//semplifica l'octree
public OctreeNode SimplifyOctree(OctreeNode node, float threshold)
{
if (node == null)
{
return(null);
}
if (node.type != NodeType.INTERNAL)
{
// can't simplify!
return(node);
}
QefSolver qef = new QefSolver();
int[] signs = new int[8] {
-1, -1, -1, -1, -1, -1, -1, -1,
};
int midsign = -1;
int edgeCount = 0;
bool isCollapsible = true;
for (int i = 0; i < 8; i++)
{
node.children[i] = SimplifyOctree(node.children[i], threshold);
if (node.children[i] != null)
{
OctreeNode child = node.children[i];
if (child.type == NodeType.INTERNAL)
{
isCollapsible = false;
}
else
{
qef.Add(child.nodeInfo.qef);
midsign = (child.nodeInfo.corners >> (7 - i)) & 1;
signs[i] = (child.nodeInfo.corners >> i) & 1;
edgeCount++;
}
}
}
if (!isCollapsible)
{
// at least one child is an internal node, can't collapse
return(node);
}
Vector3 qefPosition = new Vector3();
float error = qef.Solve(qefPosition, QEF_ERROR, QEF_SWEEPS, QEF_ERROR);
Vector3 position = new Vector3(qefPosition.x, qefPosition.y, qefPosition.z);
// at this point the masspoint will actually be a sum, so divide to make it the average
if (error > threshold)
{
// this collapse breaches the threshold
return(node);
}
if (position.x < node.min.x || position.x > (node.min.x + node.size) ||
position.y < node.min.y || position.y > (node.min.y + node.size) ||
position.z < node.min.z || position.z > (node.min.z + node.size))
{
position = qef.GetMassPoint();
}
// change the node from an internal node to a 'pseudo leaf' node
NodeInfo info = new NodeInfo();
for (int i = 0; i < 8; i++)
{
if (signs[i] == -1)
{
// Undetermined, use centre sign instead
info.corners |= (midsign << i);
}
else
{
info.corners |= (signs[i] << i);
}
}
info.avgNormal = new Vector3(0, 0, 0);
for (int i = 0; i < 8; i++)
{
if (node.children[i] != null)
{
if (node.children[i].type == NodeType.PSEUDO ||
node.children[i].type == NodeType.LEAF)
{
info.avgNormal += node.children[i].nodeInfo.avgNormal;
}
}
}
info.avgNormal = info.avgNormal.normalized;
info.position = position;
info.qef = qef.GetData();
for (int i = 0; i < 8; i++)
{
DestroyOctree(node.children[i]);
node.children[i] = null;
}
node.type = NodeType.PSEUDO;
node.nodeInfo.Set(info);
return(node);
}
//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);
}