[BUG] Snake turns to wrong direction -- Fixed

[BernaTameirao]

So, there was an error (issue #500 ) that if you started the game, and specifically pressed the left-arrow or A-button, the snake would turn to the right instead of left.

It was because of this piece of code, localized on prefabs/snake.py:

    # In autoplay mode, start with zero velocity so autoplay can set the first direction
    # Otherwise start moving right
    if autoplay_mode:
        initial_dx, initial_dy = 0, 0
    else:
        initial_dx, initial_dy = 1, 0

It initialized the initial_dx with 1, that meant to move right.

The fix sets the initial direction to (0, 0) when the game starts in manual mode, so the first user input defines the direction.

[BernaTameirao]

So, this PR fixes a bug where pressing the left arrow (or A) at the very start of the game would incorrectly turn the snake to the right.

The snake was initialized with initial_dx = 1, meaning it always had an initial orientation to the right, even when speed was zero.
My first fix removed that assumption, allowing the snake to start oriented in any direction.
However, several parts of the game logic and the tests assume that the snake starts the game facing right, even if it's not moving yet. And the player cannot turn left from the initial state, only up, down, or keep going right.

I prevented the original bug, through changing the initial orientation of the snake sprite to the right.
This preserves game rules and makes all tests pass again.

[JeanJPNM]

This doesn't really fix the problem, now if someone wants to start with the up arrow (or w) the same thing will happen

[BernaTameirao]

@JeanJPNM I don't think I understand your proposition.

What I did was align the sprite with its initially assigned orientation in the code. So, whenever the game starts, the snake is turned to the right, and will respond as it should. The rest of the game stays exactly the same.

I just tested, and it doesn't have any error if the up-arrow is pressed, nor any other possible direction (down, or right).

[JeanJPNM]

My bad, I forgot to take the sprite into consideration.