updating sweepline algorithm with AVLTrees, needs

more work

Author: souma4

src/utils/sweepline.jl

@@ -25,8 +25,8 @@ function bentleyottmann(segments)
   S = Tuple{P,P}
 
   # initialization
-  𝒬 = AVLTree{P}()
-  𝒯 = AVLTree{S}()
+  𝒬 = BinaryTrees.AVLTree{P}()
+  𝒯 = BinaryTrees.AVLTree{S}()
   ℒ = Dict{P,Vector{S}}()
   𝒰 = Dict{P,Vector{S}}()
   𝒞 = Dict{P,Vector{S}}()
@@ -57,20 +57,72 @@ function bentleyottmann(segments)
 end
 
 function handle!(I, p, 𝒬, 𝒯, ℒ, 𝒰, 𝒞)
-  ss = ℒ[p] ∪ 𝒰[p] ∪ 𝒞[p]
-  if length(ss) > 1
-    I[p] = ss
+  # Segments that start, end, or intersect at p
+  start_segments = ℒ[p]
+  end_segments = 𝒰[p]
+  intersection_segments = 𝒞[p]
+
+  # If there are multiple segments intersecting at p, record the intersection
+  if length(start_segments ∪ end_segments ∪ intersection_segments) > 1
+    I[p] = start_segments ∪ end_segments ∪ intersection_segments
   end
-  for s in ℒ[p] ∪ 𝒞[p]
+
+  # Remove segments that end at p from the status structure
+  for s in end_segments ∪ intersection_segments
     BinaryTrees.delete!(𝒯, s)
   end
-  for s in 𝒰[p] ∪ 𝒞[p]
+
+  # Insert segments that start at p into the status structure
+  for s in start_segments ∪ intersection_segments
     BinaryTrees.insert!(𝒯, s)
   end
-  if length(𝒰[p] ∪ 𝒞[p]) == 0
-    # n = BinaryTrees.search(𝒯, p)
-  else
+  node = BinaryTrees.root(𝒬)
+
+  # Find new event points caused by the insertion or deletion of segments
+  for s in start_segments
+    s = Segment(s)
+    pred = BinaryTrees.left(node)
+    succ = BinaryTrees.right(node)
+    ns = Segment(pred, succ)
+    if pred !== nothing
+      new_geom, new_type = _newevent(s, ns)
+      if new_geom == IntersectionType(0)
+        BinaryTrees.insert!(𝒬, new_geom)
+      end
+    end
+    if succ !== nothing
+      new_geom, new_type = _newevent(s, ns)
+      if new_type == IntersectionType(0)
+        BinaryTrees.insert!(𝒬, new_geom)
+      end
+    end
+  end
+
+  for s in end_segments
+    s = Segment(s)
+    pred = BinaryTrees.left(node)
+    succ = BinaryTrees.right(node)
+    ns = Segment(pred, succ)
+    if pred !== nothing && succ !== nothing
+      new_geom, new_type = _newevent(s, ns)
+      if new_type == IntersectionType(0)
+        BinaryTrees.insert!(𝒬, new_geom)
+      end
+    end
   end
 end
 
-_key(node::BinaryTrees.AVLNode) = node.key
+_key(node::BinaryTrees.AVLNode) = node.key
+_geom(intersect::Intersection) = intersect.geom
+_type(intersect::Intersection) = intersect.type
+function _newevent(s₁::Segment, s₂::Segment)
+  new_event = intersection(s₁, s₂)
+  _geom(new_event), _type(new_event)
+end
+
+
+function Segment(node₁::BinaryTrees.BinaryNode, node₂::BinaryTrees.BinaryNode)
+  node₁ = _key(node₁)
+  node₂ = _key(node₂)
+  Segment((node₁, node₂))
+end