public T[] GetSamples(int count)
{
lock (_lock)
{
//TODO: May want to consider when count > one of these lists. But probably not
// This is used when the front of the list should be favored
Random rand = StaticRandom.GetRandomForThread();
var randFunc = new Func <int, int, int>((min, max) => min + UtilityCore.GetIndexIntoList(rand.NextPow(2), max - min));
if (_longTermIndex < 0 && _tentativeBuffer.Count == 0)
{
// Empty
return(new T[0]);
}
else if (_longTermIndex >= _abandonTentativeSize)
{
#region all from longterm
return(UtilityCore.RandomRange(0, _longTermIndex + 1, count). // the randrange function takes care of reducing count if greater than range
Select(o => _longTermBuffer[o].Item).
ToArray());
#endregion
}
else if (_longTermIndex < 0)
{
#region all from tentative
// Don't pull uniform randomly from tentative. Favor items at the front of the list
return(UtilityCore.RandomRange(0, _tentativeBuffer.Count, count, randFunc).
Select(o => _tentativeBuffer[o].Item).
ToArray());
#endregion
}
else
{
#region mixture
// Pull from long term then tentative
return(UtilityCore.RandomRange(0, _longTermIndex + 1 + _tentativeBuffer.Count, count, randFunc).
Select(o =>
{
if (o <= _longTermIndex)
{
return _longTermBuffer[o].Item;
}
else
{
return _tentativeBuffer[o - (_longTermIndex + 1)].Item;
}
}).
ToArray());
#endregion
}
}
}
private static Point3D[] GetVoronoiCtrlPoints(HullVoronoiExploder_ShotHit[] hits, ITriangle[] convexHull, int minCount, int maxCount, double aabbLen)
{
const int MIN = 5;
Random rand = StaticRandom.GetRandomForThread();
#region examine hits
Tuple <int, double>[] hitsByLength = hits.
Select((o, i) => Tuple.Create(i, (o.Hit.Item2 - o.Hit.Item1).Length)).
OrderByDescending(o => o.Item2).
ToArray();
double totalLength = hitsByLength.Sum(o => o.Item2);
Tuple <int, double>[] hitsByPercentLength = hitsByLength.
Select(o => Tuple.Create(o.Item1, o.Item2 / totalLength)).
ToArray();
#endregion
#region define control point cones
double entryRadius = aabbLen * .05;
double exitRadius = aabbLen * .35;
double maxAxisLength = aabbLen * .75;
int count = hits.Length * 2;
count += (totalLength / (aabbLen * .1)).ToInt_Round();
if (count < minCount)
{
count = minCount;
}
else if (count > maxCount)
{
count = maxCount;
}
#endregion
#region randomly pick control points
// Keep adding rings around shots until the count is exceeded
var sets = new List <Tuple <int, List <Point3D> > >();
int runningSum = 0;
// Make sure each hit line gets some points
for (int cntr = 0; cntr < hits.Length; cntr++)
{
AddToHitline(ref runningSum, sets, cntr, hits[cntr].Hit, entryRadius, exitRadius, maxAxisLength, rand);
}
// Now that all hit lines have points, randomly choose lines until count is exceeded
while (runningSum < count)
{
var pointsPerLength = hitsByLength.
Select(o =>
{
var pointsForIndex = sets.FirstOrDefault(p => p.Item1 == o.Item1);
int countForIndex = pointsForIndex == null ? 0 : pointsForIndex.Item2.Count;
return(Tuple.Create(o.Item1, countForIndex / o.Item2));
}).
OrderBy(o => o.Item2).
ToArray();
double sumRatio = pointsPerLength.Sum(o => o.Item2);
var pointsPerLengthNormalized = pointsPerLength.
Select(o => (o.Item1, o.Item2 / sumRatio)).
ToArray();
int index = UtilityCore.GetIndexIntoList(rand.NextPow(3), pointsPerLengthNormalized);
AddToHitline(ref runningSum, sets, index, hits[index].Hit, entryRadius, exitRadius, maxAxisLength, rand);
}
#endregion
#region remove excessive points
while (runningSum > count)
{
var fractions = sets.
Select((o, i) => (i, o.Item2.Count.ToDouble() / runningSum.ToDouble())).
OrderByDescending(o => o.Item2).
ToArray();
int fractionIndex = UtilityCore.GetIndexIntoList(rand.NextPow(1.5), fractions); //nextPow will favor the front of the list, which is where the rings with the most points are
int setIndex = fractions[fractionIndex].Item1;
sets[setIndex].Item2.RemoveAt(UtilityCore.GetIndexIntoList(rand.NextDouble(), sets[setIndex].Item2.Count));
runningSum--;
}
#endregion
#region ensure enough for voronoi algorithm
List <Point3D> retVal = new List <Point3D>();
retVal.AddRange(sets.SelectMany(o => o.Item2));
// The voronoi algrorithm fails if there aren't at least 5 points (really should fix that). So add points that are
// way away from the hull. This will make the voronoi algorithm happy, and won't affect the local results
if (count < MIN)
{
retVal.AddRange(
Enumerable.Range(0, MIN - count).
Select(o => Math3D.GetRandomVector_Spherical_Shell(aabbLen * 20).ToPoint())
);
}
#endregion
return(retVal.ToArray());
}
