pl_system_t*
pl_new_root_system(pl_world_t *world, const char *name, double m,
double gm, double obliquity, double siderealPeriod,
double eqRadius, double flattening)
{
assert(world);
pl_system_t *sys = smalloc(sizeof(pl_system_t));
obj_array_init(&sys->orbits);
obj_array_init(&sys->astroObjs);
obj_array_init(&sys->rigidObjs);
sys->name = strdup(name);
sys->world = world;
sys->parent = NULL;
lwcoord_t p;
lwc_set(&p, 0.0, 0.0, 0.0);
quaternion_t q = q_rot(1.0, 0.0, 0.0, DEG_TO_RAD(obliquity));
sys->orbitalBody = pl_new_obj(world, name, m, gm, &p, q, siderealPeriod, obliquity,
eqRadius, flattening);
sys->orbitalBody->kepler = NULL;
world->rootSys = sys;
pl_sys_set_current_pos(sys);
return sys;
}
static float sol_test_body(float dt,
float T[3], float V[3],
const struct v_ball *up,
const struct s_vary *vary,
const struct v_body *bp)
{
float U[3], O[3], E[4], W[3], u;
const struct b_node *np = vary->base->nv + bp->base->ni;
sol_body_p(O, vary, bp, 0.0f);
sol_body_v(W, vary, bp, dt);
sol_body_e(E, vary, bp, 0.0f);
/*
* For rotating bodies, rather than rotate every normal and vertex
* of the body, we temporarily pretend the ball is rotating and
* moving about a static body.
*/
/*
* Linear velocity of a point rotating about the origin:
* v = w x p
*/
if (E[0] != 1.0f || sol_body_w(vary, bp))
{
/* The body has a non-identity orientation or it is rotating. */
struct v_ball ball;
float e[4], p0[3], p1[3];
const float z[3] = { 0 };
/* First, calculate position at start and end of time interval. */
v_sub(p0, up->p, O);
v_cpy(p1, p0);
q_conj(e, E);
q_rot(p0, e, p0);
v_mad(p1, p1, up->v, dt);
v_mad(p1, p1, W, -dt);
sol_body_e(e, vary, bp, dt);
q_conj(e, e);
q_rot(p1, e, p1);
/* Set up ball struct with values relative to body. */
ball = *up;
v_cpy(ball.p, p0);
/* Calculate velocity from start/end positions and time. */
v_sub(ball.v, p1, p0);
v_scl(ball.v, ball.v, 1.0f / dt);
if ((u = sol_test_node(dt, U, &ball, vary->base, np, z, z)) < dt)
{
/* Compute the final orientation. */
sol_body_e(e, vary, bp, u);
/* Return world space coordinates. */
q_rot(T, e, U);
v_add(T, O, T);
/* Move forward. */
v_mad(T, T, W, u);
/* Express "non-ball" velocity. */
q_rot(V, e, ball.v);
v_sub(V, up->v, V);
dt = u;
}
}
else
{
if ((u = sol_test_node(dt, U, up, vary->base, np, O, W)) < dt)
{
v_cpy(T, U);
v_cpy(V, W);
dt = u;
}
}
return dt;
}
