Grid NextTurn()
{
GridSet targets;
GRID_SET_RESERVE(targets, m_cellMap.size() * 9);
for (GridKey key : m_cellMap)
{
int y = key.first;
int x = key.second;
targets.insert(MakeKeySafe(x - 1, y - 1));
targets.insert(MakeKeySafe(x - 1, y + 0));
targets.insert(MakeKeySafe(x - 1, y + 1));
targets.insert(MakeKeySafe(x + 1, y - 1));
targets.insert(MakeKeySafe(x + 1, y + 0));
targets.insert(MakeKeySafe(x + 1, y + 1));
targets.insert(MakeKeySafe(x + 0, y - 1));
targets.insert(MakeKeySafe(x + 0, y + 0));
targets.insert(MakeKeySafe(x + 0, y + 1));
}
Grid next(m_width, m_height);
for (GridKey key : targets)
{
int y = key.first;
int x = key.second;
bool target = FindCell(x, y);
int num = NumNeighbors(x, y);
// Any live cell with fewer than two live neighbors dies, as if caused by underpopulation.
// Any live cell with two or three live neighbors lives on to the next generation.
// Any live cell with more than three live neighbors dies, as if by overpopulation.
// Any dead cell with exactly three live neighbors becomes a live cell, as if by reproduction.
if (!target)
{
// Any dead cell with exactly three live neighbors becomes a live cell, as if by reproduction.
if (num == 3)
{
next.SetCell(x, y);
}
}
else if (num == 2 || num == 3)
{
// Any live cell with fewer than two live neighbors dies, as if caused by under population.
next.SetCell(x, y);
}
// Any live cell with more than three live neighbors dies, as if by overpopulation. ?
}
return std::move(next);
}
void PopulateRandomlyUntilCount(int count)
{
GRID_SET_RESERVE(m_cellMap, count);
for (int x = 0; x < m_width; ++x)
{
for (int y = 0; y < m_height; ++y)
{
if ((std::rand() % 16) == 0)
{
m_cellMap.insert(MakeKeySafe(x + 0, y + 0));
m_cellMap.insert(MakeKeySafe(x + 1, y + 0));
m_cellMap.insert(MakeKeySafe(x + 1, y + 1));
}
if ((std::rand() % 8) == 0)
{
m_cellMap.insert(MakeKeySafe(x, y));
}
if (m_cellMap.size() >= count)
{
return;
}
}
}
}
