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/*
* Copyright (c) 2008-2017, NVIDIA CORPORATION. All rights reserved.
*
* NVIDIA CORPORATION and its licensors retain all intellectual property
* and proprietary rights in and to this software, related documentation
* and any modifications thereto. Any use, reproduction, disclosure or
* distribution of this software and related documentation without an express
* license agreement from NVIDIA CORPORATION is strictly prohibited.
*/
#ifndef SIMPLEX_NOISE_H
#define SIMPLEX_NOISE_H
#include "PxVec4.h"
namespace nvidia
{
namespace apex
{
class SimplexNoise
{
static const int X_NOISE_GEN = 1619;
static const int Y_NOISE_GEN = 31337;
static const int Z_NOISE_GEN = 6971;
static const int W_NOISE_GEN = 1999;
static const int SEED_NOISE_GEN = 1013;
static const int SHIFT_NOISE_GEN = 8;
PX_CUDA_CALLABLE static PX_INLINE int fastfloor(float x)
{
return (x >= 0) ? (int)x : (int)(x - 1);
}
public:
// 4D simplex noise
// returns: (x,y,z) = noise grad, w = noise value
PX_CUDA_CALLABLE static physx::PxVec4 eval4D(float x, float y, float z, float w, int seed)
{
// The skewing and unskewing factors are hairy again for the 4D case
const float F4 = (physx::PxSqrt(5.0f) - 1.0f) / 4.0f;
const float G4 = (5.0f - physx::PxSqrt(5.0f)) / 20.0f;
// Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
float s = (x + y + z + w) * F4; // Factor for 4D skewing
int ix = fastfloor(x + s);
int iy = fastfloor(y + s);
int iz = fastfloor(z + s);
int iw = fastfloor(w + s);
float t = (ix + iy + iz + iw) * G4; // Factor for 4D unskewing
// Unskew the cell origin back to (x,y,z,w) space
float x0 = x - (ix - t); // The x,y,z,w distances from the cell origin
float y0 = y - (iy - t);
float z0 = z - (iz - t);
float w0 = w - (iw - t);
int c = (x0 > y0) ? (1 << 0) : (1 << 2);
c += (x0 > z0) ? (1 << 0) : (1 << 4);
c += (x0 > w0) ? (1 << 0) : (1 << 6);
c += (y0 > z0) ? (1 << 2) : (1 << 4);
c += (y0 > w0) ? (1 << 2) : (1 << 6);
c += (z0 > w0) ? (1 << 4) : (1 << 6);
physx::PxVec4 res;
res.setZero();
// Calculate the contribution from the five corners
#ifdef __CUDACC__
#pragma unroll
#endif
for (int p = 4; p >= 0; --p)
{
int ixp = ((c >> 0) & 3) >= p ? 1 : 0;
int iyp = ((c >> 2) & 3) >= p ? 1 : 0;
int izp = ((c >> 4) & 3) >= p ? 1 : 0;
int iwp = ((c >> 6) & 3) >= p ? 1 : 0;
float xp = x0 - ixp + (4 - p) * G4;
float yp = y0 - iyp + (4 - p) * G4;
float zp = z0 - izp + (4 - p) * G4;
float wp = w0 - iwp + (4 - p) * G4;
float t = 0.6f - xp * xp - yp * yp - zp * zp - wp * wp;
if (t > 0)
{
//get index
int gradIndex = int((
X_NOISE_GEN * (ix + ixp)
+ Y_NOISE_GEN * (iy + iyp)
+ Z_NOISE_GEN * (iz + izp)
+ W_NOISE_GEN * (iw + iwp)
+ SEED_NOISE_GEN * seed)
& 0xffffffff);
gradIndex ^= (gradIndex >> SHIFT_NOISE_GEN);
gradIndex &= 31;
physx::PxVec4 g;
{
const int h = gradIndex;
const int hs = 2 - (h >> 4);
const int h1 = (h >> 3);
g.x = (h1 == 0) ? 0.0f : ((h & 4) ? -1.0f : 1.0f);
g.y = (h1 == 1) ? 0.0f : ((h & (hs << 1)) ? -1.0f : 1.0f);
g.z = (h1 == 2) ? 0.0f : ((h & hs) ? -1.0f : 1.0f);
g.w = (h1 == 3) ? 0.0f : ((h & 1) ? -1.0f : 1.0f);
}
float gdot = (g.x * xp + g.y * yp + g.z * zp + g.w * wp);
float t2 = t * t;
float t3 = t2 * t;
float t4 = t3 * t;
float dt4gdot = 8 * t3 * gdot;
res.x += t4 * g.x - dt4gdot * xp;
res.y += t4 * g.y - dt4gdot * yp;
res.z += t4 * g.z - dt4gdot * zp;
res.w += t4 * gdot;
}
}
// scale the result to cover the range [-1,1]
res *= 27;
return res;
}
};
}
} // namespace nvidia::apex
#endif
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