Module: Zif::Layers::Bitmaskable

Included in:
ActiveBitmaskedTiledLayer, BitmaskedTiledLayer
Defined in:
lib/zif/layers/bitmaskable.rb

Overview

A mixin to extend Tileable functionality. Sprites are chosen via bitmasked adjacency rules on the presence data layer - otherwise known as Autotiling. This is a bit opinionated! Here is how the bitmask is calculated:

+-----+----+-----+
| 128 | 1  |  16 |
+-----+----+-----+
|  8  | <> |  2  |
+-----+----+-----+
|  64 | 4  |  32 |
+-----+----+-----+

(Cardinal directions clockwise, then diagonal directions clockwise)

So if a tile has a neighbor to the north, east and northeast, it’ll try to load the sprite “mytiles_19” – 1+2+16 from the SpriteRegistry. See the SpriteRegistry for more info on filenames and aliasing.

Some background (note the author uses a different numbering scheme): gamedevelopment.tutsplus.com/tutorials/how-to-use-tile-bitmasking-to-auto-tile-your-level-layouts–cms-25673

See Also:

Instance Attribute Summary collapse

1. Public Interface collapse

2. Private-ish methods collapse

Instance Attribute Details

#bitmask_data ⇒ Array<Array<Integer>> (readonly)

Returns A 2-dimensional array of bitmasked integers calculated from #presence_data This array is the size of your map’s logical height, containing arrays the size of the logical width.

Returns:

  • (Array<Array<Integer>>) —

    A 2-dimensional array of bitmasked integers calculated from #presence_data This array is the size of your map’s logical height, containing arrays the size of the logical width.



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# File 'lib/zif/layers/bitmaskable.rb', line 32

def bitmask_data
  @bitmask_data
end

#bitmasked_sprite_name_prefix ⇒ String

Returns The prefix to use when referencing image paths.

Returns:

  • (String) —

    The prefix to use when referencing image paths



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# File 'lib/zif/layers/bitmaskable.rb', line 35

def bitmasked_sprite_name_prefix
  @bitmasked_sprite_name_prefix
end

#presence_data ⇒ Array<Array<Boolean>>

Returns A 2-dimensional array of true and false values This array is the size of your map’s logical height, containing arrays the size of the logical width.

Returns:

  • (Array<Array<Boolean>>) —

    A 2-dimensional array of true and false values This array is the size of your map’s logical height, containing arrays the size of the logical width.



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# File 'lib/zif/layers/bitmaskable.rb', line 28

def presence_data
  @presence_data
end

Instance Method Details

#add_at(x, y) ⇒ Object

Add presence at this logical position, then redraw

Parameters:

  • x (Integer) —

    logical_x position to add

  • y (Integer) —

    logical_y position to add



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# File 'lib/zif/layers/bitmaskable.rb', line 60

def add_at(x, y)
  @presence_data[y][x] = true
  redraw_at(x, y)
end

#exclude_from_serialize ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/zif/layers/bitmaskable.rb', line 154

def exclude_from_serialize
  %w[presence_data bitmask_data sprites primitives]
end

#recalculate_bitmask(from_x: 0, from_y: 0, to_x: @map.logical_width - 1, to_y: @map.logical_height - 1) ⇒ Object

This will recalculte the #bitmask_data for a rectangle of logical positions, from #presence_data

Parameters:

  • from_x (Integer) (defaults to: 0) —

    Lower left logical X position of the rectangle to update

  • from_y (Integer) (defaults to: 0) —

    Lower left logical Y position of the rectangle to update

  • to_x (Integer) (defaults to: @map.logical_width - 1) —

    Upper right logical X position of the rectangle to update

  • to_y (Integer) (defaults to: @map.logical_height - 1) —

    Upper right logical Y position of the rectangle to update



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# File 'lib/zif/layers/bitmaskable.rb', line 78

def recalculate_bitmask(from_x: 0, from_y: 0, to_x: @map.logical_width - 1, to_y: @map.logical_height - 1)
  from_x = [from_x, 0].max
  from_y = [from_y, 0].max
  to_x   = [to_x, @map.logical_width - 1].min
  to_y   = [to_y, @map.logical_height - 1].min

  (from_y..to_y).each do |i|
    (from_x..to_x).each do |j|
      @bitmask_data[i][j] = nil
      next unless @presence_data[i][j]

      map_north = (i + 1) <= @map.logical_height
      map_south = (i - 1).positive?

      map_east  = (j + 1) <= @map.logical_width
      map_west  = (j - 1).positive?

      bitmask = 0

      # The presence of a bit in the bitmask indicates the presence of a tile relative to this one
      # Edges
      # Edges - North
      bitmask += 1 if map_north && @presence_data[i + 1][j]
      # Edges - East
      bitmask += 2 if map_east  && @presence_data[i][j + 1]
      # Edges - South
      bitmask += 4 if map_south && @presence_data[i - 1][j]
      # Edges - West
      bitmask += 8 if map_west  && @presence_data[i][j - 1]

      # Corners
      # Corners - NE
      bitmask += 16  if map_north && map_east && @presence_data[i + 1][j + 1]
      # Corners - SE
      bitmask += 32  if map_south && map_east && @presence_data[i - 1][j + 1]
      # Corners - SW
      bitmask += 64  if map_south && map_west && @presence_data[i - 1][j - 1]
      # Corners - NW
      bitmask += 128 if map_north && map_west && @presence_data[i + 1][j - 1]

      @bitmask_data[i][j] = bitmask
    end
  end
end

#redraw_at(x, y) ⇒ Object

Recalculates bitmask and sets sprites for the specified location and the 9 tiles surrounding it

Parameters:

  • x (Integer) —

    Logical X location

  • y (Integer) —

    Logical Y location



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# File 'lib/zif/layers/bitmaskable.rb', line 68

def redraw_at(x, y)
  recalculate_bitmask(from_x: x - 1, from_y: y - 1, to_x: x + 1, to_y: y + 1)
  set_sprites_from_bitmask(from_x: x - 1, from_y: y - 1, to_x: x + 1, to_y: y + 1)
end

#reinitialize_sprites ⇒ Object

Overrides Tileable#reinitialize_sprites Clears @sprites and resets #presence_data and #bitmask_data



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# File 'lib/zif/layers/bitmaskable.rb', line 42

def reinitialize_sprites
  super()
  @presence_data = Array.new(@map.logical_height) { Array.new(@map.logical_width, false) }
  @bitmask_data  = Array.new(@map.logical_height) { Array.new(@map.logical_width, nil) }
end

#remove_at(x, y) ⇒ Object

Remove the tile / presence at this logical position, then redraw

Parameters:

  • x (Integer) —

    logical_x position to remove

  • y (Integer) —

    logical_y position to remove



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# File 'lib/zif/layers/bitmaskable.rb', line 51

def remove_at(x, y)
  @presence_data[y][x] = false
  remove_tile(x, y)
  redraw_at(x, y)
end

#set_sprites_from_bitmask(from_x: 0, from_y: 0, to_x: @map.logical_width - 1, to_y: @map.logical_height - 1) ⇒ Object

This will reset the tiles for a rectangle, based on the #bitmask_data

Parameters:

  • from_x (Integer) (defaults to: 0) —

    Lower left logical X position of the rectangle to update

  • from_y (Integer) (defaults to: 0) —

    Lower left logical Y position of the rectangle to update

  • to_x (Integer) (defaults to: @map.logical_width - 1) —

    Upper right logical X position of the rectangle to update

  • to_y (Integer) (defaults to: @map.logical_height - 1) —

    Upper right logical Y position of the rectangle to update



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# File 'lib/zif/layers/bitmaskable.rb', line 128

def set_sprites_from_bitmask(from_x: 0, from_y: 0, to_x: @map.logical_width - 1, to_y: @map.logical_height - 1)
  raise 'BitmaskedTiledLayer: Please set @bitmasked_sprite_name_prefix' unless @bitmasked_sprite_name_prefix

  from_x = [from_x, 0].max
  from_y = [from_y, 0].max
  to_x   = [to_x, @map.logical_width - 1].min
  to_y   = [to_y, @map.logical_height - 1].min

  (from_y..to_y).each do |i|
    (from_x..to_x).each do |j|
      remove_tile(j, i)
      bitmask = @bitmask_data[i][j]
      next unless bitmask

      full_name = "#{@bitmasked_sprite_name_prefix}_#{bitmask}".to_sym
      sprite = $services[:sprite_registry].construct(full_name)

      add_positioned_sprite(sprite: sprite, logical_x: j, logical_y: i)
    end
  end
end