bool BBox::intersect(const Ray& ray, float *tnear, float *tfar) const {
// you may already have those values hanging around somewhere
const __m128
plus_inf = loadps(ps_cst_plus_inf),
minus_inf = loadps(ps_cst_minus_inf);
// use whatever's apropriate to load.
const __m128
box_min = loadps(&min),
box_max = loadps(&max),
pos = loadps(&ray.o),
inv_dir = loadps(&ray.inv_d);
// use a div if inverted directions aren't available
const __m128 l1 = mulps(subps(box_min, pos), inv_dir);
const __m128 l2 = mulps(subps(box_max, pos), inv_dir);
// the order we use for those min/max is vital to filter out
// NaNs that happens when an inv_dir is +/- inf and
// (box_min - pos) is 0. inf * 0 = NaN
const __m128 filtered_l1a = minps(l1, plus_inf);
const __m128 filtered_l2a = minps(l2, plus_inf);
const __m128 filtered_l1b = maxps(l1, minus_inf);
const __m128 filtered_l2b = maxps(l2, minus_inf);
// now that we're back on our feet, test those slabs.
__m128 lmax = maxps(filtered_l1a, filtered_l2a);
__m128 lmin = minps(filtered_l1b, filtered_l2b);
// unfold back. try to hide the latency of the shufps & co.
const __m128 lmax0 = rotatelps(lmax);
const __m128 lmin0 = rotatelps(lmin);
lmax = minss(lmax, lmax0);
lmin = maxss(lmin, lmin0);
const __m128 lmax1 = muxhps(lmax,lmax);
const __m128 lmin1 = muxhps(lmin,lmin);
lmax = minss(lmax, lmax1);
lmin = maxss(lmin, lmin1);
const bool ret = _mm_comige_ss(lmax, _mm_setzero_ps()) & _mm_comige_ss(lmax,lmin);
storess(lmin, tnear);
storess(lmax, tfar);
return ret;
}
inline bool ray_box_intersect(const box_t & b, const ray_t & ray, rayseg_t & rs) {
/* you may already have those values hanging around somewhere */
const __m128
plus_inf = loadps(ps_cst_plus_inf), minus_inf = loadps(ps_cst_minus_inf);
/* use whatever's apropriate to load. */
const __m128
box_min = loadps(&b.min), box_max = loadps(&b.max), pos =
loadps(&ray.pos), inv_dir = loadps(&ray.inv_dir);
/* use a div if inverted directions aren't available */
const __m128 l1 = mulps(subps(box_min, pos), inv_dir);
const __m128 l2 = mulps(subps(box_max, pos), inv_dir);
/* the order we use for those min/max is vital to filter out */
/* NaNs that happens when an inv_dir is +/- inf and */
/* (box_min - pos) is 0. inf * 0 = NaN */
const __m128 filtered_l1a = minps(l1, plus_inf);
const __m128 filtered_l2a = minps(l2, plus_inf);
const __m128 filtered_l1b = maxps(l1, minus_inf);
const __m128 filtered_l2b = maxps(l2, minus_inf);
/* now that we're back on our feet, test those slabs. */
__m128 lmax = maxps(filtered_l1a, filtered_l2a);
__m128 lmin = minps(filtered_l1b, filtered_l2b);
/* unfold back. try to hide the latency of the shufps & co. */
const __m128 lmax0 = rotatelps(lmax);
const __m128 lmin0 = rotatelps(lmin);
lmax = minss(lmax, lmax0);
lmin = maxss(lmin, lmin0);
const __m128 lmax1 = muxhps(lmax, lmax);
const __m128 lmin1 = muxhps(lmin, lmin);
lmax = minss(lmax, lmax1);
lmin = maxss(lmin, lmin1);
const bool ret =
_mm_comige_ss(lmax, _mm_setzero_ps()) & _mm_comige_ss(lmax, lmin);
storess(lmin, &rs.t_near);
storess(lmax, &rs.t_far);
return ret;
}
