void Cluster::calculateAcceleration() // Calculates forces between bodies
{
double G = gravitationalConstant;
// Set acceleration to zero to avoid addition from previous run
resetAllAcceleration();
for(int i=0; i<numberOfBodies(); i++)
{
CelestialBody *body1 = &bodies.at(i);
for(int j=i+1; j<numberOfBodies(); j++)
{
CelestialBody *body2 = &bodies[j];
vec3 deltaRVector = body2->position - body1->position; // deltaRVector pointing from body1 to body2
double dr = deltaRVector.length();
double dr_cubed = dr*dr*dr;
double accFactor = body2->mass/dr_cubed;
vec3 accVector= deltaRVector*accFactor;
body1->acceleration = body1->acceleration+accVector; // Force on body1 points same direction as deltaRVector
accFactor = body1->mass/dr_cubed;
accVector= deltaRVector*accFactor;
body2->acceleration = body2->acceleration-accVector; // Force on body2 points opposite direction as deltaRvector
}
// Finally, multiplying the sum of "acceleration vectors" with G to get the proper acceleration
body1->acceleration = body1->acceleration*G;
}
}
void simulation::calcAllAcceleration(void) {
resetAllAcceleration(); // Set all accelerations to 0;
for(unsigned int x = 0; x < bodies.size(); x++) {
// Evaluate bottom left of calculation matrix
for(unsigned int y = x+1; y < bodies.size(); y++) {
#ifdef PRINTAC
std::cerr << x << "-" << y << std::endl;
#endif
// Same body relationships do not occur
calcAcceleration(bodies[x], bodies[y]);
}
}
}
