/**
* Make some progress in the WaveFunctionCollapseAlgorithm
*/
public Resolution Step()
{
if (status != Resolution.Undecided)
{
return(status);
}
if (backtrack)
{
prevWaves.Push(wave.Clone());
prevCompatible.Push((int[, , ])compatible.Clone());
}
int index, pattern;
Observe(out index, out pattern);
if (backtrack)
{
prevChoices.Push(new PropagateItem {
Index = index, Pattern = pattern
});
}
restart:
if (status == Resolution.Undecided)
{
status = Propagate();
}
if (status == Resolution.Undecided)
{
status = StepConstraints();
}
if (backtrack && status == Resolution.Contradiction)
{
// Actually backtrack
while (true)
{
if (prevWaves.Count == 0)
{
// We've backtracked as much as we can, but
// it's still not possible. That means it is imposible
return(Resolution.Contradiction);
}
wave = prevWaves.Pop();
compatible = prevCompatible.Pop();
var item = prevChoices.Pop();
backtrackCount++;
toPropagate.Clear();
// Mark the given choice as impossible
if (InternalBan(item.Index, item.Pattern))
{
// Still in contradiction, need to backtrack further
continue;
}
status = Resolution.Undecided;
goto restart;
}
}
return(status);
}