private CellAction EvaluatePoint(Vector3 position)
{
byte neighborCount = 0;
int neighbors = 0;
/*
* A cell has 26 possible neighbors; All we care about is whether or not an adjacent cell is occupied.
* So, we are going to store that in an int and use only 26 of the bits, where each adjacent cell is represented by a bit,
* with 0 meaning that the cell is empty, and 1 meaning that it is occupied.
*
* A cell's neighbors are organized into three layers:
* TOP3 MID3 BTM3
* (1,1,1)------> X X X X X X X X X
* X X X X O X X X X
* X X X X X X X X X (-1,-1,-1) <-------
* ... where X's are adjacent to the cell of interest O
* We store that as this:
* TOP3: MID3: BTM3:
* top mid btm top ... ... ... ... ...
* XXX XXX XXX XXX XOX XXX XXX XXX XXX
* [0, 1, 2, ... ..., 24, 25]
*/
bool isCellOccupied = _cells.ContainsKey(position);
for (float x = position.x - xUnit; x <= position.x + xUnit; x++)
{
for (float y = position.x - yUnit; y <= position.y + yUnit; y++)
{
for (float z = position.z - zUnit; z <= position.z + zUnit; z++)
{
var vec = new Vector3(x, y, z);
if (_interestingCells.ContainsKey(vec))
{
if (position != vec)
{
// set this cell's bit to 1;
neighbors++;
neighborCount++;
}
}
// shift bit to the left;
neighbors <<= 1;
}
}
}
if (neighborCount == 0 && isCellOccupied == false)
{
return(new CellAction(position, CellActionID.IgnorePos));
}
else
{
return(new CellAction(position, ruleSet.CellRule(neighbors, neighborCount, isCellOccupied)));
}
}