yggdrasil75/stupidsimcpp
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particle sim stuff

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yggdrasil75
2026-02-05 07:42:48 -05:00
parent 39c38e4061
commit 47b264d016
2 changed files with 19 additions and 17 deletions
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10
tests/fluidsim.cpp
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@@ -11,8 +11,8 @@ int main() {
// Setup Camera
Camera cam;
cam.origin = Eigen::Vector3f(0.0f, 400.0f, -1800.0f); // Back and slightly up
cam.direction = (Eigen::Vector3f(0.0f, 0.0f, 0.0f) - cam.origin).normalized(); // Look at center
cam.origin = Eigen::Vector3f(0.0f, 1000.0f, -1800.0f);
cam.direction = (Eigen::Vector3f(0.0f, 0.0f, 0.0f) - cam.origin).normalized();
cam.up = Eigen::Vector3f(0.0f, 1.0f, 0.0f);
cam.fov = 60.0f;
@@ -31,8 +31,8 @@ int main() {
if (frameIdx % 10 == 0) {
if (frameIdx < (TOTAL_FRAMES * 0.1f)) {
float t = static_cast<float>(frameIdx) / (TOTAL_FRAMES * 0.9f);
int spawnCount = 2 + static_cast<int>(t * 4);
//float t = static_cast<float>(frameIdx) / (TOTAL_FRAMES * 0.9f);
int spawnCount = 2; // + static_cast<int>(t * 4);
sim.spawnParticles(baseParticle, spawnCount);
}
}
@@ -42,7 +42,7 @@ int main() {
if (frameIdx % 50 == 0) {
std::cout << "Rendering Frame " << frameIdx << " / " << TOTAL_FRAMES << std::endl;
frame renderedFrame = sim.grid.renderFrame(cam, HEIGHT, WIDTH, frame::colormap::RGB, 5, 4, true, false);
frame renderedFrame = sim.grid.renderFrame(cam, HEIGHT, WIDTH, frame::colormap::RGB, 4, 4, true, false);
std::stringstream ss;
ss << "output/frame_" << std::setw(4) << std::setfill('0') << frameIdx << ".bmp";

26
util/sim/fluidsim.hpp
View File

@@ -35,7 +35,7 @@ struct fluidParticle {
struct gridConfig {
float gridSizeCube = 1024;
const float SMOOTHING_RADIUS = 32.0f;
const float SMOOTHING_RADIUS = 320.0f;
const float REST_DENSITY = 0.5f;
const float TIMESTEP = 0.016f;
const float G_ATTRACTION = 50.0f;
@@ -104,11 +104,11 @@ public:
gradientmap.emplace(0.0, Eigen::Vector3f(1, 0, 0));
gradientmap.emplace(0.5, Eigen::Vector3f(0, 1, 0));
gradientmap.emplace(1.0, Eigen::Vector3f(0, 0, 1));
}
void spawnParticles(fluidParticle toSpawn, int count, bool resize = true) {
TIME_FUNCTION;
toSpawn.mass = newMass;
float size = toSpawn.mass / 10;
Eigen::Vector3f color = buildGradient(toSpawn.mass / 1000, gradientmap);
std::cout << "spawning " << count << " particles with a mass of " << toSpawn.mass << " and a size of " << size << std::endl;
@@ -116,11 +116,11 @@ public:
Eigen::Matrix<float, 3, 1> pos = posGen();
int id = nextObjectId++;
grid.set(toSpawn, pos, true, color, size, true, id, (toSpawn.mass > 100) : true ? false, 1);
grid.set(toSpawn, pos, true, color, size, true, id, (toSpawn.mass > 100) ? true : false, 1);
idposMap[id] = pos;
}
if (resize){
newMass -= newMass * .01;
newMass *= 0.99f;
}
}
@@ -129,14 +129,16 @@ public:
for (auto& point : idposMap) {
auto node = grid.find(point.second);
if (!node) continue;
std::vector<std::shared_ptr<Octree<fluidParticle>::NodeData>> neighbors = grid.findInRadius(point.second, config.SMOOTHING_RADIUS * node->data.mass);
std::vector<std::shared_ptr<Octree<fluidParticle>::NodeData>> neighbors = grid.findInRadius(point.second, config.SMOOTHING_RADIUS);
float density = 0.0f;
for (const auto& neighbor : neighbors) {
if (node == neighbor) continue;
float dist = (point.second-neighbor->position).norm();
density += neighbor->data.mass * poly6Kernel(dist, config.SMOOTHING_RADIUS * node->data.mass);
float dist = (point.second - neighbor->position).norm();
density += neighbor->data.mass * poly6Kernel(dist, config.SMOOTHING_RADIUS);
}
node->data.density = density;
node->data.density = std::max(density, EPSILON);
float pressure = node->data.restitution * (density - config.REST_DENSITY);
node->data.pressure = std::max(pressure, 0.0f);
}
@@ -148,7 +150,7 @@ public:
auto node = grid.find(point.second);
if (!node) continue;
Eigen::Vector3f totalForce = -point.second.normalized() * 10.0f * node->data.mass;
std::vector<std::shared_ptr<Octree<fluidParticle>::NodeData>> neighbors = grid.findInRadius(point.second, config.SMOOTHING_RADIUS * node->data.mass);
std::vector<std::shared_ptr<Octree<fluidParticle>::NodeData>> neighbors = grid.findInRadius(point.second, config.SMOOTHING_RADIUS);
for (const auto& neighbor : neighbors) {
if (node == neighbor) continue;
@@ -157,10 +159,10 @@ public:
if (dist < EPSILON) continue;
float densj = neighbor->data.density;
if (densj < EPSILON) densj = EPSILON;
float pressj = neighbor->data.pressure;
Eigen::Vector3f pressureForceVec = -neighbor->data.mass * ((node->data.pressure + pressj) / (2.0f * densj)) * spikyGradientKernel(diff, dist, config.SMOOTHING_RADIUS);
Eigen::Vector3f pressureForceVec = -neighbor->data.mass * ((node->data.pressure + neighbor->data.pressure) / (2.0f * densj)) * spikyGradientKernel(diff, dist, config.SMOOTHING_RADIUS);
totalForce += pressureForceVec;
Eigen::Vector3f velDiff = neighbor->data.velocity - node->data.velocity;
float viscositCoef = node->data.viscosity * neighbor->data.mass * (1.0f / densj) * poly6Kernel(dist, config.SMOOTHING_RADIUS);
totalForce += velDiff * viscositCoef;
@@ -189,9 +191,9 @@ public:
if (!idsToRemove.empty()) {
fluidParticle newParticles;
newParticles.mass = newMass;
spawnParticles(newParticles, idsToRemove.size(), false);
}
std::cout << "replacing " << idsToRemove.size() << "particles" << std::endl;
}
void applyPhysics() {