Fix wrong area light pdf in Cycles MNEE
Area light sampling use special techniques to reduce noise with small spread angles; the change in sampled area was not taken into consideration when computing the pdf in MNEE. Pull Request: https://projects.blender.org/blender/blender/pulls/107897
This commit is contained in:
Weizhen Huang
Weizhen Huang
parent
9870d8fd27
commit
3d96cab01f
@ -227,55 +227,43 @@ ccl_device bool area_light_spread_clamp_light(const float3 P,
|
||||
}
|
||||
|
||||
/* Common API. */
|
||||
|
||||
/* Compute `eval_fac` and `pdf`. Also sample a new position on the light if `sample_coord`. */
|
||||
template<bool in_volume_segment>
|
||||
ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
|
||||
const float randu,
|
||||
const float randv,
|
||||
const float3 P,
|
||||
ccl_private LightSample *ls)
|
||||
ccl_device_inline bool area_light_eval(const ccl_global KernelLight *klight,
|
||||
const float3 ray_P,
|
||||
ccl_private float3 *light_P,
|
||||
ccl_private LightSample *ccl_restrict ls,
|
||||
float randu,
|
||||
float randv,
|
||||
bool sample_coord)
|
||||
{
|
||||
ls->P = klight->co;
|
||||
float3 axis_u = klight->area.axis_u;
|
||||
float3 axis_v = klight->area.axis_v;
|
||||
float len_u = klight->area.len_u;
|
||||
float len_v = klight->area.len_v;
|
||||
|
||||
float3 Ng = klight->area.dir;
|
||||
const float3 Ng = klight->area.dir;
|
||||
const float invarea = fabsf(klight->area.invarea);
|
||||
bool sample_rectangle = (klight->area.invarea > 0.0f);
|
||||
|
||||
if (!in_volume_segment) {
|
||||
if (dot(ls->P - P, Ng) > 0.0f) {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
const float3 axis_u = klight->area.axis_u;
|
||||
const float3 axis_v = klight->area.axis_v;
|
||||
const float len_u = klight->area.len_u;
|
||||
const float len_v = klight->area.len_v;
|
||||
float invarea = fabsf(klight->area.invarea);
|
||||
bool is_ellipse = (klight->area.invarea < 0.0f);
|
||||
bool sample_rectangle = !is_ellipse;
|
||||
float3 inplane;
|
||||
float3 light_P_new = *light_P;
|
||||
|
||||
if (in_volume_segment) {
|
||||
inplane = sample_rectangle ?
|
||||
rectangle_sample(axis_u * len_u * 0.5f, axis_v * len_v * 0.5f, randu, randv) :
|
||||
ellipse_sample(axis_u * len_u * 0.5f, axis_v * len_v * 0.5f, randu, randv);
|
||||
ls->P += inplane;
|
||||
light_P_new += sample_rectangle ?
|
||||
rectangle_sample(
|
||||
axis_u * len_u * 0.5f, axis_v * len_v * 0.5f, randu, randv) :
|
||||
ellipse_sample(axis_u * len_u * 0.5f, axis_v * len_v * 0.5f, randu, randv);
|
||||
ls->pdf = invarea;
|
||||
}
|
||||
else {
|
||||
float3 old_P = ls->P;
|
||||
float3 sample_axis_u = axis_u;
|
||||
float3 sample_axis_v = axis_v;
|
||||
float sample_len_u = len_u;
|
||||
float sample_len_v = len_v;
|
||||
|
||||
if (klight->area.normalize_spread > 0) {
|
||||
if (!area_light_spread_clamp_light(P,
|
||||
if (!area_light_spread_clamp_light(ray_P,
|
||||
Ng,
|
||||
&ls->P,
|
||||
&sample_axis_u,
|
||||
&sample_len_u,
|
||||
&sample_axis_v,
|
||||
&sample_len_v,
|
||||
&light_P_new,
|
||||
&axis_u,
|
||||
&len_u,
|
||||
&axis_v,
|
||||
&len_v,
|
||||
klight->area.tan_half_spread,
|
||||
&sample_rectangle))
|
||||
{
|
||||
@ -285,53 +273,82 @@ ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
|
||||
|
||||
if (sample_rectangle) {
|
||||
ls->pdf = area_light_rect_sample(
|
||||
P, &ls->P, sample_axis_u, sample_len_u, sample_axis_v, sample_len_v, randu, randv, true);
|
||||
ray_P, &light_P_new, axis_u, len_u, axis_v, len_v, randu, randv, sample_coord);
|
||||
}
|
||||
else {
|
||||
if (klight->area.tan_half_spread == 0.0f) {
|
||||
ls->pdf = 1.0f;
|
||||
}
|
||||
else {
|
||||
ls->P += ellipse_sample(sample_axis_u * sample_len_u * 0.5f,
|
||||
sample_axis_v * sample_len_v * 0.5f,
|
||||
randu,
|
||||
randv);
|
||||
ls->pdf = 4.0f * M_1_PI_F / (sample_len_u * sample_len_v);
|
||||
if (sample_coord) {
|
||||
light_P_new += ellipse_sample(
|
||||
axis_u * len_u * 0.5f, axis_v * len_v * 0.5f, randu, randv);
|
||||
}
|
||||
ls->pdf = 4.0f * M_1_PI_F / (len_u * len_v);
|
||||
}
|
||||
}
|
||||
inplane = ls->P - old_P;
|
||||
}
|
||||
|
||||
const float light_u = dot(inplane, axis_u) / len_u;
|
||||
const float light_v = dot(inplane, axis_v) / len_v;
|
||||
|
||||
/* Sampled point lies outside of the area light. */
|
||||
if (is_ellipse && (sqr(light_u) + sqr(light_v) > 0.25f)) {
|
||||
return false;
|
||||
if (sample_coord) {
|
||||
*light_P = light_P_new;
|
||||
ls->D = normalize_len(*light_P - ray_P, &ls->t);
|
||||
}
|
||||
if (!is_ellipse && (fabsf(light_u) > 0.5f || fabsf(light_v) > 0.5f)) {
|
||||
return false;
|
||||
}
|
||||
|
||||
/* NOTE: Return barycentric coordinates in the same notation as Embree and OptiX. */
|
||||
ls->u = light_v + 0.5f;
|
||||
ls->v = -light_u - light_v;
|
||||
|
||||
ls->Ng = Ng;
|
||||
ls->D = normalize_len(ls->P - P, &ls->t);
|
||||
|
||||
ls->eval_fac = 0.25f * invarea;
|
||||
|
||||
if (klight->area.normalize_spread > 0) {
|
||||
/* Area Light spread angle attenuation */
|
||||
ls->eval_fac *= area_light_spread_attenuation(
|
||||
ls->D, ls->Ng, klight->area.tan_half_spread, klight->area.normalize_spread);
|
||||
ls->D, Ng, klight->area.tan_half_spread, klight->area.normalize_spread);
|
||||
}
|
||||
|
||||
if (in_volume_segment || (!sample_rectangle && klight->area.tan_half_spread > 0)) {
|
||||
ls->pdf *= lamp_light_pdf(Ng, -ls->D, ls->t);
|
||||
}
|
||||
|
||||
return ls->eval_fac > 0;
|
||||
}
|
||||
|
||||
template<bool in_volume_segment>
|
||||
ccl_device_inline bool area_light_sample(const ccl_global KernelLight *klight,
|
||||
const float randu,
|
||||
const float randv,
|
||||
const float3 P,
|
||||
ccl_private LightSample *ls)
|
||||
{
|
||||
ls->P = klight->co;
|
||||
ls->Ng = klight->area.dir;
|
||||
|
||||
if (!in_volume_segment) {
|
||||
if (dot(ls->P - P, ls->Ng) > 0.0f) {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
if (!area_light_eval<in_volume_segment>(klight, P, &ls->P, ls, randu, randv, true)) {
|
||||
return false;
|
||||
}
|
||||
|
||||
const float3 inplane = ls->P - klight->co;
|
||||
const float light_u = dot(inplane, klight->area.axis_u) / klight->area.len_u;
|
||||
const float light_v = dot(inplane, klight->area.axis_v) / klight->area.len_v;
|
||||
|
||||
if (!in_volume_segment) {
|
||||
const bool is_ellipse = (klight->area.invarea < 0.0f);
|
||||
|
||||
/* Sampled point lies outside of the area light. */
|
||||
if (is_ellipse && (sqr(light_u) + sqr(light_v) > 0.25f)) {
|
||||
return false;
|
||||
}
|
||||
if (!is_ellipse && (fabsf(light_u) > 0.5f || fabsf(light_v) > 0.5f)) {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
/* NOTE: Return barycentric coordinates in the same notation as Embree and OptiX. */
|
||||
ls->u = light_v + 0.5f;
|
||||
ls->v = -light_u - light_v;
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
@ -339,20 +356,15 @@ ccl_device_forceinline void area_light_update_position(const ccl_global KernelLi
|
||||
ccl_private LightSample *ls,
|
||||
const float3 P)
|
||||
{
|
||||
const float invarea = fabsf(klight->area.invarea);
|
||||
if (klight->area.tan_half_spread == 0) {
|
||||
/* Update position on the light to keep the direction fixed. */
|
||||
area_light_sample<false>(klight, 0.0f, 0.0f, P, ls);
|
||||
area_light_eval<false>(klight, P, &ls->P, ls, 0, 0, true);
|
||||
}
|
||||
else {
|
||||
ls->D = normalize_len(ls->P - P, &ls->t);
|
||||
ls->pdf = invarea;
|
||||
}
|
||||
|
||||
if (klight->area.normalize_spread > 0) {
|
||||
ls->eval_fac = 0.25f * invarea;
|
||||
ls->eval_fac *= area_light_spread_attenuation(
|
||||
ls->D, ls->Ng, klight->area.tan_half_spread, klight->area.normalize_spread);
|
||||
area_light_eval<false>(klight, P, &ls->P, ls, 0, 0, false);
|
||||
/* Convert pdf to be in area measure. */
|
||||
ls->pdf /= lamp_light_pdf(ls->Ng, -ls->D, ls->t);
|
||||
}
|
||||
}
|
||||
|
||||
@ -403,60 +415,13 @@ ccl_device_inline bool area_light_sample_from_intersection(
|
||||
const float3 ray_D,
|
||||
ccl_private LightSample *ccl_restrict ls)
|
||||
{
|
||||
|
||||
/* area light */
|
||||
float invarea = fabsf(klight->area.invarea);
|
||||
|
||||
float3 Ng = klight->area.dir;
|
||||
float3 light_P = klight->co;
|
||||
|
||||
ls->u = isect->u;
|
||||
ls->v = isect->v;
|
||||
ls->D = ray_D;
|
||||
ls->Ng = Ng;
|
||||
ls->Ng = klight->area.dir;
|
||||
|
||||
float3 sample_axis_u = klight->area.axis_u;
|
||||
float3 sample_axis_v = klight->area.axis_v;
|
||||
float sample_len_u = klight->area.len_u;
|
||||
float sample_len_v = klight->area.len_v;
|
||||
bool is_ellipse = (klight->area.invarea < 0.0f);
|
||||
bool sample_rectangle = !is_ellipse;
|
||||
|
||||
if (klight->area.normalize_spread > 0) {
|
||||
if (!area_light_spread_clamp_light(ray_P,
|
||||
Ng,
|
||||
&light_P,
|
||||
&sample_axis_u,
|
||||
&sample_len_u,
|
||||
&sample_axis_v,
|
||||
&sample_len_v,
|
||||
klight->area.tan_half_spread,
|
||||
&sample_rectangle))
|
||||
{
|
||||
return false;
|
||||
}
|
||||
}
|
||||
|
||||
if (sample_rectangle) {
|
||||
ls->pdf = area_light_rect_sample(
|
||||
ray_P, &light_P, sample_axis_u, sample_len_u, sample_axis_v, sample_len_v, 0, 0, false);
|
||||
}
|
||||
else {
|
||||
ls->pdf = klight->area.tan_half_spread == 0.0f ?
|
||||
1.0f :
|
||||
4.0f * M_1_PI_F / (sample_len_u * sample_len_v) *
|
||||
lamp_light_pdf(Ng, -ray_D, ls->t);
|
||||
}
|
||||
|
||||
ls->eval_fac = 0.25f * invarea;
|
||||
|
||||
if (klight->area.normalize_spread > 0) {
|
||||
/* Area Light spread angle attenuation */
|
||||
ls->eval_fac *= area_light_spread_attenuation(
|
||||
ls->D, ls->Ng, klight->area.tan_half_spread, klight->area.normalize_spread);
|
||||
}
|
||||
|
||||
return ls->eval_fac > 0;
|
||||
float3 light_P = klight->co;
|
||||
return area_light_eval<false>(klight, ray_P, &light_P, ls, 0, 0, false);
|
||||
}
|
||||
|
||||
template<bool in_volume_segment>
|
||||
|
||||
Loading…
Reference in New Issue
Block a user