lol/doc/samples/simplex.cpp

//
//  Lol Engine — Simplex Noise tutorial
//
//  Copyright © 2010—2017 Sam Hocevar <sam@hocevar.net>
//            © 2013-2014 Guillaume Bittoun <guillaume.bittoun@gmail.com>
//
//  Lol Engine is free software. It comes without any warranty, to
//  the extent permitted by applicable law. You can redistribute it
//  and/or modify it under the terms of the Do What the Fuck You Want
//  to Public License, Version 2, as published by the WTFPL Task Force.
//  See http://www.wtfpl.net/ for more details.
//

#if HAVE_CONFIG_H
#   include "config.h"
#endif

#include <lol/engine.h>

using namespace lol;

/* Constants to tweak */
ivec2 const size(1280 * 1, 720 * 1);
float const zoom = 0.03f / 1;
int const octaves = 1;

int main(int argc, char **argv)
{
    UNUSED(argc, argv);

    srand(time(nullptr));

    /* Create an image */
    image img(size);
    array2d<vec4> &data = img.lock2d<PixelFormat::RGBA_F32>();

    /* Declare plenty of allocators */
    simplex_noise<2> s2;
    simplex_noise<3> s3;
    simplex_noise<4> s4;
    simplex_noise<5> s5;
    simplex_noise<6> s6;
    simplex_noise<7> s7;
    simplex_noise<8> s8;
    simplex_noise<9> s9;
    simplex_noise<10> s10;
    simplex_noise<11> s11;
    simplex_noise<12> s12;

    /* Fill image with simplex noise */
    for (int j = 0; j < size.y; ++j)
    for (int i = 0; i < size.x; ++i)
    {
        int cell = j / (size.y / 2) * 3 + i / (size.x / 3);

        float x = (float)i, y = (float)j;
        float sum = 0.f, coeff = 0.f;
        int const max_k = 1 << octaves;
        bool b_centre = false, b_sphere1 = false, b_sphere2 = false;

        for (int k = 1; k < max_k; k *= 2)
        {
            float t = 0.f;

            switch (cell)
            {
            case 0:
                t = s2.eval(zoom * k * vec2(x, y));
                break;
            case 1:
                t = s3.eval(zoom * k * vec3(x, 1.f, y));
                break;
            case 2:
                t = s4.eval(zoom * k * vec4(x, 1.f, y, 2.f));
                break;
            case 3:
                t = s6.eval(zoom * k * vec6(x, 1.f, 2.f, y, 3.f, 4.f));
                break;
            case 4:
                t = s8.eval(zoom * k * vec8(x, 1.f, 2.f, 3.f,
                                            y, 4.f, 5.f, 6.f));
                break;
            case 5:
                //t = s12.eval(zoom * k * vec12(x / 2, -x / 2, y / 2, -y / 2,
                //                              -x / 2, x / 2, -y / 2, y / 2,
                //                              7.f, 8.f, 9.f, 10.f));
                t = s12.eval(zoom * k * vec12(x, 1.f, 2.f, 3.f, 4.f, 5.f,
                                              y, 6.f, 7.f, 8.f, 9.f, 10.f));
                break;
            default:
                break;
            }

            if (t == -2.f) b_centre = true;
            if (t == -3.f) b_sphere1 = true;
            if (t == -4.f) b_sphere2 = true;

            sum += 1.f / k * t;
            coeff += 1.f / k;
        }

        if (b_centre)
            data[i][j] = vec4(1.f, 0.f, 1.f, 1.f);
        else if (b_sphere1)
            data[i][j] = vec4(0.f, 1.f, 0.f, 1.f);
        else if (b_sphere2)
            data[i][j] = vec4(0.f, 0.f, 1.f, 1.f);
        else
        {
            float c = saturate(0.5f + 0.5f * sum / coeff);
            data[i][j] = vec4(c, c, c, 1.f);
            //data[i][j] = Color::HSVToRGB(vec4(c, 1.0f, 0.5f, 1.f));
        }
    }

#if 0
    /* Mark simplex vertices */
    vec2 diagonal = normalize(vec2(1.f));
    vec2 dx = mat2::rotate(radians(60.f)) * diagonal;
    vec2 dy = mat2::rotate(radians(-60.f)) * diagonal;
    for (int j = -100; j < 100; ++j)
    for (int i = -100; i < 100; ++i)
    {
        auto putpixel = [&](ivec2 p, vec4 c = vec4(1.f, 0.f, 1.f, 1.f))
        {
            if (p.x >= 0 && p.x < size.x - 1 && p.y >= 0 && p.y < size.y - 1)
                data[p.x][p.y] = c;
        };

        ivec2 coord = ivec2(i / zoom * dx + j / zoom * dy);

        vec2 g = s2.gradient((i + 0.1f) * dx + (j + 0.1f) * dy);
        for (int t = 0; t < 40; ++t)
            putpixel(coord + (ivec2)(g * (t / 2.f)), vec4(0.f, 1.f, 0.f, 1.f));

        putpixel(coord);
        putpixel(coord + ivec2(1, 0));
        putpixel(coord + ivec2(0, 1));
        putpixel(coord + ivec2(1, 1));
    }
#endif

    /* Save image */
    img.unlock2d(data);
    img.save("simplex.png");
}