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blender/intern/cycles/kernel/kernel_path.h
Sergey Sharybin dd58390d71 Fix emissive volumes generates unexpected fireflies around intersections 
Discard the whole volume stack on the last bounce (but keep
world volume if present).

Volumes are expected to be closed manifol meshes, meaning if
ray entered the volume there should be an intersection event
of ray exisintg the volume. Case when ray hit nothing and
there are still non-world volumes in the stack can happen in
either of cases.

1. Mesh is not closed manifold.

Such configurations are not really supported anyway and should
not be used.

Previous code would have consider the infinite length of the
ray to sample across, so render result wasn't really correct
anyway.

2. Exit intersection is more far away than the camera far
   clip distance.

This case also will behave differently now, but previously it
wasn't really correct either, so it's not like we're breaking
something which was working as expected.

3. We missed exit event due to intersection precision issues.

This is exact the case which this patch fixes and avoid
fireflies.

4. Volume has Camera only visibility (all the rest visibility
is set to off)

This is what could be considered a regression but could be
solved quite easily by checking volume stack's objects flags
and keep entries which doesn't have Volume Scatter visibility
(or even better: ensure Volume Scatter visibility for objects
with volume closure),

Fixes T46108: Cycles - Overlapping emissive volumes generates unexpected bright hotspots around the intersection
Also fixes fireflies appearing on the edges of cube with
emissive volue.

Reviewers: juicyfruit, brecht

Reviewed By: brecht

Maniphest Tasks: T46108

Differential Revision: https://developer.blender.org/D2212
2016-12-08 17:35:43 +01:00

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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifdef __OSL__
# include "osl_shader.h"
#endif
#include "kernel_random.h"
#include "kernel_projection.h"
#include "kernel_montecarlo.h"
#include "kernel_differential.h"
#include "kernel_camera.h"
#include "geom/geom.h"
#include "bvh/bvh.h"
#include "kernel_accumulate.h"
#include "kernel_shader.h"
#include "kernel_light.h"
#include "kernel_passes.h"
#ifdef __SUBSURFACE__
# include "kernel_subsurface.h"
#endif
#ifdef __VOLUME__
# include "kernel_volume.h"
#endif
#include "kernel_path_state.h"
#include "kernel_shadow.h"
#include "kernel_emission.h"
#include "kernel_path_common.h"
#include "kernel_path_surface.h"
#include "kernel_path_volume.h"
#ifdef __KERNEL_DEBUG__
# include "kernel_debug.h"
#endif
CCL_NAMESPACE_BEGIN
ccl_device_noinline void kernel_path_ao(KernelGlobals *kg,
ShaderData *sd,
ShaderData *emission_sd,
PathRadiance *L,
PathState *state,
RNG *rng,
float3 throughput,
float3 ao_alpha)
{
/* todo: solve correlation */
float bsdf_u, bsdf_v;
path_state_rng_2D(kg, rng, state, PRNG_BSDF_U, &bsdf_u, &bsdf_v);
float ao_factor = kernel_data.background.ao_factor;
float3 ao_N;
float3 ao_bsdf = shader_bsdf_ao(kg, sd, ao_factor, &ao_N);
float3 ao_D;
float ao_pdf;
sample_cos_hemisphere(ao_N, bsdf_u, bsdf_v, &ao_D, &ao_pdf);
if(dot(ccl_fetch(sd, Ng), ao_D) > 0.0f && ao_pdf != 0.0f) {
Ray light_ray;
float3 ao_shadow;
light_ray.P = ray_offset(ccl_fetch(sd, P), ccl_fetch(sd, Ng));
light_ray.D = ao_D;
light_ray.t = kernel_data.background.ao_distance;
#ifdef __OBJECT_MOTION__
light_ray.time = ccl_fetch(sd, time);
#endif /* __OBJECT_MOTION__ */
light_ray.dP = ccl_fetch(sd, dP);
light_ray.dD = differential3_zero();
if(!shadow_blocked(kg, emission_sd, state, &light_ray, &ao_shadow)) {
path_radiance_accum_ao(L, throughput, ao_alpha, ao_bsdf, ao_shadow, state->bounce);
}
}
}
ccl_device void kernel_path_indirect(KernelGlobals *kg,
ShaderData *sd,
ShaderData *emission_sd,
RNG *rng,
Ray *ray,
float3 throughput,
int num_samples,
PathState *state,
PathRadiance *L)
{
/* path iteration */
for(;;) {
/* intersect scene */
Intersection isect;
uint visibility = path_state_ray_visibility(kg, state);
bool hit = scene_intersect(kg,
*ray,
visibility,
&isect,
NULL,
0.0f, 0.0f);
#ifdef __LAMP_MIS__
if(kernel_data.integrator.use_lamp_mis && !(state->flag & PATH_RAY_CAMERA)) {
/* ray starting from previous non-transparent bounce */
Ray light_ray;
light_ray.P = ray->P - state->ray_t*ray->D;
state->ray_t += isect.t;
light_ray.D = ray->D;
light_ray.t = state->ray_t;
light_ray.time = ray->time;
light_ray.dD = ray->dD;
light_ray.dP = ray->dP;
/* intersect with lamp */
float3 emission;
if(indirect_lamp_emission(kg, emission_sd, state, &light_ray, &emission)) {
path_radiance_accum_emission(L,
throughput,
emission,
state->bounce);
}
}
#endif /* __LAMP_MIS__ */
#ifdef __VOLUME__
/* Sanitize volume stack. */
if(!hit) {
kernel_volume_clean_stack(kg, state->volume_stack);
}
/* volume attenuation, emission, scatter */
if(state->volume_stack[0].shader != SHADER_NONE) {
Ray volume_ray = *ray;
volume_ray.t = (hit)? isect.t: FLT_MAX;
bool heterogeneous =
volume_stack_is_heterogeneous(kg,
state->volume_stack);
# ifdef __VOLUME_DECOUPLED__
int sampling_method =
volume_stack_sampling_method(kg,
state->volume_stack);
bool decoupled = kernel_volume_use_decoupled(kg, heterogeneous, false, sampling_method);
if(decoupled) {
/* cache steps along volume for repeated sampling */
VolumeSegment volume_segment;
shader_setup_from_volume(kg,
sd,
&volume_ray);
kernel_volume_decoupled_record(kg,
state,
&volume_ray,
sd,
&volume_segment,
heterogeneous);
volume_segment.sampling_method = sampling_method;
/* emission */
if(volume_segment.closure_flag & SD_EMISSION) {
path_radiance_accum_emission(L,
throughput,
volume_segment.accum_emission,
state->bounce);
}
/* scattering */
VolumeIntegrateResult result = VOLUME_PATH_ATTENUATED;
if(volume_segment.closure_flag & SD_SCATTER) {
int all = kernel_data.integrator.sample_all_lights_indirect;
/* direct light sampling */
kernel_branched_path_volume_connect_light(kg,
rng,
sd,
emission_sd,
throughput,
state,
L,
all,
&volume_ray,
&volume_segment);
/* indirect sample. if we use distance sampling and take just
* one sample for direct and indirect light, we could share
* this computation, but makes code a bit complex */
float rphase = path_state_rng_1D_for_decision(kg, rng, state, PRNG_PHASE);
float rscatter = path_state_rng_1D_for_decision(kg, rng, state, PRNG_SCATTER_DISTANCE);
result = kernel_volume_decoupled_scatter(kg,
state,
&volume_ray,
sd,
&throughput,
rphase,
rscatter,
&volume_segment,
NULL,
true);
}
/* free cached steps */
kernel_volume_decoupled_free(kg, &volume_segment);
if(result == VOLUME_PATH_SCATTERED) {
if(kernel_path_volume_bounce(kg,
rng,
sd,
&throughput,
state,
L,
ray))
{
continue;
}
else {
break;
}
}
else {
throughput *= volume_segment.accum_transmittance;
}
}
else
# endif /* __VOLUME_DECOUPLED__ */
{
/* integrate along volume segment with distance sampling */
VolumeIntegrateResult result = kernel_volume_integrate(
kg, state, sd, &volume_ray, L, &throughput, rng, heterogeneous);
# ifdef __VOLUME_SCATTER__
if(result == VOLUME_PATH_SCATTERED) {
/* direct lighting */
kernel_path_volume_connect_light(kg,
rng,
sd,
emission_sd,
throughput,
state,
L);
/* indirect light bounce */
if(kernel_path_volume_bounce(kg,
rng,
sd,
&throughput,
state,
L,
ray))
{
continue;
}
else {
break;
}
}
# endif /* __VOLUME_SCATTER__ */
}
}
#endif /* __VOLUME__ */
if(!hit) {
#ifdef __BACKGROUND__
/* sample background shader */
float3 L_background = indirect_background(kg, emission_sd, state, ray);
path_radiance_accum_background(L,
throughput,
L_background,
state->bounce);
#endif /* __BACKGROUND__ */
break;
}
/* setup shading */
shader_setup_from_ray(kg,
sd,
&isect,
ray);
float rbsdf = path_state_rng_1D_for_decision(kg, rng, state, PRNG_BSDF);
shader_eval_surface(kg, sd, rng, state, rbsdf, state->flag, SHADER_CONTEXT_INDIRECT);
#ifdef __BRANCHED_PATH__
shader_merge_closures(sd);
#endif /* __BRANCHED_PATH__ */
/* blurring of bsdf after bounces, for rays that have a small likelihood
* of following this particular path (diffuse, rough glossy) */
if(kernel_data.integrator.filter_glossy != FLT_MAX) {
float blur_pdf = kernel_data.integrator.filter_glossy*state->min_ray_pdf;
if(blur_pdf < 1.0f) {
float blur_roughness = sqrtf(1.0f - blur_pdf)*0.5f;
shader_bsdf_blur(kg, sd, blur_roughness);
}
}
#ifdef __EMISSION__
/* emission */
if(sd->flag & SD_EMISSION) {
float3 emission = indirect_primitive_emission(kg,
sd,
isect.t,
state->flag,
state->ray_pdf);
path_radiance_accum_emission(L, throughput, emission, state->bounce);
}
#endif /* __EMISSION__ */
/* path termination. this is a strange place to put the termination, it's
* mainly due to the mixed in MIS that we use. gives too many unneeded
* shader evaluations, only need emission if we are going to terminate */
float probability =
path_state_terminate_probability(kg,
state,
throughput*num_samples);
if(probability == 0.0f) {
break;
}
else if(probability != 1.0f) {
float terminate = path_state_rng_1D_for_decision(kg, rng, state, PRNG_TERMINATE);
if(terminate >= probability)
break;
throughput /= probability;
}
#ifdef __AO__
/* ambient occlusion */
if(kernel_data.integrator.use_ambient_occlusion || (sd->flag & SD_AO)) {
kernel_path_ao(kg, sd, emission_sd, L, state, rng, throughput, make_float3(0.0f, 0.0f, 0.0f));
}
#endif /* __AO__ */
#ifdef __SUBSURFACE__
/* bssrdf scatter to a different location on the same object, replacing
* the closures with a diffuse BSDF */
if(sd->flag & SD_BSSRDF) {
float bssrdf_probability;
ShaderClosure *sc = subsurface_scatter_pick_closure(kg, sd, &bssrdf_probability);
/* modify throughput for picking bssrdf or bsdf */
throughput *= bssrdf_probability;
/* do bssrdf scatter step if we picked a bssrdf closure */
if(sc) {
uint lcg_state = lcg_state_init(rng, state, 0x68bc21eb);
float bssrdf_u, bssrdf_v;
path_state_rng_2D(kg,
rng,
state,
PRNG_BSDF_U,
&bssrdf_u, &bssrdf_v);
subsurface_scatter_step(kg,
sd,
state,
state->flag,
sc,
&lcg_state,
bssrdf_u, bssrdf_v,
false);
}
}
#endif /* __SUBSURFACE__ */
#if defined(__EMISSION__) && defined(__BRANCHED_PATH__)
if(kernel_data.integrator.use_direct_light) {
int all = kernel_data.integrator.sample_all_lights_indirect;
kernel_branched_path_surface_connect_light(kg,
rng,
sd,
emission_sd,
state,
throughput,
1.0f,
L,
all);
}
#endif /* defined(__EMISSION__) && defined(__BRANCHED_PATH__) */
if(!kernel_path_surface_bounce(kg, rng, sd, &throughput, state, L, ray))
break;
}
}
#ifdef __SUBSURFACE__
# ifndef __KERNEL_CUDA__
ccl_device
# else
ccl_device_inline
# endif
bool kernel_path_subsurface_scatter(
KernelGlobals *kg,
ShaderData *sd,
ShaderData *emission_sd,
PathRadiance *L,
PathState *state,
RNG *rng,
Ray *ray,
float3 *throughput,
SubsurfaceIndirectRays *ss_indirect)
{
float bssrdf_probability;
ShaderClosure *sc = subsurface_scatter_pick_closure(kg, sd, &bssrdf_probability);
/* modify throughput for picking bssrdf or bsdf */
*throughput *= bssrdf_probability;
/* do bssrdf scatter step if we picked a bssrdf closure */
if(sc) {
/* We should never have two consecutive BSSRDF bounces,
* the second one should be converted to a diffuse BSDF to
* avoid this.
*/
kernel_assert(!ss_indirect->tracing);
uint lcg_state = lcg_state_init(rng, state, 0x68bc21eb);
SubsurfaceIntersection ss_isect;
float bssrdf_u, bssrdf_v;
path_state_rng_2D(kg, rng, state, PRNG_BSDF_U, &bssrdf_u, &bssrdf_v);
int num_hits = subsurface_scatter_multi_intersect(kg,
&ss_isect,
sd,
sc,
&lcg_state,
bssrdf_u, bssrdf_v,
false);
# ifdef __VOLUME__
ss_indirect->need_update_volume_stack =
kernel_data.integrator.use_volumes &&
ccl_fetch(sd, flag) & SD_OBJECT_INTERSECTS_VOLUME;
# endif /* __VOLUME__ */
/* compute lighting with the BSDF closure */
for(int hit = 0; hit < num_hits; hit++) {
/* NOTE: We reuse the existing ShaderData, we assume the path
* integration loop stops when this function returns true.
*/
subsurface_scatter_multi_setup(kg,
&ss_isect,
hit,
sd,
state,
state->flag,
sc,
false);
PathState *hit_state = &ss_indirect->state[ss_indirect->num_rays];
Ray *hit_ray = &ss_indirect->rays[ss_indirect->num_rays];
float3 *hit_tp = &ss_indirect->throughputs[ss_indirect->num_rays];
PathRadiance *hit_L = &ss_indirect->L[ss_indirect->num_rays];
*hit_state = *state;
*hit_ray = *ray;
*hit_tp = *throughput;
hit_state->rng_offset += PRNG_BOUNCE_NUM;
path_radiance_init(hit_L, kernel_data.film.use_light_pass);
hit_L->direct_throughput = L->direct_throughput;
path_radiance_copy_indirect(hit_L, L);
kernel_path_surface_connect_light(kg, rng, sd, emission_sd, *hit_tp, state, hit_L);
if(kernel_path_surface_bounce(kg,
rng,
sd,
hit_tp,
hit_state,
hit_L,
hit_ray))
{
# ifdef __LAMP_MIS__
hit_state->ray_t = 0.0f;
# endif /* __LAMP_MIS__ */
# ifdef __VOLUME__
if(ss_indirect->need_update_volume_stack) {
Ray volume_ray = *ray;
/* Setup ray from previous surface point to the new one. */
volume_ray.D = normalize_len(hit_ray->P - volume_ray.P,
&volume_ray.t);
kernel_volume_stack_update_for_subsurface(
kg,
emission_sd,
&volume_ray,
hit_state->volume_stack);
}
# endif /* __VOLUME__ */
path_radiance_reset_indirect(L);
ss_indirect->num_rays++;
}
else {
path_radiance_accum_sample(L, hit_L, 1);
}
}
return true;
}
return false;
}
ccl_device_inline void kernel_path_subsurface_init_indirect(
SubsurfaceIndirectRays *ss_indirect)
{
ss_indirect->tracing = false;
ss_indirect->num_rays = 0;
}
ccl_device void kernel_path_subsurface_accum_indirect(
SubsurfaceIndirectRays *ss_indirect,
PathRadiance *L)
{
if(ss_indirect->tracing) {
path_radiance_sum_indirect(L);
path_radiance_accum_sample(&ss_indirect->direct_L, L, 1);
if(ss_indirect->num_rays == 0) {
*L = ss_indirect->direct_L;
}
}
}
ccl_device void kernel_path_subsurface_setup_indirect(
KernelGlobals *kg,
SubsurfaceIndirectRays *ss_indirect,
PathState *state,
Ray *ray,
PathRadiance *L,
float3 *throughput)
{
if(!ss_indirect->tracing) {
ss_indirect->direct_L = *L;
}
ss_indirect->tracing = true;
/* Setup state, ray and throughput for indirect SSS rays. */
ss_indirect->num_rays--;
Ray *indirect_ray = &ss_indirect->rays[ss_indirect->num_rays];
PathRadiance *indirect_L = &ss_indirect->L[ss_indirect->num_rays];
*state = ss_indirect->state[ss_indirect->num_rays];
*ray = *indirect_ray;
*L = *indirect_L;
*throughput = ss_indirect->throughputs[ss_indirect->num_rays];
state->rng_offset += ss_indirect->num_rays * PRNG_BOUNCE_NUM;
}
#endif /* __SUBSURFACE__ */
ccl_device_inline float4 kernel_path_integrate(KernelGlobals *kg,
RNG *rng,
int sample,
Ray ray,
ccl_global float *buffer)
{
/* initialize */
PathRadiance L;
float3 throughput = make_float3(1.0f, 1.0f, 1.0f);
float L_transparent = 0.0f;
path_radiance_init(&L, kernel_data.film.use_light_pass);
/* shader data memory used for both volumes and surfaces, saves stack space */
ShaderData sd;
/* shader data used by emission, shadows, volume stacks */
ShaderData emission_sd;
PathState state;
path_state_init(kg, &emission_sd, &state, rng, sample, &ray);
#ifdef __KERNEL_DEBUG__
DebugData debug_data;
debug_data_init(&debug_data);
#endif /* __KERNEL_DEBUG__ */
#ifdef __SUBSURFACE__
SubsurfaceIndirectRays ss_indirect;
kernel_path_subsurface_init_indirect(&ss_indirect);
for(;;) {
#endif /* __SUBSURFACE__ */
/* path iteration */
for(;;) {
/* intersect scene */
Intersection isect;
uint visibility = path_state_ray_visibility(kg, &state);
#ifdef __HAIR__
float difl = 0.0f, extmax = 0.0f;
uint lcg_state = 0;
if(kernel_data.bvh.have_curves) {
if((kernel_data.cam.resolution == 1) && (state.flag & PATH_RAY_CAMERA)) {
float3 pixdiff = ray.dD.dx + ray.dD.dy;
/*pixdiff = pixdiff - dot(pixdiff, ray.D)*ray.D;*/
difl = kernel_data.curve.minimum_width * len(pixdiff) * 0.5f;
}
extmax = kernel_data.curve.maximum_width;
lcg_state = lcg_state_init(rng, &state, 0x51633e2d);
}
bool hit = scene_intersect(kg, ray, visibility, &isect, &lcg_state, difl, extmax);
#else
bool hit = scene_intersect(kg, ray, visibility, &isect, NULL, 0.0f, 0.0f);
#endif /* __HAIR__ */
#ifdef __KERNEL_DEBUG__
if(state.flag & PATH_RAY_CAMERA) {
debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
debug_data.num_bvh_traversed_instances += isect.num_traversed_instances;
}
debug_data.num_ray_bounces++;
#endif /* __KERNEL_DEBUG__ */
#ifdef __LAMP_MIS__
if(kernel_data.integrator.use_lamp_mis && !(state.flag & PATH_RAY_CAMERA)) {
/* ray starting from previous non-transparent bounce */
Ray light_ray;
light_ray.P = ray.P - state.ray_t*ray.D;
state.ray_t += isect.t;
light_ray.D = ray.D;
light_ray.t = state.ray_t;
light_ray.time = ray.time;
light_ray.dD = ray.dD;
light_ray.dP = ray.dP;
/* intersect with lamp */
float3 emission;
if(indirect_lamp_emission(kg, &emission_sd, &state, &light_ray, &emission))
path_radiance_accum_emission(&L, throughput, emission, state.bounce);
}
#endif /* __LAMP_MIS__ */
#ifdef __VOLUME__
/* Sanitize volume stack. */
if(!hit) {
kernel_volume_clean_stack(kg, state.volume_stack);
}
/* volume attenuation, emission, scatter */
if(state.volume_stack[0].shader != SHADER_NONE) {
Ray volume_ray = ray;
volume_ray.t = (hit)? isect.t: FLT_MAX;
bool heterogeneous = volume_stack_is_heterogeneous(kg, state.volume_stack);
# ifdef __VOLUME_DECOUPLED__
int sampling_method = volume_stack_sampling_method(kg, state.volume_stack);
bool decoupled = kernel_volume_use_decoupled(kg, heterogeneous, true, sampling_method);
if(decoupled) {
/* cache steps along volume for repeated sampling */
VolumeSegment volume_segment;
shader_setup_from_volume(kg, &sd, &volume_ray);
kernel_volume_decoupled_record(kg, &state,
&volume_ray, &sd, &volume_segment, heterogeneous);
volume_segment.sampling_method = sampling_method;
/* emission */
if(volume_segment.closure_flag & SD_EMISSION)
path_radiance_accum_emission(&L, throughput, volume_segment.accum_emission, state.bounce);
/* scattering */
VolumeIntegrateResult result = VOLUME_PATH_ATTENUATED;
if(volume_segment.closure_flag & SD_SCATTER) {
int all = false;
/* direct light sampling */
kernel_branched_path_volume_connect_light(kg, rng, &sd,
&emission_sd, throughput, &state, &L, all,
&volume_ray, &volume_segment);
/* indirect sample. if we use distance sampling and take just
* one sample for direct and indirect light, we could share
* this computation, but makes code a bit complex */
float rphase = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_PHASE);
float rscatter = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_SCATTER_DISTANCE);
result = kernel_volume_decoupled_scatter(kg,
&state, &volume_ray, &sd, &throughput,
rphase, rscatter, &volume_segment, NULL, true);
}
/* free cached steps */
kernel_volume_decoupled_free(kg, &volume_segment);
if(result == VOLUME_PATH_SCATTERED) {
if(kernel_path_volume_bounce(kg, rng, &sd, &throughput, &state, &L, &ray))
continue;
else
break;
}
else {
throughput *= volume_segment.accum_transmittance;
}
}
else
# endif /* __VOLUME_DECOUPLED__ */
{
/* integrate along volume segment with distance sampling */
VolumeIntegrateResult result = kernel_volume_integrate(
kg, &state, &sd, &volume_ray, &L, &throughput, rng, heterogeneous);
# ifdef __VOLUME_SCATTER__
if(result == VOLUME_PATH_SCATTERED) {
/* direct lighting */
kernel_path_volume_connect_light(kg, rng, &sd, &emission_sd, throughput, &state, &L);
/* indirect light bounce */
if(kernel_path_volume_bounce(kg, rng, &sd, &throughput, &state, &L, &ray))
continue;
else
break;
}
# endif /* __VOLUME_SCATTER__ */
}
}
#endif /* __VOLUME__ */
if(!hit) {
/* eval background shader if nothing hit */
if(kernel_data.background.transparent && (state.flag & PATH_RAY_CAMERA)) {
L_transparent += average(throughput);
#ifdef __PASSES__
if(!(kernel_data.film.pass_flag & PASS_BACKGROUND))
#endif /* __PASSES__ */
break;
}
#ifdef __BACKGROUND__
/* sample background shader */
float3 L_background = indirect_background(kg, &emission_sd, &state, &ray);
path_radiance_accum_background(&L, throughput, L_background, state.bounce);
#endif /* __BACKGROUND__ */
break;
}
/* setup shading */
shader_setup_from_ray(kg, &sd, &isect, &ray);
float rbsdf = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_BSDF);
shader_eval_surface(kg, &sd, rng, &state, rbsdf, state.flag, SHADER_CONTEXT_MAIN);
/* holdout */
#ifdef __HOLDOUT__
if((sd.flag & (SD_HOLDOUT|SD_HOLDOUT_MASK)) && (state.flag & PATH_RAY_CAMERA)) {
if(kernel_data.background.transparent) {
float3 holdout_weight;
if(sd.flag & SD_HOLDOUT_MASK)
holdout_weight = make_float3(1.0f, 1.0f, 1.0f);
else
holdout_weight = shader_holdout_eval(kg, &sd);
/* any throughput is ok, should all be identical here */
L_transparent += average(holdout_weight*throughput);
}
if(sd.flag & SD_HOLDOUT_MASK)
break;
}
#endif /* __HOLDOUT__ */
/* holdout mask objects do not write data passes */
kernel_write_data_passes(kg, buffer, &L, &sd, sample, &state, throughput);
/* blurring of bsdf after bounces, for rays that have a small likelihood
* of following this particular path (diffuse, rough glossy) */
if(kernel_data.integrator.filter_glossy != FLT_MAX) {
float blur_pdf = kernel_data.integrator.filter_glossy*state.min_ray_pdf;
if(blur_pdf < 1.0f) {
float blur_roughness = sqrtf(1.0f - blur_pdf)*0.5f;
shader_bsdf_blur(kg, &sd, blur_roughness);
}
}
#ifdef __EMISSION__
/* emission */
if(sd.flag & SD_EMISSION) {
/* todo: is isect.t wrong here for transparent surfaces? */
float3 emission = indirect_primitive_emission(kg, &sd, isect.t, state.flag, state.ray_pdf);
path_radiance_accum_emission(&L, throughput, emission, state.bounce);
}
#endif /* __EMISSION__ */
/* path termination. this is a strange place to put the termination, it's
* mainly due to the mixed in MIS that we use. gives too many unneeded
* shader evaluations, only need emission if we are going to terminate */
float probability = path_state_terminate_probability(kg, &state, throughput);
if(probability == 0.0f) {
break;
}
else if(probability != 1.0f) {
float terminate = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_TERMINATE);
if(terminate >= probability)
break;
throughput /= probability;
}
#ifdef __AO__
/* ambient occlusion */
if(kernel_data.integrator.use_ambient_occlusion || (sd.flag & SD_AO)) {
kernel_path_ao(kg, &sd, &emission_sd, &L, &state, rng, throughput, shader_bsdf_alpha(kg, &sd));
}
#endif /* __AO__ */
#ifdef __SUBSURFACE__
/* bssrdf scatter to a different location on the same object, replacing
* the closures with a diffuse BSDF */
if(sd.flag & SD_BSSRDF) {
if(kernel_path_subsurface_scatter(kg,
&sd,
&emission_sd,
&L,
&state,
rng,
&ray,
&throughput,
&ss_indirect))
{
break;
}
}
#endif /* __SUBSURFACE__ */
/* direct lighting */
kernel_path_surface_connect_light(kg, rng, &sd, &emission_sd, throughput, &state, &L);
/* compute direct lighting and next bounce */
if(!kernel_path_surface_bounce(kg, rng, &sd, &throughput, &state, &L, &ray))
break;
}
#ifdef __SUBSURFACE__
kernel_path_subsurface_accum_indirect(&ss_indirect, &L);
/* Trace indirect subsurface rays by restarting the loop. this uses less
* stack memory than invoking kernel_path_indirect.
*/
if(ss_indirect.num_rays) {
kernel_path_subsurface_setup_indirect(kg,
&ss_indirect,
&state,
&ray,
&L,
&throughput);
}
else {
break;
}
}
#endif /* __SUBSURFACE__ */
float3 L_sum = path_radiance_clamp_and_sum(kg, &L);
kernel_write_light_passes(kg, buffer, &L, sample);
#ifdef __KERNEL_DEBUG__
kernel_write_debug_passes(kg, buffer, &state, &debug_data, sample);
#endif /* __KERNEL_DEBUG__ */
return make_float4(L_sum.x, L_sum.y, L_sum.z, 1.0f - L_transparent);
}
ccl_device void kernel_path_trace(KernelGlobals *kg,
ccl_global float *buffer, ccl_global uint *rng_state,
int sample, int x, int y, int offset, int stride)
{
/* buffer offset */
int index = offset + x + y*stride;
int pass_stride = kernel_data.film.pass_stride;
rng_state += index;
buffer += index*pass_stride;
/* initialize random numbers and ray */
RNG rng;
Ray ray;
kernel_path_trace_setup(kg, rng_state, sample, x, y, &rng, &ray);
/* integrate */
float4 L;
if(ray.t != 0.0f)
L = kernel_path_integrate(kg, &rng, sample, ray, buffer);
else
L = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
/* accumulate result in output buffer */
kernel_write_pass_float4(buffer, sample, L);
path_rng_end(kg, rng_state, rng);
}
CCL_NAMESPACE_END
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