public static OctreeNode SimplifyOctree(OctreeNode node, float threshold)
{
if (node == null)
{
return(null);
}
if (node.Type != OctreeNodeType.Node_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 == OctreeNodeType.Node_Internal)
{
isCollapsible = false;
}
else
{
qef.add(child.drawInfo.qef);
midsign = (child.drawInfo.corners >> (7 - i)) & 1;
signs[i] = (child.drawInfo.corners >> i) & 1;
edgeCount++;
}
}
}
if (!isCollapsible)
{
// at least one child is an internal node, can't collapse
return(node);
}
Vector3 qefPosition = Vector3.zero;
qef.solve(qefPosition, QEF_ERROR, QEF_SWEEPS, QEF_ERROR);
float error = qef.getError();
// convert to glm vec3 for ease of use
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 'psuedo leaf' node
OctreeDrawInfo drawInfo = new OctreeDrawInfo();
drawInfo.corners = 0;
drawInfo.index = -1;
for (int i = 0; i < 8; i++)
{
if (signs[i] == -1)
{
// Undetermined, use centre sign instead
drawInfo.corners |= (midsign << i);
}
else
{
drawInfo.corners |= (signs[i] << i);
}
}
drawInfo.averageNormal = Vector3.zero;
for (int i = 0; i < 8; i++)
{
if (node.children[i] != null)
{
OctreeNode child = node.children[i];
if (child.Type == OctreeNodeType.Node_Psuedo ||
child.Type == OctreeNodeType.Node_Leaf)
{
drawInfo.averageNormal += child.drawInfo.averageNormal;
}
}
}
drawInfo.averageNormal = drawInfo.averageNormal.normalized;
drawInfo.position = position;
drawInfo.qef = qef.getData();
for (int i = 0; i < 8; i++)
{
DestroyOctree(node.children[i]);
node.children[i] = null;
}
node.Type = OctreeNodeType.Node_Psuedo;
node.drawInfo = drawInfo;
return(node);
}
public static OctreeNode ConstructLeaf(OctreeNode leaf)
{
if (leaf == null || leaf.size != 1)
{
return(null);
}
int corners = 0;
for (int i = 0; i < 8; i++)
{
Vector3 cornerPos = leaf.min + CHILD_MIN_OFFSETS[i];
float density = glm.Density_Func(cornerPos);
int material = density < 0.0f ? MATERIAL_SOLID : MATERIAL_AIR;
corners |= (material << i);
}
if (corners == 0 || corners == 255)
{
// voxel is full inside or outside the volume
//delete leaf
//setting as null isn't required by the GC in C#... but its in the original, so why not!
leaf = null;
return(null);
}
// otherwise the voxel contains the surface, so find the edge intersections
const int MAX_CROSSINGS = 6;
int edgeCount = 0;
Vector3 averageNormal = Vector3.zero;
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 == MATERIAL_AIR && m2 == MATERIAL_AIR) || (m1 == MATERIAL_SOLID && m2 == MATERIAL_SOLID))
{
// no zero crossing on this edge
continue;
}
Vector3 p1 = leaf.min + CHILD_MIN_OFFSETS[c1];
Vector3 p2 = leaf.min + CHILD_MIN_OFFSETS[c2];
Vector3 p = ApproximateZeroCrossingPosition(p1, p2);
Vector3 n = CalculateSurfaceNormal(p);
qef.add(p.x, p.y, p.z, n.x, n.y, n.z);
averageNormal += n;
edgeCount++;
}
Vector3 qefPosition = Vector3.zero;
qef.solve(qefPosition, QEF_ERROR, QEF_SWEEPS, QEF_ERROR);
OctreeDrawInfo drawInfo = new OctreeDrawInfo();
drawInfo.corners = 0;
drawInfo.index = -1;
drawInfo.position = new Vector3(qefPosition.x, qefPosition.y, qefPosition.z);
drawInfo.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 (drawInfo.position.x < min.x || drawInfo.position.x > max.x ||
drawInfo.position.y < min.y || drawInfo.position.y > max.y ||
drawInfo.position.z < min.z || drawInfo.position.z > max.z)
{
drawInfo.position = qef.getMassPoint();
}
drawInfo.averageNormal = Vector3.Normalize(averageNormal / (float)edgeCount);
drawInfo.corners = corners;
leaf.Type = OctreeNodeType.Node_Leaf;
leaf.drawInfo = drawInfo;
return(leaf);
}
public GridCell(Vector3 center, float gridScale = 1f)
{
QefSolver qef = new QefSolver();
//check each corner against the density function
//and generate SOMETHING at that position to see if our density function is right
//we can cache the results from each corner, as we need to check every one anyways
//is there a smarter way
//we can have up to 4 sign changes per cell..
// 0 ---- 1
// | |
// 1------0 <---- opposite for the top face = 4 total
//get corner positions
//take the center (int coords), convert them to world positions, then +/- on every axis
this.gridScale = gridScale;
worldPos = center * gridScale;
//need to do corners in the same order every time
//assign the corners to their density value at that corner position
for (int i = 0; i < 8; i++)
{
float v = DualContouring1.density(worldPos + DualContouring1.cornerOffsets[i] * 0.5f * gridScale);
//thresholding here to turn the density into an ID
corners[i] = v >= 0 ? 1 : 0;
}
//check if any edges have sign changes
//I guess only store the edges that are important, like the ones that have a sign change.
//we need to check every corner against it's neighbour cells, so we need to know which ones are it's neighbours.
//Each corner has three neighbours,
for (int i = 0; i < 4; i++) //but we only want to check half of them, otherwise we have doubles?
{
for (int j = 0; j < 3; j++)
{
int neighbour = cornerNeighbours[i, j];
if (corners[i] != corners[neighbour]) //if this corner has a different density value than any of it's neighbours
//we need to be able to find neighbours based on edges...
//not sure how
//make a naive implimentation first
{
GridEdge e = new GridEdge(i, neighbour, center);
edges.Add(e);
DualContouring1.edges.Add(e);
Vector3 edgeCornerA = worldPos + DualContouring1.cornerOffsets[e.corners[0]] * 0.5f * gridScale;
Vector3 edgeCornerB = worldPos + DualContouring1.cornerOffsets[e.corners[1]] * 0.5f * gridScale;
//need these for meshing to find shared edges I guess
e.cornersOffset[0] = DualContouring1.cornerOffsets[e.corners[0]];
e.cornersOffset[1] = DualContouring1.cornerOffsets[e.corners[1]];
//computing the intersection position and normal of this edge against the density function
e.position = DualContouring1.ApproximateEdgeIntersection(edgeCornerA, edgeCornerB, DualContouring1.density);
e.normal = DualContouring1.CalculateSurfaceNormal(e.position, DualContouring1.density);
//from here we have to get the actual position of the vertex for this cell
//we do this using the QefSolver. For every edge intersection add the position and normal
qef.add(e.position, e.normal);
//add the normal so we can grab it later (summed, so we have to grab normal/edges.Count
normal += e.normal;
Debug.Log("1");
}
}
}
if (edges.Count != 0)
{
vertex = Vector3.zero;
qef.solve(vertex, QEF_ERROR, QEF_SWEEPS, QEF_ERROR);
Vector3 min = center + DualContouring1.cornerOffsets[0] * 0.5f * gridScale;
Vector3 max = center + DualContouring1.cornerOffsets[6] * 0.5f * gridScale;
if (vertex.x < min.x || vertex.x > max.x ||
vertex.y < min.y || vertex.y > max.y ||
vertex.z < min.z || vertex.z > max.z)
{
vertex = qef.getMassPoint();
}
DualContouring1.verticies.Add(new MeshVertex(vertex, (normal / edges.Count).normalized));
vertexIndex = DualContouring1.verticies.Count - 1;
if (vertex == Vector3.zero)
{
Debug.Log("Zero");
}
Debug.Log("2");
hasVertex = true;
}
}