Smooth Movement¶

For a better experience, the player figure should not jump from one tile to the next, but rather slide. This makes the drawing more complex. What you want to happen is something like this:

the player presses a move key
set a counter to 0
draw the player figure at the position + counter
increase the counter by one
repeat from 3. until the figure has completed its movement

This gets more complicated, because other things might happen in the meantime: the player presses another key that should be executed once the movement completes, or monsters move around as well. The code in main.py can handle this kind of situation already. You still need to tell it what to do. In this chapter, you will create a data structure for moves.

A new module¶

Start by defining what a “Move” is. A Move should represent a graphical element that moves on the screen. It needs a starting position, a direction and what graphical tile is moving. We also need a counter that tracks how far the movement has proceeded. This structure is generic enough that we can use it not only for the player, but also for other things.

Create a new Python file moves.py in the same directory as your other code. Insert the following code:

from typing import Callable
from pydantic import BaseModel

class Move(BaseModel):
    tile: str
    from_x: int
    from_y: int
    speed_x: int
    speed_y: int
    progress: int = 0
    complete: bool = False
    finished: Callable = None

Warning

Do not change any of these names, the code in main.py needs them.

Import the module¶

Now you can use the Move class in your program. First, the game.py module needs to know about it. Add on top of the game.py file:

from moves import Move

and add to the DungeonGame class:

moves: list[Move] = []

Test the program. It should still work although the movement looks the same as before.

Create moves¶

Every time the player moves, you would add a new Move object and add it to game.moves. The main.py module does the rest. Add to the move_player() function:

if direction == "right":
    move = Move(tile="player",
                from_x=game.x, from_y=game.y,
                speed_x = 2, speed_y = 0
                )
    game.moves.append(move)
    game.x += 1

When you start the game, you should see the figure moving smoothly to the right.

Add similar code for the other directions as well.

Hint

to make the figure move to the left, you will need a negative value. Try different speed parameters and see which one works best.

A secret door¶

You can use the moves mechanics for other things as well. Lets add a secret door that opens when you reach a specific location. You need the following steps to happen:

check if the player has reached the location opening the secret door
replace a wall by a floor tile
create a move of a wall tile

Implement all of this at the end of the move_player() function. Complete the following code:

if game.x == ... and ...:
   game.level[3][2] = "."  # wall in row 4 column 3
   move = Move(tile="wall",
               ...
   )

Callback functions (Optional)¶

Sometimes you may want something specific to happen exactly after a movement ends. A powerful mechanic for this kind of behavior is using a callback function. In the Move class, you can add callback functions that are called when the movement ends.

You don’t need this for any game feature right now, but maybe you get some good ideas from it. Here is a proof of concept. First, define the callback function:

def player_move_finished(game):
    """outputs the coordinates of the player"
    print(game.x, game.y)

Then specify the callback when creating a move:

move = Move(tile="player",
                from_x=game.x, from_y=game.y,
                speed_x = 2, speed_y = 0,
                callback = player_move_finished,
                )
game.moves.append(move)

Note

Do not include round brackets after player_move_finished, because main.py takes care of calling it.