SimplexNoise.cpp

/*
===============================================================================
Ported the SimplexNoise algorithm from the C++ versions mentioned below 
to a reuseable Arduino Library.

By Jordan Shaw / http://jordanshaw.com / 2017-02

A C++ port of a speed-improved simplex noise algorithm for 2D in Java.
Based on example code by Stefan Gustavson (stegu@itn.liu.se).
Optimisations by Peter Eastman (peastman@drizzle.stanford.edu).
Better rank ordering method by Stefan Gustavson in 2012.
C++ port and minor type and algorithm changes by Josh Koch (jdk1337@gmail.com).
This could be speeded up even further, but it's useful as it is.
Version 2012-04-12
The original Java code was placed in the public domain by its original author,
Stefan Gustavson. You may use it as you see fit,
but attribution is appreciated.

Original gist url: https://gist.github.com/Slipyx/2372043

===============================================================================
*/

#include <math.h>
#include "Arduino.h"
#include "SimplexNoise.h"

// Private static member definitions
const double SimplexNoise::F2 = 0.5 * (sqrt( 3.0 ) - 1.0);
const double SimplexNoise::G2 = (3.0 - sqrt( 3.0 )) / 6.0;
const uint8_t SimplexNoise::p[256] = {
    151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,
    142,8,99,37,240,21,10,23,190,6,148,247,120,234,75,0,26,197,62,94,252,219,
    203,117,35,11,32,57,177,33,88,237,149,56,87,174,20,125,136,171,168,68,175,
    74,165,71,134,139,48,27,166,77,146,158,231,83,111,229,122,60,211,133,230,
    220,105,92,41,55,46,245,40,244,102,143,54,65,25,63,161,1,216,80,73,209,76,
    132,187,208,89,18,169,200,196,135,130,116,188,159,86,164,100,109,198,173,
    186,3,64,52,217,226,250,124,123,5,202,38,147,118,126,255,82,85,212,207,206,
    59,227,47,16,58,17,182,189,28,42,223,183,170,213,119,248,152,2,44,154,163,
    70,221,153,101,155,167,43,172,9,129,22,39,253,19,98,108,110,79,113,224,232,
    178,185,112,104,218,246,97,228,251,34,242,193,238,210,144,12,191,179,162,
    241,81,51,145,235,249,14,239,107,49,192,214,31,181,199,106,157,184,84,204,
    176,115,121,50,45,127,4,150,254,138,236,205,93,222,114,67,29,24,72,243,141,
    128,195,78,66,215,61,156,180
};
const Grad SimplexNoise::grad3[12] = {
    Grad(1,1,0),Grad(-1,1,0),Grad(1,-1,0),Grad(-1,-1,0),Grad(1,0,1),
    Grad(-1,0,1),Grad(1,0,-1),Grad(-1,0,-1),Grad(0,1,1),Grad(0,-1,1),
    Grad(0,1,-1),Grad(0,-1,-1)
};
uint8_t SimplexNoise::perm[512] = {0};
uint8_t SimplexNoise::permMod12[512] = {0};

// Initialize permutaion arrays
void SimplexNoise::init() {
    for ( uint16_t i = 0; i < 512; ++i ) {
        perm[i] = p[i & 255];
        permMod12[i] = static_cast<uint8_t>(perm[i] % 12);
    }
    delete[] &p; // lol what
}

// Fast floor
int32_t SimplexNoise::fastFloor( double x ) {
    int32_t xi = static_cast<int32_t>(x);
    return x < xi ? xi - 1 : xi;
}

double SimplexNoise::dot( const Grad& g, double x, double y ) {
    return g.x * x + g.y * y;
}

// 2D SimplexNoise noise
double SimplexNoise::noise( double xin, double yin ) {
    double s = (xin + yin) * F2;
    int32_t i = fastFloor( xin + s );
    int32_t j = fastFloor( yin + s );
    double t = (i + j) * G2;
    double x0 = xin - (i - t);
    double y0 = yin - (j - t);
    uint8_t i1 = 0, j1 = 1;
    if ( x0 > y0 ) {
        i1 = 1;
        j1 = 0;
    }
    double x1 = x0 - i1 + G2;
    double y1 = y0 - j1 + G2;
    double x2 = x0 - 1.0 + 2.0 * G2;
    double y2 = y0 - 1.0 + 2.0 * G2;
    uint8_t ii = i & 255;
    uint8_t jj = j & 255;
    uint8_t gi0 = permMod12[ii + perm[jj]];
    uint8_t gi1 = permMod12[ii + i1 + perm[jj + j1]];
    uint8_t gi2 = permMod12[ii + 1 + perm[jj + 1]];
    double n0 = 0.0;
    double t0 = 0.5 - x0 * x0 - y0 * y0;
    if ( t0 >= 0.0 ) {
        t0 *= t0;
        n0 = t0 * t0 * dot( grad3[gi0], x0, y0 );
    }
    double n1 = 0.0;
    double t1 = 0.5 - x1 * x1 - y1 * y1;
    if ( t1 >= 0.0 ) {
        t1 *= t1;
        n1 = t1 * t1 * dot( grad3[gi1], x1, y1 );
    }
    double n2 = 0.0;
    double t2 = 0.5 - x2 * x2 - y2 * y2;
    if ( t2 >= 0.0 ) {
        t2 *= t2;
        n2 = t2 * t2 * dot( grad3[gi2], x2, y2 );
    }
    return 70.0 * (n0 + n1 + n2);
}