forked from bartvdbraak/blender
6ea54fe9ff
The intention of this commit it to address issues mentioned in the
reports T43865,T50164 and T50452.
The code is based on Embree code with some extra vectorization
to speed up single ray to single triangle intersection.
Unfortunately, such a fix is not coming for free. There is some
slowdown for AVX2 processors, mainly due to different vectorization
code, which caused different number of instructions to be executed
and different instructions-per-cycle counters. But on another hand
this commit makes pre-AVX2 platforms such as AVX and SSE4.1 a bit
faster. The prerformance goes as following:
2.78c AVX2 2.78c AVX Patch AVX2 Patch AVX
BMW 05:21.09 06:05.34 05:32.97 (+3.5%) 05:34.97 (-8.5%)
Classroom 16:55.36 18:24.51 17:10.41 (+1.4%) 17:15.87 (-6.3%)
Fishy Cat 08:08.49 08:36.26 08:09.19 (+0.2%) 08:12.25 (-4.7%
Koro 11:22.54 11:45.24 11:13.25 (-1.5%) 11:43.81 (-0.3%)
Barcelone 14:18.32 16:09.46 14:15.20 (-0.4%) 14:25.15 (-10.8%)
On GPU the performance is about 1.5-2% slower in my tests on GTX1080
but afraid we can't do much as a part of this chaneg here and
consider it a price to pay for more proper intersection check.
Made in collaboration with Maxym Dmytrychenko, big thanks to him!
Reviewers: brecht, juicyfruit, lukasstockner97, dingto
Differential Revision: https://developer.blender.org/D1574
292 lines
9.2 KiB
C
292 lines
9.2 KiB
C
/*
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* Copyright 2014, Blender Foundation.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* Triangle/Ray intersections.
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*
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* For BVH ray intersection we use a precomputed triangle storage to accelerate
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* intersection at the cost of more memory usage.
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*/
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CCL_NAMESPACE_BEGIN
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ccl_device_inline bool triangle_intersect(KernelGlobals *kg,
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Intersection *isect,
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float3 P,
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float3 dir,
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uint visibility,
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int object,
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int prim_addr)
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{
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const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, prim_addr);
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#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
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const ssef *ssef_verts = (ssef*)&kg->__prim_tri_verts.data[tri_vindex];
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#else
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const float4 tri_a = kernel_tex_fetch(__prim_tri_verts, tri_vindex+0),
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tri_b = kernel_tex_fetch(__prim_tri_verts, tri_vindex+1),
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tri_c = kernel_tex_fetch(__prim_tri_verts, tri_vindex+2);
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#endif
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float t, u, v;
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if(ray_triangle_intersect(P,
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dir,
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isect->t,
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#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
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ssef_verts,
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#else
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float4_to_float3(tri_a),
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float4_to_float3(tri_b),
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float4_to_float3(tri_c),
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#endif
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&u, &v, &t))
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{
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#ifdef __VISIBILITY_FLAG__
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/* Visibility flag test. we do it here under the assumption
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* that most triangles are culled by node flags.
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*/
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if(kernel_tex_fetch(__prim_visibility, prim_addr) & visibility)
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#endif
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{
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isect->prim = prim_addr;
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isect->object = object;
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isect->type = PRIMITIVE_TRIANGLE;
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isect->u = u;
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isect->v = v;
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isect->t = t;
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return true;
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}
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}
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return false;
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}
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/* Special ray intersection routines for subsurface scattering. In that case we
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* only want to intersect with primitives in the same object, and if case of
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* multiple hits we pick a single random primitive as the intersection point.
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*/
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#ifdef __SUBSURFACE__
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ccl_device_inline void triangle_intersect_subsurface(
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KernelGlobals *kg,
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SubsurfaceIntersection *ss_isect,
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float3 P,
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float3 dir,
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int object,
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int prim_addr,
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float tmax,
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uint *lcg_state,
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int max_hits)
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{
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const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, prim_addr);
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#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
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const ssef *ssef_verts = (ssef*)&kg->__prim_tri_verts.data[tri_vindex];
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#else
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const float3 tri_a = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+0)),
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tri_b = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+1)),
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tri_c = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+2));
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#endif
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float t, u, v;
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if(!ray_triangle_intersect(P,
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dir,
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tmax,
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#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
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ssef_verts,
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#else
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tri_a, tri_b, tri_c,
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#endif
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&u, &v, &t))
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{
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return;
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}
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for(int i = min(max_hits, ss_isect->num_hits) - 1; i >= 0; --i) {
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if(ss_isect->hits[i].t == t) {
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return;
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}
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}
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ss_isect->num_hits++;
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int hit;
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if(ss_isect->num_hits <= max_hits) {
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hit = ss_isect->num_hits - 1;
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}
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else {
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/* reservoir sampling: if we are at the maximum number of
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* hits, randomly replace element or skip it */
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hit = lcg_step_uint(lcg_state) % ss_isect->num_hits;
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if(hit >= max_hits)
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return;
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}
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/* record intersection */
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Intersection *isect = &ss_isect->hits[hit];
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isect->prim = prim_addr;
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isect->object = object;
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isect->type = PRIMITIVE_TRIANGLE;
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isect->u = u;
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isect->v = v;
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isect->t = t;
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/* Record geometric normal. */
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#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
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const float3 tri_a = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+0)),
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tri_b = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+1)),
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tri_c = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+2));
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#endif
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ss_isect->Ng[hit] = normalize(cross(tri_b - tri_a, tri_c - tri_a));
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}
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#endif /* __SUBSURFACE__ */
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/* Refine triangle intersection to more precise hit point. For rays that travel
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* far the precision is often not so good, this reintersects the primitive from
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* a closer distance. */
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/* Reintersections uses the paper:
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*
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* Tomas Moeller
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* Fast, minimum storage ray/triangle intersection
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* http://www.cs.virginia.edu/~gfx/Courses/2003/ImageSynthesis/papers/Acceleration/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf
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*/
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ccl_device_inline float3 triangle_refine(KernelGlobals *kg,
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ShaderData *sd,
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const Intersection *isect,
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const Ray *ray)
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{
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float3 P = ray->P;
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float3 D = ray->D;
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float t = isect->t;
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#ifdef __INTERSECTION_REFINE__
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if(isect->object != OBJECT_NONE) {
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if(UNLIKELY(t == 0.0f)) {
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return P;
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}
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# ifdef __OBJECT_MOTION__
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Transform tfm = sd->ob_itfm;
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# else
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Transform tfm = object_fetch_transform(kg, isect->object, OBJECT_INVERSE_TRANSFORM);
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# endif
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P = transform_point(&tfm, P);
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D = transform_direction(&tfm, D*t);
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D = normalize_len(D, &t);
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}
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P = P + D*t;
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const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, isect->prim);
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const float4 tri_a = kernel_tex_fetch(__prim_tri_verts, tri_vindex+0),
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tri_b = kernel_tex_fetch(__prim_tri_verts, tri_vindex+1),
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tri_c = kernel_tex_fetch(__prim_tri_verts, tri_vindex+2);
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float3 edge1 = make_float3(tri_a.x - tri_c.x, tri_a.y - tri_c.y, tri_a.z - tri_c.z);
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float3 edge2 = make_float3(tri_b.x - tri_c.x, tri_b.y - tri_c.y, tri_b.z - tri_c.z);
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float3 tvec = make_float3(P.x - tri_c.x, P.y - tri_c.y, P.z - tri_c.z);
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float3 qvec = cross(tvec, edge1);
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float3 pvec = cross(D, edge2);
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float det = dot(edge1, pvec);
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if(det != 0.0f) {
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/* If determinant is zero it means ray lies in the plane of
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* the triangle. It is possible in theory due to watertight
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* nature of triangle intersection. For such cases we simply
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* don't refine intersection hoping it'll go all fine.
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*/
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float rt = dot(edge2, qvec) / det;
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P = P + D*rt;
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}
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if(isect->object != OBJECT_NONE) {
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# ifdef __OBJECT_MOTION__
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Transform tfm = sd->ob_tfm;
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# else
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Transform tfm = object_fetch_transform(kg, isect->object, OBJECT_TRANSFORM);
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# endif
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P = transform_point(&tfm, P);
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}
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return P;
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#else
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return P + D*t;
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#endif
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}
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/* Same as above, except that isect->t is assumed to be in object space for
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* instancing.
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*/
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ccl_device_inline float3 triangle_refine_subsurface(KernelGlobals *kg,
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ShaderData *sd,
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const Intersection *isect,
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const Ray *ray)
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{
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float3 P = ray->P;
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float3 D = ray->D;
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float t = isect->t;
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if(isect->object != OBJECT_NONE) {
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#ifdef __OBJECT_MOTION__
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Transform tfm = sd->ob_itfm;
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#else
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Transform tfm = object_fetch_transform(kg,
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isect->object,
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OBJECT_INVERSE_TRANSFORM);
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#endif
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P = transform_point(&tfm, P);
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D = transform_direction(&tfm, D);
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D = normalize(D);
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}
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P = P + D*t;
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#ifdef __INTERSECTION_REFINE__
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const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, isect->prim);
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const float4 tri_a = kernel_tex_fetch(__prim_tri_verts, tri_vindex+0),
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tri_b = kernel_tex_fetch(__prim_tri_verts, tri_vindex+1),
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tri_c = kernel_tex_fetch(__prim_tri_verts, tri_vindex+2);
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float3 edge1 = make_float3(tri_a.x - tri_c.x, tri_a.y - tri_c.y, tri_a.z - tri_c.z);
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float3 edge2 = make_float3(tri_b.x - tri_c.x, tri_b.y - tri_c.y, tri_b.z - tri_c.z);
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float3 tvec = make_float3(P.x - tri_c.x, P.y - tri_c.y, P.z - tri_c.z);
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float3 qvec = cross(tvec, edge1);
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float3 pvec = cross(D, edge2);
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float det = dot(edge1, pvec);
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if(det != 0.0f) {
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/* If determinant is zero it means ray lies in the plane of
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* the triangle. It is possible in theory due to watertight
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* nature of triangle intersection. For such cases we simply
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* don't refine intersection hoping it'll go all fine.
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*/
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float rt = dot(edge2, qvec) / det;
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P = P + D*rt;
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}
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#endif /* __INTERSECTION_REFINE__ */
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if(isect->object != OBJECT_NONE) {
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#ifdef __OBJECT_MOTION__
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Transform tfm = sd->ob_tfm;
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#else
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Transform tfm = object_fetch_transform(kg,
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isect->object,
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OBJECT_TRANSFORM);
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#endif
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P = transform_point(&tfm, P);
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}
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return P;
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}
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CCL_NAMESPACE_END
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