//Calcola la normale del punto passato
public Vector3 CalculateSurfaceNormal(Vector3 p)
{
float H = 0.001f;
float dx = Density.DensityFunc(p + new Vector3(H, 0, 0)) - Density.DensityFunc(p - new Vector3(H, 0, 0));
float dy = Density.DensityFunc(p + new Vector3(0, H, 0)) - Density.DensityFunc(p - new Vector3(0, H, 0));
float dz = Density.DensityFunc(p + new Vector3(0, 0, H)) - Density.DensityFunc(p - new Vector3(0, 0, H));
Vector3 res = new Vector3(dx, dy, dz);
return(res.normalized);
}
//approssima il punto di incontro dei vettori
public Vector3 ApproximateZeroCrossingPosition(Vector3 p1, Vector3 p2, int steps)
{
float minVal = float.MaxValue;
float t = 0, curT = 0;
float increment = 1.0f / (float)steps;
while (curT <= 1.0f)
{
Vector3 p = p1 + ((p2 - p1) * curT);
float density = Mathf.Abs(Density.DensityFunc(p));
if (density < minVal)
{
minVal = density;
t = curT;
}
curT += increment;
}
return(p1 + ((p2 - p1) * t));
}
//costruisce il nodo terminale (foglia) calcolando le NodeInfo per la generazione della mesh
public OctreeNode BuildLeaf(OctreeNode leaf, int size)
{
if (leaf == null || leaf.size != size)
{
return(null);
}
int corners = 0;
for (int i = 0; i < 8; i++)
{
Vector3 cornerPos = leaf.min + (CHILD_MIN_OFFSETS[i] * size);
float density = Density.DensityFunc(cornerPos);
int material = density < 0.0f ? SOLID : AIR;
corners |= (material << i);
}
if (corners == 0 || corners == 255)
{
leaf = null;
return(null);
}
int edgeCount = 0;
Vector3 averageNormal = new Vector3();
QefSolver qef = new QefSolver();
for (int i = 0; i < 12 && edgeCount < MAX_CROSSINGS; i++)
{
int c1 = edgevmap[i][0];
int c2 = edgevmap[i][1];
int m1 = (corners >> c1) & 1;
int m2 = (corners >> c2) & 1;
if ((m1 == AIR && m2 == AIR) || (m1 == SOLID && m2 == SOLID))
{
continue;
}
Vector3 p1 = leaf.min + (CHILD_MIN_OFFSETS[c1] * size);
Vector3 p2 = leaf.min + (CHILD_MIN_OFFSETS[c2] * size);
Vector3 p = ApproximateZeroCrossingPosition(p1, p2, 8);
Vector3 n = CalculateSurfaceNormal(p);
qef.Add(p.x, p.y, p.z, n.x, n.y, n.z);
averageNormal += n;
edgeCount++;
}
Vector3 qefPosition = new Vector3();
qef.Solve(qefPosition, QEF_ERROR, QEF_SWEEPS, QEF_ERROR);
NodeInfo info = new NodeInfo();
info.index = -1;
info.corners = 0;
info.position = qefPosition;
info.qef = qef.GetData();
Vector3 min = leaf.min;
Vector3 max = new Vector3(leaf.min.x + leaf.size, leaf.min.y + leaf.size, leaf.min.z + leaf.size);
if (info.position.x < min.x || info.position.x > max.x ||
info.position.y < min.y || info.position.y > max.y ||
info.position.z < min.z || info.position.z > max.z)
{
info.position = qef.GetMassPoint();
}
info.avgNormal = (averageNormal / (float)edgeCount).normalized;
info.corners = corners;
leaf.type = NodeType.LEAF;
leaf.nodeInfo = info;
return(leaf);
}
