Frame stepping for DragonRuby

framestep.rb

# Frame stepping for DragonRuby - MIT License - (c) mooff 
# 
# 1. Copy to your_game/lib/framestep.rb (and require it) 
# 2. Add "return if FrameStep.tick" to your tick method 
# 3. Press Ctrl-/ in-game to activate, then / to advance 
# 
# Version 1.1 
# - Keep GTK tick count in step when frozen
module FrameStep
  SCREENSHOT_PATH = 'freeze-frame.png'

  class << self
    attr_accessor :step

    def toggle?
      $inputs.keyboard.control && $inputs.keyboard.key_down.forward_slash
    end

    def advance?
      $inputs.keyboard.key_down.forward_slash
    end

    def tick
      if toggle?
        @step = @step ? nil : 0
        @did_cap = false
        $inputs.clear
        puts "(FrameStep) #{@step ? 'Enter' : 'Leave'}"
      end

      if @step
        if advance?
          @step += 1
          @did_cap = false
          puts "(FrameStep) Advance: #{@step}"
        else
          Kernel.tick_count -= 1
        end

        if !@did_cap
          @did_cap = true
          $outputs.screenshots << { x: 0, y: 0, w: $grid.w, h: $grid.h, path: SCREENSHOT_PATH }
          $gtk.reset_sprite SCREENSHOT_PATH
          return false
        end

        $outputs.sprites << [0, 0, $grid.w, $grid.h, SCREENSHOT_PATH]
        return true
      else
        return false
      end
    end
  end
end

main.rb

def tick(args)
  return if FrameStep.tick
  update_state
  render_game
end

main_fancy.rb

def tick(args)
  if $gtk.development?
    render_cool_debug_overlay
    return if FrameStep.tick
  end

  update
  render
end

# Custom activation
def FrameStep.toggle?
  $inputs.keyboard.key_down.home
end

def FrameStep.advance?
  $inputs.keyboard.key_down.end
end