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| -rw-r--r-- | Tools/NoiseSpeedTest/SimplexNoise.h | 263 |
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diff --git a/Tools/NoiseSpeedTest/SimplexNoise.h b/Tools/NoiseSpeedTest/SimplexNoise.h new file mode 100644 index 000000000..33af8f007 --- /dev/null +++ b/Tools/NoiseSpeedTest/SimplexNoise.h @@ -0,0 +1,263 @@ +// SimplexNoise.h + +// Declares and implements the simplex noise, using a template parameter for the underlying datatype + +/* +Note: +This code has been adapted from the public domain code by Stefan Gustavson, available at +http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf +*/ + +#include <random> + + + + + +template<typename Datatype> +class cSimplexNoise +{ +public: + cSimplexNoise(int a_Seed) + { + // Based on the seed, initialize the permutation table, using a simple LCG and swapping + + // Initialize with sorted sequence: + for (size_t i = 0; i < ARRAYCOUNT(m_Perm) / 2; i++) + { + m_Perm[i] = static_cast<int>(i); + } + + // Use swaps to randomize: + std::linear_congruential_engine<unsigned, 48271, 0, 2147483647> lcg(a_Seed); + for (size_t i = 0; i < 2000; i++) + { + std::swap(m_Perm[lcg() % (ARRAYCOUNT(m_Perm) / 2)], m_Perm[lcg() % (ARRAYCOUNT(m_Perm) / 2)]); + } + + // Copy to the upper half of the buffer (to avoid the need for modulo when accessing neighbors): + for (size_t i = ARRAYCOUNT(m_Perm) / 2; i < ARRAYCOUNT(m_Perm); i++) + { + m_Perm[i] = m_Perm[i - ARRAYCOUNT(m_Perm) / 2]; + } + + // Copy to the "modulo 12" table to optimize away four modulo ops per value calculation: + for (size_t i = 0; i < ARRAYCOUNT(m_Perm); i++) + { + m_PermMod12[i] = m_Perm[i] % 12; + } + } + + + + /** Returns a dot product of an int vector with a Datatype vector. */ + inline Datatype dot(const int * g, const Datatype x, const Datatype y, const Datatype z) + { + return g[0] * x + g[1] * y + g[2] * z; + } + + + + /** Returns a dot product of two Datatype vectors. */ + inline Datatype dot(const Datatype * g, const Datatype x, const Datatype y, const Datatype z) + { + return g[0] * x + g[1] * y + g[2] * z; + } + + + + /** Returns the floor of the specified value, already type-cast to proper int type. */ + inline int datafloor(const Datatype a_Val) + { + return (a_Val > 0) ? static_cast<int>(a_Val) : static_cast<int>(a_Val - 1); // This is faster than std::floor() + } + + + /** Returns a single noise value based on the 3D coords. */ + Datatype GetValueAt3D(const Datatype a_X, const Datatype a_Y, const Datatype a_Z) + { + // The gradients are the midpoints of the vertices of a cube. + static const Datatype grad3[12][3] = { + {1, 1, 0}, {-1, 1, 0}, {1, -1, 0}, {-1, -1, 0}, + {1, 0, 1}, {-1, 0, 1}, {1, 0, -1}, {-1, 0, -1}, + {0, 1, 1}, { 0, -1, 1}, {0, 1, -1}, { 0, -1, -1} + }; + + // Skew factors: + static const Datatype F3 = static_cast<Datatype>(1.0 / 3.0); + static const Datatype G3 = static_cast<Datatype>(1.0 / 6.0); + + // Noise contributions from the four corners: + Datatype n0, n1, n2, n3; + + // Skew the input space to determine which simplex cell we're in + Datatype s = (a_X + a_Y + a_Z) * F3; + int i = datafloor(a_X + s); + int j = datafloor(a_Y + s); + int k = datafloor(a_Z + s); + + // Unskew back into the XYZ space to calculate the distances from cell origin: + Datatype t = (i + j + k) * G3; + Datatype X0 = i - t; + Datatype Y0 = j - t; + Datatype Z0 = k - t; + Datatype x0 = a_X - X0; + Datatype y0 = a_Y - Y0; + Datatype z0 = a_Z - Z0; + + // For the 3D case, the simplex shape is a slightly irregular tetrahedron. + // Determine which simplex we are in. + int i1, j1, k1; // Offsets for second corner of simplex in IJK coords + int i2, j2, k2; // Offsets for third corner of simplex in IJK coords + if (x0 >= y0) + { + if (y0 >= z0) + { + // X Y Z order + i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0; + } + else if (x0 >= z0) + { + // X Z Y order + i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1; + } + else + { + // Z X Y order + i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1; + } + } + else + { + if (y0 < z0) + { + // Z Y X order + i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1; + } + else if (x0 < z0) + { + // Y Z X order + i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1; + } + else + { + // Y X Z order + i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0; + } + } + + // A step of (1, 0, 0) in IJK means a step of (1 - c, -c, -c) in XYZ, + // a step of (0, 1, 0) in IJK means a step of (-c, 1 - c, -c) in XYZ, and + // a step of (0, 0, 1) in IJK means a step of (-c, -c, 1 - c) in XYZ, where c = G3 = 1 / 6. + Datatype x1 = x0 - i1 + G3; // Offsets for second corner in XYZ coords + Datatype y1 = y0 - j1 + G3; + Datatype z1 = z0 - k1 + G3; + Datatype x2 = x0 - i2 + static_cast<Datatype>(2) * G3; // Offsets for third corner in XYZ coords + Datatype y2 = y0 - j2 + static_cast<Datatype>(2) * G3; + Datatype z2 = z0 - k2 + static_cast<Datatype>(2) * G3; + Datatype x3 = x0 - static_cast<Datatype>(1) + static_cast<Datatype>(3) * G3; // Offsets for last corner in XYZ coords + Datatype y3 = y0 - static_cast<Datatype>(1) + static_cast<Datatype>(3) * G3; + Datatype z3 = z0 - static_cast<Datatype>(1) + static_cast<Datatype>(3) * G3; + + // Work out the hashed gradient indices of the four simplex corners + int ii = i & 255; + int jj = j & 255; + int kk = k & 255; + int gi0 = m_PermMod12[ii + m_Perm[jj + m_Perm[kk]]]; + int gi1 = m_PermMod12[ii + i1 + m_Perm[jj + j1 + m_Perm[kk + k1]]]; + int gi2 = m_PermMod12[ii + i2 + m_Perm[jj + j2 + m_Perm[kk + k2]]]; + int gi3 = m_PermMod12[ii + 1 + m_Perm[jj + 1 + m_Perm[kk + 1]]]; + + // Calculate the contribution from the four corners + Datatype t0 = static_cast<Datatype>(0.6) - x0 * x0 - y0 * y0 - z0 * z0; + if (t0 < 0) + { + n0 = 0.0; + } + else + { + t0 *= t0; + n0 = t0 * t0 * dot(grad3[gi0], x0, y0, z0); + } + + Datatype t1 = static_cast<Datatype>(0.6) - x1 * x1 - y1 * y1 - z1 * z1; + if (t1 < 0) + { + n1 = 0.0; + } + else + { + t1 *= t1; + n1 = t1 * t1 * dot(grad3[gi1], x1, y1, z1); + } + + Datatype t2 = static_cast<Datatype>(0.6) - x2 * x2 - y2 * y2 - z2 * z2; + if (t2 < 0) + { + n2 = 0.0; + } + else + { + t2 *= t2; + n2 = t2 * t2 * dot(grad3[gi2], x2, y2, z2); + } + + Datatype t3 = static_cast<Datatype>(0.6) - x3 * x3 - y3 * y3 - z3 * z3; + if (t3 < 0) + { + n3 = 0.0; + } + else + { + t3 *= t3; + n3 = t3 * t3 * dot(grad3[gi3], x3, y3, z3); + } + + // Add contributions from each corner to get the final noise value. + // The result is scaled to stay just inside [-1, 1] + return static_cast<Datatype>(32) * (n0 + n1 + n2 + n3); + } + + + + + /** Generates the 3D version of the SImplex noise. + a_Out is the 3D array into which the noise is output. Organized as [x + a_SizeX * y + a_SizeX * a_SizeY * z]. + a_SizeX, a_SizeY, a_SizeZ are the dimensions of the a_Out array. + a_Start and a_End are the coords of the 3D array in the noise-space. */ + void Generate3D( + Datatype * a_Out, + int a_SizeX, int a_SizeY, int a_SizeZ, + Datatype a_StartX, Datatype a_EndX, + Datatype a_StartY, Datatype a_EndY, + Datatype a_StartZ, Datatype a_EndZ + ) + { + Datatype * out = a_Out; + for (int z = 0; z < a_SizeZ; ++z) + { + Datatype nz = a_StartZ + z * (a_EndZ - a_StartZ) / a_SizeZ; + for (int y = 0; y < a_SizeY; ++y) + { + Datatype ny = a_StartY + y * (a_EndY - a_StartY) / a_SizeY; + for (int x = 0; x < a_SizeX; ++x) + { + Datatype nx = a_StartX + x * (a_EndX - a_StartX) / a_SizeX; + *out = GetValueAt3D(nx, ny, nz); + ++out; + } // for x + } // for y + } // for z + } + +protected: + /** The permutation table, initialized by the seed. */ + int m_Perm[512]; + + /** A copy of the permutation table, with each item modulo 12, to avoid 4 modulo operations per value calculation. */ + int m_PermMod12[512]; +}; + + + + |