A minimal rust implementation of Tetris

The goal of the exercise is to run the most minimalist terminal-running Tetris. Rendering is done using Termion and that's about it.

|                              |
|                              |
|                              |
|                              |
|                              |
|                              |
|                              |
|            OOOOOO            |
|            OOOOOO            |
|            OOOOOO            |
|            OOOOOO            |
|                              |
|                              |
|                              |
|                              |
|                              |
|                              |
|                              |
|                              |
|                              |
|                              |
|                           III|
|                           III|
|                           III|
|                           III|
|                           III|
|                           III|
|   ZZZ               ZZZ   III|
|   ZZZ               ZZZ   III|
|ZZZZZZTTT         ZZZZZZ   LLL|
|ZZZZZZTTT         ZZZZZZ   LLL|
|ZZZTTTTTTTTT      ZZZLLLLLLLLL|
|ZZZTTTTTTTTT      ZZZLLLLLLLLL|
--------------------------------

Install and run

Be sure so install Rust first.

Clone the repository, go the directory, run with cargo

git clone https://github.com/Keksoj/tetris.git
cd tetris
cargo run

The challenges and the solutions

I first thought of using (x, y) coordinates for representing the board and the shapes, but it is much easier to have just one axis and chuck it like so :

 200 201 202 203 204 205 206 207 208 209
 190 191 192 193 194 195 196 197 198 199
 // ------
  20  21  22  23  24  25  26  27  28  29
  10  11  12  13  14  15  16  17  18  19
   0   1   2   3   4   5   6   7   8   9

And a Tetromino is just a set of 4 coordinates:

struct Tetromino {
  blocks: [u8; 4],
}

Moving the pieces

• move a Tetromino one row down by doing -= 10 on all its coordinate.
• -= 1 to push it to the left, += 1 to the right
• Turning is done by changing the coordinates depending on the shape, by and recording the "spin", the number of turns.

Detecting collisions

There are a number of elegant ways to do this but I chose the rookie method :

1. compute the new coordinates
2. check for overlapping with the walls, the bottom, other pieces
3. performing the move or not

Ticking down AND accepting moves from the player

Wether or not it's moved around by the player, the Tetromino has to tick down every, say, one second. This is a case study for multi-threading and other nightmares. The easy way is to do this is to

1. set a mutable time stamp at every tick
2. check the elapsed time since the last tick, and if it's time :
3. perform the tick
4. reset the time stamp to now

let mut last_tick = std::time::SystemTime::now();

  loop {
      // takes user input and move the shape accordingly
      self.take_directions();

      if last_tick.elapsed().unwrap().as_millis() >= 1000 {
          
          // move the shape one square down
          self.tick();
          
          last_tick = std::time::SystemTime::now();
      }
  }