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Microfacet fix #1264

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merged 4 commits into from
Jul 26, 2021
Merged

Microfacet fix #1264

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32dff7f
updated
xelatihy Jul 21, 2021
d694c8c
updated
xelatihy Jul 21, 2021
0d775ac
updated
xelatihy Jul 21, 2021
4822f5e
updatd
xelatihy Jul 26, 2021
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7 changes: 7 additions & 0 deletions libs/yocto/yocto_bvh.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1087,6 +1087,13 @@ void overlap_bvh_elems(const bvh_data& bvh1, const bvh_data& bvh2,
}
#endif

bvh_intersection intersect_bvh(const bvh_data& bvh, const shape_data& shape,
const ray3f& ray, bool find_any) {
auto intersection = bvh_intersection{};
intersection.hit = intersect_bvh(bvh, shape, ray, intersection.element,
intersection.uv, intersection.distance, find_any);
return intersection;
}
bvh_intersection intersect_bvh(const bvh_data& bvh, const scene_data& scene,
const ray3f& ray, bool find_any, bool non_rigid_frames) {
auto intersection = bvh_intersection{};
Expand Down
18 changes: 10 additions & 8 deletions libs/yocto/yocto_shading.h
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Original file line number Diff line number Diff line change
Expand Up @@ -421,6 +421,7 @@ inline float microfacet_shadowing1(float roughness, const vec3f& normal,
const vec3f& halfway, const vec3f& direction, bool ggx) {
// https://google.github.io/filament/Filament.html#materialsystem/specularbrdf
// http://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#appendix-b-brdf-implementation
auto cosine = dot(normal, direction);
auto cosineh = dot(halfway, direction);
if (cosine * cosineh <= 0) return 0;
Expand All @@ -445,7 +446,7 @@ inline float microfacet_shadowing(float roughness, const vec3f& normal,
microfacet_shadowing1(roughness, normal, halfway, incoming, ggx);
}

// Sample a microfacet ditribution.
// Sample a microfacet distribution.
inline vec3f sample_microfacet(
float roughness, const vec3f& normal, const vec2f& rn, bool ggx) {
auto phi = 2 * pif * rn.x;
Expand Down Expand Up @@ -488,12 +489,10 @@ inline vec3f sample_microfacet(float roughness, const vec3f& normal,
: vec3f{1, 0, 0};
auto T2 = cross(Vh, T1);
// Section 4.2: parameterization of the projected area
auto r = sqrt(rn.y);
auto phi = 2 * pif * rn.x;
auto t1 = r * cos(phi);
auto t2 = r * sin(phi);
auto s = 0.5f * (1 + Vh.z);
t2 = (1 - s) * sqrt(1 - t1 * t1) + s * t2;
auto r = sqrt(rn.y), phi = 2 * pif * rn.x;
auto t1 = r * cos(phi), t2 = r * sin(phi);
auto s = 0.5f * (1 + Vh.z);
t2 = (1 - s) * sqrt(1 - t1 * t1) + s * t2;
// Section 4.3: reprojection onto hemisphere
auto Nh = t1 * T1 + t2 * T2 + sqrt(max(0.0f, 1 - t1 * t1 - t2 * t2)) * Vh;
// Section 3.4: transforming the normal back to the ellipsoid configuration
Expand Down Expand Up @@ -904,6 +903,7 @@ inline vec3f sample_refractive(const vec3f& color, float ior, float roughness,
auto entering = dot(normal, outgoing) >= 0;
auto up_normal = entering ? normal : -normal;
auto halfway = sample_microfacet(roughness, up_normal, rn);
// auto halfway = sample_microfacet(roughness, up_normal, outgoing, rn);
if (rnl < fresnel_dielectric(entering ? ior : (1 / ior), halfway, outgoing)) {
auto incoming = reflect(outgoing, halfway);
if (!same_hemisphere(up_normal, outgoing, incoming)) return {0, 0, 0};
Expand All @@ -926,14 +926,16 @@ inline float sample_refractive_pdf(const vec3f& color, float ior,
auto halfway = normalize(incoming + outgoing);
return fresnel_dielectric(rel_ior, halfway, outgoing) *
sample_microfacet_pdf(roughness, up_normal, halfway) /
// sample_microfacet_pdf(roughness, up_normal, halfway, outgoing) /
(4 * abs(dot(outgoing, halfway)));
} else {
auto halfway = -normalize(rel_ior * incoming + outgoing) *
(entering ? 1.0f : -1.0f);
// [Walter 2007] equation 17
return (1 - fresnel_dielectric(rel_ior, halfway, outgoing)) *
sample_microfacet_pdf(roughness, up_normal, halfway) *
abs(dot(halfway, outgoing)) /
// sample_microfacet_pdf(roughness, up_normal, halfway, outgoing) /
abs(dot(halfway, incoming)) / // here we use incoming as from pbrt
pow(rel_ior * dot(halfway, incoming) + dot(halfway, outgoing), 2);
}
}
Expand Down
14 changes: 12 additions & 2 deletions libs/yocto/yocto_trace.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -471,6 +471,7 @@ static trace_result trace_path(const scene_data& scene, const bvh_data& bvh,
incoming = sample_lights(
scene, lights, position, rand1f(rng), rand1f(rng), rand2f(rng));
}
if (incoming == vec3f{0, 0, 0}) break;
weight *=
eval_bsdfcos(material, normal, outgoing, incoming) /
(0.5f * sample_bsdfcos_pdf(material, normal, outgoing, incoming) +
Expand Down Expand Up @@ -512,6 +513,7 @@ static trace_result trace_path(const scene_data& scene, const bvh_data& bvh,
incoming = sample_lights(
scene, lights, position, rand1f(rng), rand1f(rng), rand2f(rng));
}
if (incoming == vec3f{0, 0, 0}) break;
weight *=
eval_scattering(vsdf, outgoing, incoming) /
(0.5f * sample_scattering_pdf(vsdf, outgoing, incoming) +
Expand Down Expand Up @@ -642,13 +644,15 @@ static trace_result trace_pathdirect(const scene_data& scene,
incoming = sample_lights(
scene, lights, position, rand1f(rng), rand1f(rng), rand2f(rng));
}
if (incoming == vec3f{0, 0, 0}) break;
weight *=
eval_bsdfcos(material, normal, outgoing, incoming) /
(0.5f * sample_bsdfcos_pdf(material, normal, outgoing, incoming) +
0.5f *
sample_lights_pdf(scene, bvh, lights, position, incoming));
} else {
incoming = sample_delta(material, normal, outgoing, rand1f(rng));
if (incoming == vec3f{0, 0, 0}) break;
weight *= eval_delta(material, normal, outgoing, incoming) /
sample_delta_pdf(material, normal, outgoing, incoming);
}
Expand Down Expand Up @@ -680,6 +684,7 @@ static trace_result trace_pathdirect(const scene_data& scene,
incoming = sample_lights(
scene, lights, position, rand1f(rng), rand1f(rng), rand2f(rng));
}
if (incoming == vec3f{0, 0, 0}) break;
weight *=
eval_scattering(vsdf, outgoing, incoming) /
(0.5f * sample_scattering_pdf(vsdf, outgoing, incoming) +
Expand Down Expand Up @@ -789,10 +794,11 @@ static trace_result trace_pathmis(const scene_data& scene, const bvh_data& bvh,
if (!is_delta(material)) {
// direct with MIS --- light
for (auto sample_light : {true, false}) {
incoming = sample_light ? sample_lights(scene, lights, position,
incoming = sample_light ? sample_lights(scene, lights, position,
rand1f(rng), rand1f(rng), rand2f(rng))
: sample_bsdfcos(material, normal, outgoing,
: sample_bsdfcos(material, normal, outgoing,
rand1f(rng), rand2f(rng));
if (incoming == vec3f{0, 0, 0}) break;
auto bsdfcos = eval_bsdfcos(material, normal, outgoing, incoming);
auto light_pdf = sample_lights_pdf(
scene, bvh, lights, position, incoming);
Expand Down Expand Up @@ -936,10 +942,12 @@ static trace_result trace_naive(const scene_data& scene, const bvh_data& bvh,
if (material.roughness != 0) {
incoming = sample_bsdfcos(
material, normal, outgoing, rand1f(rng), rand2f(rng));
if (incoming == vec3f{0, 0, 0}) break;
weight *= eval_bsdfcos(material, normal, outgoing, incoming) /
sample_bsdfcos_pdf(material, normal, outgoing, incoming);
} else {
incoming = sample_delta(material, normal, outgoing, rand1f(rng));
if (incoming == vec3f{0, 0, 0}) break;
weight *= eval_delta(material, normal, outgoing, incoming) /
sample_delta_pdf(material, normal, outgoing, incoming);
}
Expand Down Expand Up @@ -1016,6 +1024,7 @@ static trace_result trace_eyelight(const scene_data& scene, const bvh_data& bvh,
// continue path
if (!is_delta(material)) break;
incoming = sample_delta(material, normal, outgoing, rand1f(rng));
if (incoming == vec3f{0, 0, 0}) break;
weight *= eval_delta(material, normal, outgoing, incoming) /
sample_delta_pdf(material, normal, outgoing, incoming);
if (weight == vec3f{0, 0, 0} || !isfinite(weight)) break;
Expand Down Expand Up @@ -1086,6 +1095,7 @@ static trace_result trace_eyelightao(const scene_data& scene,
// continue path
if (!is_delta(material)) break;
incoming = sample_delta(material, normal, outgoing, rand1f(rng));
if (incoming == vec3f{0, 0, 0}) break;
weight *= eval_delta(material, normal, outgoing, incoming) /
sample_delta_pdf(material, normal, outgoing, incoming);
if (weight == vec3f{0, 0, 0} || !isfinite(weight)) break;
Expand Down