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