/// Detects pyramid or hole (if any) at the given coordinates in the <see cref="grid" />, and randomly switches
/// between pyramid and hole, based on <see cref="probabilityP" /> and <see cref="probabilityQ" /> parameters
/// (or switches anyway, if forceSwitch is on).
/// </summary>
public void RandomlySwitchFourCells(bool forceSwitch)
{
uint randomNumber1 = Random1.NextUInt32();
var centerX = (int)(randomNumber1 & (GridWidth - 1));
var centerY = (int)((randomNumber1 >> 16) & (GridHeight - 1));
int centerIndex = GetIndexFromXY(centerX, centerY);
uint randomNumber2 = Random2.NextUInt32();
uint randomVariable1 = randomNumber2 & ((1 << 16) - 1);
uint randomVariable2 = (randomNumber2 >> 16) & ((1 << 16) - 1);
int rightNeighbourIndex;
int bottomNeighbourIndex;
// Get neighbor indexes:
int rightNeighbourX = (centerX < GridWidth - 1) ? centerX + 1 : 0;
int rightNeighbourY = centerY;
int bottomNeighbourX = centerX;
int bottomNeighbourY = (centerY < GridHeight - 1) ? centerY + 1 : 0;
rightNeighbourIndex = rightNeighbourY * GridWidth + rightNeighbourX;
bottomNeighbourIndex = bottomNeighbourY * GridWidth + bottomNeighbourX;
// We check our own {dx,dy} values, and the right neighbor's dx, and bottom neighbor's dx.
if (
// If we get the pattern {01, 01} we have a pyramid:
((GetGridDx(centerIndex) && !GetGridDx(rightNeighbourIndex)) &&
(GetGridDy(centerIndex) && !GetGridDy(bottomNeighbourIndex)) &&
(forceSwitch || randomVariable1 < IntegerProbabilityP)) ||
// If we get the pattern {10, 10} we have a hole:
((!GetGridDx(centerIndex) && GetGridDx(rightNeighbourIndex)) &&
(!GetGridDy(centerIndex) && GetGridDy(bottomNeighbourIndex)) &&
(forceSwitch || randomVariable2 < IntegerProbabilityQ))
)
{
// We make a hole into a pyramid, and a pyramid into a hole.
SetGridDx(centerIndex, !GetGridDx(centerIndex));
SetGridDy(centerIndex, !GetGridDy(centerIndex));
SetGridDx(rightNeighbourIndex, !GetGridDx(rightNeighbourIndex));
SetGridDy(bottomNeighbourIndex, !GetGridDy(bottomNeighbourIndex));
}
}