Class: GameSpace

Inherits:
Object
  • Object
show all
Defined in:
lib/game_2d/game_space.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(game = nil) ⇒ GameSpace

Returns a new instance of GameSpace.



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# File 'lib/game_2d/game_space.rb', line 56

def initialize(game=nil)
  @game = game
  @grid = @storage = nil
  @highest_id = 0

  @registry = {}

  # I create a @doomed array so we can remove entities after all collisions
  # have been processed, to avoid confusion
  @doomed = []

  @players = []
  @npcs = []
end

Instance Attribute Details

#cell_height ⇒ Object (readonly)

Returns the value of attribute cell_height.



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# File 'lib/game_2d/game_space.rb', line 53

def cell_height
  @cell_height
end

#cell_width ⇒ Object (readonly)

Returns the value of attribute cell_width.



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# File 'lib/game_2d/game_space.rb', line 53

def cell_width
  @cell_width
end

#game ⇒ Object (readonly)

Returns the value of attribute game.



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# File 'lib/game_2d/game_space.rb', line 53

def game
  @game
end

#highest_id ⇒ Object

Returns the value of attribute highest_id.



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# File 'lib/game_2d/game_space.rb', line 54

def highest_id
  @highest_id
end

#npcs ⇒ Object (readonly)

Returns the value of attribute npcs.



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# File 'lib/game_2d/game_space.rb', line 53

def npcs
  @npcs
end

#players ⇒ Object (readonly)

Returns the value of attribute players.



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# File 'lib/game_2d/game_space.rb', line 53

def players
  @players
end

#storage ⇒ Object

Returns the value of attribute storage.



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# File 'lib/game_2d/game_space.rb', line 54

def storage
  @storage
end

#world_id ⇒ Object (readonly)

Returns the value of attribute world_id.



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# File 'lib/game_2d/game_space.rb', line 53

def world_id
  @world_id
end

#world_name ⇒ Object (readonly)

Returns the value of attribute world_name.



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# File 'lib/game_2d/game_space.rb', line 53

def world_name
  @world_name
end

Class Method Details

.load(game, storage) ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 118

def self.load(game, storage)
  name, id, cell_width, cell_height =
    storage[:world_name], storage[:world_id],
    storage[:cell_width], storage[:cell_height]
  space = GameSpace.new(game).establish_world(name, id, cell_width, cell_height)
  space.storage = storage
  space.load
end

Instance Method Details

#<<(entity) ⇒ Object

Add an entity. Will wake neighboring entities



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# File 'lib/game_2d/game_space.rb', line 351

def <<(entity)
  entity.registry_id = next_id unless entity.registry_id?

  fail "Already registered: #{entity}" if registered?(entity)

  # Need to assign the space before entities_obstructing()
  entity.space = self
  conflicts = entity.entities_obstructing(entity.x, entity.y)
  if conflicts.empty?
    register(entity)
    add_entity_to_grid(entity)
    entities_bordering_entity_at(entity.x, entity.y).each(&:wake!)
    entity
  else
    entity.space = nil
    # TODO: Convey error to user somehow
    $stderr.puts "Can't create #{entity}, occupied by #{conflicts.inspect}"
  end
end

#==(other) ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 456

def ==(other)
  other.class.equal?(self.class) && other.all_state == self.all_state
end

#[](registry_id) ⇒ Object

Retrieve entity by ID



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# File 'lib/game_2d/game_space.rb', line 157

def [](registry_id)
  return nil unless registry_id
  @registry[registry_id.to_sym]
end

#add_entity_to_grid(entity) ⇒ Object

Add the entity to the grid



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# File 'lib/game_2d/game_space.rb', line 300

def add_entity_to_grid(entity)
  cells_overlapping(entity.x, entity.y).each {|s| s << entity }
end

#all_registered ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 162

def all_registered
  @registry.values
end

#all_state ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 459

def all_state
  [@world_name, @world_id, @registry, @grid, @highest_id]
end

#assert_ok_coords(cell_x, cell_y) ⇒ Object

We can safely look up cell_x == -1, cell_x == @cell_width, cell_y == -1, and/or cell_y == @cell_height – any of these returns a Wall instance



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# File 'lib/game_2d/game_space.rb', line 210

def assert_ok_coords(cell_x, cell_y)
  raise "Illegal coordinate #{cell_x}x#{cell_y}" if (
    cell_x < -1 ||
    cell_y < -1 ||
    cell_x > @cell_width ||
    cell_y > @cell_height
  )
end

#at(cell_x, cell_y) ⇒ Object

Retrieve set of entities falling (partly) within cell coordinates, zero-based



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# File 'lib/game_2d/game_space.rb', line 221

def at(cell_x, cell_y)
  assert_ok_coords(cell_x, cell_y)
  @grid[cell_x + 1][cell_y + 1]
end

#cell_at_point(x, y) ⇒ Object

Translate a subpixel point (X, Y) to a cell coordinate (cell_x, cell_y)



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# File 'lib/game_2d/game_space.rb', line 237

def cell_at_point(x, y)
  [x / Entity::WIDTH, y / Entity::HEIGHT ]
end

#cells_at_points(coords) ⇒ Object

Translate multiple subpixel points (X, Y) to a set of cell coordinates (cell_x, cell_y)



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# File 'lib/game_2d/game_space.rb', line 243

def cells_at_points(coords)
  coords.collect {|x, y| cell_at_point(x, y) }.to_set
end

#cells_overlapping(x, y) ⇒ Object

Retrieve list of cells that overlap with a theoretical entity at position [x, y] (in subpixels).



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# File 'lib/game_2d/game_space.rb', line 295

def cells_overlapping(x, y)
  cells_at_points(corner_points_of_entity(x, y)).collect {|cx, cy| at(cx, cy) }
end

#check_for_grid_corruption ⇒ Object

Assertion



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# File 'lib/game_2d/game_space.rb', line 401

def check_for_grid_corruption
  0.upto(@cell_height - 1) do |cell_y|
    0.upto(@cell_width - 1) do |cell_x|
      cell = at(cell_x, cell_y)
      cell.each do |entity|
        ok = cells_overlapping(entity.x, entity.y)
        unless ok.include? cell
          raise "#{entity} shouldn't be in cell #{cell}"
        end
      end
    end
  end
  @registry.values.each do |entity|
    cells_overlapping(entity.x, entity.y).each do |cell|
      unless cell.include? entity
        raise "Expected #{entity} to be in cell #{cell}"
      end
    end
  end
end

#check_for_registry_leaks ⇒ Object

Assertion. Useful server-side only



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# File 'lib/game_2d/game_space.rb', line 423

def check_for_registry_leaks
  expected = @players.size + @npcs.size
  actual = @registry.size
  if expected != actual
    raise "We have #{expected} game entities, #{actual} in registry (delta: #{actual - expected})"
  end
end

#copy_from(original) ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 105

def copy_from(original)
  establish_world(original.world_name, original.world_id, original.cell_width, original.cell_height)
  @highest_id = original.highest_id

  # @game and @storage should point to the same object (no clone)
  @game, @storage = original.game, original.storage

  # Registry should contain all objects - clone those
  original.all_registered.each {|ent| self << ent.clone }

  self
end

#corner_points_of_entity(x, y) ⇒ Object

Given the (X, Y) position of a theoretical entity, return the list of all the coordinates of its corners



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# File 'lib/game_2d/game_space.rb', line 249

def corner_points_of_entity(x, y)
  [
    [x, y],
    [x + Entity::WIDTH - 1, y],
    [x, y + Entity::HEIGHT - 1],
    [x + Entity::WIDTH - 1, y + Entity::HEIGHT - 1],
  ]
end

#cut(cell_x, cell_y, entity) ⇒ Object

Low-level remover



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# File 'lib/game_2d/game_space.rb', line 232

def cut(cell_x, cell_y, entity)
  at(cell_x, cell_y).delete entity
end

#deregister(entity) ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 202

def deregister(entity)
  fail "#{entity} not registered" unless registered?(entity)
  entity_list(entity).delete entity
  @registry.delete entity.registry_id
end

#doom(entity) ⇒ Object

Doom an entity (mark it to be deleted but don’t remove it yet)



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# File 'lib/game_2d/game_space.rb', line 372

def doom(entity); @doomed << entity; end

#doomed?(entity) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/game_2d/game_space.rb', line 374

def doomed?(entity); @doomed.include?(entity); end

#entities_at_point(x, y) ⇒ Object

Return a list of the entities (if any) at a subpixel point (X, Y)



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# File 'lib/game_2d/game_space.rb', line 259

def entities_at_point(x, y)
  at(*cell_at_point(x, y)).find_all do |e|
    e.x <= x && e.x > (x - Entity::WIDTH) &&
    e.y <= y && e.y > (y - Entity::HEIGHT)
  end
end

#entities_at_points(coords) ⇒ Object

Accepts a collection of (x, y) Returns a Set of entities



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# File 'lib/game_2d/game_space.rb', line 268

def entities_at_points(coords)
  coords.collect {|x, y| entities_at_point(x, y) }.flatten.to_set
end

#entities_bordering_entity_at(x, y) ⇒ Object

The set of entities that may be affected by an entity moving to (or from) the specified (x, y) coordinates This includes the coordinates of eight points just beyond the entity’s borders



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# File 'lib/game_2d/game_space.rb', line 276

def entities_bordering_entity_at(x, y)
  r = x + Entity::WIDTH - 1
  b = y + Entity::HEIGHT - 1
  entities_at_points([
    [x - 1, y], [x, y - 1], # upper-left corner
    [r + 1, y], [r, y - 1], # upper-right corner
    [x - 1, b], [x, b + 1], # lower-left corner
    [r + 1, b], [r, b + 1], # lower-right corner
  ])
end

#entities_overlapping(x, y) ⇒ Object

Retrieve set of entities that overlap with a theoretical entity created at position [x, y] (in subpixels)



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# File 'lib/game_2d/game_space.rb', line 289

def entities_overlapping(x, y)
  entities_at_points(corner_points_of_entity(x, y))
end

#entity_list(entity) ⇒ Object

List of entities by type matching the specified entity



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# File 'lib/game_2d/game_space.rb', line 167

def entity_list(entity)
  case entity
  when Player then @players
  else @npcs
  end
end

#establish_world(name, id, cell_width, cell_height) ⇒ Object

Width and height, measured in cells



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# File 'lib/game_2d/game_space.rb', line 72

def establish_world(name, id, cell_width, cell_height)
  @world_name = name
  @world_id = (id || SecureRandom.uuid).to_sym
  @cell_width, @cell_height = cell_width, cell_height

  # Outer array is X-indexed; inner arrays are Y-indexed
  # Therefore you can look up @grid[cell_x][cell_y] ...
  # However, for convenience, we make the grid two cells wider, two cells
  # taller.  Then we can populate the edge with Wall instances, and treat (0,
  # 0) as a usable coordinate.  (-1, -1) contains a Wall, for example.  The
  # at(), put(), and cut() methods do the translation, so only they should
  # access @grid directly
  @grid = Array.new(cell_width + 2) do |cx|
    Array.new(cell_height + 2) do |cy|
      Cell.new(cx-1, cy-1)
    end.freeze
  end.freeze

  # Top and bottom, including corners
  (-1 .. cell_width).each do |cell_x|
    put(cell_x, -1, Wall.new(self, cell_x, -1))                   # top
    put(cell_x, cell_height, Wall.new(self, cell_x, cell_height)) # bottom
  end

  # Left and right, skipping corners
  (0 .. cell_height - 1).each do |cell_y|
    put(-1, cell_y, Wall.new(self, -1, cell_y))                 # left
    put(cell_width, cell_y, Wall.new(self, cell_width, cell_y)) # right
  end

  self
end

#fire_duplicate_id(old_entity, new_entity) ⇒ Object

Override to be informed when trying to add an entity that we already have (registry ID clash)



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# File 'lib/game_2d/game_space.rb', line 176

def fire_duplicate_id(old_entity, new_entity); end

#fire_entity_not_found(entity) ⇒ Object

Override to be informed when trying to purge an entity that turns out not to exist



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# File 'lib/game_2d/game_space.rb', line 378

def fire_entity_not_found(entity); end

#good_camera_position_for(entity, screen_width, screen_height) ⇒ Object

Used client-side only. Determine an appropriate camera position, given the specified window size, and preferring that the specified entity be in the center. Inputs and outputs are in pixels



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# File 'lib/game_2d/game_space.rb', line 434

def good_camera_position_for(entity, screen_width, screen_height)
  # Given plenty of room, put the entity in the middle of the screen
  # If doing so would expose the area outside the world, move the camera just enough
  # to avoid that
  # If the world is smaller than the window, center it

#   puts "Screen in pixels is #{screen_width}x#{screen_height}; world in pixels is #{pixel_width}x#{pixel_height}"
  camera_x = if screen_width > pixel_width
    (pixel_width - screen_width) / 2 # negative
  else
    [[entity.pixel_x - screen_width/2, pixel_width - screen_width].min, 0].max
  end
  camera_y = if screen_height > pixel_height
    (pixel_height - screen_height) / 2 # negative
  else
    [[entity.pixel_y - screen_height/2, pixel_height - screen_height].min, 0].max
  end

#   puts "Camera at #{camera_x}x#{camera_y}"
  [ camera_x, camera_y ]
end

#height ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 150

def height; @cell_height * Entity::HEIGHT; end

#load ⇒ Object

TODO: Handle this while server is running and players are connected TODO: Handle resizing the space



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# File 'lib/game_2d/game_space.rb', line 138

def load
  @highest_id = @storage[:highest_id]
  @storage[:npcs].each do |json|
    puts "Loading #{json.inspect}"
    self << Serializable.from_json(json)
  end
  self
end

#next_id ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 152

def next_id
  "R#{@highest_id += 1}".to_sym
end

#pixel_height ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 148

def pixel_height; @cell_height * Entity::CELL_WIDTH_IN_PIXELS; end

#pixel_width ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 147

def pixel_width; @cell_width * Entity::CELL_WIDTH_IN_PIXELS; end

#process_moving_entity(entity) ⇒ Object

Execute a block during which an entity may move If it did, we will update the grid appropriately, and wake nearby entities

All entity motion should be passed through this method



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# File 'lib/game_2d/game_space.rb', line 326

def process_moving_entity(entity)
  unless registered?(entity)
    puts "#{entity} not in registry yet, no move to process"
    yield
    return
  end

  before_x, before_y = entity.x, entity.y

  yield

  if moved = (entity.x != before_x || entity.y != before_y)
    update_grid_for_moved_entity(entity, before_x, before_y)
    # Note: Maybe we should only wake entities in either set
    # and not both.  For now we'll wake them all
    (
      entities_bordering_entity_at(before_x, before_y) +
      entities_bordering_entity_at(entity.x, entity.y)
    ).each(&:wake!)
  end

  moved
end

#purge_doomed_entities ⇒ Object

Actually remove all previously-marked entities. Wakes neighbors



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# File 'lib/game_2d/game_space.rb', line 381

def purge_doomed_entities
  @doomed.each do |entity|
    if registered?(entity)
      entity.destroy!
      deregister(entity)
      entities_bordering_entity_at(entity.x, entity.y).each(&:wake!)
      remove_entity_from_grid(entity)
    else
      fire_entity_not_found(entity)
    end
  end
  @doomed.clear
end

#put(cell_x, cell_y, entity) ⇒ Object

Low-level adder



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# File 'lib/game_2d/game_space.rb', line 227

def put(cell_x, cell_y, entity)
  at(cell_x, cell_y) << entity
end

#register(entity) ⇒ Object

Returns nil if registration worked, or the exact same object was already registered If another object was registered, calls fire_duplicate_id and then returns the previously-registered object



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# File 'lib/game_2d/game_space.rb', line 182

def register(entity)
  reg_id = entity.registry_id
  old = @registry[reg_id]
  return nil if old.equal? entity
  if old
    fire_duplicate_id(old, entity)
    return old
  end
  @registry[reg_id] = entity
  entity_list(entity) << entity
  nil
end

#registered?(entity) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/game_2d/game_space.rb', line 195

def registered?(entity)
  return false unless old = @registry[entity.registry_id]
  return true if old.equal? entity
  fail("Registered entity #{old} has ID #{old.object_id}; " +
    "passed entity #{entity} has ID #{entity.object_id}")
end

#remove_entity_from_grid(entity) ⇒ Object

Remove the entity from the grid



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# File 'lib/game_2d/game_space.rb', line 305

def remove_entity_from_grid(entity)
  cells_overlapping(entity.x, entity.y).each do |s|
    raise "#{entity} not where expected" unless s.delete entity
  end
end

#save ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 127

def save
  @storage[:world_name] = @world_name
  @storage[:world_id] = @world_id
  @storage[:cell_width], @storage[:cell_height] = @cell_width, @cell_height
  @storage[:highest_id] = @highest_id
  @storage[:npcs] = @npcs
  @storage.save
end

#update ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 395

def update
  @registry.values.find_all(&:moving?).each(&:update)
  purge_doomed_entities
end

#update_grid_for_moved_entity(entity, old_x, old_y) ⇒ Object

Update grid after an entity moves



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# File 'lib/game_2d/game_space.rb', line 312

def update_grid_for_moved_entity(entity, old_x, old_y)
  cells_before = cells_overlapping(old_x, old_y)
  cells_after = cells_overlapping(entity.x, entity.y)

  (cells_before - cells_after).each do |s|
    raise "#{entity} not where expected" unless s.delete entity
  end
  (cells_after - cells_before).each {|s| s << entity }
end

#width ⇒ Object 



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# File 'lib/game_2d/game_space.rb', line 149

def width; @cell_width * Entity::WIDTH; end