Class: WindingPolygon::EventQueue

Inherits:
Object
  • Object
show all
Defined in:
lib/winding-polygon/event_queue.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(polygon) ⇒ EventQueue

Returns a new instance of EventQueue.



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# File 'lib/winding-polygon/event_queue.rb', line 7

def initialize(polygon)
  #last vertex in geojson is equal to first vertex
  @individual_vertices = polygon.vertices.length - 1
  #2 per edge - last event looping back to 0 is handled by +1 below
  @number_of_events =   2 * (@individual_vertices)
  @events = []

  #build up 2 'events' per edge. One for left vertex, one for right.
  for i in 0..@individual_vertices-1
    a = 2*i
    b = 2*i+1
    @events[a] = {:edge=>i}
    @events[b] = {:edge=>i}
    @events[a][:vertex] = polygon.vertices[i]
    @events[b][:vertex] = polygon.vertices[i+1]
    if @events[a][:vertex].compare(@events[b][:vertex]) < 0
      @events[a][:type] = 'left'
      @events[b][:type] = 'right'
    else
      @events[a][:type] = 'right'
      @events[b][:type] = 'left'
    end
  end

  # sort events lexicographically
  #@events.sort!{|a,b| [a[:vertex], b[:type], a[:other_endpoint]] <=> [b[:vertex], a[:type], b[:other_endpoint]] }
  @events.sort!{|a,b| [a[:vertex], b[:type]] <=> [b[:vertex], a[:type]] }

end

Instance Attribute Details

#events ⇒ Object (readonly)

Returns the value of attribute events.



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# File 'lib/winding-polygon/event_queue.rb', line 4

def events
  @events
end

#individual_vertices ⇒ Object (readonly)

Returns the value of attribute individual_vertices.



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# File 'lib/winding-polygon/event_queue.rb', line 5

def individual_vertices
  @individual_vertices
end

#number_of_events ⇒ Object (readonly)

Returns the value of attribute number_of_events.



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# File 'lib/winding-polygon/event_queue.rb', line 3

def number_of_events
  @number_of_events
end

Instance Method Details

#exist(point) ⇒ Object 



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# File 'lib/winding-polygon/event_queue.rb', line 46

def exist(point)
  for i in 0..@events.size-1
    return true if @events[i][:vertex] ==point
  end

  return false
end

#insert(point_hash) ⇒ Object 



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# File 'lib/winding-polygon/event_queue.rb', line 37

def insert(point_hash)
  for i in 0..@events.size-1
    next if @events[i][:vertex].x < point_hash[:point].x
    next if @events[i][:vertex].x == point_hash[:point].x && @events[i][:vertex].y<point_hash[:point].y
    @events.insert(i,{:type=>'intersection_point',:vertex=>point_hash[:point],:edge1=>point_hash[:edge1],:edge2=>point_hash[:edge2]})
    break
  end
end