public static QuadTree FromOctree(Octree octree, Vec2 zRange)
{
var sliceMin = new Vec3(octree.Min.xy, zRange.X);
var sliceMax = new Vec3(octree.Max.xy, zRange.Y);
var heightThreshold = (zRange.Y - zRange.X) / 2 * 0.99f;
octree = octree.Transform((path, transformChildren) =>
path.Intersects(sliceMin, sliceMax) ? transformChildren() : Octree.Node.Empty);
if (!octree.RootPath.FullLeaves.Any())
{
return(new QuadTree(octree.Min.xy, octree.Max.xy, Node.Empty, octree.Isosurface));
}
octree = octree.MakeFullDepthUniform();
var maxDepth = octree.RootPath.FullLeaves.First().Depth;
Node Build(Vec2 min, Vec2 max, int depth)
{
if (depth < maxDepth)
{
var halfSize = (max - min) / 2;
var center = min + halfSize;
var children = Quadrants.Select(x => {
var corner = center - halfSize * x;
return(Build(corner, corner + halfSize, depth + 1));
}).ToArray();
return(children.All(x => x == Node.Empty)
? Node.Empty
: children.All(x => x == Node.Full)
? Node.Full
: new Node {
Children = children
});
}
var vcenter = (max - min) / 2 + min;
var height = octree.FindLeaves(path => path.Contains(vcenter)).Where(path => path.IsFull)
.Select(x => x.Max.Z - x.Min.Z).DefaultIfEmpty(0).Sum();
return(height >= heightThreshold ? Node.Full : Node.Empty);
}
return(new QuadTree(octree.Min.xy, octree.Max.xy, Build(octree.Min.xy, octree.Max.xy, 0), octree.Isosurface));
}
