mirror of https://github.com/bjornbytes/lovr.git
467 lines
19 KiB
C
467 lines
19 KiB
C
/* SimplexNoise1234, Simplex noise with true analytic
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* derivative in 1D to 4D.
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*
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* Author: Stefan Gustavson, 2003-2005
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* Contact: stefan.gustavson@liu.se
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*
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* This code was GPL licensed until February 2011.
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* As the original author of this code, I hereby
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* release it into the public domain.
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* Please feel free to use it for whatever you want.
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* Credit is appreciated where appropriate, and I also
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* appreciate being told where this code finds any use,
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* but you may do as you like.
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*/
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/*
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* This implementation is "Simplex Noise" as presented by
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* Ken Perlin at a relatively obscure and not often cited course
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* session "Real-Time Shading" at Siggraph 2001 (before real
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* time shading actually took off), under the title "hardware noise".
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* The 3D function is numerically equivalent to his Java reference
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* code available in the PDF course notes, although I re-implemented
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* it from scratch to get more readable code. The 1D, 2D and 4D cases
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* were implemented from scratch by me from Ken Perlin's text.
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*
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* This file has no dependencies on any other file, not even its own
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* header file. The header file is made for use by external code only.
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*/
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// We don't really need to include this, but play nice and do it anyway.
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#include "simplexnoise1234.h"
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#define FASTFLOOR(x) ( ((int)(x)<=(x)) ? ((int)x) : (((int)x)-1) )
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//---------------------------------------------------------------------
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// Static data
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/*
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* Permutation table. This is just a random jumble of all numbers 0-255,
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* repeated twice to avoid wrapping the index at 255 for each lookup.
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* This needs to be exactly the same for all instances on all platforms,
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* so it's easiest to just keep it as static explicit data.
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* This also removes the need for any initialisation of this class.
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*
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* Note that making this an int[] instead of a char[] might make the
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* code run faster on platforms with a high penalty for unaligned single
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* byte addressing. Intel x86 is generally single-byte-friendly, but
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* some other CPUs are faster with 4-aligned reads.
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* However, a char[] is smaller, which avoids cache trashing, and that
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* is probably the most important aspect on most architectures.
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* This array is accessed a *lot* by the noise functions.
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* A vector-valued noise over 3D accesses it 96 times, and a
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* float-valued 4D noise 64 times. We want this to fit in the cache!
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*/
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unsigned char perm[512] = {151,160,137,91,90,15,
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131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
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190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
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88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
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77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
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102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
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135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
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5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
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223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
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129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
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251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
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49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
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138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180,
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151,160,137,91,90,15,
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131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
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190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
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88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
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77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
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102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
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135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
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5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
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223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
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129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
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251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
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49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
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138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
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};
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//---------------------------------------------------------------------
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/*
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* Helper functions to compute gradients-dot-residualvectors (1D to 4D)
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* Note that these generate gradients of more than unit length. To make
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* a close match with the value range of classic Perlin noise, the final
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* noise values need to be rescaled to fit nicely within [-1,1].
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* (The simplex noise functions as such also have different scaling.)
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* Note also that these noise functions are the most practical and useful
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* signed version of Perlin noise. To return values according to the
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* RenderMan specification from the SL noise() and pnoise() functions,
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* the noise values need to be scaled and offset to [0,1], like this:
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* float SLnoise = (noise(x,y,z) + 1.0) * 0.5;
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*/
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double grad1( int hash, double x ) {
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int h = hash & 15;
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double grad = 1.0 + (h & 7); // Gradient value 1.0, 2.0, ..., 8.0
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if (h&8) grad = -grad; // Set a random sign for the gradient
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return ( grad * x ); // Multiply the gradient with the distance
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}
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double grad2( int hash, double x, double y ) {
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int h = hash & 7; // Convert low 3 bits of hash code
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double u = h<4 ? x : y; // into 8 simple gradient directions,
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double v = h<4 ? y : x; // and compute the dot product with (x,y).
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return ((h&1)? -u : u) + ((h&2)? -2.0*v : 2.0*v);
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}
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double grad3( int hash, double x, double y , double z ) {
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int h = hash & 15; // Convert low 4 bits of hash code into 12 simple
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double u = h<8 ? x : y; // gradient directions, and compute dot product.
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double v = h<4 ? y : h==12||h==14 ? x : z; // Fix repeats at h = 12 to 15
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return ((h&1)? -u : u) + ((h&2)? -v : v);
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}
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double grad4( int hash, double x, double y, double z, double t ) {
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int h = hash & 31; // Convert low 5 bits of hash code into 32 simple
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double u = h<24 ? x : y; // gradient directions, and compute dot product.
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double v = h<16 ? y : z;
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double w = h<8 ? z : t;
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return ((h&1)? -u : u) + ((h&2)? -v : v) + ((h&4)? -w : w);
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}
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// A lookup table to traverse the simplex around a given point in 4D.
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// Details can be found where this table is used, in the 4D noise method.
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/* TODO: This should not be required, backport it from Bill's GLSL code! */
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static unsigned char simplex[64][4] = {
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{0,1,2,3},{0,1,3,2},{0,0,0,0},{0,2,3,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,2,3,0},
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{0,2,1,3},{0,0,0,0},{0,3,1,2},{0,3,2,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,3,2,0},
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{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},
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{1,2,0,3},{0,0,0,0},{1,3,0,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,3,0,1},{2,3,1,0},
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{1,0,2,3},{1,0,3,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,0,3,1},{0,0,0,0},{2,1,3,0},
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{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},
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{2,0,1,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,0,1,2},{3,0,2,1},{0,0,0,0},{3,1,2,0},
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{2,1,0,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,1,0,2},{0,0,0,0},{3,2,0,1},{3,2,1,0}};
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// 1D simplex noise
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double snoise1(double x) {
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int i0 = FASTFLOOR(x);
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int i1 = i0 + 1;
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double x0 = x - i0;
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double x1 = x0 - 1.0;
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double n0, n1;
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double t0 = 1.0 - x0*x0;
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// if(t0 < 0.0) t0 = 0.0; // this never happens for the 1D case
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t0 *= t0;
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n0 = t0 * t0 * grad1(perm[i0 & 0xff], x0);
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double t1 = 1.0 - x1*x1;
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// if(t1 < 0.0) t1 = 0.0; // this never happens for the 1D case
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t1 *= t1;
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n1 = t1 * t1 * grad1(perm[i1 & 0xff], x1);
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// The maximum value of this noise is 8*(3/4)^4 = 2.53125
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// A factor of 0.395 would scale to fit exactly within [-1,1], but
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// we want to match PRMan's 1D noise, so we scale it down some more.
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return 0.25f * (n0 + n1);
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}
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// 2D simplex noise
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double snoise2(double x, double y) {
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#define F2 0.366025403 // F2 = 0.5*(sqrt(3.0)-1.0)
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#define G2 0.211324865 // G2 = (3.0-Math.sqrt(3.0))/6.0
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double n0, n1, n2; // Noise contributions from the three corners
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// Skew the input space to determine which simplex cell we're in
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double s = (x+y)*F2; // Hairy factor for 2D
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double xs = x + s;
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double ys = y + s;
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int i = FASTFLOOR(xs);
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int j = FASTFLOOR(ys);
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double t = (double)(i+j)*G2;
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double X0 = i-t; // Unskew the cell origin back to (x,y) space
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double Y0 = j-t;
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double x0 = x-X0; // The x,y distances from the cell origin
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double y0 = y-Y0;
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// For the 2D case, the simplex shape is an equilateral triangle.
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// Determine which simplex we are in.
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int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
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if(x0>y0) {i1=1; j1=0;} // lower triangle, XY order: (0,0)->(1,0)->(1,1)
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else {i1=0; j1=1;} // upper triangle, YX order: (0,0)->(0,1)->(1,1)
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// A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
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// a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
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// c = (3-sqrt(3))/6
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double x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
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double y1 = y0 - j1 + G2;
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double x2 = x0 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords
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double y2 = y0 - 1.0 + 2.0 * G2;
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// Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
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int ii = i & 0xff;
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int jj = j & 0xff;
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// Calculate the contribution from the three corners
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double t0 = 0.5f - x0*x0-y0*y0;
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if(t0 < 0.0) n0 = 0.0;
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else {
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t0 *= t0;
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n0 = t0 * t0 * grad2(perm[ii+perm[jj]], x0, y0);
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}
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double t1 = 0.5f - x1*x1-y1*y1;
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if(t1 < 0.0) n1 = 0.0;
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else {
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t1 *= t1;
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n1 = t1 * t1 * grad2(perm[ii+i1+perm[jj+j1]], x1, y1);
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}
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double t2 = 0.5f - x2*x2-y2*y2;
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if(t2 < 0.0) n2 = 0.0;
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else {
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t2 *= t2;
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n2 = t2 * t2 * grad2(perm[ii+1+perm[jj+1]], x2, y2);
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}
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// Add contributions from each corner to get the final noise value.
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// The result is scaled to return values in the interval [-1,1].
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return 40.0 * (n0 + n1 + n2); // TODO: The scale factor is preliminary!
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}
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// 3D simplex noise
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double snoise3(double x, double y, double z) {
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// Simple skewing factors for the 3D case
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#define F3 0.333333333
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#define G3 0.166666667
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double n0, n1, n2, n3; // Noise contributions from the four corners
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// Skew the input space to determine which simplex cell we're in
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double s = (x+y+z)*F3; // Very nice and simple skew factor for 3D
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double xs = x+s;
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double ys = y+s;
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double zs = z+s;
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int i = FASTFLOOR(xs);
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int j = FASTFLOOR(ys);
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int k = FASTFLOOR(zs);
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double t = (double)(i+j+k)*G3;
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double X0 = i-t; // Unskew the cell origin back to (x,y,z) space
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double Y0 = j-t;
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double Z0 = k-t;
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double x0 = x-X0; // The x,y,z distances from the cell origin
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double y0 = y-Y0;
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double z0 = z-Z0;
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// For the 3D case, the simplex shape is a slightly irregular tetrahedron.
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// Determine which simplex we are in.
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int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
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int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
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/* This code would benefit from a backport from the GLSL version! */
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if(x0>=y0) {
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if(y0>=z0)
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{ i1=1; j1=0; k1=0; i2=1; j2=1; k2=0; } // X Y Z order
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else if(x0>=z0) { i1=1; j1=0; k1=0; i2=1; j2=0; k2=1; } // X Z Y order
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else { i1=0; j1=0; k1=1; i2=1; j2=0; k2=1; } // Z X Y order
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}
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else { // x0<y0
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if(y0<z0) { i1=0; j1=0; k1=1; i2=0; j2=1; k2=1; } // Z Y X order
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else if(x0<z0) { i1=0; j1=1; k1=0; i2=0; j2=1; k2=1; } // Y Z X order
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else { i1=0; j1=1; k1=0; i2=1; j2=1; k2=0; } // Y X Z order
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}
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// A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
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// a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
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// a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
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// c = 1/6.
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double x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
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double y1 = y0 - j1 + G3;
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double z1 = z0 - k1 + G3;
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double x2 = x0 - i2 + 2.0*G3; // Offsets for third corner in (x,y,z) coords
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double y2 = y0 - j2 + 2.0*G3;
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double z2 = z0 - k2 + 2.0*G3;
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double x3 = x0 - 1.0 + 3.0*G3; // Offsets for last corner in (x,y,z) coords
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double y3 = y0 - 1.0 + 3.0*G3;
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double z3 = z0 - 1.0 + 3.0*G3;
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// Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
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int ii = i & 0xff;
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int jj = j & 0xff;
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int kk = k & 0xff;
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// Calculate the contribution from the four corners
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double t0 = 0.5f - x0*x0 - y0*y0 - z0*z0;
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if(t0 < 0.0) n0 = 0.0;
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else {
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t0 *= t0;
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n0 = t0 * t0 * grad3(perm[ii+perm[jj+perm[kk]]], x0, y0, z0);
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}
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double t1 = 0.5f - x1*x1 - y1*y1 - z1*z1;
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if(t1 < 0.0) n1 = 0.0;
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else {
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t1 *= t1;
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n1 = t1 * t1 * grad3(perm[ii+i1+perm[jj+j1+perm[kk+k1]]], x1, y1, z1);
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}
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double t2 = 0.5f - x2*x2 - y2*y2 - z2*z2;
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if(t2 < 0.0) n2 = 0.0;
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else {
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t2 *= t2;
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n2 = t2 * t2 * grad3(perm[ii+i2+perm[jj+j2+perm[kk+k2]]], x2, y2, z2);
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}
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double t3 = 0.5f - x3*x3 - y3*y3 - z3*z3;
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if(t3<0.0) n3 = 0.0;
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else {
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t3 *= t3;
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n3 = t3 * t3 * grad3(perm[ii+1+perm[jj+1+perm[kk+1]]], x3, y3, z3);
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}
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// Add contributions from each corner to get the final noise value.
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// The result is scaled to stay just inside [-1,1]
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return 72.0 * (n0 + n1 + n2 + n3);
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}
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// 4D simplex noise
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double snoise4(double x, double y, double z, double w) {
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// The skewing and unskewing factors are hairy again for the 4D case
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#define F4 0.309016994 // F4 = (Math.sqrt(5.0)-1.0)/4.0
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#define G4 0.138196601 // G4 = (5.0-Math.sqrt(5.0))/20.0
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double n0, n1, n2, n3, n4; // Noise contributions from the five corners
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// Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
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double s = (x + y + z + w) * F4; // Factor for 4D skewing
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double xs = x + s;
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double ys = y + s;
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double zs = z + s;
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double ws = w + s;
|
||
int i = FASTFLOOR(xs);
|
||
int j = FASTFLOOR(ys);
|
||
int k = FASTFLOOR(zs);
|
||
int l = FASTFLOOR(ws);
|
||
|
||
double t = (i + j + k + l) * G4; // Factor for 4D unskewing
|
||
double X0 = i - t; // Unskew the cell origin back to (x,y,z,w) space
|
||
double Y0 = j - t;
|
||
double Z0 = k - t;
|
||
double W0 = l - t;
|
||
|
||
double x0 = x - X0; // The x,y,z,w distances from the cell origin
|
||
double y0 = y - Y0;
|
||
double z0 = z - Z0;
|
||
double w0 = w - W0;
|
||
|
||
// For the 4D case, the simplex is a 4D shape I won't even try to describe.
|
||
// To find out which of the 24 possible simplices we're in, we need to
|
||
// determine the magnitude ordering of x0, y0, z0 and w0.
|
||
// The method below is a good way of finding the ordering of x,y,z,w and
|
||
// then find the correct traversal order for the simplex were in.
|
||
// First, six pair-wise comparisons are performed between each possible pair
|
||
// of the four coordinates, and the results are used to add up binary bits
|
||
// for an integer index.
|
||
int c1 = (x0 > y0) ? 32 : 0;
|
||
int c2 = (x0 > z0) ? 16 : 0;
|
||
int c3 = (y0 > z0) ? 8 : 0;
|
||
int c4 = (x0 > w0) ? 4 : 0;
|
||
int c5 = (y0 > w0) ? 2 : 0;
|
||
int c6 = (z0 > w0) ? 1 : 0;
|
||
int c = c1 + c2 + c3 + c4 + c5 + c6;
|
||
|
||
int i1, j1, k1, l1; // The integer offsets for the second simplex corner
|
||
int i2, j2, k2, l2; // The integer offsets for the third simplex corner
|
||
int i3, j3, k3, l3; // The integer offsets for the fourth simplex corner
|
||
|
||
// simplex[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
|
||
// Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
|
||
// impossible. Only the 24 indices which have non-zero entries make any sense.
|
||
// We use a thresholding to set the coordinates in turn from the largest magnitude.
|
||
// The number 3 in the "simplex" array is at the position of the largest coordinate.
|
||
i1 = simplex[c][0]>=3 ? 1 : 0;
|
||
j1 = simplex[c][1]>=3 ? 1 : 0;
|
||
k1 = simplex[c][2]>=3 ? 1 : 0;
|
||
l1 = simplex[c][3]>=3 ? 1 : 0;
|
||
// The number 2 in the "simplex" array is at the second largest coordinate.
|
||
i2 = simplex[c][0]>=2 ? 1 : 0;
|
||
j2 = simplex[c][1]>=2 ? 1 : 0;
|
||
k2 = simplex[c][2]>=2 ? 1 : 0;
|
||
l2 = simplex[c][3]>=2 ? 1 : 0;
|
||
// The number 1 in the "simplex" array is at the second smallest coordinate.
|
||
i3 = simplex[c][0]>=1 ? 1 : 0;
|
||
j3 = simplex[c][1]>=1 ? 1 : 0;
|
||
k3 = simplex[c][2]>=1 ? 1 : 0;
|
||
l3 = simplex[c][3]>=1 ? 1 : 0;
|
||
// The fifth corner has all coordinate offsets = 1, so no need to look that up.
|
||
|
||
double x1 = x0 - i1 + G4; // Offsets for second corner in (x,y,z,w) coords
|
||
double y1 = y0 - j1 + G4;
|
||
double z1 = z0 - k1 + G4;
|
||
double w1 = w0 - l1 + G4;
|
||
double x2 = x0 - i2 + 2.0*G4; // Offsets for third corner in (x,y,z,w) coords
|
||
double y2 = y0 - j2 + 2.0*G4;
|
||
double z2 = z0 - k2 + 2.0*G4;
|
||
double w2 = w0 - l2 + 2.0*G4;
|
||
double x3 = x0 - i3 + 3.0*G4; // Offsets for fourth corner in (x,y,z,w) coords
|
||
double y3 = y0 - j3 + 3.0*G4;
|
||
double z3 = z0 - k3 + 3.0*G4;
|
||
double w3 = w0 - l3 + 3.0*G4;
|
||
double x4 = x0 - 1.0 + 4.0*G4; // Offsets for last corner in (x,y,z,w) coords
|
||
double y4 = y0 - 1.0 + 4.0*G4;
|
||
double z4 = z0 - 1.0 + 4.0*G4;
|
||
double w4 = w0 - 1.0 + 4.0*G4;
|
||
|
||
// Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
|
||
int ii = i & 0xff;
|
||
int jj = j & 0xff;
|
||
int kk = k & 0xff;
|
||
int ll = l & 0xff;
|
||
|
||
// Calculate the contribution from the five corners
|
||
double t0 = 0.5f - x0*x0 - y0*y0 - z0*z0 - w0*w0;
|
||
if(t0 < 0.0) n0 = 0.0;
|
||
else {
|
||
t0 *= t0;
|
||
n0 = t0 * t0 * grad4(perm[ii+perm[jj+perm[kk+perm[ll]]]], x0, y0, z0, w0);
|
||
}
|
||
|
||
double t1 = 0.5f - x1*x1 - y1*y1 - z1*z1 - w1*w1;
|
||
if(t1 < 0.0) n1 = 0.0;
|
||
else {
|
||
t1 *= t1;
|
||
n1 = t1 * t1 * grad4(perm[ii+i1+perm[jj+j1+perm[kk+k1+perm[ll+l1]]]], x1, y1, z1, w1);
|
||
}
|
||
|
||
double t2 = 0.5f - x2*x2 - y2*y2 - z2*z2 - w2*w2;
|
||
if(t2 < 0.0) n2 = 0.0;
|
||
else {
|
||
t2 *= t2;
|
||
n2 = t2 * t2 * grad4(perm[ii+i2+perm[jj+j2+perm[kk+k2+perm[ll+l2]]]], x2, y2, z2, w2);
|
||
}
|
||
|
||
double t3 = 0.5f - x3*x3 - y3*y3 - z3*z3 - w3*w3;
|
||
if(t3 < 0.0) n3 = 0.0;
|
||
else {
|
||
t3 *= t3;
|
||
n3 = t3 * t3 * grad4(perm[ii+i3+perm[jj+j3+perm[kk+k3+perm[ll+l3]]]], x3, y3, z3, w3);
|
||
}
|
||
|
||
double t4 = 0.5f - x4*x4 - y4*y4 - z4*z4 - w4*w4;
|
||
if(t4 < 0.0) n4 = 0.0;
|
||
else {
|
||
t4 *= t4;
|
||
n4 = t4 * t4 * grad4(perm[ii+1+perm[jj+1+perm[kk+1+perm[ll+1]]]], x4, y4, z4, w4);
|
||
}
|
||
|
||
// Sum up and scale the result to cover the range [-1,1]
|
||
return 62.0 * (n0 + n1 + n2 + n3 + n4);
|
||
}
|
||
//---------------------------------------------------------------------
|