DoW Smooth Scroll

#===============================================================
# ● [VX] ◦ Smooth Scrolling ◦ □
# * Nice scrolling effect like an action game~! *
# *   Ported from XP Version (by Toby Zerner)   *
#--------------------------------------------------------------
# ◦ by Woratana [[email protected]]
# ◦ Thaiware RPG Maker Community
# ◦ Released on: 08/02/2009
# ◦ Version: 1.0
#--------------------------------------------------------------
# ◦ Compatibility:
#--------------------------------------------------------------
# □ This script will rewrite 6 method(s):
#     Game_Map.start_scroll
#     Game_Map.scroll_up
#     Game_Map.scroll_down
#     Game_Map.scroll_left
#     Game_Map.scroll_right
#     Game_Map.update_scroll
#
# □ This script will alias 1 method(s):
#     Game_Map.setup_scroll
#
# □ This script would crash with other custom scripts that rewrite same method(s)
#
# □ This script may not work with maps that use loop.
#--------------------------------------------------------------
# ◦ Installation:
#--------------------------------------------------------------
# 1) This script should be placed JUST AFTER ▼ Materials.
#
# □ Like this:
# ▼ Materials
# * Smooth Scrolling
# ...
# ...
# ▼ Main Process
# Main
#
# 2) Setup this script in Setup Part below.
#
#--------------------------------------------------------------
# ◦ How to use:
#--------------------------------------------------------------
# □ Just place this script and try moving player in your game.
#
#=================================================================

class Game_System

  #=================================================================
  # ++ Setup Part
  #-----------------------------------------------------------------
  DEFAULT_DECELERATION_START = 4 # (default: 4)
  # How fast before it will start decelerating (Higher = Start Faster)
  # You can change this value in game by call script:
  #   $game_system.decel_start = (value)

  DEFAULT_DECELERATION_SPEED = 4 # (default: 4)
  # How fast it will decelerate each frame (Higher = Decelerate Faster)
  # You can change this value in game by call script:
  #   $game_system.decel_speed = (value)
  #-----------------------------------------------------------------

  def decel_start
    @decel_start ||= DEFAULT_DECELERATION_START
    return @decel_start
  end

  def decel_speed
    @decel_speed ||= DEFAULT_DECELERATION_SPEED
    return @decel_speed
  end

  def decel_start=(value)
    @decel_start = value
  end

  def decel_speed=(value)
    @decel_speed = value
  end
end

class Game_Map
  #--------------------------------------------------------------------------
  # * Scroll Setup
  #--------------------------------------------------------------------------
  alias wora_smoscr_gammap_setscr setup_scroll unless $@
  def setup_scroll(*args)
    wora_smoscr_gammap_setscr(*args)
    # Initialize smooth scrolling variables
    # scroll_remain: the number of pixels * 4 the still need to be scrolled
    @scroll_remain_x = 0
    @scroll_remain_y = 0
    # scroll_take: the number of pixels * 4 that are being scrolled every frame
    #   i.e. scrolling speed
    @scroll_take_x = 0
    @scroll_take_y = 0
    # scroll_decel: variables for calculating decelaration
    @scroll_decel_x = 0
    @scroll_decel_y = 0
  end
  #--------------------------------------------------------------------------
  # * Start Scroll
  #--------------------------------------------------------------------------
  def start_scroll(direction, distance, speed)
    # Set scrolling variables
    distance          = distance.ceil * 256
    @scroll_direction = direction
    @scroll_speed     = speed
    @scroll_rest      = distance
    # Execute scrolling
    case @scroll_direction
    when 2  # Down
      scroll_down(@scroll_rest)
    when 4  # Left
      scroll_left(@scroll_rest)
    when 6  # Right
      scroll_right(@scroll_rest)
    when 8  # Up
      scroll_up(@scroll_rest)
    end
  end
  #--------------------------------------------------------------------------
  # * Scroll Down
  #--------------------------------------------------------------------------
  def scroll_down(distance)
    # Ceil the distance
    distance = distance.ceil
    # If the map is scrolling from an event command, then use that scroll speed
    if scrolling? then @scroll_take_y = 2 ** @scroll_speed
    # If the map is not scrolling
    else
      # Make sure the distance is always divisible by 4
      if distance.ceil % 4 == 0 then @scroll_take_y = distance.ceil
      elsif distance.ceil % 4 <= 2 then @scroll_take_y = distance.ceil - distance.ceil % 4
      else @scroll_take_y = distance.ceil + (4 - (distance.ceil % 4)) end
    end
    # If scrolling coordinates are inside the map's boundaries
    unless @display_y + @scroll_remain_y + distance > (self.height - 13) * 256
      # Add onto the amount left to be scrolled
      @scroll_remain_y += distance
    end
  end
  #--------------------------------------------------------------------------
  # * Scroll Left
  #--------------------------------------------------------------------------
  def scroll_left(distance)
    # Ceil the distance
    distance = distance.ceil
    # If the map is scrolling from an event command, then use that scroll speed
    if scrolling? then @scroll_take_x = 2 ** @scroll_speed
    # If the map is not scrolling
    else
      # Make sure the distance is always divisible by 4
      if distance.ceil % 4 == 0 then @scroll_take_x = distance.ceil
      elsif distance.ceil % 4 <= 2 then @scroll_take_x = distance.ceil - distance.ceil % 4
      else @scroll_take_x = distance.ceil + (4 - (distance.ceil % 4)) end
    end
    # If scrolling coordinates are inside the map's boundaries
    unless @display_x - @scroll_remain_x - distance < 0
      # Add onto the amount left to be scrolled
      @scroll_remain_x -= distance
    end
  end
  #--------------------------------------------------------------------------
  # * Scroll Right
  #--------------------------------------------------------------------------
  def scroll_right(distance)
    # Ceil the distance
    distance = distance.ceil
    # If the map is scrolling from an event command, then use that scroll speed
    if scrolling? then @scroll_take_x = 2 ** @scroll_speed
    # If the map is not scrolling
    else
      # Make sure the distance is always divisible by 4
      if distance.ceil % 4 == 0 then @scroll_take_x = distance.ceil
      elsif distance.ceil % 4 <= 2 then @scroll_take_x = distance.ceil - distance.ceil % 4
      else @scroll_take_x = distance.ceil + (4 - (distance.ceil % 4)) end
    end
    # If scrolling coordinates are inside the map's boundaries
    unless @display_x + @scroll_remain_x + distance > (self.width - 17) * 256
      # Add onto the amount left to be scrolled
      @scroll_remain_x += distance
    end
  end
  #--------------------------------------------------------------------------
  # * Scroll Up
  #--------------------------------------------------------------------------
  def scroll_up(distance)
    # Ceil the distance
    distance = distance.ceil
    # If the map is scrolling from an event command, then use that scroll speed
    if scrolling? then @scroll_take_y = 2 ** @scroll_speed
    # If the map is not scrolling
    else
      # Make sure the distance is always divisible by 4
      if distance.ceil % 4 == 0 then @scroll_take_y = distance.ceil
      elsif distance.ceil % 4 <= 2 then @scroll_take_y = distance.ceil - distance.ceil % 4
      else @scroll_take_y = distance.ceil + (4 - (distance.ceil % 4)) end
    end
    # If scrolling coordinates are inside the map's boundaries
    unless @display_y - @scroll_remain_y - distance < 0
      # Add onto the amount left to be scrolled
      @scroll_remain_y -= distance
    end
  end
  #--------------------------------------------------------------------------
  # * Update Scroll
  #--------------------------------------------------------------------------
  def update_scroll
    # If the map is still scrolling
    if @scroll_rest > 0 then @scroll_rest -= 2 ** @scroll_speed end

    # If the x axis needs to be scrolled to the right
    if @scroll_remain_x > 0
      # If the amount to be scrolled is close enough to 0 to decelerate
      if @scroll_remain_x <= @scroll_take_x * $game_system.decel_start
        old_display_x = @display_x
        # Add onto the deceleration variable
        @scroll_decel_x += $game_system.decel_speed
        # Work out how much to scroll
        distance = [@scroll_take_x - @scroll_decel_x, 4].max
        # If the scrolling coordinates are within the map's boundaries
        unless @display_x + distance > (self.width - 17) * 256
          @display_x += distance
          @parallax_x += distance
        end
        # Subtract the amount that was scrolled
        @scroll_remain_x += old_display_x - @display_x
        if @scroll_remain_x < 0 then @scroll_remain_x = 0 end
      # Otherwise, scroll at a normal speed
      else
        # Reset the deceleration variable
        @scroll_decel_x = 0
        # If the scrolling coordinates are out of range
        if @display_x + @scroll_take_x > (self.width - 17) * 256
          @display_x = (self.width - 20) * 256
          @scroll_remain_x = 0
        # Otherwise, scroll normally
        else
          @display_x += @scroll_take_x
          @parallax_x += @scroll_take_x
          @scroll_remain_x -= @scroll_take_x
        end
      end

    # If the x axis needs to be scrolled to the left
    elsif @scroll_remain_x < 0
      # If the amount to be scrolled is close enough to 0 to decelerate
      if @scroll_remain_x >= -@scroll_take_x * $game_system.decel_start
        old_display_x = @display_x
        # Add onto the deceleration variable
        @scroll_decel_x += $game_system.decel_speed
        # Work out how much to scroll
        distance = [@scroll_take_x - @scroll_decel_x, 4].max
        # If the scrolling coordinates are within the map's boundaries
        unless @display_x - distance < 0
          @display_x -= distance
          @parallax_x -= distance
        end
        # Subtract the amount that was scrolled
        @scroll_remain_x += old_display_x - @display_x
        if @scroll_remain_x > 0 then @scroll_remain_x = 0 end
      # Otherwise, scroll at a normal speed
      else
        # Reset the deceleration variable
        @scroll_decel_x = 0
        # If the scrolling coordinates are out of range
        if @display_x - @scroll_take_x < 0
          @display_x = 0
          @scroll_remain_x = 0
        # Otherwise, scroll normally
        else
          @display_x -= @scroll_take_x
          @parallax_x -= @scroll_take_x
          @scroll_remain_x += @scroll_take_x
        end
      end

    # If no x scrolling needs to be done, reset the deceleration variable
    else @scroll_decel_x = 0 end

    # If the y axis needs to be scrolled downwards
    if @scroll_remain_y > 0
      # If the amount to be scrolled is close enough to 0 to decelerate
      if @scroll_remain_y <= @scroll_take_y * $game_system.decel_start
        old_display_y = @display_y
        # Add onto the deceleration variable
        @scroll_decel_y += $game_system.decel_speed
        # Work out how much to scroll
        distance = [@scroll_take_y - @scroll_decel_y, 4].max
        # If the scrolling coordinates are within the map's boundaries
        unless @display_y + distance > (self.height - 13) * 256
          @display_y += distance
          @parallax_y += distance
        end
        # Subtract the amount that was scrolled
        @scroll_remain_y += old_display_y - @display_y
        if @scroll_remain_y < 0 then @scroll_remain_y = 0 end
      # Otherwise, scroll at a normal speed
      else
        # Reset the deceleration variable
        @scroll_speed_accel_y = 0
        # If the scrolling coordinates are out of range
        if @display_y + @scroll_take_y > (self.height - 13) * 256
          @display_y = (self.height - 15) * 256
          @scroll_remain_y = 0
        # Otherwise, scroll normally
        else
          @display_y += @scroll_take_y
          @parallax_y += @scroll_take_y
          @scroll_remain_y -= @scroll_take_y
        end
      end

    # If the y axis needs to be scrolled upwards
    elsif @scroll_remain_y < 0
      # If the amount to be scrolled is close enough to 0 to decelerate
      if @scroll_remain_y >= -@scroll_take_y * $game_system.decel_start
        old_display_y = @display_y
        # Add onto the deceleration variable
        @scroll_decel_y += $game_system.decel_speed
        # Work out how much to scroll
        distance = [@scroll_take_y - @scroll_decel_y, 4].max
        # If the scrolling coordinates are within the map's boundaries
        unless @display_y - distance < 0
          @display_y -= distance
          @parallax_y -= distance
        end
        # Subtract the amount that was scrolled
        @scroll_remain_y += old_display_y - @display_y
        if @scroll_remain_y > 0 then @scroll_remain_y = 0 end
      # Otherwise, scroll at a normal speed
      else
        # Reset the deceleration variable
        @scroll_speed_accel_y = 0
        # If the scrolling coordinates are out of range
        if @display_y - @scroll_take_y < 0
          @display_y = 0
          @scroll_remain_y = 0
        # Otherwise, scroll normally
        else
          @display_y -= @scroll_take_y
          @parallax_y -= @scroll_take_y
          @scroll_remain_y += @scroll_take_y
        end
      end

    # If no y scrolling needs to be done, reset the deceleration variable
    else
      @scroll_decel_y = 0
    end
  end
end