public void FillCoin(Coin coin, int id)
{
int r = coin.size / 2;
for (int i = -r; i <= r; i++)
for (int j = -r; j <= r; j++)
if ((i * i) + (j * j) <= r * r)
// disallow snake overriding
if (!pointsHistory.ContainsKey(field[coin.x + i, coin.y + j]))
field[coin.x + i, coin.y + j] = id;
}
void createCoin()
{
Coin c = new Coin(259, 0, 3, 20, GetNewId());
c.ChangeLocation(randomPosition(20, gameField.Width), randomPosition(20, gameField.Height));
GetCollisions().FillCoin(c, c.id);
coins.Add(c);
}