// adds a mesh face, not a polytope face
// give vertices in clockwise order
private void AddFace(List <Vector4> vs, int subMesh)
{
int n = vs.Count;
for (int i = 0; i < n; i++)
{
uvs.Add(new Vector2((float)Mathf.Cos(i * 2 * Mathf.PI / n) * 0.5f + 0.5f,
(float)Mathf.Sin(i * 2 * Mathf.PI / n) * 0.5f + 0.5f));
}
pos.AddRange(vs);
Vector4[] cross = new Vector4[n];
cross[0] = Rot4.Cross(vs[0], vs[1], vs[2]).normalized;
for (int i = 1; i < n; i++)
{
cross[i] = cross[0];
}
nor.AddRange(cross);
for (int i = 2; i < n; i++)
{
idx[subMesh].AddRange(new[] { inext, inext + i - 1, inext + i });
}
inext += n;
}
// breaks a face into smaller triangles
// WARNING: modifies input
private void AddFaceRefined(List <Vector4> vs, int lod, int subMesh, int totalVertices = -1)
{
if (vs.Count < 3)
{
return;
}
int n = (lod + 2) * (lod + 1) / 2; // total # of new vertices
if (totalVertices == -1) // in all child calls of this function totalVertices will remain the same
{
totalVertices = vs.Count;
}
Vector4[] cross = new Vector4[n];
cross[0] = Rot4.Cross(vs[0], vs[1], vs[2]).normalized;
for (int i = 1; i < n; i++)
{
cross[i] = cross[0];
}
nor.AddRange(cross);
// uvs of the three main vertices in question
Vector2 uv0 = new Vector2(1.0f, 0.5f);
Vector2 uv1 = new Vector2((float)Mathf.Cos((1 - vs.Count) * 2 * Mathf.PI / totalVertices) * 0.5f + 0.5f,
(float)Mathf.Sin((1 - vs.Count) * 2 * Mathf.PI / totalVertices) * 0.5f + 0.5f);
Vector2 uv2 = new Vector2((float)Mathf.Cos((2 - vs.Count) * 2 * Mathf.PI / totalVertices) * 0.5f + 0.5f,
(float)Mathf.Sin((2 - vs.Count) * 2 * Mathf.PI / totalVertices) * 0.5f + 0.5f);
// square for loop iterates over rows of increasing length
for (int i = 0; i <= lod; i++)
{
inext += i;
// the ends of the current row
Quaternion start = Quaternion.Slerp((R4)vs[1], (R4)vs[0], i / (float)lod);
Quaternion end = Quaternion.Slerp((R4)vs[1], (R4)vs[2], i / (float)lod);
Vector2 startUV = Vector2.Lerp(uv1, uv0, i / (float)lod);
Vector2 endUV = Vector2.Lerp(uv1, uv2, i / (float)lod);
for (int j = 0; j <= i; j++)
{
// numerical instability when start == end
if (i > 0)
{
pos.Add((R4)Quaternion.Slerp(start, end, j / (float)i));
uvs.Add(Vector2.Lerp(startUV, endUV, j / (float)i));
}
else
{
pos.Add(vs[1]);
uvs.Add(uv1);
}
// two orientations of triangles
int cur = inext + j;
if (j < i)
{
idx[subMesh].AddRange(new[] { cur, cur - i, cur + 1 });
}
if (j > 0 && j < i)
{
idx[subMesh].AddRange(new[] { cur, cur - i - 1, cur - i });
}
}
}
inext += lod + 1;
vs.RemoveAt(1);
AddFaceRefined(vs, lod, subMesh, totalVertices);
}
