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Star.cpp
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Star.cpp
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// Copyright (c) Conni Bilham & Lucy Coward 2022, All Rights Reserved.
#include "Star.h"
#include "Region.h"
#include "includes/logging.h"
void Star::find_regions() {
int max_bound = this->parent->regions.size();
logging::debug("Finding regions for star " + std::to_string(this->id) + " - position: ", this->position);
//regions_we_are_in.clear();
// weird math that works to find the index of the region the star is in
long double tmp = (this->position.x - this->parent->simulationSpaceStart.x) / this->parent->step.x;
long double tmp2 = std::floor(tmp);
long double remainder = tmp - tmp2;
int index = (tmp2) * this->parent->divisions.y * this->parent->divisions.z; //indexing works
int neighbour_x = 0;
int neighbour_y = 0;
int neighbour_z = 0;
int mode_neighbours = 1; // 1 = 1 region, 2 = 2 regions, 4 = 4 regions, 8 = 8 regions
if(remainder <= this->parent->overlap_factor) { // need to check all 3 directions to see if we are in a neighbour region
// logging::verbose("[ find_regions - 1 ] - We are overlapping the below region", "");
neighbour_x = -1;
mode_neighbours *= 2;
}
else if (remainder >= 1 - this->parent->overlap_factor) {
// logging::verbose("[ find_regions - 1 ] - We are overlapping the above region", "");
neighbour_x = 1;
mode_neighbours *= 2;
}
tmp = (this->position.y - this->parent->simulationSpaceStart.y) / this->parent->step.y;
tmp2 = std::floor(tmp);
remainder = tmp - tmp2;
index += (tmp2) * this->parent->divisions.z;
if(remainder <= this->parent->overlap_factor) {
// We are overlapping the below region
neighbour_y = -1;
mode_neighbours *= 2;
}
else if (remainder >= 1 - this->parent->overlap_factor) {
// We are overlapping the above region
neighbour_y = 1;
mode_neighbours *= 2;
}
// TODO: Will need to check weather the type of int/float work correctly when Star pos and playspace are large
tmp = (this->position.z - this->parent->simulationSpaceStart.z) / this->parent->step.z;
tmp2 = std::floor(tmp);
remainder = tmp - tmp2;
index += (tmp2);
if(remainder <= this->parent->overlap_factor) {
// We are overlapping the below region
neighbour_z = -1;
mode_neighbours *= 2;
}
else if (remainder >= 1 - this->parent->overlap_factor) {
// We are overlapping the above region
neighbour_z = 1;
mode_neighbours *= 2;
}
// std::list<int> neighbour_list = (neighbour_x, neighbour_y, neighbour_z);
// Vector neighbour_vector = Vector(neighbour_x,neighbour_y,neighbour_z);
logging::verbose("We are in " + std::to_string(mode_neighbours) + " regions. Index of box we are in is: ", index);
if(mode_neighbours == 0) {
logging::verbose("[ find_regions - 3 ] - We are in no region???");
}
else if (mode_neighbours == 1) {
if(index > this->parent->regions.size()){
// std::cout << "Index is out of bounds {MAYBE}" << std::endl;
}
else {
regions_we_are_in.push_back(this->parent->regions[index]);
}
}
else if (mode_neighbours == 2) {
tmp = index;
tmp += (neighbour_x * this->parent->divisions.y * this->parent->divisions.z);
tmp += (neighbour_y * this->parent->divisions.z);
tmp += neighbour_z;
// if(this->parent->debug) std::cout << "The index of the neighbouring region is: " << tmp << std::endl;
regions_we_are_in.emplace_back(this->parent->regions[index]);
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
}
else if (mode_neighbours == 4) {
tmp = index;
tmp += (neighbour_x * this->parent->divisions.y * this->parent->divisions.z);
tmp += (neighbour_y * this->parent->divisions.z);
tmp += neighbour_z;
regions_we_are_in.emplace_back(this->parent->regions[index]);
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "The index of the corner neighbouring regions is: " << tmp << std::endl;
if (neighbour_x != 0) {
tmp = (index + (neighbour_x * this->parent->divisions.y * this->parent->divisions.z));
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "The index of one of the neighbouring regions is: " << tmp << std::endl;
}
if (neighbour_y != 0) {
tmp = (index + (neighbour_y * this->parent->divisions.z));
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "The index of one of the neighbouring regions is: " << tmp << std::endl;
}
if (neighbour_z != 0) {
tmp = (index + neighbour_z);
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "The index of one of the neighbouring regions is: " << tmp << std::endl;
}
}
else if (mode_neighbours == 8) {
tmp = index;
tmp += (neighbour_x * this->parent->divisions.y * this->parent->divisions.z) + (neighbour_y * this->parent->divisions.z) + neighbour_z;
regions_we_are_in.emplace_back(this->parent->regions[index]);
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "The index of the corner neighbouring regions is: " << tmp << std::endl;
tmp = index + (neighbour_x * this->parent->divisions.y * this->parent->divisions.z);
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "(X) The index of one of the neighbouring regions is: " << tmp << std::endl;
tmp = index + (neighbour_y * this->parent->divisions.z);
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "(Y) The index of one of the neighbouring regions is: " << tmp << std::endl;
tmp = index + neighbour_z;
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "(Z) The index of one of the neighbouring regions is: " << tmp << std::endl;
tmp = index + (neighbour_x * this->parent->divisions.y * this->parent->divisions.z) + (neighbour_y * this->parent->divisions.z);
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "(XY) The index of one of the neighbouring regions is: " << tmp << std::endl;
tmp = index + (neighbour_x * this->parent->divisions.y * this->parent->divisions.z) + neighbour_z;
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "(XZ) The index of one of the neighbouring regions is: " << tmp << std::endl;
tmp = index + (neighbour_y * this->parent->divisions.z) + neighbour_z;
if(tmp >= 0 && tmp <= max_bound) regions_we_are_in.emplace_back(this->parent->regions[tmp]);
// if(this->parent->debug) std::cout << "(YZ) The index of one of the neighbouring regions is: " << tmp << std::endl;
}
for(Region *region : regions_we_are_in) {
region->stars_in_region.emplace_back(this);
}
}
// code for updating the acceleration of the star
// this is the most important part of the simulation
// TODO: make this use the regioning system to update stars only in their current and neighbouring regions
// TODO: When a star is overlapping regions it should update the acceleration using the other stars in the overlapping regions
// TODO: Make stars update using regions COM
double Star::acceleration_update_stars_in_region(bool clear_accel) {
if (clear_accel) {
logging::debug("Clearing acceleration");
acceleration = Vectorr(0, 0, 0);
}
auto accelerationStartTime = std::chrono::high_resolution_clock::now();
for (auto region : this->regions_we_are_in) {
for (auto star : region->stars_in_region) {
if (star->id == id)
continue;
long double r = this->position.distTo(star->position); // r needs to me in km
long double r_in_km = r * parsec_to_km;
long double accel_from_star = (gravitationalConstantFinal * star->mass)/(pow(r_in_km, 2)); // Now gives acceleration in pc/year^2
auto position_delta = star->position - this->position;
position_delta * r;
this->acceleration += (position_delta / r) * accel_from_star;
}
}
return std::chrono::duration_cast<std::chrono::milliseconds>((std::chrono::high_resolution_clock::now())-accelerationStartTime).count();
}
double Star::acceleration_update_region_com(bool clear_accel) {
if (clear_accel)
acceleration = Vectorr(0, 0, 0);
auto accelerationStartTime = std::chrono::high_resolution_clock::now();
for (auto region : this->parent->regions){
if (region->stars_in_region.size() == 0)
continue;
// Conni you might want to make this your way
if (std::find(regions_we_are_in.begin(), regions_we_are_in.end(), region) != regions_we_are_in.end())
continue;
long double r = this->position.distTo(region->centreMass.position); // r needs to me in km
long double r_in_km = r * parsec_to_km;
long double accel_from_region = (gravitationalConstantFinal * region->centreMass.mass)/(pow(r_in_km, 2)); // Now gives acceleration in pc/year^2
this->acceleration += ((region->centreMass.position - this->position) / r) * accel_from_region;
}
auto accelerationEndTime = std::chrono::high_resolution_clock::now();
auto accelerationDuration = std::chrono::duration_cast<std::chrono::milliseconds>(accelerationEndTime-accelerationStartTime).count();
return accelerationDuration;
}
void Star::velocity_update() {
if(!this->is_static())
this->velocity += this->acceleration * time_step;
this->history_tmp.velocity = this->velocity;
this->history_tmp.acceleration = this->acceleration;
// this->history_velocity.emplace_back(this->velocity.x, this->velocity.y, this->velocity.z);
// this->history_acceleration.emplace_back(this->acceleration.x, this->acceleration.y, this->acceleration.z);
}
void Star::position_update(long double override_timestep) {
if(override_timestep)
time_step = override_timestep;
if(!this->is_static()) {
this->position.x += this->velocity.x * time_step - 0.5 * this->acceleration.x * (time_step * time_step);
this->position.y += this->velocity.y * time_step - 0.5 * this->acceleration.y * (time_step * time_step);
this->position.z += this->velocity.z * time_step - 0.5 * this->acceleration.z * (time_step * time_step);
}
this->history_tmp.position = this->position;
this->history.emplace_back(this->history_tmp);
this->history_tmp = history_record_t();
this->regions_we_are_in.clear();
}
bool Star::is_static() const {
return this->flags & (int)STAR_FLAGS::STATIC;
}
long double Star::kinetic_energy(int history_index, bool reverse) {
history_index -= 1;
// Return the live value of the star
if(history_index == -1)
return (0.5 * this->mass) * this->velocity.magnitude_squared();
history_index = reverse ? this->history.size() - history_index : history_index;
auto tmp_mass = 0.5 * this->mass;
auto tmp_velocity = this->history[history_index].velocity; // in ps/year
// logging::info("Velocity ps/year - ", tmp_velocity);
tmp_velocity = tmp_velocity * parsecsPerYear_to_metersPerSecond; // convert to m/s
// logging::info("Velocity m/s - ", tmp_velocity);
auto energy = tmp_mass * tmp_velocity.magnitude_squared(); // in J
// logging::info("Energy J - ", energy);
return energy;
}