How can I jump on Gosu gem from Ruby?

Question

I'm trying to recreate a simple game but I'm stuck at the moment that I'm trying to make jump my character( or player). I've been checking the example from gosu but it's not really clear for me. Can someone help me?

Here is my window code:

class Game < Gosu::Window
  def initialize(background,player)
    super 640,480
    self.caption = "My First Game!"
    @background = background
    @player = player
    @player.warp(170,352)
    @x_back = @y_back = 0
    @allow_to_press = true
  end
# ...
def update
#...
   if Gosu.button_down? Gosu::KbSpace and @allow_to_press
      @allow_to_press = false
      @player.jump

    end



    end
end

Then my player class:

class Player
  def initialize(image)
    @image = image
    @x = @y = @vel_x = @vel_y = @angle = 0.0
    @score = 0
  end
  def warp(x,y)
    @x,@y = x,y
  end

  def draw

    @image.draw_rot(@x,@y,1,@angle,0.5,0.5,0.3,0.3)
  end
  def jump
    #@y -= 15 # THIS IS NOT CORRECT
  end
end

Basically, the idea is when u press Space, then the jump method is invoked and here i should be able to recreate an animation to move the "y" position up ( for example 15 px) and then go down again. Just i have on my mind change the value of @y variable but i don't know how to do it with an animation and then come back at the original point.

Thanks!

Answer 1

Finally I got it!

What I did is split the jump and an update method inside player:

class Player
  def initialize(image)
    @image = image
    @x = @y   = @angle = 0.0
    @score = @vel_y = @down_y = 0
    @allow = true
  end
  def warp(x,y)
    @x,@y = x,y
  end
  def update(jump_max)
      #Jump UP
      if @vel_y > 0
        @allow = false
        @vel_y.times do
          @y-=0.5
        end
        @vel_y-=1
      end

      #Jump DOWN
      if @vel_y < 0
        (@vel_y*-1).times do
          @y+=0.5
        end
        @vel_y+=1
      end
      check_jump
  end
  def draw
    @image.draw_rot(@x,@y,1,@angle,0.5,0.5,0.3,0.3)
  end
  def jump(original)
     @vel_y = original
     @down_y = original * -1

  end
  def check_jump
    if @vel_y == 0 and @allow == false
        @vel_y = @down_y
        @down_y = 0
        @allow = true
      end
    end
end

And then on my Game class

...

def initialize(background,player,enemy_picture)
    #size of the game
    super 640,480
    
    @original_y = 352
    @original_x = 170
    self.caption = "Le Wagon Game!"
    @background = background


       @player = player
        @player.warp(@original_x,@original_y)
        @enemy_anim = enemy_picture
        @enemy = Array.new
        #Scrolling effect
        @x_back = @y_back = 0
        @jump = true
        @jumpy = 25
      end

def update      
    if Gosu.button_down? Gosu::KbSpace and @jump
      @jump = false
       @player.jump(@jumpy)
    end
    @player.update(@jumpy)
end
def button_up(id)
    if id == Gosu::KbSpace
      @jump = true
    end
    super
  end

end

So now I can press Space and it goes up, after finish the transition, it goes down