blender/intern/cycles/kernel/kernel_path.h
2014-08-24 23:08:07 +02:00

1156 lines
35 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"
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);
#ifdef __HAIR__
bool hit = scene_intersect(kg, &ray, visibility, &isect, NULL, 0.0f, 0.0f);
#else
bool hit = scene_intersect(kg, &ray, visibility, &isect);
#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, 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, 1.0f);
/* 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__
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);
/* 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
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);
/* 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);
#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, 1.0f);
/* 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);
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, 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);
/* 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);
#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);
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);
#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);
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;
/* 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, num_samples_inv);
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);
}
}
#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, 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 __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);
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