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++ // Copyright 2009-2021 Intel Corporation
++ // SPDX-License-Identifier: Apache-2.0
++
++ #pragma once
++
++ namespace embree
++ {
++ namespace isa
++ {
++ /*! Intersects a ray with a quad with backface culling
++ * enabled. The quad v0,v1,v2,v3 is split into two triangles
++ * v0,v1,v3 and v2,v3,v1. The edge v1,v2 decides which of the two
++ * triangles gets intersected. */
++ template<int N>
++ __forceinline vbool<N> intersect_quad_backface_culling(const vbool<N>& valid0,
++ const Vec3fa& ray_org,
++ const Vec3fa& ray_dir,
++ const float ray_tnear,
++ const float ray_tfar,
++ const Vec3vf<N>& quad_v0,
++ const Vec3vf<N>& quad_v1,
++ const Vec3vf<N>& quad_v2,
++ const Vec3vf<N>& quad_v3,
++ vfloat<N>& u_o,
++ vfloat<N>& v_o,
++ vfloat<N>& t_o)
++ {
++ /* calculate vertices relative to ray origin */
++ vbool<N> valid = valid0;
++ const Vec3vf<N> O = Vec3vf<N>(ray_org);
++ const Vec3vf<N> D = Vec3vf<N>(ray_dir);
++ const Vec3vf<N> va = quad_v0-O;
++ const Vec3vf<N> vb = quad_v1-O;
++ const Vec3vf<N> vc = quad_v2-O;
++ const Vec3vf<N> vd = quad_v3-O;
++
++ const Vec3vf<N> edb = vb-vd;
++ const vfloat<N> WW = dot(cross(vd,edb),D);
++ const Vec3vf<N> v0 = select(WW <= 0.0f,va,vc);
++ const Vec3vf<N> v1 = select(WW <= 0.0f,vb,vd);
++ const Vec3vf<N> v2 = select(WW <= 0.0f,vd,vb);
++
++ /* calculate edges */
++ const Vec3vf<N> e0 = v2-v0;
++ const Vec3vf<N> e1 = v0-v1;
++
++ /* perform edge tests */
++ const vfloat<N> U = dot(cross(v0,e0),D);
++ const vfloat<N> V = dot(cross(v1,e1),D);
++ valid &= max(U,V) <= 0.0f;
++ if (unlikely(none(valid))) return false;
++
++ /* calculate geometry normal and denominator */
++ const Vec3vf<N> Ng = cross(e1,e0);
++ const vfloat<N> den = dot(Ng,D);
++ const vfloat<N> rcpDen = rcp(den);
++
++ /* perform depth test */
++ const vfloat<N> t = rcpDen*dot(v0,Ng);
++ valid &= vfloat<N>(ray_tnear) <= t & t <= vfloat<N>(ray_tfar);
++ if (unlikely(none(valid))) return false;
++
++ /* avoid division by 0 */
++ valid &= den != vfloat<N>(zero);
++ if (unlikely(none(valid))) return false;
++
++ /* update hit information */
++ t_o = t;
++ u_o = U * rcpDen;
++ v_o = V * rcpDen;
++ u_o = select(WW <= 0.0f,u_o,1.0f-u_o);
++ v_o = select(WW <= 0.0f,v_o,1.0f-v_o);
++ return valid;
++ }
++ }
++ }