Moving Screen help, like an overhead scrolling shooter Options

[Claytonic]

I am wondering how to make a minigame like an overhead-scrolling-shooter where the screen moves at a slow pace on a set route while the player can move about freely within that space. I won't actually be using a plane, shooting down other ships.... What I think is hard to do is to keep the player trapped within the space shown on screen. This might be possible through eventing only, but may be easier with scripting? Can someone please help make this possible? (Or show me where someone has already made this?)

This post has been edited by Claytonic: Jan 12 2013, 03:44 PM

[Jens of Zanicuud]

You need some scripts to do that... Events and Common Events can't handle this efficiently.
Are you planning to scroll it like an Aero Fighter game (from south to north) or more like Gradius (from left to right)?

For a Gradius-like effect, you could try this one...

CODE

#===============================================================================
# ** Jens of Zanicuud horizontal scroll engine v 0.8
# - free use, just credit
# - free customization, just PM me the modified version
# - you can find me at www.rpgrevolution.com
#===============================================================================
# This script will confine the player between the screen's limits by setting
# a certain switch to ON (see next lines for a more precise description).
# This script could have some compatibility problem, since when the switch
# is active, it overruns the update method of the Game_Player class.
# Use it carefully and ask for troubleshooting anytime!
# NOTE: for now, it works ONLY with horizontal scrolling from LEFT to RIGHT!
#===============================================================================

#--------------------------------------------------------------------------
# ** Game_Player
#--------------------------------------------------------------------------
class Game_Player < Game_Character
  #--------------------------------------------------------------------------
  # * Constants
  #--------------------------------------------------------------------------
  #id of the switch which triggers the scroll game (e.g. 1 means you have to
  #set the Switch[0001] to ON.
  Scroll_game_switch = 1
  #--------------------------------------------------------------------------
  # * Aliases
  #--------------------------------------------------------------------------
  alias scroll_system_center center
  alias scroll_update        update
  alias scroll_moving        moving?
  #--------------------------------------------------------------------------
  # * Center camera on the player
  #--------------------------------------------------------------------------
  def center(x, y)
    if !$game_switches[Scroll_game_switch]
      scroll_system_center(x,y)
    end
  end
  #--------------------------------------------------------------------------
  # * Scroll_Moving?
  #--------------------------------------------------------------------------
  def scroll_moving?
    if @real_x  <= $game_map.display_x
      if @real_y != @y * 128
        return true
      else
        return false
      end
    elsif @real_x  >= $game_map.display_x + 640*4 - 128
      if @real_y != @y * 128
        return true
      else
        return false
      end
    else
      return moving?
    end
  end
  #--------------------------------------------------------------------------
  # * Update
  #--------------------------------------------------------------------------
  def update
    if $game_switches[Scroll_game_switch]
    last_moving = moving?
    unless scroll_moving? or $game_system.map_interpreter.running? or
           @move_route_forcing or $game_temp.message_window_showing
      case Input.dir4
      when 2
        move_down
      when 4
        move_left
      when 6
        move_right
      when 8
        move_up
      end
      update_move
    end
    last_real_x = @real_x
    last_real_y = @real_y
    super
    unless moving?
      if last_moving
        result = check_event_trigger_here([1,2])
        if result == false
          unless $DEBUG and Input.press?(Input::CTRL)
            if @encounter_count > 0
              @encounter_count -= 1
            end
          end
        end
      end
      if Input.trigger?(Input::C)
        check_event_trigger_here([0])
        check_event_trigger_there([0,1,2])
        end
      end
  else
    scroll_update
  end
end
  #--------------------------------------------------------------------------
  # * Update Move
  #--------------------------------------------------------------------------
  def update_move
   if $game_switches[Scroll_game_switch]
     screen = [$game_map.display_x,
               $game_map.display_y,
               $game_map.display_x + 640*4 - 128,
               $game_map.display_y + 480*4 - 128]
     distance = 2 ** @move_speed
     if @y * 128 > @real_y
       @real_y = [[@real_y + distance, @y * 128].min, screen[3]].min
       @real_x = [[screen[0], @real_x].max,screen[2]].min
       if @real_y  == screen[3]
         @y = @real_y / 128
       end
     end
     if @x * 128 < @real_x
       @real_x = [[@real_x - distance, @x * 128].max, screen[0]].max
       @real_y = [[screen[1], @real_y].max,screen[3]].min
       if @real_x  == screen[0]
         @x = @real_x / 128
       end
     end
     if @x * 128 > @real_x
       @real_x = [[@real_x + distance, @x * 128].min, screen[2]].min
       @real_y = [[screen[1], @real_y].max,screen[3]].min
       if @real_x  == screen[2]
         @x = @real_x / 128
       end
     end
     if @y * 128 < @real_y
       @real_y = [[@real_y - distance, @y * 128].max, screen[1]].max
       @real_x = [[screen[0], @real_x].max,screen[2]].min
       if @real_y  == screen[1]
         @y = @real_y / 128
       end
     end
     if @walk_anime
      @anime_count += 1.5
     elsif @step_anime
      @anime_count += 1
     end
   else
     super
   end
end
  #--------------------------------------------------------------------------
  # * Update Stop
  #--------------------------------------------------------------------------
  def update_stop
    super
    if $game_switches[Scroll_game_switch]
      screen = [$game_map.display_x,
               $game_map.display_y,
               $game_map.display_x + 640*4 - 128,
               $game_map.display_y + 480*4 - 128]
      @real_x = [[screen[0], @real_x].max,screen[2]].min
      @real_y = [[screen[1], @real_y].max,screen[3]].min
    end
  end
end

Jens

[Claytonic]

You need some scripts to do that... Events and Common Events can't handle this efficiently.
Are you planning to scroll it like an Aero Fighter game (from south to north) or more like Gradius (from left to right)?

For a Gradius-like effect, you could try this one...

CODE

#===============================================================================
# ** Jens of Zanicuud horizontal scroll engine v 0.8
# - free use, just credit
# - free customization, just PM me the modified version
# - you can find me at www.rpgrevolution.com
#===============================================================================
# This script will confine the player between the screen's limits by setting
# a certain switch to ON (see next lines for a more precise description).
# This script could have some compatibility problem, since when the switch
# is active, it overruns the update method of the Game_Player class.
# Use it carefully and ask for troubleshooting anytime!
# NOTE: for now, it works ONLY with horizontal scrolling from LEFT to RIGHT!
#===============================================================================

#--------------------------------------------------------------------------
# ** Game_Player
#--------------------------------------------------------------------------
class Game_Player < Game_Character
  #--------------------------------------------------------------------------
  # * Constants
  #--------------------------------------------------------------------------
  #id of the switch which triggers the scroll game (e.g. 1 means you have to
  #set the Switch[0001] to ON.
  Scroll_game_switch = 1
  #--------------------------------------------------------------------------
  # * Aliases
  #--------------------------------------------------------------------------
  alias scroll_system_center center
  alias scroll_update        update
  alias scroll_moving        moving?
  #--------------------------------------------------------------------------
  # * Center camera on the player
  #--------------------------------------------------------------------------
  def center(x, y)
    if !$game_switches[Scroll_game_switch]
      scroll_system_center(x,y)
    end
  end
  #--------------------------------------------------------------------------
  # * Scroll_Moving?
  #--------------------------------------------------------------------------
  def scroll_moving?
    if @real_x  <= $game_map.display_x
      if @real_y != @y * 128
        return true
      else
        return false
      end
    elsif @real_x  >= $game_map.display_x + 640*4 - 128
      if @real_y != @y * 128
        return true
      else
        return false
      end
    else
      return moving?
    end
  end
  #--------------------------------------------------------------------------
  # * Update
  #--------------------------------------------------------------------------
  def update
    if $game_switches[Scroll_game_switch]
    last_moving = moving?
    unless scroll_moving? or $game_system.map_interpreter.running? or
           @move_route_forcing or $game_temp.message_window_showing
      case Input.dir4
      when 2
        move_down
      when 4
        move_left
      when 6
        move_right
      when 8
        move_up
      end
      update_move
    end
    last_real_x = @real_x
    last_real_y = @real_y
    super
    unless moving?
      if last_moving
        result = check_event_trigger_here([1,2])
        if result == false
          unless $DEBUG and Input.press?(Input::CTRL)
            if @encounter_count > 0
              @encounter_count -= 1
            end
          end
        end
      end
      if Input.trigger?(Input::C)
        check_event_trigger_here([0])
        check_event_trigger_there([0,1,2])
        end
      end
  else
    scroll_update
  end
end
  #--------------------------------------------------------------------------
  # * Update Move
  #--------------------------------------------------------------------------
  def update_move
   if $game_switches[Scroll_game_switch]
     screen = [$game_map.display_x,
               $game_map.display_y,
               $game_map.display_x + 640*4 - 128,
               $game_map.display_y + 480*4 - 128]
     distance = 2 ** @move_speed
     if @y * 128 > @real_y
       @real_y = [[@real_y + distance, @y * 128].min, screen[3]].min
       @real_x = [[screen[0], @real_x].max,screen[2]].min
       if @real_y  == screen[3]
         @y = @real_y / 128
       end
     end
     if @x * 128 < @real_x
       @real_x = [[@real_x - distance, @x * 128].max, screen[0]].max
       @real_y = [[screen[1], @real_y].max,screen[3]].min
       if @real_x  == screen[0]
         @x = @real_x / 128
       end
     end
     if @x * 128 > @real_x
       @real_x = [[@real_x + distance, @x * 128].min, screen[2]].min
       @real_y = [[screen[1], @real_y].max,screen[3]].min
       if @real_x  == screen[2]
         @x = @real_x / 128
       end
     end
     if @y * 128 < @real_y
       @real_y = [[@real_y - distance, @y * 128].max, screen[1]].max
       @real_x = [[screen[0], @real_x].max,screen[2]].min
       if @real_y  == screen[1]
         @y = @real_y / 128
       end
     end
     if @walk_anime
      @anime_count += 1.5
     elsif @step_anime
      @anime_count += 1
     end
   else
     super
   end
end
  #--------------------------------------------------------------------------
  # * Update Stop
  #--------------------------------------------------------------------------
  def update_stop
    super
    if $game_switches[Scroll_game_switch]
      screen = [$game_map.display_x,
               $game_map.display_y,
               $game_map.display_x + 640*4 - 128,
               $game_map.display_y + 480*4 - 128]
      @real_x = [[screen[0], @real_x].max,screen[2]].min
      @real_y = [[screen[1], @real_y].max,screen[3]].min
    end
  end
end

Jens

I tried loking through the code, again I'm not nuch of a scripter, and I couldn't identify the exact spot where the code controls the screen movement, but...would it be possible to change the moving switch to a variable and then change the code to be just like how it is but with up, down, left and right sections for what the variable is set to?
How much different is the up-scrolling code versus the right-scrolling code?