public Octree(MeshToolkit mesh, bool cubic = true)
{
this._mesh = mesh;
this._cubic = cubic;
//this.triangles = _mesh.Triangles();
this.vertices = _mesh.Vertices();
this.vertexIndexByTri = Core.List.Chop <int>(_mesh.VertexIndicesByTri(), 3);
BoundingBox bbox = Graphical.Geometry.MeshToolkit.BoundingBox(this._mesh);
// Extending the BoundingBox to be cubical from the centre.
// Done by getting the max component of the Bounding box and translating min and max points outwards.
// https://github.com/diwi/Space_Partitioning_Octree_BVH/blob/b7f66fe04e4af3b98ab9404363ab33f5dc1628a9/SpacePartitioning/src/DwOctree/Octree.java#L83
if (cubic)
{
using (Point center = Geometry.Point.MidPoint(bbox.MinPoint, bbox.MaxPoint))
{
Vector bboxSize = Vector.ByTwoPoints(bbox.MinPoint, bbox.MaxPoint);
Vector halfSize = bboxSize.Scale(0.5);
double[] halfComponents = new double[3] {
halfSize.X, halfSize.Y, halfSize.Z
};
double maxComponent = halfComponents[getSubdivisionPlane(bbox)];
Vector expansionDirection = Vector.ByCoordinates(maxComponent, maxComponent, maxComponent);
bbox = BoundingBox.ByCorners(
(Point)center.Translate(-maxComponent, -maxComponent, -maxComponent),
(Point)center.Translate(maxComponent, maxComponent, maxComponent)
);
}
}
_root = new OctreeNode(0, bbox);
}
internal bool AssureChildren(OctreeNode ot, int maxDepth)
{
if (ot.depth >= maxDepth)
{
return(false);
}
if (ot.isLeaf())
{
ot.children = new OctreeNode[8];
// Half vector size, by scaling total diagonal or maybe faster creating the MidPoint?
Vector halfSize = Vector.ByTwoPoints(ot.bbox.MinPoint, ot.bbox.MaxPoint).Scale(0.5);
int childDepth = ot.depth + 1;
for (int i = 0; i < ot.children.Count(); i++)
{
Point min = Point.ByCoordinates(
ot.bbox.MinPoint.X + (((i & 4) > 0) ? halfSize.X : 0),
ot.bbox.MinPoint.Y + (((i & 2) > 0) ? halfSize.Y : 0),
ot.bbox.MinPoint.Z + (((i & 1) > 0) ? halfSize.Z : 0)
);
Point max = (Point)min.Translate(halfSize);
ot.children[i] = new OctreeNode(childDepth, BoundingBox.ByCorners(min, max));
}
}
return(true);
}
