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Optimize ColumnNoise with Thread-Local Storage #84

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Optimize ColumnNoise with Thread-Local Storage #84

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65 changes: 49 additions & 16 deletions Math/Noise/NewNormalizedSimplexFractalNoise.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -126,8 +126,19 @@ public ColumnNoise ForColumn(double relativeYFrequency, double[] amplitudes, dou

public struct ColumnNoise
{
OctaveEntry[] orderedOctaveEntries;
PastEvaluation[] pastEvaluations;
// Thread-isolated static arrays (TLS).
// Size 48 covers any possible world height.
[ThreadStatic] private static OctaveEntry[] _threadOctaves;
[ThreadStatic] private static PastEvaluation[] _threadPastEvals;
[ThreadStatic] private static double[] _threadMaxValues;
[ThreadStatic] private static int[] _threadOrder;

// References to TLS arrays for quick access within methods
private OctaveEntry[] orderedOctaveEntries;
private PastEvaluation[] pastEvaluations;

// Strict limitation for loops since arrays can be longer
private int nUsedOctaves;

public double UncurvedBound { get; private set; }
public double BoundMin { get; private set; }
Expand All @@ -147,9 +158,22 @@ struct PastEvaluation
public ColumnNoise(NewNormalizedSimplexFractalNoise terrainNoise, double relativeYFrequency, double[] amplitudes, double[] thresholds, double noiseX, double noiseZ)
{
int nAvailableOctaves = terrainNoise.frequencies.Length;
int nUsedOctaves = 0;
double[] maxValues = new double[nAvailableOctaves];
int[] order = new int[nAvailableOctaves];

// Initialize or expand TLS arrays on first call in a thread
if (_threadOctaves == null || _threadOctaves.Length < nAvailableOctaves)
{
int newSize = Math.Max(48, nAvailableOctaves);
_threadOctaves = new OctaveEntry[newSize];
_threadPastEvals = new PastEvaluation[newSize];
_threadMaxValues = new double[newSize];
_threadOrder = new int[newSize];
}

// Binding local links to TLS arrays
double[] maxValues = _threadMaxValues;
int[] order = _threadOrder;

int nUsedOctavesLocal = 0;
double bound = 0;
for (int i = nAvailableOctaves - 1; i >= 0; i--)
{
Expand All @@ -161,8 +185,8 @@ public ColumnNoise(NewNormalizedSimplexFractalNoise terrainNoise, double relativ
if (maxValues[i] == 0) continue;

// Descending order: Biggest octaves first, so we can rule out layers sooner.
order[nUsedOctaves] = i;
for (int j = nUsedOctaves - 1; j >= 0; j--)
order[nUsedOctavesLocal] = i;
for (int j = nUsedOctavesLocal - 1; j >= 0; j--)
{
if (maxValues[order[j + 1]] > maxValues[order[j]])
{
Expand All @@ -171,17 +195,20 @@ public ColumnNoise(NewNormalizedSimplexFractalNoise terrainNoise, double relativ
order[j + 1] = temp;
}
}
nUsedOctaves++;
nUsedOctavesLocal++;
}

this.UncurvedBound = bound;
this.BoundMin = NoiseValueCurve(-bound);
this.BoundMax = NoiseValueCurve(bound);
this.nUsedOctaves = nUsedOctavesLocal;

// reuse _threadOctaves and _threadPastEvals
this.orderedOctaveEntries = _threadOctaves;
this.pastEvaluations = _threadPastEvals;

// Fill out noise generators in order
this.orderedOctaveEntries = new OctaveEntry[nUsedOctaves];
this.pastEvaluations = new PastEvaluation[nUsedOctaves];
double uncertaintySum = 0;
for (int j = nUsedOctaves - 1; j >= 0; j--)
for (int j = nUsedOctavesLocal - 1; j >= 0; j--)
{
int i = order[j];
uncertaintySum += maxValues[i];
Expand Down Expand Up @@ -212,7 +239,9 @@ public double NoiseSign(double y, double inverseCurvedThresholder)
const double maxYSlope = NewSimplexNoiseLayer.MaxYSlope_ImprovedXZ;
double valueTempMin = inverseCurvedThresholder;
double valueTempMax = inverseCurvedThresholder;
for (int j = 0; j < orderedOctaveEntries.Length; j++)

// Iterate strictly up to nUsedOctaves
for (int j = 0; j < nUsedOctaves; j++)
{
// Exit if we couldn't possibly trigger an early return within this loop.
if (!(valueTempMax <= 0) && !(valueTempMin >= 0)) break;
Expand All @@ -227,10 +256,10 @@ public double NoiseSign(double y, double inverseCurvedThresholder)
double evalY = y * octaveEntry.FrequencyY;
double deltaY = Math.Abs(pastEvaluations[j].Y - evalY);
valueTempMin += ApplyThresholding(Math.Max(-1, pastEvaluations[j].Value - deltaY * maxYSlope) * octaveEntry.Amplitude, octaveEntry.Threshold, octaveEntry.SmoothingFactor);
valueTempMax += ApplyThresholding(Math.Min( 1, pastEvaluations[j].Value + deltaY * maxYSlope) * octaveEntry.Amplitude, octaveEntry.Threshold, octaveEntry.SmoothingFactor);
valueTempMax += ApplyThresholding(Math.Min(1, pastEvaluations[j].Value + deltaY * maxYSlope) * octaveEntry.Amplitude, octaveEntry.Threshold, octaveEntry.SmoothingFactor);
}

for (int j = 0; j < orderedOctaveEntries.Length; j++)
for (int j = 0; j < nUsedOctaves; j++)
{
ref readonly OctaveEntry octaveEntry = ref orderedOctaveEntries[j];

Expand All @@ -252,7 +281,9 @@ public double NoiseSign(double y, double inverseCurvedThresholder)
public double Noise(double y)
{
double value = 0.0;
for (int j = 0; j < orderedOctaveEntries.Length; j++)

// Iterate strictly up to nUsedOctaves
for (int j = 0; j < nUsedOctaves; j++)
{
ref readonly OctaveEntry octaveEntry = ref orderedOctaveEntries[j];

Expand All @@ -262,6 +293,8 @@ public double Noise(double y)
}
return NoiseValueCurve(value);
}


}
}
}