libcruft-util/tools/noise.cpp

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#include "image.hpp"
#include "noise.hpp"
#include "noise/fractal/fbm.hpp"
#include "noise/fractal/rmf.hpp"
#include "noise/fractal/hmf.hpp"
#include "noise/fractal/hetero.hpp"
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#include "noise/lerp.hpp"
#include "noise/basis/constant.hpp"
#include "noise/basis/value.hpp"
#include "noise/basis/perlin.hpp"
#include "noise/basis/worley.hpp"
#include "noise/turbulence.hpp"
#include "extent.hpp"
#include "colour.hpp"
#include "netpbm.hpp"
#include "types.hpp"
template struct util::noise::fractal::fbm<float, util::noise::basis::perlin<float,util::lerp::cubic>>;
template struct util::noise::fractal::hmf<float, util::noise::basis::value<float,util::lerp::cubic>>;
template struct util::noise::fractal::rmf<float, util::noise::basis::constant<float>>;
template struct util::noise::fractal::hetero<float, util::noise::basis::worley<float,2>>;
void
hydraulic_erode (util::image::buffer<float> &height, const unsigned ticks)
{
CHECK_GT (ticks, 0);
std::cerr << "hydraulic_erosion\n";
const float RAINFALL = 0.001f; // quantity of water added each tick
const float SOLUBILITY = 0.1001f; // quantity of land picked up by unit rain
const float EVAPORATION = RAINFALL * .85f; // quantity of water evaporated each tick
auto water = height.alloc ();
CHECK (water.is_packed ());
CHECK (height.is_packed ());
std::fill (water.begin (), water.end (), 0);
for (unsigned t = 0; t < ticks; ++t) {
// apply new rain and erosion
for (auto &w: water)
w += RAINFALL;
for (auto &h: height)
h -= RAINFALL * SOLUBILITY;
float total = 0.f;
// move water to lowest neighbour cell
for (size_t y = 1; y < height.h - 1; ++y)
for (size_t x = 1; x < height.w - 1; ++x) {
const size_t indices[9] = {
(y - 1) * height.s + (x - 1),
(y - 1) * height.s + (x + 0),
(y - 1) * height.s + (x + 1),
(y + 0) * height.s + (x - 1),
(y + 0) * height.s + (x + 0),
(y + 0) * height.s + (x + 1),
(y + 1) * height.s + (x - 1),
(y + 1) * height.s + (x + 0),
(y + 1) * height.s + (x + 1),
};
const float level[9] = {
height[indices[0]] + water[indices[0]],
height[indices[1]] + water[indices[1]],
height[indices[2]] + water[indices[2]],
height[indices[3]] + water[indices[3]],
height[indices[4]] + water[indices[4]],
height[indices[5]] + water[indices[5]],
height[indices[6]] + water[indices[6]],
height[indices[7]] + water[indices[7]],
height[indices[8]] + water[indices[8]],
};
size_t dst = std::min_element (std::begin (level), std::end (level)) - level;
if (dst == 4) // if centre, bail
continue;
// transfer as much water as possible to even the heights
float total_diff = level[4] - level[dst];
float transfer;
if (total_diff > water[4])
transfer = water[4];
else
transfer = (water[4] - total_diff) / 2;
water[indices[ 4]] -= transfer;
water[indices[dst]] += transfer;
total += transfer;
}
// evaporate water, deposit sediment
for (size_t i = 0; i < water.area (); ++i) {
water[i] -= EVAPORATION;
height[i] += SOLUBILITY * EVAPORATION;
}
std::cerr << "eroded: " << total << '\n';
}
// forcibly evaporate all remaining water.
CHECK_EQ (water.area (), height.area ());
for (size_t i = 0; i < water.area (); ++i)
height[i] += water[i] * SOLUBILITY;
}
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/// talus: maximum desired slope in radians. [0, 90]
/// resistance: proportion of world to keep. [1, 0]
/// scale: horizontal distance scaling factor (relative to vertical)
void
thermal_erode (util::image::buffer<float> &height,
const float talus,
const float scale,
const float resistance)
{
CHECK_LIMIT (talus, 0, to_radians (90.f));
CHECK_GT (scale, 0);
CHECK_LIMIT (resistance, 0, 1);
// maximum height difference
const auto maxdiff = scale * std::atan (talus);
float total = 0.f;
for (size_t y = 1; y < height.h - 1; ++y)
for (size_t x = 1; x < height.w - 1; ++x) {
float centre = height[y * height.s + x];
float h[9] = {
height[(y - 1) * height.s + (x - 1)],
height[(y - 1) * height.s + (x + 0)],
height[(y - 1) * height.s + (x + 1)],
height[(y + 0) * height.s + (x - 1)],
height[(y + 0) * height.s + (x + 0)],
height[(y + 0) * height.s + (x + 1)],
height[(y + 1) * height.s + (x - 1)],
height[(y + 1) * height.s + (x + 0)],
height[(y + 1) * height.s + (x + 1)],
};
float diff = 0.f;
unsigned dests = 0;
for (size_t i = 0; i < elems (h); ++i) {
if (h[i] < centre - maxdiff) {
dests++;
diff = std::max (diff, centre - h[i]);
}
}
if (diff < maxdiff)
continue;
float size = diff * (1 - resistance) / 2;
float dist = size / dests;
total += size;
height[y * height.s + x] -= size;
if (h[0] < centre) height[(y - 1) * height.s + (x - 1)] += dist;
if (h[1] < centre) height[(y - 1) * height.s + (x + 0)] += dist;
if (h[2] < centre) height[(y - 1) * height.s + (x + 1)] += dist;
if (h[3] < centre) height[(y + 0) * height.s + (x - 1)] += dist;
if (h[5] < centre) height[(y + 0) * height.s + (x + 1)] += dist;
if (h[6] < centre) height[(y + 1) * height.s + (x - 1)] += dist;
if (h[7] < centre) height[(y + 1) * height.s + (x + 0)] += dist;
if (h[8] < centre) height[(y + 1) * height.s + (x + 1)] += dist;
}
std::cerr << "eroded: " << total << '\n';
}
// create a coloured map with this gradient (from libnoise tut3)
static const struct {
float scale;
util::colour3u value;
} GRADPOINT[] = {
{-1000000.f, { 0, 0, 128 } },
{ 0 / 32.f, { 0, 0, 128 } }, // deeps
{ 12 / 32.f, { 0, 0, 255 } }, // shallow
{ 16 / 32.f, { 0, 128, 255 } }, // shore
{ 17 / 32.f, { 240, 240, 64 } }, // sand
{ 18 / 32.f, { 32, 160, 0 } }, // grass
{ 22 / 32.f, { 224, 224, 0 } }, // dirt
{ 28 / 32.f, { 128, 128, 128 } }, // rock
{ 32 / 32.f, { 255, 255, 255 } }, // snow
{ 1000000.f, { 255, 255, 255 } },
};
void
write_map (const util::image::buffer<float> &map, boost::filesystem::path name)
{
std::unique_ptr<uint8_t[]> coloured (new uint8_t[map.w * map.h * 3]);
for (size_t i = 0; i < map.w * map.h; ++i) {
auto v = map[i] + 0/32.f;
auto c1 = std::upper_bound (std::begin (GRADPOINT),
std::end (GRADPOINT),
v,
[] (auto a, auto b) { return a < b.scale; });
auto c0 = c1-1;
CHECK_GE (v, c0->scale);
CHECK_LT (v, c1->scale);
float t = (v - c0->scale) / (c1->scale - c0->scale);
CHECK_LIMIT (t, 0, 1);
auto c = (
(1 - t) * c0->value.template cast<float> () +
( t) * c1->value.template cast<float> ()
).template cast<uint8_t> ();
coloured[i*3+0] = c[0];
coloured[i*3+1] = c[1];
coloured[i*3+2] = c[2];
}
name.replace_extension (".ppm");
util::ppm::write (coloured.get (), map.w, map.h, map.w*3, name);
// write the image to disk
auto grey = map.clone<uint8_t> ();
name.replace_extension (".pgm");
util::pgm::write (grey, name);
}
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// offset a map so a fixed percentage of tiles are below the water height
void
adjust_ocean (util::image::buffer<float> &height,
const float percentage = .2f)
{
static const float WATER_HEIGHT = 0.5f;
CHECK_LIMIT (percentage, 0, 1);
// we assume fully packed data for iteration purposes
CHECK (height.is_packed ());
std::array<unsigned,256> buckets{ 0 };
for (const auto h: height)
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buckets[size_t (h * 255u)]++;
size_t pivot = 0;
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for (size_t accum = 0, target = size_t (percentage * height.area ()); pivot < buckets.size (); ++pivot) {
accum += buckets[pivot];
if (accum > target)
break;
}
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std::cerr << "ocean pivot: " << pivot << '\n';
float offset = WATER_HEIGHT - pivot / 256.f;
for (auto &h: height)
h += offset;
}
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static const unsigned THERMAL_ITERATIONS = 10;
static const unsigned HYDRAULIC_ITERATIONS = 100;
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int
main (void)
{
// setup the output buffer
#ifdef ENABLE_DEBUGGING
util::extent2u size {320, 240};
#else
util::extent2u size {1920, 1080};
#endif
util::image::buffer<float> img (size);
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uint64_t seed = time (nullptr);
// setup the noise generator
#if 0
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//util::noise::fractal::fbm<float, util::noise::basis::worley<float>> b (seed);
//util::noise::fractal::rmf<float, util::noise::basis::worley<float>> b (seed);
//util::noise::fractal::fbm<float, util::noise::basis::perlin<float,util::lerp::cubic>> b (seed);
//util::noise::fractal::rmf<float, util::noise::basis::perlin<float,util::lerp::cubic>> b (seed);
//util::noise::fractal::hmf<float, util::noise::basis::perlin<float,util::lerp::cubic>> b (seed);
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util::noise::fractal::hetero<float, util::noise::basis::value<float,util::lerp::quintic>> b (seed);
b.octaves (8);
b.frequency (10.f / size.w);
b.lacunarity = 2.f;
b.H = 1.0f;
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b.seed (seed);
#else
util::noise::turbulence<
float,
//util::noise::fractal::hetero<float, util::noise::basis::worley<float>>,
util::noise::fractal::hetero<float, util::noise::basis::perlin<float,util::lerp::cubic>>,
util::noise::fractal::fbm<float, util::noise::basis::perlin<float,util::lerp::quintic>>
> b (seed, { 0.13f, 0.13f });
b.data.frequency (1.f / size.w);
b.perturb[0].octaves (4);
b.perturb[1].octaves (4);
b.perturb[0].frequency (10.f / size.w);
b.perturb[1].frequency (10.f / size.w);
#endif
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// generate the values. offset positions slightly to observe simple axis issues with perlin basis
{
auto offset = util::vector2f { -100 };
for (size_t y = 0; y < size.h; ++y)
for (size_t x = 0; x < size.w; ++x) {
auto v = b (util::point2f {float (x), float (y)} + offset);
img.data ()[y * size.w + x] = v;
}
}
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// rescale into the range [0, 1]
auto range = std::minmax_element (img.begin (), img.end ());
auto offset = *range.first;
auto div = *range.second - *range.first;
std::cerr << "range: [" << *range.first << ", " << *range.second << "]\n";
std::transform (img.begin (), img.end (), img.begin (), [offset,div] (auto i) { return (i - offset) / div; });
// ensure the ocean isn't too big
adjust_ocean (img, 0.2f);
// write the images to disk
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write_map (img, "raw");
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auto soft = img.clone ();
std::cerr << "thermal_erosion\n";
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for (size_t i = 0; i < THERMAL_ITERATIONS; ++i)
thermal_erode (soft, to_radians (30.f), 1.f / size.w, 0.f);
hydraulic_erode (soft, HYDRAULIC_ITERATIONS);
write_map (soft, "soft");
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}