Trying to get character movement similar to FinalFantasy V or VI. The character should move smoothly but always stop moving directly over a tile. Tiles are 64x64.

character.cr

def initialize
  @tile_x = 9
  @tile_y = 7
  @fine_x = 0
  @fine_y = 0
end
 
def draw(renderer)
  renderer.copy(sprite, dstrect: SDL::Rect[
                                      @tile_x * 64 + @fine_x, 
                                      @tile_y * 64 + @fine_y, 
                                      64, 
                                      64])
end

def move(x, y)
  @fine_x += x
  @fine_y += y
  if @fine_x <= -64
    @tile_x -= 1
    @fine_x = 0
  end
  if @fine_y <= -64
    @tile_y -= 1
    @fine_y = 0
  end
  if @fine_x >= 64
    @tile_x += 1
    @fine_x = 0
  end
  if @fine_y >= 64
    @tile_y += 1
    @fine_y = 0
  end
  return @fine_x.zero? && @fine_y.zero?
end

game_loop.cr

character = Character.new
loop do
  case event = SDL::Event.poll
  when SDL::Event::Quit
    break
  when SDL::Event::Keyboard
    case event.sym
    when .escape?
      @game_running = false
    when .right?
      character.move(1, 0)
    end if event.keydown?
  end
  renderer.draw_color = SDL::Color[0, 0, 0, 255]
  renderer.clear

  character.draw(renderer)
  renderer.present
  break unless @game_running
end

This current setup omits all of the SDL setup code. Running this code makes the character move 1px at a time but only while holding the arrow key down. I'm leaving off the other directions for now because if I can get moving to the right, then I can duplicate that for the other directions.