yggdrasil75/stupidsimcpp
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added move and more of the particle stuff

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yggdrasil75
2026-02-05 06:52:02 -05:00
parent 341066a0cf
commit 39c38e4061
3 changed files with 54 additions and 45 deletions
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27
tests/fluidsim.cpp
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@@ -29,42 +29,27 @@ int main() {
for (int frameIdx = 0; frameIdx < TOTAL_FRAMES; ++frameIdx) {
// --- Spawning Logic ---
// Spawn throughout the simulation (e.g., until 90% completion)
if (frameIdx % 10 == 0) {
if (frameIdx < (TOTAL_FRAMES * 0.9f)) {
if (frameIdx < (TOTAL_FRAMES * 0.1f)) {
float t = static_cast<float>(frameIdx) / (TOTAL_FRAMES * 0.9f);
// Linear interpolation for Mass: Heavy (10.0) -> Light (0.5)
float currentMass = (1.0f - t) * 10.0f + t * 0.5f;
// Linear interpolation for Size: Large (12.0) -> Small (2.0)
float currentSize = (1.0f - t) * 12.0f + t * 2.0f;
// Number of particles to spawn this frame (can increase as they get smaller)
int spawnCount = 2 + static_cast<int>(t * 4);
sim.spawnParticles(baseParticle, spawnCount, currentSize, currentMass);
sim.spawnParticles(baseParticle, spawnCount);
}
}
// --- Physics Step ---
sim.applyPhysics();
// --- Render & Save ---
if (frameIdx % 50 == 0) {
std::cout << "Rendering Frame " << frameIdx << " / " << TOTAL_FRAMES << std::endl;
// Generate LODs for faster/better rendering
sim.grid.generateLODs();
frame renderedFrame = sim.grid.renderFrame(cam, HEIGHT, WIDTH, frame::colormap::RGB, 5, 4, true, false);
// Render frame
frame renderedFrame = sim.grid.renderFrame(cam, HEIGHT, WIDTH, frame::colormap::RGB, 4, 4, true, false);
// Save to BMP
std::stringstream ss;
ss << "output/frame_" << std::setw(4) << std::setfill('0') << frameIdx << ".bmp";
BMPWriter::saveBMP(ss.str(), renderedFrame);
}
if (frameIdx % 100 == 0) {
sim.grid.printStats();
}
}

11
util/grid/grid3eigen.hpp
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@@ -647,7 +647,7 @@ public:
}
bool inGrid(PointType pos) {
return root_.contains(pos);
return root_->contains(pos);
}
bool remove(const PointType& pos, float tolerance = 0.0001f) {
@@ -792,6 +792,15 @@ public:
}
}
bool move(const PointType& pos, const PointType& newPos) {
auto pointData = find(pos);
if (!pointData) return false;
if (!remove(pos)) return false;
return set(pointData->data, pointData->position, pointData->visible, pointData->color, pointData->size,
pointData->active, pointData->objectId, pointData->light, pointData->emittance,
pointData->refraction, pointData->reflection, pointData->shape);
}
bool setObjectId(const PointType& pos, int objectId, float tolerance = 0.0001f) {
auto pointData = find(pos, tolerance);
if (!pointData) return false;

61
util/sim/fluidsim.hpp
View File

@@ -23,14 +23,13 @@
#include "../stb/stb_image.h"
struct fluidParticle {
Eigen::Matrix<float, 3, 1> pos;
Eigen::Matrix<float, 3, 1> velocity;
Eigen::Matrix<float, 3, 1> acceleration;
Eigen::Matrix<float, 3, 1> forceAccumulator;
float density;
float pressure;
float viscosity;
float restitution;
float density = 0.0f;
float pressure = 0.0f;
float viscosity = 25.0f;
float restitution = 500.0f;
float mass;
};
@@ -108,17 +107,21 @@ public:
}
void spawnParticles(fluidParticle toSpawn, int count) {
void spawnParticles(fluidParticle toSpawn, int count, bool resize = true) {
TIME_FUNCTION;
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;
for (int i = 0; i < count; i++) {
Eigen::Matrix<float, 3, 1> pos = posGen();
int id = nextObjectId++;
Eigen::Vector3f color = buildGradient(toSpawn.mass / 1000, gradientmap);
grid.set(toSpawn, pos, true, color, 1, true, id, false);
grid.set(toSpawn, pos, true, color, size, true, id, (toSpawn.mass > 100) : true ? false, 1);
idposMap[id] = pos;
}
newMass -= newMass / 10;
if (resize){
newMass -= newMass * .01;
}
}
void applyPressureDensity() {
@@ -172,27 +175,39 @@ public:
}
void replaceLost() {
int toReplace = 0;
#pragma omp parallel for
std::vector<size_t> idsToRemove;
for (auto& point : idposMap) {
if (!grid.inGrid(point.second)) {
grid.remove(point.second);
toReplace++;
idsToRemove.push_back(point.first);
}
}
fluidParticle newParticles;
newParticles.mass = newMass;
spawnParticles(newParticles, toReplace);
for (size_t id : idsToRemove) {
grid.remove(idposMap[id]);
idposMap.erase(id);
}
if (!idsToRemove.empty()) {
fluidParticle newParticles;
newParticles.mass = newMass;
spawnParticles(newParticles, idsToRemove.size(), false);
}
}
void applyPhysics() {
TIME_FUNCTION;
///TODO:
// apply velocity to have particle move
// use mass of neighboring particles to change direction towards them
// ressure pushes particles away if they are too close
// resitution controls how much pressure builds up based on how close particles are
// have to find a way to have a clump use their combined mass instead of individual mass.
//if a particle leaves the grid, destroy it and spawn a new one
applyPressureDensity();
applyForce();
for (auto& point : idposMap) {
auto node = grid.find(point.second);
if (!node) continue;
Eigen::Matrix<float, 3, 1> acceleration = node->data.forceAccumulator / node->data.mass;
node->data.velocity += acceleration * config.TIMESTEP;
Eigen::Matrix<float, 3, 1> newPos = point.second + (node->data.velocity * config.TIMESTEP);
idposMap[point.first] = newPos;
grid.move(point.second, newPos);
}
replaceLost();
}
};