More 2d shallow water tests
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1 changed files with 114 additions and 22 deletions
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@ -2,6 +2,7 @@
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#include <psemek/app/default_application_factory.hpp>
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#include <psemek/gfx/painter.hpp>
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#include <psemek/math/orthographic.hpp>
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#include <psemek/math/camera.hpp>
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#include <psemek/log/log.hpp>
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#include <psemek/util/array.hpp>
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#include <psemek/random/device.hpp>
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@ -31,7 +32,7 @@ struct water_2d_app
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random::generator rng{random::device{}};
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int const N = 128;
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int const N = 256;
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float time = 0.f;
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@ -48,14 +49,23 @@ struct water_2d_app
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bool paused = true;
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bool show_water = true;
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bool show_velocity = false;
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bool show_particles = false;
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bool erosion_on = false;
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bool rain_on = false;
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struct particle
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{
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math::point<float, 2> position;
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int lifetime;
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};
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std::vector<particle> particles;
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};
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water_2d_app::water_2d_app(options const &, context const & ctx)
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{
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(void)ctx;
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ctx.vsync(true);
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// ctx.vsync(true);
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simulation_area[0] = {-1.f, 1.f};
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simulation_area[1] = {-1.f, 1.f};
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@ -86,8 +96,8 @@ water_2d_app::water_2d_app(options const &, context const & ctx)
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// if (x == N / 2 && (y != N / 4 && y != 3 * N / 4))
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// bed(x, y) = 100.f;
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float tx = (x + 0.5f) / N;
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float ty = (y + 0.5f) / N;
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[[maybe_unused]] float tx = (x + 0.5f) / N;
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[[maybe_unused]] float ty = (y + 0.5f) / N;
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float n = 0.f;
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@ -106,7 +116,9 @@ water_2d_app::water_2d_app(options const &, context const & ctx)
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// n = 4.f * std::abs(2.f * noise(tx, ty) - 1.f) * std::pow(4.f * tx * (1.f - tx), 2.f);
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// River
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n = std::min(4.f, math::lerp(10.f, 20.f, noise(tx, ty)) * std::abs(ty - math::lerp({0.4f, 0.6f}, noise(tx, 0.f))));
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// n = std::min(4.f, math::lerp(10.f, 20.f, noise(tx, ty)) * std::abs(ty - math::lerp({0.4f, 0.6f}, noise(tx, 0.f))));
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// n = 0.f;
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// Canyon
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// n = 10.f * math::clamp(10.f * math::lerp(-1.f, 1.f, noise(tx, ty)), {0.f, 1.f});
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@ -128,13 +140,17 @@ water_2d_app::water_2d_app(options const &, context const & ctx)
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// if (x == 0)
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// water(x, y) = 100.f - bed(x, y);
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water(x, y) = std::max(0.f, 1.f - bed(x, y)) * (0.5f + 0.5f * noise(tx, ty));
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flowx(x, y) = (2.f * ty - 1.f) * water(x, y) * 10.f / N;
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}
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}
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// water(N / 2, N / 2) = 10000.f;
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}
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float const dt = 0.002f;
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float const dt = 0.001f;
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void water_2d_app::update()
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{
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@ -144,11 +160,15 @@ void water_2d_app::update()
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float const dx = simulation_area[0].length() / N;
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float const dy = simulation_area[1].length() / N;
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float const g = 10.f;
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float const friction = std::pow(0.5f, dt);
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float const friction = std::pow(1.f, dt);
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float const viscosity = 0.f;
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float const sediment_capacity = 0.1f;
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float const erosion = 1.f;
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float const deposition = 10.f;
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float const coriolis = 0.01f;
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int const max_particles = 16 * 1024;
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int const particles_per_frame = 16;
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int const max_particle_lifetime = max_particles / particles_per_frame;
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// Init boundary flows
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for (int x = 0; x < N; ++x)
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@ -160,13 +180,16 @@ void water_2d_app::update()
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// if (x < N / 4) flowy(x, N) = -3.f / N;
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// flowy(x, 0) = 5.f * std::sin(10.f * time) / N;
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flowy(x, 0) = 0.f;
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flowy(x, N) = 0.f;
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}
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for (int y = 0; y < N; ++y)
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{
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// flowx(0, y) = 5.f * std::sin(10.f * time) / N;
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// flowx(0, y) = 1.f / N;
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// flowx(0, y) = 10.f / N;
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// flowx(N, y) = 1.f / N;
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// flowx(0, y) = 10.f * ((y + 0.5f) / N) / N;
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@ -175,12 +198,12 @@ void water_2d_app::update()
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// if (y < N / 4) flowx(0, y) = 3.f / N;
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// if (y >= 3 * N / 4) flowx(N, y) = -3.f / N;
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if (bed(0, y) < 0.75f)
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flowx(0, y) = 4.f / N;
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// if (bed(0, y) < 0.75f)
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// flowx(0, y) = 4.f / N;
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// flowx(0, y) = 5.f * math::sqr(std::max(0.f, std::sin(15.f * time))) / N;
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if (bed(N - 1, y) < 0.75f)
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flowx(N, y) = 5.f / N;
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// if (bed(N - 1, y) < 0.75f)
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// flowx(N, y) = 5.f / N;
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}
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// Rain :)
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@ -195,9 +218,13 @@ void water_2d_app::update()
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// Update X flows
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for (int y = 0; y < N; ++y)
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{
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for (int x = 1; x < N; ++x)
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flowx(x, y) = friction * flowx(x, y) + g * dt * (water(x - 1, y) + bed(x - 1, y) - water(x, y) - bed(x, y));
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flowx(0, y) = friction * flowx(0, y) + g * dt * (water(N - 1, y) + bed(N - 1, y) - water(0, y) - bed(0, y));
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}
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// Update Y flows
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for (int y = 1; y < N; ++y)
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for (int x = 0; x < N; ++x)
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@ -236,7 +263,7 @@ void water_2d_app::update()
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{
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float outflow = 0.f;
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outflow += std::max(0.f, - flowx(x , y ));
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outflow += std::max(0.f, flowx(x + 1, y ));
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outflow += std::max(0.f, flowx((x + 1) % N, y ));
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outflow += std::max(0.f, - flowy(x , y ));
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outflow += std::max(0.f, flowy(x , y + 1));
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@ -247,7 +274,7 @@ void water_2d_app::update()
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float scale = std::min(1.f, max_outflow / outflow);
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if (flowx(x, y) < 0.f) flowx(x, y) *= scale;
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if (flowx(x + 1, y) > 0.f) flowx(x + 1, y) *= scale;
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if (flowx((x + 1) % N, y) > 0.f) flowx((x + 1) % N, y) *= scale;
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if (flowy(x, y) < 0.f) flowy(x, y) *= scale;
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if (flowy(x, y + 1) > 0.f) flowy(x, y + 1) *= scale;
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@ -262,7 +289,7 @@ void water_2d_app::update()
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{
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float w_old = water(x, y);
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water(x, y) += dt / dx / dy * (flowx(x, y) + flowy(x, y) - flowx(x + 1, y) - flowy(x, y + 1));
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water(x, y) += dt / dx / dy * (flowx(x, y) + flowy(x, y) - flowx((x + 1) % N, y) - flowy(x, y + 1));
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float w_avg = (w_old + water(x, y)) / 2.f;
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@ -270,7 +297,7 @@ void water_2d_app::update()
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if (w_avg > 0.f)
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{
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v[0] = (flowx(x, y) + flowx(x + 1, y)) / 2.f / dx / w_avg;
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v[0] = (flowx(x, y) + flowx((x + 1) % N, y)) / 2.f / dx / w_avg;
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v[1] = (flowy(x, y) + flowy(x, y + 1)) / 2.f / dy / w_avg;
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}
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@ -278,6 +305,20 @@ void water_2d_app::update()
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}
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}
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// Add coriolis force
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for (int y = 0; y < N; ++y)
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{
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for (int x = 0; x < N; ++x)
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{
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auto n = math::ort(velocity(x, y)) * coriolis * dt / 2.f * std::sin(float(math::pi) / 2.f * ((y + 0.5f) * 2.f / N - 1.f));
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flowx(x, y) += n[0];
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flowx((x + 1) % N, y) += n[0];
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flowy(x, y) += n[1];
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flowy(x, y + 1) += n[1];
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}
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}
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if (erosion_on)
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{
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// Erosion-deposition
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@ -332,6 +373,36 @@ void water_2d_app::update()
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std::swap(sediment, new_sediment);
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}
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// Init particles
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for (int i = 0; i < particles_per_frame; ++i)
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if (particles.size() < max_particles)
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{
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math::point pos{random::uniform<float>(rng, 0.f, N), random::uniform<float>(rng, 0.f, N)};
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if (water(std::floor(pos[0]), std::floor(pos[1])) > 1e-3f)
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particles.push_back({pos, 0});
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}
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// Update particles
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for (auto & p : particles)
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{
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p.position += velocity(std::min<int>(N - 1, std::floor(p.position[0])), std::min<int>(N - 1, std::floor(p.position[1]))) * (N * dt);
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p.position[0] = math::fmod(p.position[0], float(N));
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p.position[1] = math::clamp(p.position[1], {0.f, N});
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p.lifetime += 1;
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}
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// Destroy particles
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for (int i = 0; i < particles.size();)
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{
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if (particles[i].lifetime >= max_particle_lifetime)
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{
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std::swap(particles[i], particles.back());
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particles.pop_back();
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}
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else
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++i;
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}
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time += dt;
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}
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@ -371,8 +442,8 @@ void water_2d_app::present()
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float w = 1.f - std::exp(- 1.f * water(x, y));
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float s = 1.f - std::exp(- 1.f * sediment(x, y));
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if (water(x, y) > 1e-3f)
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w = 0.5f + 0.5f * w;
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// if (water(x, y) > 1e-3f)
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// w = 0.5f + 0.5f * w;
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auto bed_color = gfx::to_coloru8(gfx::color_4f{0.96f, 0.72f, 0.53f, b});
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// auto bed_color = gfx::to_coloru8(gfx::color_4f{0.3f, 0.5f, 0.1f, b});
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@ -398,20 +469,33 @@ void water_2d_app::present()
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{
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auto center = simulation_area.corner((x + 0.5f) * invN, (y + 0.5f) * invN);
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auto v = water(x, y) * velocity(x, y) / 100.f;
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auto v = water(x, y) * velocity(x, y) / 40.f;
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float max_length = 0.02f;
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float max_length = 0.05f;
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auto l = math::length(v);
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auto color = gfx::to_coloru8(gfx::color_4f{1.f, std::exp(- 10.f * l), 0.f, 1.f});
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// auto color = gfx::to_coloru8(gfx::color_4f{1.f, std::exp(- 10.f * l), 0.f, 1.f});
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auto color = gfx::color_rgba{255, 255, 255, 255};
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float s = std::min(1.f, l / max_length);
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// s = 1.f;
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painter.line(center, center + math::normalized(v) * max_length * s, s * 0.004f, s * 0.002f, color, color, false);
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auto d = math::normalized(v) * max_length * s / 2.f;
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painter.line(center - d, center + d, s * 0.001f, 0.f, color, color, false);
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}
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}
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}
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if (show_particles)
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{
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for (auto const & p : particles)
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{
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auto pos = math::lerp(simulation_area, math::vector{p.position[0] / N, p.position[1] / N});
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painter.circle(pos, 0.005f, {255, 255, 255, 127}, 6);
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}
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}
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auto mouse = math::cast<float>(state().mouse);
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mouse[0] = math::lerp(view_area[0], mouse[0] / state().size[0]);
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@ -447,6 +531,11 @@ void water_2d_app::present()
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}
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painter.render(transform);
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{
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painter.text({20.f, 20.f}, std::format("{} particles", particles.size()), {.scale = {2.f, 2.f}, .x = gfx::painter::x_align::left, .y = gfx::painter::y_align::top, .c = {0, 0, 0, 255}});
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painter.render(math::window_camera{state().size[0], state().size[1]}.transform());
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}
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}
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void water_2d_app::on_event(app::resize_event const & event)
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@ -467,6 +556,9 @@ void water_2d_app::on_event(app::key_event const & event)
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if (event.down && event.key == app::keycode::V)
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show_velocity ^= true;
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if (event.down && event.key == app::keycode::P)
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show_particles ^= true;
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if (event.down && event.key == app::keycode::E)
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erosion_on ^= true;
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