Class: PolygonCollidable

Inherits:
CollidableShape show all
Defined in:
lib/gamebox/behaviors/collidable/polygon_collidable.rb

Instance Attribute Summary collapse

Attributes inherited from CollidableShape

#actor, #opts, #radius

Instance Method Summary collapse

Methods inherited from CollidableShape

#actor_x, #actor_y, #initialize, #width

Constructor Details

This class inherits a constructor from CollidableShape

Instance Attribute Details

#cw_local_points ⇒ Object

Returns the value of attribute cw_local_points.



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 4

def cw_local_points
  @cw_local_points
end

Instance Method Details

#calculate_radius ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 19

def calculate_radius
  local_avg = cw_local_points.inject([0,0]) {|s, (x,y)| s[0] += x; s[1]+=y; s}.map {|x| x / cw_local_points.size}
  max_dist = 0
  cw_local_points.each do |lp|
    x_dist = local_avg[0]-lp[0]
    y_dist = local_avg[1]-lp[1]
    dist = Math.sqrt(x_dist*x_dist + y_dist*y_dist)
    max_dist = dist if dist > max_dist
  end 
  max_dist
end

#center_x ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 31

def center_x
  poly_center[0]
end

#center_y ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 35

def center_y
  poly_center[1]
end

#clear_collidable_cache ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 79

def clear_collidable_cache
  @cached_points = nil
  @cached_lines = nil
  @cached_poly_center = nil
end

#cw_world_edge_normals ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 59

def cw_world_edge_normals
  return @cached_normals if @cached_normals

  @cached_normals = cw_world_lines.map do |edge|
    # vector subtraction
    v = edge[1][0]-edge[0][0], edge[1][1]-edge[0][1]
    [-v[1],v[0]]
  end

  @cached_normals
end

#cw_world_lines ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 47

def cw_world_lines
  return @cached_lines if @cached_lines
  lines = [] 

  cw_world_points.each_cons(2) do |a,b|
    lines << [a,b]
  end
  lines << [cw_world_points[-1],cw_world_points[0]]

  @cached_lines = lines
end

#cw_world_points ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 43

def cw_world_points
  @cached_points ||= @cw_local_points.map{|lp| [lp[0]+actor_x,lp[1]+actor_y]}
end

#poly_center ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 39

def poly_center
  @cached_poly_center ||= cw_world_points.inject([0,0]) {|s, (x,y)| s[0] += x; s[1]+=y; s}.map {|x| x / cw_world_points.size}
end

#recalculate_collidable_cache ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 71

def recalculate_collidable_cache
  unless @old_x == actor_x && @old_y == actor_y
    clear_collidable_cache
    @old_x = actor_x
    @old_y = actor_y
  end
end

#setup ⇒ Object 



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# File 'lib/gamebox/behaviors/collidable/polygon_collidable.rb', line 6

def setup
  @shape_type = opts[:shape]

  @cw_local_points = opts[:cw_local_points]
  @cw_local_points ||= opts[:points]

  @radius = opts[:radius]
  @radius ||= calculate_radius

  @old_x = actor_x
  @old_y = actor_y
end