
{
ListHelper <int> vcount = new ListHelper <int>();
ListHelper <int> vids = new ListHelper <int>();
for (int i = 0; i < vertices.Count; i++)
{
Vertex v = vertices[i];
v.border = 0;
vertices[i] = v;
}
for (int i = 0; i < vertices.Count; i++)
{
Vertex v = vertices[i];
vcount.Clear();
vids.Clear();
for (int j = 0; j < v.tcount; j++)
{
int kb = refs[v.tstart + j].tid;
Triangle t = triangles[kb];
for (int k = 0; k < 3; k++)
{
int ofs = 0, id = t.v[k];
while (ofs < vcount.Count)
{
if (vids[ofs] == id)
{
break;
}
ofs++;
}
if (ofs == vcount.Count)
{
vcount.Add(1);
vids.Add(id);
}
else
{
vcount[ofs]++;
}
}
triangles[kb] = t;
}
for (int j = 0; j < vcount.Count; j++)
{
if (vcount[j] == 1)
{
Vertex vt = vertices[vids[j]];
vt.border = 1;
vertices[vids[j]] = vt;
}
}
}
}
}
