Adding the snake

Well, maybe not a snake yet, but a square that moves according to your wishes! In this section, you can try to apply what you have learned so far. If you don't know how to continue, you can either ask for help, or look at one way of solving the problems on the next page.

  1. In the lib folder, make a new file called snake.rs.

  2. Add the following line to the top of snake.rs

    
#![allow(unused_variables)]
fn main() {
use crate::lib::types::{Cell, SnakeHead, Grid};
}

  3. Add pub mod snake; right below the existing pub mod types;.

  4. Write a function that initializes the snake as a SnakeHead. SnakeHead is a struct that contains fields for a row, a column and a Cell value. The row and column values need to be i32 instead of u32. Why?

Defining a tuple

In fn main(), after the grid is initialized, we define a tuple for direction. direction.0 is the row value, direction.1 is the column value.


#![allow(unused_variables)]
fn main() {
let mut direction = (1, 0);
}

Movement

  1. In snake.rs, write a function that takes a mutable reference of the SnakeHead. It calculates a new position with direction values and the coordinates from SnakeHead and then returns a new SnakeHead with an updated position.

  2. Write a function that takes ownership of the grid and changes the color of the square, where the current SnakeHead is located. The grid is then the return value.

Adding User Input

  1. Add Events for up, down, left and right key.

  2. How does the direction.0 and the direction.1 value change, when each of these buttons is pushed? Implement it!

Changing the Game Loop

  1. Add this line to the top of main.rs:

    
#![allow(unused_variables)]
fn main() {
use crate::lib::snake;
}

  2. Call the functions in the following order:

  • update position of snake
  • update grid with position of snake
  • display frame

Run the game! Play the game!