arduino-snake/snake.ino

const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

// cursor position:
int x = 4;
int y = 4;
int z = 0;

// up: 1
// right: 2
// down: 3
// left: 4
int cur_dir = 0;
int snake_x = 4,
    snake_y = 4;

void setup() {
  //Serial.begin(9600);          // 9600 bps
  // Enable the Z pin
  pinMode(z, INPUT_PULLUP);
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  // initialize the pixel matrix:
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = HIGH;
    }
  }

  /*pixels[2][3] = LOW;
  pixels[3][2] = LOW;
  pixels[4][2] = LOW;
  pixels[4][3] = LOW;
  pixels[4][4] = LOW;*/
  pixels[snake_x][snake_y] = LOW;
}

void loop() {
  for (int i = 0; i < 420; ++i) {
    refresh_screen();
  }
  delay(42);
  if (!move_snake(read_sensors())) {
    switch(cur_dir)
    {
      case 0: // iddle
        // Just don't
      break;
      case 1: // up
        // Move
        if (snake_y+1 <= 7) {
          pixels[snake_x][++snake_y] = LOW;
        }
      break;
      case 2: // right
        // Move
        if (snake_x+1 <= 7) {
          pixels[++snake_x][snake_y] = LOW;
        }
      break;
      case 3: // down
        // Move
        if (snake_y-1 >= 0) {
          pixels[snake_x][--snake_y] = LOW;
        }
      break;
      case 4: // left
        // Move
        if (snake_x-1 >= 0) {
          pixels[--snake_x][snake_y] = LOW;
        }
      break;
    }
  }

  // draw the screen:
  refresh_screen();
}

// true if it has moved, false otherwise
bool move_snake(int dir) {
  // read input:
  switch(dir)
  {
    case 0: // iddle
      // Just don't
    break;
    case 1: // up
      // Move
      if (cur_dir != 3) {
        pixels[snake_x][++snake_y] = LOW;
        cur_dir = 1;
        return true;
      }
    break;
    case 2: // right
      // Move
      if (cur_dir != 4) {
        pixels[++snake_x][snake_y] = LOW;
        cur_dir = 2;
        return true;
      }
    break;
    case 3: // down
      // Move
      if (cur_dir != 1) {
        pixels[snake_x][--snake_y] = LOW;
        cur_dir = 3;
        return true;
      }
    break;
    case 4: // left
      // Move
      if (cur_dir != 2) {
        pixels[--snake_x][snake_y] = LOW;
        cur_dir = 4;
        return true;
      }
    break;
  }
  return false;
}

// iddle: 0
// up: 1
// right: 2
// down: 3
// left: 4
int read_sensors() {
  int clicked = digitalRead(z); // if 0, then clicked
  x = 7 - map(analogRead(A0), 0, 1021, 0, 7);
  Serial.print("Just read x=: ");
  Serial.print(x);
  Serial.print("\n");
  y = map(analogRead(A1), 0, 1021, 0, 7)+1;
  Serial.print("Just read y=: ");
  Serial.print(y);
  Serial.print("\n");

  if (x == 4 && y == 4) {
    Serial.print("We're iddle\n");
    return 0;
  }
  else if (abs(4-x) > abs(4-y)) // X
  {
    Serial.print("Let's consider x\n");
    if (x < 4) {
      Serial.print("Move right\n");
      return 2;
    } else {
      Serial.print("Move left\n");
      return 4;
    }
  }
  else
  {
    Serial.print("Let's consider y\n");
    if (y > 4) {
      Serial.print("Move up\n");
      return 1;
    } else {
      Serial.print("Move down\n");
      return 3;
    }
  }

  // set the new pixel position low so that the LED will turn on
  // in the next screen refresh:
}

/*bool to_right() {
  // read the sensors for X
  x = 7 - map(analogRead(A0), 0, 1021, 0, 7);
  Serial.print("rX is: ");
  Serial.print(x);
    Serial.print("\n");
  if ((x > 4 && cur_dir != 4) || // user inputs right and it isn't currently going left
      (cur_dir == 2 && (x == 4 && y == 4)) // user has no input and cur_dir is set
     ) {
      cur_dir = 2;
      return true;
  }
  return false;
}

bool to_left() {
  // read the sensors for X
  x = 7 - map(analogRead(A0), 0, 1021, 0, 7);
  Serial.print("lX is: ");
  Serial.print(x);
    Serial.print("\n");
  if ((x < 4 && cur_dir != 2) || // user inputs right and it isn't currently going left
      (cur_dir == 4 && (x == 4 && y == 4)) // user has no input and cur_left is set
     ) {
      cur_dir = 4;
      return true;
  }
  return false;
}

void blink(int x, int y)
{

  
}*/

void write_new_screen(int delay_write, int x, int y) {
  for (int i = 0; i < 20; ++i) {
    refresh_screen();
  }
  pixels[x][y] = LOW;
}

void refresh_screen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}