void ray_reflect(
Ray* result,
const Ray* r,
const Point* intersect,
const Vector* norm) {
result->o.x = intersect->x;
result->o.y = intersect->y;
result->o.z = intersect->z;
double dot_norm_ray = Vector_dot(norm, &r->d);
double norm_mag_squared = Vector_mag(norm) * Vector_mag(norm);
double double_proj_mag = 2 * dot_norm_ray / norm_mag_squared;
result->d.x = r->d.x - double_proj_mag*norm->x;
result->d.y = r->d.y - double_proj_mag*norm->y;
result->d.z = r->d.z - double_proj_mag*norm->z;
}
void NBody_tick(NBody* self, uint32_t dt) {
self->player->acceleration = Vector_init(0.0f, 0.0f, 0.0f);
Vector accelerations[NUM_STARS] = {{0.0f, 0.0f, 0.0f}};
// Update player
for (size_t i = 0; i < NUM_STARS; ++i) {
Star* star = &self->stars[i];
Vector delta = Vector_subtract(star->position, self->player->position);
float distance = Vector_mag(delta) + 0.00001f; // Add small amount to avoid collision
Vector force = Vector_scale(delta, 0.001f / (distance * distance * distance));
self->player->acceleration = Vector_add(self->player->acceleration, Vector_scale(force, star->mass));
}
self->player->velocity = Vector_add(self->player->velocity, Vector_scale(self->player->acceleration, 0.001f * dt));
self->player->position = Vector_add(self->player->position, Vector_scale(self->player->velocity, 0.001f * dt));
// Update stars
for (size_t i = 0; i < NUM_STARS; ++i) {
Star* star_i = &self->stars[i];
for (size_t j = i + 1; j < NUM_STARS; ++j) {
Star* star_j = &self->stars[j];
Vector delta = Vector_subtract(star_j->position, star_i->position);
float distance = Vector_mag(delta) + 0.00001f; // Add small amount to avoid collision
Vector force = Vector_scale(delta, 0.001f / (distance * distance * distance));
accelerations[i] = Vector_add(accelerations[i], Vector_scale(force, star_j->mass));
accelerations[j] = Vector_add(accelerations[j], Vector_scale(force, -star_i->mass));
}
star_i->velocity = Vector_add(star_i->velocity, Vector_scale(accelerations[i], 0.001f * dt));
star_i->position = Vector_add(star_i->position, Vector_scale(star_i->velocity, 0.001f * dt));
}
}
