blender/intern/cycles/kernel/kernel_path.h
Sergey Sharybin 25f33e058a Fix T43562: Cycles gets stuck with camera in volume in certain setup
The issue was caused by the way how we shoot the ray to see which rays we're
inside which might start bouncing back-n-forth between two close to parallel
intersecting faces.

Real solution would be to record all the intersections when shooting the ray,
but it's kinda tricky on GPU because of needed sorting and uncertainty of
how huge intersection array should be.

For now we'll just limit number of steps in the check so in worst case we'll
have some samples not being correct which will be compensated with further
sampling. Shouldn't be an issue since probability of such a lock is quite
small actually.
2015-02-05 16:10:50 +05:00

1270 lines
38 KiB
C

/*
* 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 "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_surface.h"
#include "kernel_path_volume.h"
#ifdef __KERNEL_DEBUG__
#include "kernel_debug.h"
#endif
CCL_NAMESPACE_BEGIN
ccl_device void kernel_path_indirect(KernelGlobals *kg, 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, &state, &light_ray, &emission))
path_radiance_accum_emission(L, throughput, emission, state.bounce);
}
#endif
#ifdef __VOLUME__
/* 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;
ShaderData volume_sd;
shader_setup_from_volume(kg, &volume_sd, &volume_ray, state.bounce, state.transparent_bounce);
kernel_volume_decoupled_record(kg, &state,
&volume_ray, &volume_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) {
bool all = kernel_data.integrator.sample_all_lights_indirect;
/* direct light sampling */
kernel_branched_path_volume_connect_light(kg, rng, &volume_sd,
throughput, &state, L, 1.0f, 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, &volume_sd, &throughput,
rphase, rscatter, &volume_segment, NULL, true);
}
if(result != VOLUME_PATH_SCATTERED)
throughput *= volume_segment.accum_transmittance;
/* free cached steps */
kernel_volume_decoupled_free(kg, &volume_segment);
if(result == VOLUME_PATH_SCATTERED) {
if(kernel_path_volume_bounce(kg, rng, &volume_sd, &throughput, &state, L, &ray))
continue;
else
break;
}
}
else
#endif
{
/* integrate along volume segment with distance sampling */
ShaderData volume_sd;
VolumeIntegrateResult result = kernel_volume_integrate(
kg, &state, &volume_sd, &volume_ray, L, &throughput, rng, heterogeneous);
#ifdef __VOLUME_SCATTER__
if(result == VOLUME_PATH_SCATTERED) {
/* direct lighting */
kernel_path_volume_connect_light(kg, rng, &volume_sd, throughput, &state, L);
/* indirect light bounce */
if(kernel_path_volume_bounce(kg, rng, &volume_sd, &throughput, &state, L, &ray))
continue;
else
break;
}
#endif
}
}
#endif
if(!hit) {
#ifdef __BACKGROUND__
/* sample background shader */
float3 L_background = indirect_background(kg, &state, &ray);
path_radiance_accum_background(L, throughput, L_background, state.bounce);
#endif
break;
}
/* setup shading */
ShaderData sd;
shader_setup_from_ray(kg, &sd, &isect, &ray, state.bounce, state.transparent_bounce);
float rbsdf = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_BSDF);
shader_eval_surface(kg, &sd, rbsdf, state.flag, SHADER_CONTEXT_INDIRECT);
#ifdef __BRANCHED_PATH__
shader_merge_closures(&sd);
#endif
/* 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
/* 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)) {
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;
float3 ao_alpha = make_float3(0.0f, 0.0f, 0.0f);
sample_cos_hemisphere(ao_N, bsdf_u, bsdf_v, &ao_D, &ao_pdf);
if(dot(sd.Ng, ao_D) > 0.0f && ao_pdf != 0.0f) {
Ray light_ray;
float3 ao_shadow;
light_ray.P = ray_offset(sd.P, sd.Ng);
light_ray.D = ao_D;
light_ray.t = kernel_data.background.ao_distance;
#ifdef __OBJECT_MOTION__
light_ray.time = sd.time;
#endif
light_ray.dP = sd.dP;
light_ray.dD = differential3_zero();
if(!shadow_blocked(kg, &state, &light_ray, &ao_shadow))
path_radiance_accum_ao(L, throughput, ao_alpha, ao_bsdf, ao_shadow, state.bounce);
}
}
#endif
#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.flag, sc, &lcg_state, bssrdf_u, bssrdf_v, false);
state.flag |= PATH_RAY_BSSRDF_ANCESTOR;
}
}
#endif
#if defined(__EMISSION__) && defined(__BRANCHED_PATH__)
if(kernel_data.integrator.use_direct_light) {
bool all = kernel_data.integrator.sample_all_lights_indirect;
kernel_branched_path_surface_connect_light(kg, rng, &sd, &state, throughput, 1.0f, L, all);
}
#endif
if(!kernel_path_surface_bounce(kg, rng, &sd, &throughput, &state, L, &ray))
break;
}
}
ccl_device void kernel_path_ao(KernelGlobals *kg, ShaderData *sd, PathRadiance *L, PathState *state, RNG *rng, float3 throughput)
{
/* 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;
float3 ao_alpha = shader_bsdf_alpha(kg, sd);
sample_cos_hemisphere(ao_N, bsdf_u, bsdf_v, &ao_D, &ao_pdf);
if(dot(sd->Ng, ao_D) > 0.0f && ao_pdf != 0.0f) {
Ray light_ray;
float3 ao_shadow;
light_ray.P = ray_offset(sd->P, sd->Ng);
light_ray.D = ao_D;
light_ray.t = kernel_data.background.ao_distance;
#ifdef __OBJECT_MOTION__
light_ray.time = sd->time;
#endif
light_ray.dP = sd->dP;
light_ray.dD = differential3_zero();
if(!shadow_blocked(kg, state, &light_ray, &ao_shadow))
path_radiance_accum_ao(L, throughput, ao_alpha, ao_bsdf, ao_shadow, state->bounce);
}
}
ccl_device void kernel_branched_path_ao(KernelGlobals *kg, ShaderData *sd, PathRadiance *L, PathState *state, RNG *rng, float3 throughput)
{
int num_samples = kernel_data.integrator.ao_samples;
float num_samples_inv = 1.0f/num_samples;
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_alpha = shader_bsdf_alpha(kg, sd);
for(int j = 0; j < num_samples; j++) {
float bsdf_u, bsdf_v;
path_branched_rng_2D(kg, rng, state, j, num_samples, PRNG_BSDF_U, &bsdf_u, &bsdf_v);
float3 ao_D;
float ao_pdf;
sample_cos_hemisphere(ao_N, bsdf_u, bsdf_v, &ao_D, &ao_pdf);
if(dot(sd->Ng, ao_D) > 0.0f && ao_pdf != 0.0f) {
Ray light_ray;
float3 ao_shadow;
light_ray.P = ray_offset(sd->P, sd->Ng);
light_ray.D = ao_D;
light_ray.t = kernel_data.background.ao_distance;
#ifdef __OBJECT_MOTION__
light_ray.time = sd->time;
#endif
light_ray.dP = sd->dP;
light_ray.dD = differential3_zero();
if(!shadow_blocked(kg, state, &light_ray, &ao_shadow))
path_radiance_accum_ao(L, throughput*num_samples_inv, ao_alpha, ao_bsdf, ao_shadow, state->bounce);
}
}
}
#ifdef __SUBSURFACE__
#ifdef __VOLUME__
ccl_device void kernel_path_subsurface_update_volume_stack(KernelGlobals *kg,
Ray *ray,
VolumeStack *stack)
{
kernel_assert(kernel_data.integrator.use_volumes);
Ray volume_ray = *ray;
Intersection isect;
int step = 0;
while(step < VOLUME_STACK_SIZE &&
scene_intersect_volume(kg, &volume_ray, &isect))
{
ShaderData sd;
shader_setup_from_ray(kg, &sd, &isect, &volume_ray, 0, 0);
kernel_volume_stack_enter_exit(kg, &sd, stack);
/* Move ray forward. */
volume_ray.P = ray_offset(sd.P, -sd.Ng);
volume_ray.t -= sd.ray_length;
++step;
}
}
#endif
ccl_device bool kernel_path_subsurface_scatter(KernelGlobals *kg, ShaderData *sd, PathRadiance *L, PathState *state, RNG *rng, Ray *ray, float3 *throughput)
{
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);
ShaderData bssrdf_sd[BSSRDF_MAX_HITS];
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_step(kg, sd, bssrdf_sd, state->flag, sc, &lcg_state, bssrdf_u, bssrdf_v, false);
#ifdef __VOLUME__
Ray volume_ray = *ray;
bool need_update_volume_stack = kernel_data.integrator.use_volumes &&
sd->flag & SD_OBJECT_INTERSECTS_VOLUME;
#endif
/* compute lighting with the BSDF closure */
for(int hit = 0; hit < num_hits; hit++) {
float3 tp = *throughput;
PathState hit_state = *state;
Ray hit_ray = *ray;
hit_state.flag |= PATH_RAY_BSSRDF_ANCESTOR;
hit_state.rng_offset += PRNG_BOUNCE_NUM;
kernel_path_surface_connect_light(kg, rng, &bssrdf_sd[hit], tp, state, L);
if(kernel_path_surface_bounce(kg, rng, &bssrdf_sd[hit], &tp, &hit_state, L, &hit_ray)) {
#ifdef __LAMP_MIS__
hit_state.ray_t = 0.0f;
#endif
#ifdef __VOLUME__
if(need_update_volume_stack) {
/* 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_path_subsurface_update_volume_stack(
kg,
&volume_ray,
hit_state.volume_stack);
/* Move volume ray forward. */
volume_ray.P = hit_ray.P;
}
#endif
kernel_path_indirect(kg, rng, hit_ray, tp, state->num_samples, hit_state, L);
/* for render passes, sum and reset indirect light pass variables
* for the next samples */
path_radiance_sum_indirect(L);
path_radiance_reset_indirect(L);
}
}
return true;
}
return false;
}
#endif
ccl_device 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);
PathState state;
path_state_init(kg, &state, rng, sample, &ray);
#ifdef __KERNEL_DEBUG__
DebugData debug_data;
debug_data_init(&debug_data);
#endif
/* 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
#ifdef __KERNEL_DEBUG__
if(state.flag & PATH_RAY_CAMERA) {
debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
}
#endif
#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, &state, &light_ray, &emission))
path_radiance_accum_emission(&L, throughput, emission, state.bounce);
}
#endif
#ifdef __VOLUME__
/* 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;
ShaderData volume_sd;
shader_setup_from_volume(kg, &volume_sd, &volume_ray, state.bounce, state.transparent_bounce);
kernel_volume_decoupled_record(kg, &state,
&volume_ray, &volume_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) {
bool all = false;
/* direct light sampling */
kernel_branched_path_volume_connect_light(kg, rng, &volume_sd,
throughput, &state, &L, 1.0f, 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, &volume_sd, &throughput,
rphase, rscatter, &volume_segment, NULL, true);
}
if(result != VOLUME_PATH_SCATTERED)
throughput *= volume_segment.accum_transmittance;
/* free cached steps */
kernel_volume_decoupled_free(kg, &volume_segment);
if(result == VOLUME_PATH_SCATTERED) {
if(kernel_path_volume_bounce(kg, rng, &volume_sd, &throughput, &state, &L, &ray))
continue;
else
break;
}
}
else
#endif
{
/* integrate along volume segment with distance sampling */
ShaderData volume_sd;
VolumeIntegrateResult result = kernel_volume_integrate(
kg, &state, &volume_sd, &volume_ray, &L, &throughput, rng, heterogeneous);
#ifdef __VOLUME_SCATTER__
if(result == VOLUME_PATH_SCATTERED) {
/* direct lighting */
kernel_path_volume_connect_light(kg, rng, &volume_sd, throughput, &state, &L);
/* indirect light bounce */
if(kernel_path_volume_bounce(kg, rng, &volume_sd, &throughput, &state, &L, &ray))
continue;
else
break;
}
#endif
}
}
#endif
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
break;
}
#ifdef __BACKGROUND__
/* sample background shader */
float3 L_background = indirect_background(kg, &state, &ray);
path_radiance_accum_background(&L, throughput, L_background, state.bounce);
#endif
break;
}
/* setup shading */
ShaderData sd;
shader_setup_from_ray(kg, &sd, &isect, &ray, state.bounce, state.transparent_bounce);
float rbsdf = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_BSDF);
shader_eval_surface(kg, &sd, 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 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
/* 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, &L, &state, rng, throughput);
}
#endif
#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, &L, &state, rng, &ray, &throughput))
break;
}
#endif
/* direct lighting */
kernel_path_surface_connect_light(kg, rng, &sd, throughput, &state, &L);
/* compute direct lighting and next bounce */
if(!kernel_path_surface_bounce(kg, rng, &sd, &throughput, &state, &L, &ray))
break;
}
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
return make_float4(L_sum.x, L_sum.y, L_sum.z, 1.0f - L_transparent);
}
#ifdef __BRANCHED_PATH__
/* branched path tracing: bounce off surface and integrate indirect light */
ccl_device_noinline void kernel_branched_path_surface_indirect_light(KernelGlobals *kg,
RNG *rng, ShaderData *sd, float3 throughput, float num_samples_adjust,
PathState *state, PathRadiance *L)
{
for(int i = 0; i< sd->num_closure; i++) {
const ShaderClosure *sc = &sd->closure[i];
if(!CLOSURE_IS_BSDF(sc->type))
continue;
/* transparency is not handled here, but in outer loop */
if(sc->type == CLOSURE_BSDF_TRANSPARENT_ID)
continue;
int num_samples;
if(CLOSURE_IS_BSDF_DIFFUSE(sc->type))
num_samples = kernel_data.integrator.diffuse_samples;
else if(CLOSURE_IS_BSDF_BSSRDF(sc->type))
num_samples = 1;
else if(CLOSURE_IS_BSDF_GLOSSY(sc->type))
num_samples = kernel_data.integrator.glossy_samples;
else
num_samples = kernel_data.integrator.transmission_samples;
num_samples = ceil_to_int(num_samples_adjust*num_samples);
float num_samples_inv = num_samples_adjust/num_samples;
RNG bsdf_rng = cmj_hash(*rng, i);
for(int j = 0; j < num_samples; j++) {
PathState ps = *state;
float3 tp = throughput;
Ray bsdf_ray;
if(!kernel_branched_path_surface_bounce(kg, &bsdf_rng, sd, sc, j, num_samples, &tp, &ps, L, &bsdf_ray))
continue;
kernel_path_indirect(kg, rng, bsdf_ray, tp*num_samples_inv, num_samples, ps, L);
/* for render passes, sum and reset indirect light pass variables
* for the next samples */
path_radiance_sum_indirect(L);
path_radiance_reset_indirect(L);
}
}
}
#ifdef __SUBSURFACE__
ccl_device void kernel_branched_path_subsurface_scatter(KernelGlobals *kg,
ShaderData *sd,
PathRadiance *L,
PathState *state,
RNG *rng,
Ray *ray,
float3 throughput)
{
for(int i = 0; i< sd->num_closure; i++) {
ShaderClosure *sc = &sd->closure[i];
if(!CLOSURE_IS_BSSRDF(sc->type))
continue;
/* set up random number generator */
uint lcg_state = lcg_state_init(rng, state, 0x68bc21eb);
int num_samples = kernel_data.integrator.subsurface_samples;
float num_samples_inv = 1.0f/num_samples;
RNG bssrdf_rng = cmj_hash(*rng, i);
state->flag |= PATH_RAY_BSSRDF_ANCESTOR;
/* do subsurface scatter step with copy of shader data, this will
* replace the BSSRDF with a diffuse BSDF closure */
for(int j = 0; j < num_samples; j++) {
ShaderData bssrdf_sd[BSSRDF_MAX_HITS];
float bssrdf_u, bssrdf_v;
path_branched_rng_2D(kg, &bssrdf_rng, state, j, num_samples, PRNG_BSDF_U, &bssrdf_u, &bssrdf_v);
int num_hits = subsurface_scatter_multi_step(kg, sd, bssrdf_sd, state->flag, sc, &lcg_state, bssrdf_u, bssrdf_v, true);
#ifdef __VOLUME__
Ray volume_ray = *ray;
bool need_update_volume_stack = kernel_data.integrator.use_volumes &&
sd->flag & SD_OBJECT_INTERSECTS_VOLUME;
#endif
/* compute lighting with the BSDF closure */
for(int hit = 0; hit < num_hits; hit++) {
PathState hit_state = *state;
path_state_branch(&hit_state, j, num_samples);
#ifdef __VOLUME__
if(need_update_volume_stack) {
/* Setup ray from previous surface point to the new one. */
float3 P = ray_offset(bssrdf_sd[hit].P, -bssrdf_sd[hit].Ng);
volume_ray.D = normalize_len(P - volume_ray.P,
&volume_ray.t);
kernel_path_subsurface_update_volume_stack(
kg,
&volume_ray,
hit_state.volume_stack);
/* Move volume ray forward. */
volume_ray.P = P;
}
#endif
#if defined(__EMISSION__) && defined(__BRANCHED_PATH__)
/* direct light */
if(kernel_data.integrator.use_direct_light) {
bool all = kernel_data.integrator.sample_all_lights_direct;
kernel_branched_path_surface_connect_light(kg, rng,
&bssrdf_sd[hit], &hit_state, throughput, num_samples_inv, L, all);
}
#endif
/* indirect light */
kernel_branched_path_surface_indirect_light(kg, rng,
&bssrdf_sd[hit], throughput, num_samples_inv,
&hit_state, L);
}
}
state->flag &= ~PATH_RAY_BSSRDF_ANCESTOR;
}
}
#endif
ccl_device float4 kernel_branched_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);
PathState state;
path_state_init(kg, &state, rng, sample, &ray);
#ifdef __KERNEL_DEBUG__
DebugData debug_data;
debug_data_init(&debug_data);
#endif
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
#ifdef __KERNEL_DEBUG__
if(state.flag & PATH_RAY_CAMERA) {
debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
}
#endif
#ifdef __VOLUME__
/* 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__
/* decoupled ray marching only supported on CPU */
/* cache steps along volume for repeated sampling */
VolumeSegment volume_segment;
ShaderData volume_sd;
shader_setup_from_volume(kg, &volume_sd, &volume_ray, state.bounce, state.transparent_bounce);
kernel_volume_decoupled_record(kg, &state,
&volume_ray, &volume_sd, &volume_segment, heterogeneous);
/* direct light sampling */
if(volume_segment.closure_flag & SD_SCATTER) {
volume_segment.sampling_method = volume_stack_sampling_method(kg, state.volume_stack);
bool all = kernel_data.integrator.sample_all_lights_direct;
kernel_branched_path_volume_connect_light(kg, rng, &volume_sd,
throughput, &state, &L, 1.0f, all, &volume_ray, &volume_segment);
/* indirect light sampling */
int num_samples = kernel_data.integrator.volume_samples;
float num_samples_inv = 1.0f/num_samples;
for(int j = 0; j < num_samples; j++) {
/* workaround to fix correlation bug in T38710, can find better solution
* in random number generator later, for now this is done here to not impact
* performance of rendering without volumes */
RNG tmp_rng = cmj_hash(*rng, state.rng_offset);
PathState ps = state;
Ray pray = ray;
float3 tp = throughput;
/* branch RNG state */
path_state_branch(&ps, j, num_samples);
/* scatter 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, &tmp_rng, &ps, PRNG_PHASE);
float rscatter = path_state_rng_1D_for_decision(kg, &tmp_rng, &ps, PRNG_SCATTER_DISTANCE);
VolumeIntegrateResult result = kernel_volume_decoupled_scatter(kg,
&ps, &pray, &volume_sd, &tp, rphase, rscatter, &volume_segment, NULL, false);
(void)result;
kernel_assert(result == VOLUME_PATH_SCATTERED);
if(kernel_path_volume_bounce(kg, rng, &volume_sd, &tp, &ps, &L, &pray)) {
kernel_path_indirect(kg, rng, pray, tp*num_samples_inv, num_samples, ps, &L);
/* for render passes, sum and reset indirect light pass variables
* for the next samples */
path_radiance_sum_indirect(&L);
path_radiance_reset_indirect(&L);
}
}
}
/* emission and transmittance */
if(volume_segment.closure_flag & SD_EMISSION)
path_radiance_accum_emission(&L, throughput, volume_segment.accum_emission, state.bounce);
throughput *= volume_segment.accum_transmittance;
/* free cached steps */
kernel_volume_decoupled_free(kg, &volume_segment);
#else
/* GPU: no decoupled ray marching, scatter probalistically */
int num_samples = kernel_data.integrator.volume_samples;
float num_samples_inv = 1.0f/num_samples;
/* todo: we should cache the shader evaluations from stepping
* through the volume, for now we redo them multiple times */
for(int j = 0; j < num_samples; j++) {
PathState ps = state;
Ray pray = ray;
ShaderData volume_sd;
float3 tp = throughput * num_samples_inv;
/* branch RNG state */
path_state_branch(&ps, j, num_samples);
VolumeIntegrateResult result = kernel_volume_integrate(
kg, &ps, &volume_sd, &volume_ray, &L, &tp, rng, heterogeneous);
#ifdef __VOLUME_SCATTER__
if(result == VOLUME_PATH_SCATTERED) {
/* todo: support equiangular, MIS and all light sampling.
* alternatively get decoupled ray marching working on the GPU */
kernel_path_volume_connect_light(kg, rng, &volume_sd, tp, &state, &L);
if(kernel_path_volume_bounce(kg, rng, &volume_sd, &tp, &ps, &L, &pray)) {
kernel_path_indirect(kg, rng, pray, tp, num_samples, ps, &L);
/* for render passes, sum and reset indirect light pass variables
* for the next samples */
path_radiance_sum_indirect(&L);
path_radiance_reset_indirect(&L);
}
}
#endif
}
/* todo: avoid this calculation using decoupled ray marching */
kernel_volume_shadow(kg, &state, &volume_ray, &throughput);
#endif
}
#endif
if(!hit) {
/* eval background shader if nothing hit */
if(kernel_data.background.transparent) {
L_transparent += average(throughput);
#ifdef __PASSES__
if(!(kernel_data.film.pass_flag & PASS_BACKGROUND))
#endif
break;
}
#ifdef __BACKGROUND__
/* sample background shader */
float3 L_background = indirect_background(kg, &state, &ray);
path_radiance_accum_background(&L, throughput, L_background, state.bounce);
#endif
break;
}
/* setup shading */
ShaderData sd;
shader_setup_from_ray(kg, &sd, &isect, &ray, state.bounce, state.transparent_bounce);
shader_eval_surface(kg, &sd, 0.0f, state.flag, SHADER_CONTEXT_MAIN);
shader_merge_closures(&sd);
/* holdout */
#ifdef __HOLDOUT__
if(sd.flag & (SD_HOLDOUT|SD_HOLDOUT_MASK)) {
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 mask objects do not write data passes */
kernel_write_data_passes(kg, buffer, &L, &sd, sample, &state, throughput);
#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
/* transparency termination */
if(state.flag & PATH_RAY_TRANSPARENT) {
/* 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_branched_path_ao(kg, &sd, &L, &state, rng, throughput);
}
#endif
#ifdef __SUBSURFACE__
/* bssrdf scatter to a different location on the same object */
if(sd.flag & SD_BSSRDF) {
kernel_branched_path_subsurface_scatter(kg, &sd, &L, &state,
rng, &ray, throughput);
}
#endif
if(!(sd.flag & SD_HAS_ONLY_VOLUME)) {
PathState hit_state = state;
#ifdef __EMISSION__
/* direct light */
if(kernel_data.integrator.use_direct_light) {
bool all = kernel_data.integrator.sample_all_lights_direct;
kernel_branched_path_surface_connect_light(kg, rng,
&sd, &hit_state, throughput, 1.0f, &L, all);
}
#endif
/* indirect light */
kernel_branched_path_surface_indirect_light(kg, rng,
&sd, throughput, 1.0f, &hit_state, &L);
/* continue in case of transparency */
throughput *= shader_bsdf_transparency(kg, &sd);
if(is_zero(throughput))
break;
}
path_state_next(kg, &state, LABEL_TRANSPARENT);
ray.P = ray_offset(sd.P, -sd.Ng);
ray.t -= sd.ray_length; /* clipping works through transparent */
#ifdef __RAY_DIFFERENTIALS__
ray.dP = sd.dP;
ray.dD.dx = -sd.dI.dx;
ray.dD.dy = -sd.dI.dy;
#endif
#ifdef __VOLUME__
/* enter/exit volume */
kernel_volume_stack_enter_exit(kg, &sd, state.volume_stack);
#endif
}
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
return make_float4(L_sum.x, L_sum.y, L_sum.z, 1.0f - L_transparent);
}
#endif
ccl_device_inline void kernel_path_trace_setup(KernelGlobals *kg, ccl_global uint *rng_state, int sample, int x, int y, RNG *rng, Ray *ray)
{
float filter_u;
float filter_v;
int num_samples = kernel_data.integrator.aa_samples;
path_rng_init(kg, rng_state, sample, num_samples, rng, x, y, &filter_u, &filter_v);
/* sample camera ray */
float lens_u = 0.0f, lens_v = 0.0f;
if(kernel_data.cam.aperturesize > 0.0f)
path_rng_2D(kg, rng, sample, num_samples, PRNG_LENS_U, &lens_u, &lens_v);
float time = 0.0f;
#ifdef __CAMERA_MOTION__
if(kernel_data.cam.shuttertime != -1.0f)
time = path_rng_1D(kg, rng, sample, num_samples, PRNG_TIME);
#endif
camera_sample(kg, x, y, filter_u, filter_v, lens_u, lens_v, time, ray);
}
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);
}
#ifdef __BRANCHED_PATH__
ccl_device void kernel_branched_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_branched_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);
}
#endif
CCL_NAMESPACE_END