76 lines
2.9 KiB
C++
76 lines
2.9 KiB
C++
// Copyright 2009-2020 Intel Corporation
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// SPDX-License-Identifier: Apache-2.0
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#pragma once
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namespace embree
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{
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namespace isa
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{
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/*! Intersects a ray with a quad with backface culling
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* enabled. The quad v0,v1,v2,v3 is split into two triangles
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* v0,v1,v3 and v2,v3,v1. The edge v1,v2 decides which of the two
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* triangles gets intersected. */
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template<int N>
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__forceinline vbool<N> intersect_quad_backface_culling(const vbool<N>& valid0,
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const Vec3fa& ray_org,
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const Vec3fa& ray_dir,
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const float ray_tnear,
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const float ray_tfar,
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const Vec3vf<N>& quad_v0,
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const Vec3vf<N>& quad_v1,
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const Vec3vf<N>& quad_v2,
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const Vec3vf<N>& quad_v3,
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vfloat<N>& u_o,
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vfloat<N>& v_o,
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vfloat<N>& t_o)
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{
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/* calculate vertices relative to ray origin */
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vbool<N> valid = valid0;
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const Vec3vf<N> O = Vec3vf<N>(ray_org);
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const Vec3vf<N> D = Vec3vf<N>(ray_dir);
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const Vec3vf<N> va = quad_v0-O;
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const Vec3vf<N> vb = quad_v1-O;
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const Vec3vf<N> vc = quad_v2-O;
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const Vec3vf<N> vd = quad_v3-O;
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const Vec3vf<N> edb = vb-vd;
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const vfloat<N> WW = dot(cross(vd,edb),D);
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const Vec3vf<N> v0 = select(WW <= 0.0f,va,vc);
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const Vec3vf<N> v1 = select(WW <= 0.0f,vb,vd);
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const Vec3vf<N> v2 = select(WW <= 0.0f,vd,vb);
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/* calculate edges */
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const Vec3vf<N> e0 = v2-v0;
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const Vec3vf<N> e1 = v0-v1;
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/* perform edge tests */
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const vfloat<N> U = dot(cross(v0,e0),D);
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const vfloat<N> V = dot(cross(v1,e1),D);
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valid &= max(U,V) <= 0.0f;
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if (unlikely(none(valid))) return false;
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/* calculate geometry normal and denominator */
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const Vec3vf<N> Ng = cross(e1,e0);
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const vfloat<N> den = dot(Ng,D);
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const vfloat<N> rcpDen = rcp(den);
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/* perform depth test */
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const vfloat<N> t = rcpDen*dot(v0,Ng);
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valid &= vfloat<N>(ray_tnear) <= t & t <= vfloat<N>(ray_tfar);
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if (unlikely(none(valid))) return false;
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/* avoid division by 0 */
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valid &= den != vfloat<N>(zero);
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if (unlikely(none(valid))) return false;
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/* update hit information */
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t_o = t;
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u_o = U * rcpDen;
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v_o = V * rcpDen;
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u_o = select(WW <= 0.0f,u_o,1.0f-u_o);
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v_o = select(WW <= 0.0f,v_o,1.0f-v_o);
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return valid;
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}
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}
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}
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