go-snake 🐍

Go CLI implementation of Snake game, using channels.
NB: this code works only with ANSI terminals.

Demo

Resize the terminal window to change the "difficulty".

Fruit Spawn Algorithm

To prevent the fruit from spawning over the snake, we first get a pair of random indexes f.x and f.y and we check if that location is already occupied by the snake. If so, we save those indexes and iterate over the columns (f.y) and rows (f.x) of the board, starting from f.y+1 and f.x+1. At each cycle we check if the new location is still occupied by the snake:

• If not we've found our fruit coordinates;
• otherwise we increase f.x by one (or f.y, for the external loop). When the index reaches the border (BL or BH), we reset it to 1, so it can make a complete cycle, and stop when they get to f.x or f.y (remember we started from f.x+1 and f.y+1).

This way we got a random starting point for our fruit spawn location and, in case it's not valid, we iteratively check for free coordinates.

f.x = rand.Intn(BL-2) + 1
f.y = rand.Intn(BH-2) + 1

if b.xy[f.x][f.y] == HEAD || b.xy[f.x][f.y] == BODY {
  if f.x == 1 || f.x == BL-1 {
    f.x = BL / 2
  }
  if f.y == 1 || f.y == BH-1 {
    f.y = BH / 2
  }
  found := false
  j := f.y
  i := f.x
  for f.y += 1; f.y != j; f.y++ {
    for f.x += 1; f.x != i; f.x++ {
      if b.xy[f.x][f.y] != HEAD && b.xy[f.x][f.y] != BODY && b.xy[f.x][f.y] != BORDER {
        found = true
        break
      }
      if f.x == BL-1 {
        f.x = 1
      }
    }
    if found {
      break
    }
    if f.y == BH-1 {
      f.y = 1
    }
  }
}

References

• Read character from stdin without pressing enter: Windows, UNIX
• ANSI escape codes