//-----------------------------------------------------------------------------------------------
float Compute2dFractalNoise( float posX, float posY, float scale, unsigned int numOctaves, float octavePersistence, float octaveScale, bool renormalize, unsigned int seed )
{
const float OCTAVE_OFFSET = 0.636764989593174f; // Translation/bias to add to each octave
float totalNoise = 0.f;
float totalAmplitude = 0.f;
float currentAmplitude = 1.f;
float invScale = (1.f / scale);
Vector2 currentPos( posX * invScale, posY * invScale );
for( unsigned int octaveNum = 0; octaveNum < numOctaves; ++ octaveNum )
{
// Determine noise values at nearby integer "grid point" positions
Vector2 cellMins( FastFloor( currentPos.x ), FastFloor( currentPos.y ) );
int indexWestX = (int) cellMins.x;
int indexSouthY = (int) cellMins.y;
int indexEastX = indexWestX + 1;
int indexNorthY = indexSouthY + 1;
float valueSouthWest = Get2dNoiseZeroToOne( indexWestX, indexSouthY, seed );
float valueSouthEast = Get2dNoiseZeroToOne( indexEastX, indexSouthY, seed );
float valueNorthWest = Get2dNoiseZeroToOne( indexWestX, indexNorthY, seed );
float valueNorthEast = Get2dNoiseZeroToOne( indexEastX, indexNorthY, seed );
// Do a smoothed (nonlinear) weighted average of nearby grid point values
Vector2 displacementFromMins = currentPos - cellMins;
float weightEast = SmoothStep( displacementFromMins.x );
float weightNorth = SmoothStep( displacementFromMins.y );
float weightWest = 1.f - weightEast;
float weightSouth = 1.f - weightNorth;
float blendSouth = (weightEast * valueSouthEast) + (weightWest * valueSouthWest);
float blendNorth = (weightEast * valueNorthEast) + (weightWest * valueNorthWest);
float blendTotal = (weightSouth * blendSouth) + (weightNorth * blendNorth);
float noiseThisOctave = 2.f * (blendTotal - 0.5f); // Map from [0,1] to [-1,1]
// Accumulate results and prepare for next octave (if any)
totalNoise += noiseThisOctave * currentAmplitude;
totalAmplitude += currentAmplitude;
currentAmplitude *= octavePersistence;
currentPos *= octaveScale;
currentPos.x += OCTAVE_OFFSET; // Add "irrational" offsets to noise position components
currentPos.y += OCTAVE_OFFSET; // at each octave to break up their grid alignment
++ seed; // Eliminates octaves "echoing" each other (since each octave is uniquely seeded)
}
// Re-normalize total noise to within [-1,1] and fix octaves pulling us far away from limits
if( renormalize && totalAmplitude > 0.f )
{
totalNoise /= totalAmplitude; // Amplitude exceeds 1.0 if octaves are used
totalNoise = (totalNoise * 0.5f) + 0.5f; // Map to [0,1]
totalNoise = SmoothStep( totalNoise ); // Push towards extents (octaves pull us away)
totalNoise = (totalNoise * 2.0f) - 1.f; // Map back to [-1,1]
}
return totalNoise;
}
void ShortCircuitBridge::QueueAbandon(UInt2 uberMins, UInt2 uberMaxs)
{
// look for overlapping cells
for (const auto&i:_cells) {
const auto& r = i.second;
if ( r._uberMins[0] >= uberMaxs[0] || r._uberMaxs[0] < uberMins[0]
|| r._uberMins[1] >= uberMaxs[1] || r._uberMaxs[1] < uberMins[1])
continue;
// remove any pending updates -- because they've all be abandoned now.
auto compare = CellRegion { i.first, Float2(0.f, 0.f), Float2(0.f, 0.f) };
auto range = std::equal_range(
_pendingUpdates.begin(), _pendingUpdates.end(),
compare, CompareCellHash);
_pendingUpdates.erase(range.first, range.second);
// queue a new abandon event
Float2 cellMins(
(int(uberMins[0]) - int(r._uberMins[0])) / float(r._uberMaxs[0] - r._uberMins[0]),
(int(uberMins[1]) - int(r._uberMins[1])) / float(r._uberMaxs[1] - r._uberMins[1]));
Float2 cellMaxs(
(int(uberMaxs[0]) - int(r._uberMins[0])) / float(r._uberMaxs[0] - r._uberMins[0]),
(int(uberMaxs[1]) - int(r._uberMins[1])) / float(r._uberMaxs[1] - r._uberMins[1]));
cellMins[0] = std::max(cellMins[0], 0.f);
cellMins[1] = std::max(cellMins[1], 0.f);
cellMaxs[0] = std::min(cellMaxs[0], 1.f);
cellMaxs[1] = std::min(cellMaxs[1], 1.f);
auto q = std::lower_bound(
_pendingAbandons.begin(), _pendingAbandons.end(),
compare, CompareCellHash);
// we can choose to insert this as a separate event, or just combine it with
// what is already there.
if (q != _pendingAbandons.end() && q->_cellHash == i.first) {
q->_cellMins[0] = std::min(q->_cellMins[0], cellMins[0]);
q->_cellMins[1] = std::min(q->_cellMins[1], cellMins[1]);
q->_cellMaxs[0] = std::max(q->_cellMaxs[0], cellMaxs[0]);
q->_cellMaxs[1] = std::max(q->_cellMaxs[1], cellMaxs[1]);
} else {
CellRegion region { i.first, cellMins, cellMaxs };
_pendingAbandons.insert(q, region);
}
}
}
void ShortCircuitBridge::QueueShortCircuit(UInt2 uberMins, UInt2 uberMaxs)
{
for (const auto&i:_cells) {
const auto& r = i.second;
if ( r._uberMins[0] >= uberMaxs[0] || r._uberMaxs[0] < uberMins[0]
|| r._uberMins[1] >= uberMaxs[1] || r._uberMaxs[1] < uberMins[1])
continue;
// queue a new update event
Float2 cellMins(
(int(uberMins[0]) - int(r._uberMins[0])) / float(r._uberMaxs[0] - r._uberMins[0]),
(int(uberMins[1]) - int(r._uberMins[1])) / float(r._uberMaxs[1] - r._uberMins[1]));
Float2 cellMaxs(
(int(uberMaxs[0]) - int(r._uberMins[0])) / float(r._uberMaxs[0] - r._uberMins[0]),
(int(uberMaxs[1]) - int(r._uberMins[1])) / float(r._uberMaxs[1] - r._uberMins[1]));
cellMins[0] = std::max(cellMins[0], 0.f);
cellMins[1] = std::max(cellMins[1], 0.f);
cellMaxs[0] = std::min(cellMaxs[0], 1.f);
cellMaxs[1] = std::min(cellMaxs[1], 1.f);
auto compare = CellRegion { i.first, Float2(0.f, 0.f), Float2(0.f, 0.f) };
auto q = std::lower_bound(
_pendingUpdates.begin(), _pendingUpdates.end(),
compare, CompareCellHash);
// we can choose to insert this as a separate event, or just combine it with
// what is already there.
if (q != _pendingUpdates.end() && q->_cellHash == i.first) {
q->_cellMins[0] = std::min(q->_cellMins[0], cellMins[0]);
q->_cellMins[1] = std::min(q->_cellMins[1], cellMins[1]);
q->_cellMaxs[0] = std::max(q->_cellMaxs[0], cellMaxs[0]);
q->_cellMaxs[1] = std::max(q->_cellMaxs[1], cellMaxs[1]);
} else {
CellRegion region { i.first, cellMins, cellMaxs };
_pendingUpdates.insert(q, region);
}
}
}
//-----------------------------------------------------------------------------------------------
// Perlin noise is fractal noise with "gradient vector smoothing" applied.
//
// In 4D, gradients are unit-length hyper-vectors in random (4D) directions.
//
float Compute4dPerlinNoise( float posX, float posY, float posZ, float posT, float scale, unsigned int numOctaves, float octavePersistence, float octaveScale, bool renormalize, unsigned int seed )
{
const float OCTAVE_OFFSET = 0.636764989593174f; // Translation/bias to add to each octave
const Vector4 gradients[ 16 ] = // Hard to tell if this is any better in 4D than just having 8
{
Vector4( +0.5f, +0.5f, +0.5f, +0.5f ), // Normalized unit 4D vectors pointing toward each
Vector4( -0.5f, +0.5f, +0.5f, +0.5f ), // of the 16 hypercube corners, so components are
Vector4( +0.5f, -0.5f, +0.5f, +0.5f ), // all sqrt(4)/4, i.e. one-half.
Vector4( -0.5f, -0.5f, +0.5f, +0.5f ), //
Vector4( +0.5f, +0.5f, -0.5f, +0.5f ), // It's hard to tell whether these are any better
Vector4( -0.5f, +0.5f, -0.5f, +0.5f ), // or worse than vectors facing axes (1,0,0,0) or
Vector4( +0.5f, -0.5f, -0.5f, +0.5f ), // 3D edges (.7,.7,0,0) or 4D edges (.57,.57,.57,0)
Vector4( -0.5f, -0.5f, -0.5f, +0.5f ), // but less-axial gradients looked a little better
Vector4( +0.5f, +0.5f, +0.5f, -0.5f ), // with 2D and 3D noise so I'm assuming this is as
Vector4( -0.5f, +0.5f, +0.5f, -0.5f ), // good or better as any other gradient-selection
Vector4( +0.5f, -0.5f, +0.5f, -0.5f ), // scheme (and is crazy-fast). *shrug*
Vector4( -0.5f, -0.5f, +0.5f, -0.5f ), //
Vector4( +0.5f, +0.5f, -0.5f, -0.5f ), // Plus, we want a power-of-two number of evenly-
Vector4( -0.5f, +0.5f, -0.5f, -0.5f ), // distributed gradients, so we can cheaply select
Vector4( +0.5f, -0.5f, -0.5f, -0.5f ), // one from bit-noise (use bit-mask, not modulus).
Vector4( -0.5f, -0.5f, -0.5f, -0.5f ) //
};
float totalNoise = 0.f;
float totalAmplitude = 0.f;
float currentAmplitude = 1.f;
float invScale = (1.f / scale);
Vector4 currentPos( posX * invScale, posY * invScale, posZ * invScale, posT * invScale );
for( unsigned int octaveNum = 0; octaveNum < numOctaves; ++ octaveNum )
{
// Determine random unit "gradient vectors" for 16 surrounding 4D (hypercube) cell corners
Vector4 cellMins( FastFloor( currentPos.x ), FastFloor( currentPos.y ), FastFloor( currentPos.z ), FastFloor( currentPos.w ) );
Vector4 cellMaxs( cellMins.x + 1.f, cellMins.y + 1.f, cellMins.z + 1.f, cellMins.w + 1.f );
int indexWestX = (int) cellMins.x;
int indexSouthY = (int) cellMins.y;
int indexBelowZ = (int) cellMins.z;
int indexBeforeT = (int) cellMins.w;
int indexEastX = indexWestX + 1;
int indexNorthY = indexSouthY + 1;
int indexAboveZ = indexBelowZ + 1;
int indexAfterT = indexBeforeT + 1;
// "BeforeBSW" stands for "BeforeBelowSouthWest" below (i.e. 4D hypercube mins), etc.
unsigned int noiseBeforeBSW = Get4dNoiseUint( indexWestX, indexSouthY, indexBelowZ, indexBeforeT, seed );
unsigned int noiseBeforeBSE = Get4dNoiseUint( indexEastX, indexSouthY, indexBelowZ, indexBeforeT, seed );
unsigned int noiseBeforeBNW = Get4dNoiseUint( indexWestX, indexNorthY, indexBelowZ, indexBeforeT, seed );
unsigned int noiseBeforeBNE = Get4dNoiseUint( indexEastX, indexNorthY, indexBelowZ, indexBeforeT, seed );
unsigned int noiseBeforeASW = Get4dNoiseUint( indexWestX, indexSouthY, indexAboveZ, indexBeforeT, seed );
unsigned int noiseBeforeASE = Get4dNoiseUint( indexEastX, indexSouthY, indexAboveZ, indexBeforeT, seed );
unsigned int noiseBeforeANW = Get4dNoiseUint( indexWestX, indexNorthY, indexAboveZ, indexBeforeT, seed );
unsigned int noiseBeforeANE = Get4dNoiseUint( indexEastX, indexNorthY, indexAboveZ, indexBeforeT, seed );
unsigned int noiseAfterBSW = Get4dNoiseUint( indexWestX, indexSouthY, indexBelowZ, indexAfterT, seed );
unsigned int noiseAfterBSE = Get4dNoiseUint( indexEastX, indexSouthY, indexBelowZ, indexAfterT, seed );
unsigned int noiseAfterBNW = Get4dNoiseUint( indexWestX, indexNorthY, indexBelowZ, indexAfterT, seed );
unsigned int noiseAfterBNE = Get4dNoiseUint( indexEastX, indexNorthY, indexBelowZ, indexAfterT, seed );
unsigned int noiseAfterASW = Get4dNoiseUint( indexWestX, indexSouthY, indexAboveZ, indexAfterT, seed );
unsigned int noiseAfterASE = Get4dNoiseUint( indexEastX, indexSouthY, indexAboveZ, indexAfterT, seed );
unsigned int noiseAfterANW = Get4dNoiseUint( indexWestX, indexNorthY, indexAboveZ, indexAfterT, seed );
unsigned int noiseAfterANE = Get4dNoiseUint( indexEastX, indexNorthY, indexAboveZ, indexAfterT, seed );
Vector4 gradientBeforeBSW = gradients[ noiseBeforeBSW & 0x0000000F ];
Vector4 gradientBeforeBSE = gradients[ noiseBeforeBSE & 0x0000000F ];
Vector4 gradientBeforeBNW = gradients[ noiseBeforeBNW & 0x0000000F ];
Vector4 gradientBeforeBNE = gradients[ noiseBeforeBNE & 0x0000000F ];
Vector4 gradientBeforeASW = gradients[ noiseBeforeASW & 0x0000000F ];
Vector4 gradientBeforeASE = gradients[ noiseBeforeASE & 0x0000000F ];
Vector4 gradientBeforeANW = gradients[ noiseBeforeANW & 0x0000000F ];
Vector4 gradientBeforeANE = gradients[ noiseBeforeANE & 0x0000000F ];
Vector4 gradientAfterBSW = gradients[ noiseAfterBSW & 0x0000000F ];
Vector4 gradientAfterBSE = gradients[ noiseAfterBSE & 0x0000000F ];
Vector4 gradientAfterBNW = gradients[ noiseAfterBNW & 0x0000000F ];
Vector4 gradientAfterBNE = gradients[ noiseAfterBNE & 0x0000000F ];
Vector4 gradientAfterASW = gradients[ noiseAfterASW & 0x0000000F ];
Vector4 gradientAfterASE = gradients[ noiseAfterASE & 0x0000000F ];
Vector4 gradientAfterANW = gradients[ noiseAfterANW & 0x0000000F ];
Vector4 gradientAfterANE = gradients[ noiseAfterANE & 0x0000000F ];
// Dot each corner's gradient with displacement from corner to position
Vector4 displacementFromBeforeBSW( currentPos.x - cellMins.x, currentPos.y - cellMins.y, currentPos.z - cellMins.z, currentPos.w - cellMins.w );
Vector4 displacementFromBeforeBSE( currentPos.x - cellMaxs.x, currentPos.y - cellMins.y, currentPos.z - cellMins.z, currentPos.w - cellMins.w );
Vector4 displacementFromBeforeBNW( currentPos.x - cellMins.x, currentPos.y - cellMaxs.y, currentPos.z - cellMins.z, currentPos.w - cellMins.w );
Vector4 displacementFromBeforeBNE( currentPos.x - cellMaxs.x, currentPos.y - cellMaxs.y, currentPos.z - cellMins.z, currentPos.w - cellMins.w );
Vector4 displacementFromBeforeASW( currentPos.x - cellMins.x, currentPos.y - cellMins.y, currentPos.z - cellMaxs.z, currentPos.w - cellMins.w );
Vector4 displacementFromBeforeASE( currentPos.x - cellMaxs.x, currentPos.y - cellMins.y, currentPos.z - cellMaxs.z, currentPos.w - cellMins.w );
Vector4 displacementFromBeforeANW( currentPos.x - cellMins.x, currentPos.y - cellMaxs.y, currentPos.z - cellMaxs.z, currentPos.w - cellMins.w );
Vector4 displacementFromBeforeANE( currentPos.x - cellMaxs.x, currentPos.y - cellMaxs.y, currentPos.z - cellMaxs.z, currentPos.w - cellMins.w );
Vector4 displacementFromAfterBSW( currentPos.x - cellMins.x, currentPos.y - cellMins.y, currentPos.z - cellMins.z, currentPos.w - cellMaxs.w );
Vector4 displacementFromAfterBSE( currentPos.x - cellMaxs.x, currentPos.y - cellMins.y, currentPos.z - cellMins.z, currentPos.w - cellMaxs.w );
Vector4 displacementFromAfterBNW( currentPos.x - cellMins.x, currentPos.y - cellMaxs.y, currentPos.z - cellMins.z, currentPos.w - cellMaxs.w );
Vector4 displacementFromAfterBNE( currentPos.x - cellMaxs.x, currentPos.y - cellMaxs.y, currentPos.z - cellMins.z, currentPos.w - cellMaxs.w );
Vector4 displacementFromAfterASW( currentPos.x - cellMins.x, currentPos.y - cellMins.y, currentPos.z - cellMaxs.z, currentPos.w - cellMaxs.w );
Vector4 displacementFromAfterASE( currentPos.x - cellMaxs.x, currentPos.y - cellMins.y, currentPos.z - cellMaxs.z, currentPos.w - cellMaxs.w );
Vector4 displacementFromAfterANW( currentPos.x - cellMins.x, currentPos.y - cellMaxs.y, currentPos.z - cellMaxs.z, currentPos.w - cellMaxs.w );
Vector4 displacementFromAfterANE( currentPos.x - cellMaxs.x, currentPos.y - cellMaxs.y, currentPos.z - cellMaxs.z, currentPos.w - cellMaxs.w );
float dotBeforeBSW = MathUtils::Dot( gradientBeforeBSW, displacementFromBeforeBSW );
float dotBeforeBSE = MathUtils::Dot( gradientBeforeBSE, displacementFromBeforeBSE );
float dotBeforeBNW = MathUtils::Dot( gradientBeforeBNW, displacementFromBeforeBNW );
float dotBeforeBNE = MathUtils::Dot( gradientBeforeBNE, displacementFromBeforeBNE );
float dotBeforeASW = MathUtils::Dot( gradientBeforeASW, displacementFromBeforeASW );
float dotBeforeASE = MathUtils::Dot( gradientBeforeASE, displacementFromBeforeASE );
float dotBeforeANW = MathUtils::Dot( gradientBeforeANW, displacementFromBeforeANW );
float dotBeforeANE = MathUtils::Dot( gradientBeforeANE, displacementFromBeforeANE );
float dotAfterBSW = MathUtils::Dot( gradientAfterBSW, displacementFromAfterBSW );
float dotAfterBSE = MathUtils::Dot( gradientAfterBSE, displacementFromAfterBSE );
float dotAfterBNW = MathUtils::Dot( gradientAfterBNW, displacementFromAfterBNW );
float dotAfterBNE = MathUtils::Dot( gradientAfterBNE, displacementFromAfterBNE );
float dotAfterASW = MathUtils::Dot( gradientAfterASW, displacementFromAfterASW );
float dotAfterASE = MathUtils::Dot( gradientAfterASE, displacementFromAfterASE );
float dotAfterANW = MathUtils::Dot( gradientAfterANW, displacementFromAfterANW );
float dotAfterANE = MathUtils::Dot( gradientAfterANE, displacementFromAfterANE );
// Do a smoothed (nonlinear) weighted average of dot results
float weightEast = SmoothStep( displacementFromBeforeBSW.x );
float weightNorth = SmoothStep( displacementFromBeforeBSW.y );
float weightAbove = SmoothStep( displacementFromBeforeBSW.z );
float weightAfter = SmoothStep( displacementFromBeforeBSW.w );
float weightWest = 1.f - weightEast;
float weightSouth = 1.f - weightNorth;
float weightBelow = 1.f - weightAbove;
float weightBefore = 1.f - weightAfter;
// 16-way blend (16 -> 8 -> 4 -> 2 -> 1)
float blendBeforeBelowSouth = (weightEast * dotBeforeBSE) + (weightWest * dotBeforeBSW);
float blendBeforeBelowNorth = (weightEast * dotBeforeBNE) + (weightWest * dotBeforeBNW);
float blendBeforeAboveSouth = (weightEast * dotBeforeASE) + (weightWest * dotBeforeASW);
float blendBeforeAboveNorth = (weightEast * dotBeforeANE) + (weightWest * dotBeforeANW);
float blendAfterBelowSouth = (weightEast * dotAfterBSE) + (weightWest * dotAfterBSW);
float blendAfterBelowNorth = (weightEast * dotAfterBNE) + (weightWest * dotAfterBNW);
float blendAfterAboveSouth = (weightEast * dotAfterASE) + (weightWest * dotAfterASW);
float blendAfterAboveNorth = (weightEast * dotAfterANE) + (weightWest * dotAfterANW);
float blendBeforeBelow = (weightSouth * blendBeforeBelowSouth) + (weightNorth * blendBeforeBelowNorth);
float blendBeforeAbove = (weightSouth * blendBeforeAboveSouth) + (weightNorth * blendBeforeAboveNorth);
float blendAfterBelow = (weightSouth * blendAfterBelowSouth) + (weightNorth * blendAfterBelowNorth);
float blendAfterAbove = (weightSouth * blendAfterAboveSouth) + (weightNorth * blendAfterAboveNorth);
float blendBefore = (weightBelow * blendBeforeBelow) + (weightAbove * blendBeforeAbove);
float blendAfter = (weightBelow * blendAfterBelow) + (weightAbove * blendAfterAbove);
float blendTotal = (weightBefore * blendBefore) + (weightAfter * blendAfter);
float noiseThisOctave = 1.6f * blendTotal; // 4D Perlin is in ~[-.5,.5]; map to ~[-1,1]
// Accumulate results and prepare for next octave (if any)
totalNoise += noiseThisOctave * currentAmplitude;
totalAmplitude += currentAmplitude;
currentAmplitude *= octavePersistence;
currentPos *= octaveScale;
currentPos.x += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
currentPos.y += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
currentPos.z += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
currentPos.w += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
++ seed; // Eliminates octaves "echoing" each other (since each octave is uniquely seeded)
}
// Re-normalize total noise to within [-1,1] and fix octaves pulling us far away from limits
if( renormalize && totalAmplitude > 0.f )
{
totalNoise /= totalAmplitude; // Amplitude exceeds 1.0 if octaves are used
totalNoise = (totalNoise * 0.5f) + 0.5f; // Map to [0,1]
totalNoise = SmoothStep( totalNoise ); // Push towards extents (octaves pull us away)
totalNoise = (totalNoise * 2.0f) - 1.f; // Map back to [-1,1]
}
return totalNoise;
}
//-----------------------------------------------------------------------------------------------
// Perlin noise is fractal noise with "gradient vector smoothing" applied.
//
// In 3D, gradients are unit-length vectors in random (3D) directions.
//
float Compute3dPerlinNoise( float posX, float posY, float posZ, float scale, unsigned int numOctaves, float octavePersistence, float octaveScale, bool renormalize, unsigned int seed )
{
const float OCTAVE_OFFSET = 0.636764989593174f; // Translation/bias to add to each octave
const Vector3 gradients[ 8 ] = // Traditional "12 edges" requires modulus and isn't any better.
{
Vector3( +fSQRT_3_OVER_3, +fSQRT_3_OVER_3, +fSQRT_3_OVER_3 ), // Normalized unit 3D vectors
Vector3( -fSQRT_3_OVER_3, +fSQRT_3_OVER_3, +fSQRT_3_OVER_3 ), // pointing toward cube
Vector3( +fSQRT_3_OVER_3, -fSQRT_3_OVER_3, +fSQRT_3_OVER_3 ), // corners, so components
Vector3( -fSQRT_3_OVER_3, -fSQRT_3_OVER_3, +fSQRT_3_OVER_3 ), // are all sqrt(3)/3, i.e.
Vector3( +fSQRT_3_OVER_3, +fSQRT_3_OVER_3, -fSQRT_3_OVER_3 ), // 0.5773502691896257645091f.
Vector3( -fSQRT_3_OVER_3, +fSQRT_3_OVER_3, -fSQRT_3_OVER_3 ), // These are slightly better
Vector3( +fSQRT_3_OVER_3, -fSQRT_3_OVER_3, -fSQRT_3_OVER_3 ), // than axes (1,0,0) and much
Vector3( -fSQRT_3_OVER_3, -fSQRT_3_OVER_3, -fSQRT_3_OVER_3 ) // faster than edges (1,1,0).
};
float totalNoise = 0.f;
float totalAmplitude = 0.f;
float currentAmplitude = 1.f;
float invScale = (1.f / scale);
Vector3 currentPos( posX * invScale, posY * invScale, posZ * invScale );
for( unsigned int octaveNum = 0; octaveNum < numOctaves; ++ octaveNum )
{
// Determine random unit "gradient vectors" for surrounding corners
Vector3 cellMins( FastFloor( currentPos.x ), FastFloor( currentPos.y ), FastFloor( currentPos.z ) );
Vector3 cellMaxs( cellMins.x + 1.f, cellMins.y + 1.f, cellMins.z + 1.f );
int indexWestX = (int) cellMins.x;
int indexSouthY = (int) cellMins.y;
int indexBelowZ = (int) cellMins.z;
int indexEastX = indexWestX + 1;
int indexNorthY = indexSouthY + 1;
int indexAboveZ = indexBelowZ + 1;
unsigned int noiseBelowSW = Get3dNoiseUint( indexWestX, indexSouthY, indexBelowZ, seed );
unsigned int noiseBelowSE = Get3dNoiseUint( indexEastX, indexSouthY, indexBelowZ, seed );
unsigned int noiseBelowNW = Get3dNoiseUint( indexWestX, indexNorthY, indexBelowZ, seed );
unsigned int noiseBelowNE = Get3dNoiseUint( indexEastX, indexNorthY, indexBelowZ, seed );
unsigned int noiseAboveSW = Get3dNoiseUint( indexWestX, indexSouthY, indexAboveZ, seed );
unsigned int noiseAboveSE = Get3dNoiseUint( indexEastX, indexSouthY, indexAboveZ, seed );
unsigned int noiseAboveNW = Get3dNoiseUint( indexWestX, indexNorthY, indexAboveZ, seed );
unsigned int noiseAboveNE = Get3dNoiseUint( indexEastX, indexNorthY, indexAboveZ, seed );
Vector3 gradientBelowSW = gradients[ noiseBelowSW & 0x00000007 ];
Vector3 gradientBelowSE = gradients[ noiseBelowSE & 0x00000007 ];
Vector3 gradientBelowNW = gradients[ noiseBelowNW & 0x00000007 ];
Vector3 gradientBelowNE = gradients[ noiseBelowNE & 0x00000007 ];
Vector3 gradientAboveSW = gradients[ noiseAboveSW & 0x00000007 ];
Vector3 gradientAboveSE = gradients[ noiseAboveSE & 0x00000007 ];
Vector3 gradientAboveNW = gradients[ noiseAboveNW & 0x00000007 ];
Vector3 gradientAboveNE = gradients[ noiseAboveNE & 0x00000007 ];
// Dot each corner's gradient with displacement from corner to position
Vector3 displacementFromBelowSW( currentPos.x - cellMins.x, currentPos.y - cellMins.y, currentPos.z - cellMins.z );
Vector3 displacementFromBelowSE( currentPos.x - cellMaxs.x, currentPos.y - cellMins.y, currentPos.z - cellMins.z );
Vector3 displacementFromBelowNW( currentPos.x - cellMins.x, currentPos.y - cellMaxs.y, currentPos.z - cellMins.z );
Vector3 displacementFromBelowNE( currentPos.x - cellMaxs.x, currentPos.y - cellMaxs.y, currentPos.z - cellMins.z );
Vector3 displacementFromAboveSW( currentPos.x - cellMins.x, currentPos.y - cellMins.y, currentPos.z - cellMaxs.z );
Vector3 displacementFromAboveSE( currentPos.x - cellMaxs.x, currentPos.y - cellMins.y, currentPos.z - cellMaxs.z );
Vector3 displacementFromAboveNW( currentPos.x - cellMins.x, currentPos.y - cellMaxs.y, currentPos.z - cellMaxs.z );
Vector3 displacementFromAboveNE( currentPos.x - cellMaxs.x, currentPos.y - cellMaxs.y, currentPos.z - cellMaxs.z );
float dotBelowSW = MathUtils::Dot( gradientBelowSW, displacementFromBelowSW );
float dotBelowSE = MathUtils::Dot( gradientBelowSE, displacementFromBelowSE );
float dotBelowNW = MathUtils::Dot( gradientBelowNW, displacementFromBelowNW );
float dotBelowNE = MathUtils::Dot( gradientBelowNE, displacementFromBelowNE );
float dotAboveSW = MathUtils::Dot( gradientAboveSW, displacementFromAboveSW );
float dotAboveSE = MathUtils::Dot( gradientAboveSE, displacementFromAboveSE );
float dotAboveNW = MathUtils::Dot( gradientAboveNW, displacementFromAboveNW );
float dotAboveNE = MathUtils::Dot( gradientAboveNE, displacementFromAboveNE );
// Do a smoothed (nonlinear) weighted average of dot results
float weightEast = SmoothStep5( displacementFromBelowSW.x );
float weightNorth = SmoothStep5( displacementFromBelowSW.y );
float weightAbove = SmoothStep5( displacementFromBelowSW.z );
float weightWest = 1.f - weightEast;
float weightSouth = 1.f - weightNorth;
float weightBelow = 1.f - weightAbove;
// 8-way blend (8 -> 4 -> 2 -> 1)
float blendBelowSouth = (weightEast * dotBelowSE) + (weightWest * dotBelowSW);
float blendBelowNorth = (weightEast * dotBelowNE) + (weightWest * dotBelowNW);
float blendAboveSouth = (weightEast * dotAboveSE) + (weightWest * dotAboveSW);
float blendAboveNorth = (weightEast * dotAboveNE) + (weightWest * dotAboveNW);
float blendBelow = (weightSouth * blendBelowSouth) + (weightNorth * blendBelowNorth);
float blendAbove = (weightSouth * blendAboveSouth) + (weightNorth * blendAboveNorth);
float blendTotal = (weightBelow * blendBelow) + (weightAbove * blendAbove);
float noiseThisOctave = 1.66666666f * blendTotal; // 3D Perlin is ~[-.6,.6]; map to ~[-1,1]
// Accumulate results and prepare for next octave (if any)
totalNoise += noiseThisOctave * currentAmplitude;
totalAmplitude += currentAmplitude;
currentAmplitude *= octavePersistence;
currentPos *= octaveScale;
currentPos.x += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
currentPos.y += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
currentPos.z += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
++ seed; // Eliminates octaves "echoing" each other (since each octave is uniquely seeded)
}
// Re-normalize total noise to within [-1,1] and fix octaves pulling us far away from limits
if( renormalize && totalAmplitude > 0.f )
{
totalNoise /= totalAmplitude; // Amplitude exceeds 1.0 if octaves are used
totalNoise = (totalNoise * 0.5f) + 0.5f; // Map to [0,1]
totalNoise = SmoothStep( totalNoise ); // Push towards extents (octaves pull us away)
totalNoise = (totalNoise * 2.0f) - 1.f; // Map back to [-1,1]
}
return totalNoise;
}
//-----------------------------------------------------------------------------------------------
// Perlin noise is fractal noise with "gradient vector smoothing" applied.
//
// In 2D, gradients are unit-length vectors in various directions with even angular distribution.
//
float Compute2dPerlinNoise( float posX, float posY, float scale, unsigned int numOctaves, float octavePersistence, float octaveScale, bool renormalize, unsigned int seed )
{
const float OCTAVE_OFFSET = 0.636764989593174f; // Translation/bias to add to each octave
const Vector2 gradients[ 8 ] = // Normalized unit vectors in 8 quarter-cardinal directions
{
Vector2( +0.923879533f, +0.382683432f ), // 22.5 degrees
Vector2( +0.382683432f, +0.923879533f ), // 67.5 degrees
Vector2( -0.382683432f, +0.923879533f ), // 112.5 degrees
Vector2( -0.923879533f, +0.382683432f ), // 157.5 degrees
Vector2( -0.923879533f, -0.382683432f ), // 202.5 degrees
Vector2( -0.382683432f, -0.923879533f ), // 247.5 degrees
Vector2( +0.382683432f, -0.923879533f ), // 292.5 degrees
Vector2( +0.923879533f, -0.382683432f ) // 337.5 degrees
};
float totalNoise = 0.f;
float totalAmplitude = 0.f;
float currentAmplitude = 1.f;
float invScale = (1.f / scale);
Vector2 currentPos( posX * invScale, posY * invScale );
for( unsigned int octaveNum = 0; octaveNum < numOctaves; ++ octaveNum )
{
// Determine random unit "gradient vectors" for surrounding corners
Vector2 cellMins( FastFloor( currentPos.x ), FastFloor( currentPos.y ) );
Vector2 cellMaxs( cellMins.x + 1.f, cellMins.y + 1.f );
int indexWestX = (int) cellMins.x;
int indexSouthY = (int) cellMins.y;
int indexEastX = indexWestX + 1;
int indexNorthY = indexSouthY + 1;
unsigned int noiseSW = Get2dNoiseUint( indexWestX, indexSouthY, seed );
unsigned int noiseSE = Get2dNoiseUint( indexEastX, indexSouthY, seed );
unsigned int noiseNW = Get2dNoiseUint( indexWestX, indexNorthY, seed );
unsigned int noiseNE = Get2dNoiseUint( indexEastX, indexNorthY, seed );
Vector2 gradientSW = gradients[ noiseSW & 0x00000007 ];
Vector2 gradientSE = gradients[ noiseSE & 0x00000007 ];
Vector2 gradientNW = gradients[ noiseNW & 0x00000007 ];
Vector2 gradientNE = gradients[ noiseNE & 0x00000007 ];
// Dot each corner's gradient with displacement from corner to position
Vector2 displacementFromSW( currentPos.x - cellMins.x, currentPos.y - cellMins.y );
Vector2 displacementFromSE( currentPos.x - cellMaxs.x, currentPos.y - cellMins.y );
Vector2 displacementFromNW( currentPos.x - cellMins.x, currentPos.y - cellMaxs.y );
Vector2 displacementFromNE( currentPos.x - cellMaxs.x, currentPos.y - cellMaxs.y );
float dotSouthWest = MathUtils::Dot( gradientSW, displacementFromSW );
float dotSouthEast = MathUtils::Dot( gradientSE, displacementFromSE );
float dotNorthWest = MathUtils::Dot( gradientNW, displacementFromNW );
float dotNorthEast = MathUtils::Dot( gradientNE, displacementFromNE );
// Do a smoothed (nonlinear) weighted average of dot results
float weightEast = SmoothStep5( displacementFromSW.x );
float weightNorth = SmoothStep5( displacementFromSW.y );
float weightWest = 1.f - weightEast;
float weightSouth = 1.f - weightNorth;
float blendSouth = (weightEast * dotSouthEast) + (weightWest * dotSouthWest);
float blendNorth = (weightEast * dotNorthEast) + (weightWest * dotNorthWest);
float blendTotal = (weightSouth * blendSouth) + (weightNorth * blendNorth);
float noiseThisOctave = 1.5f * blendTotal; // 2D Perlin is in ~[-.66,.66]; map to ~[-1,1]
// Accumulate results and prepare for next octave (if any)
totalNoise += noiseThisOctave * currentAmplitude;
totalAmplitude += currentAmplitude;
currentAmplitude *= octavePersistence;
currentPos *= octaveScale;
currentPos.x += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
currentPos.y += OCTAVE_OFFSET; // Add "irrational" offset to de-align octave grids
++ seed; // Eliminates octaves "echoing" each other (since each octave is uniquely seeded)
}
// Re-normalize total noise to within [-1,1] and fix octaves pulling us far away from limits
if( renormalize && totalAmplitude > 0.f )
{
totalNoise /= totalAmplitude; // Amplitude exceeds 1.0 if octaves are used
totalNoise = (totalNoise * 0.5f) + 0.5f; // Map to [0,1]
totalNoise = SmoothStep( totalNoise ); // Push towards extents (octaves pull us away)
totalNoise = (totalNoise * 2.0f) - 1.f; // Map back to [-1,1]
}
return totalNoise;
}
//-----------------------------------------------------------------------------------------------
float Compute4dFractalNoise( float posX, float posY, float posZ, float posT, float scale, unsigned int numOctaves, float octavePersistence, float octaveScale, bool renormalize, unsigned int seed )
{
const float OCTAVE_OFFSET = 0.636764989593174f; // Translation/bias to add to each octave
float totalNoise = 0.f;
float totalAmplitude = 0.f;
float currentAmplitude = 1.f;
float invScale = (1.f / scale);
Vector4 currentPos( posX * invScale, posY * invScale, posZ * invScale, posT * invScale );
for( unsigned int octaveNum = 0; octaveNum < numOctaves; ++ octaveNum )
{
// Determine noise values at nearby integer "grid point" positions
Vector4 cellMins( FastFloor( currentPos.x ), FastFloor( currentPos.y ), FastFloor( currentPos.z ), FastFloor( currentPos.w ) );
int indexWestX = (int) cellMins.x;
int indexSouthY = (int) cellMins.y;
int indexBelowZ = (int) cellMins.z;
int indexBeforeT = (int) cellMins.w;
int indexEastX = indexWestX + 1;
int indexNorthY = indexSouthY + 1;
int indexAboveZ = indexBelowZ + 1;
int indexAfterT = indexBeforeT + 1;
// Noise grid cell has 16 "corners" in 4D
float beforeBelowSW = Get4dNoiseZeroToOne( indexWestX, indexSouthY, indexBelowZ, indexBeforeT, seed );
float beforeBelowSE = Get4dNoiseZeroToOne( indexEastX, indexSouthY, indexBelowZ, indexBeforeT, seed );
float beforeBelowNW = Get4dNoiseZeroToOne( indexWestX, indexNorthY, indexBelowZ, indexBeforeT, seed );
float beforeBelowNE = Get4dNoiseZeroToOne( indexEastX, indexNorthY, indexBelowZ, indexBeforeT, seed );
float beforeAboveSW = Get4dNoiseZeroToOne( indexWestX, indexSouthY, indexAboveZ, indexBeforeT, seed );
float beforeAboveSE = Get4dNoiseZeroToOne( indexEastX, indexSouthY, indexAboveZ, indexBeforeT, seed );
float beforeAboveNW = Get4dNoiseZeroToOne( indexWestX, indexNorthY, indexAboveZ, indexBeforeT, seed );
float beforeAboveNE = Get4dNoiseZeroToOne( indexEastX, indexNorthY, indexAboveZ, indexBeforeT, seed );
float afterBelowSW = Get4dNoiseZeroToOne( indexWestX, indexSouthY, indexBelowZ, indexAfterT, seed );
float afterBelowSE = Get4dNoiseZeroToOne( indexEastX, indexSouthY, indexBelowZ, indexAfterT, seed );
float afterBelowNW = Get4dNoiseZeroToOne( indexWestX, indexNorthY, indexBelowZ, indexAfterT, seed );
float afterBelowNE = Get4dNoiseZeroToOne( indexEastX, indexNorthY, indexBelowZ, indexAfterT, seed );
float afterAboveSW = Get4dNoiseZeroToOne( indexWestX, indexSouthY, indexAboveZ, indexAfterT, seed );
float afterAboveSE = Get4dNoiseZeroToOne( indexEastX, indexSouthY, indexAboveZ, indexAfterT, seed );
float afterAboveNW = Get4dNoiseZeroToOne( indexWestX, indexNorthY, indexAboveZ, indexAfterT, seed );
float afterAboveNE = Get4dNoiseZeroToOne( indexEastX, indexNorthY, indexAboveZ, indexAfterT, seed );
// Do a smoothed (nonlinear) weighted average of nearby grid point values
Vector4 displacementFromMins = currentPos - cellMins;
float weightEast = SmoothStep( displacementFromMins.x );
float weightNorth = SmoothStep( displacementFromMins.y );
float weightAbove = SmoothStep( displacementFromMins.z );
float weightAfter = SmoothStep( displacementFromMins.w );
float weightWest = 1.f - weightEast;
float weightSouth = 1.f - weightNorth;
float weightBelow = 1.f - weightAbove;
float weightBefore = 1.f - weightAfter;
// 16-way blend (16 -> 8 -> 4 -> 2 -> 1)
float blendBeforeBelowSouth = (weightEast * beforeBelowSE) + (weightWest * beforeBelowSW);
float blendBeforeBelowNorth = (weightEast * beforeBelowNE) + (weightWest * beforeBelowNW);
float blendBeforeAboveSouth = (weightEast * beforeAboveSE) + (weightWest * beforeAboveSW);
float blendBeforeAboveNorth = (weightEast * beforeAboveNE) + (weightWest * beforeAboveNW);
float blendAfterBelowSouth = (weightEast * afterBelowSE) + (weightWest * afterBelowSW);
float blendAfterBelowNorth = (weightEast * afterBelowNE) + (weightWest * afterBelowNW);
float blendAfterAboveSouth = (weightEast * afterAboveSE) + (weightWest * afterAboveSW);
float blendAfterAboveNorth = (weightEast * afterAboveNE) + (weightWest * afterAboveNW);
float blendBeforeBelow = (weightSouth * blendBeforeBelowSouth) + (weightNorth * blendBeforeBelowNorth);
float blendBeforeAbove = (weightSouth * blendBeforeAboveSouth) + (weightNorth * blendBeforeAboveNorth);
float blendAfterBelow = (weightSouth * blendAfterBelowSouth) + (weightNorth * blendAfterBelowNorth);
float blendAfterAbove = (weightSouth * blendAfterAboveSouth) + (weightNorth * blendAfterAboveNorth);
float blendBefore = (weightBelow * blendBeforeBelow) + (weightAbove * blendBeforeAbove);
float blendAfter = (weightBelow * blendAfterBelow) + (weightAbove * blendAfterAbove);
float blendTotal = (weightBefore * blendBefore) + (weightAfter * blendAfter);
float noiseThisOctave = 2.f * (blendTotal - 0.5f); // Map from [0,1] to [-1,1]
// Accumulate results and prepare for next octave (if any)
totalNoise += noiseThisOctave * currentAmplitude;
totalAmplitude += currentAmplitude;
currentAmplitude *= octavePersistence;
currentPos *= octaveScale;
currentPos.x += OCTAVE_OFFSET; // Add "irrational" offsets to noise position components
currentPos.y += OCTAVE_OFFSET; // at each octave to break up their grid alignment
currentPos.z += OCTAVE_OFFSET;
currentPos.w += OCTAVE_OFFSET;
++ seed; // Eliminates octaves "echoing" each other (since each octave is uniquely seeded)
}
// Re-normalize total noise to within [-1,1] and fix octaves pulling us far away from limits
if( renormalize && totalAmplitude > 0.f )
{
totalNoise /= totalAmplitude; // Amplitude exceeds 1.0 if octaves are used
totalNoise = (totalNoise * 0.5f) + 0.5f; // Map to [0,1]
totalNoise = SmoothStep( totalNoise ); // Push towards extents (octaves pull us away)
totalNoise = (totalNoise * 2.0f) - 1.f; // Map back to [-1,1]
}
return totalNoise;
}