Files
blender/intern/cycles/render/integrator.cpp
Brecht Van Lommel 0df9b2c715 Cycles: random walk subsurface scattering.
It is basically brute force volume scattering within the mesh, but part
of the SSS code for faster performance. The main difference with actual
volume scattering is that we assume the boundaries are diffuse and that
all lighting is coming through this boundary from outside the volume.

This gives much more accurate results for thin features and low density.
Some challenges remain however:

* Significantly more noisy than BSSRDF. Adding Dwivedi sampling may help
  here, but it's unclear still how much it helps in real world cases.
* Due to this being a volumetric method, geometry like eyes or mouth can
  darken the skin on the outside. We may be able to reduce this effect,
  or users can compensate for it by reducing the scattering radius in
  such areas.
* Sharp corners are quite bright. This matches actual volume rendering
  and results in some other renderers, but maybe not so much real world
  objects.

Differential Revision: https://developer.blender.org/D3054
2018-02-09 19:58:33 +01:00

238 lines
7.6 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.
*/
#include "device/device.h"
#include "render/background.h"
#include "render/integrator.h"
#include "render/film.h"
#include "render/light.h"
#include "render/scene.h"
#include "render/shader.h"
#include "render/sobol.h"
#include "util/util_foreach.h"
#include "util/util_hash.h"
CCL_NAMESPACE_BEGIN
NODE_DEFINE(Integrator)
{
NodeType *type = NodeType::add("integrator", create);
SOCKET_INT(max_bounce, "Max Bounce", 7);
SOCKET_INT(max_diffuse_bounce, "Max Diffuse Bounce", 7);
SOCKET_INT(max_glossy_bounce, "Max Glossy Bounce", 7);
SOCKET_INT(max_transmission_bounce, "Max Transmission Bounce", 7);
SOCKET_INT(max_volume_bounce, "Max Volume Bounce", 7);
SOCKET_INT(transparent_max_bounce, "Transparent Max Bounce", 7);
SOCKET_INT(ao_bounces, "AO Bounces", 0);
SOCKET_INT(volume_max_steps, "Volume Max Steps", 1024);
SOCKET_FLOAT(volume_step_size, "Volume Step Size", 0.1f);
SOCKET_BOOLEAN(caustics_reflective, "Reflective Caustics", true);
SOCKET_BOOLEAN(caustics_refractive, "Refractive Caustics", true);
SOCKET_FLOAT(filter_glossy, "Filter Glossy", 0.0f);
SOCKET_INT(seed, "Seed", 0);
SOCKET_FLOAT(sample_clamp_direct, "Sample Clamp Direct", 0.0f);
SOCKET_FLOAT(sample_clamp_indirect, "Sample Clamp Indirect", 0.0f);
SOCKET_BOOLEAN(motion_blur, "Motion Blur", false);
SOCKET_INT(aa_samples, "AA Samples", 0);
SOCKET_INT(diffuse_samples, "Diffuse Samples", 1);
SOCKET_INT(glossy_samples, "Glossy Samples", 1);
SOCKET_INT(transmission_samples, "Transmission Samples", 1);
SOCKET_INT(ao_samples, "AO Samples", 1);
SOCKET_INT(mesh_light_samples, "Mesh Light Samples", 1);
SOCKET_INT(subsurface_samples, "Subsurface Samples", 1);
SOCKET_INT(volume_samples, "Volume Samples", 1);
SOCKET_INT(start_sample, "Start Sample", 0);
SOCKET_BOOLEAN(sample_all_lights_direct, "Sample All Lights Direct", true);
SOCKET_BOOLEAN(sample_all_lights_indirect, "Sample All Lights Indirect", true);
SOCKET_FLOAT(light_sampling_threshold, "Light Sampling Threshold", 0.05f);
static NodeEnum method_enum;
method_enum.insert("path", PATH);
method_enum.insert("branched_path", BRANCHED_PATH);
SOCKET_ENUM(method, "Method", method_enum, PATH);
static NodeEnum sampling_pattern_enum;
sampling_pattern_enum.insert("sobol", SAMPLING_PATTERN_SOBOL);
sampling_pattern_enum.insert("cmj", SAMPLING_PATTERN_CMJ);
SOCKET_ENUM(sampling_pattern, "Sampling Pattern", sampling_pattern_enum, SAMPLING_PATTERN_SOBOL);
return type;
}
Integrator::Integrator()
: Node(node_type)
{
need_update = true;
}
Integrator::~Integrator()
{
}
void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene)
{
if(!need_update)
return;
device_free(device, dscene);
KernelIntegrator *kintegrator = &dscene->data.integrator;
/* integrator parameters */
kintegrator->max_bounce = max_bounce + 1;
kintegrator->max_diffuse_bounce = max_diffuse_bounce + 1;
kintegrator->max_glossy_bounce = max_glossy_bounce + 1;
kintegrator->max_transmission_bounce = max_transmission_bounce + 1;
kintegrator->max_volume_bounce = max_volume_bounce + 1;
kintegrator->transparent_max_bounce = transparent_max_bounce + 1;
if(ao_bounces == 0) {
kintegrator->ao_bounces = INT_MAX;
}
else {
kintegrator->ao_bounces = ao_bounces - 1;
}
/* Transparent Shadows
* We only need to enable transparent shadows, if we actually have
* transparent shaders in the scene. Otherwise we can disable it
* to improve performance a bit. */
kintegrator->transparent_shadows = false;
foreach(Shader *shader, scene->shaders) {
/* keep this in sync with SD_HAS_TRANSPARENT_SHADOW in shader.cpp */
if((shader->has_surface_transparent && shader->use_transparent_shadow) || shader->has_volume) {
kintegrator->transparent_shadows = true;
break;
}
}
kintegrator->volume_max_steps = volume_max_steps;
kintegrator->volume_step_size = volume_step_size;
kintegrator->caustics_reflective = caustics_reflective;
kintegrator->caustics_refractive = caustics_refractive;
kintegrator->filter_glossy = (filter_glossy == 0.0f)? FLT_MAX: 1.0f/filter_glossy;
kintegrator->seed = hash_int(seed);
kintegrator->use_ambient_occlusion =
((Pass::contains(scene->film->passes, PASS_AO)) || dscene->data.background.ao_factor != 0.0f);
kintegrator->sample_clamp_direct = (sample_clamp_direct == 0.0f)? FLT_MAX: sample_clamp_direct*3.0f;
kintegrator->sample_clamp_indirect = (sample_clamp_indirect == 0.0f)? FLT_MAX: sample_clamp_indirect*3.0f;
kintegrator->branched = (method == BRANCHED_PATH);
kintegrator->volume_decoupled = device->info.has_volume_decoupled;
kintegrator->diffuse_samples = diffuse_samples;
kintegrator->glossy_samples = glossy_samples;
kintegrator->transmission_samples = transmission_samples;
kintegrator->ao_samples = ao_samples;
kintegrator->mesh_light_samples = mesh_light_samples;
kintegrator->subsurface_samples = subsurface_samples;
kintegrator->volume_samples = volume_samples;
kintegrator->start_sample = start_sample;
if(method == BRANCHED_PATH) {
kintegrator->sample_all_lights_direct = sample_all_lights_direct;
kintegrator->sample_all_lights_indirect = sample_all_lights_indirect;
}
else {
kintegrator->sample_all_lights_direct = false;
kintegrator->sample_all_lights_indirect = false;
}
kintegrator->sampling_pattern = sampling_pattern;
kintegrator->aa_samples = aa_samples;
if(light_sampling_threshold > 0.0f) {
kintegrator->light_inv_rr_threshold = 1.0f / light_sampling_threshold;
}
else {
kintegrator->light_inv_rr_threshold = 0.0f;
}
/* sobol directions table */
int max_samples = 1;
if(method == BRANCHED_PATH) {
foreach(Light *light, scene->lights)
max_samples = max(max_samples, light->samples);
max_samples = max(max_samples, max(diffuse_samples, max(glossy_samples, transmission_samples)));
max_samples = max(max_samples, max(ao_samples, max(mesh_light_samples, subsurface_samples)));
max_samples = max(max_samples, volume_samples);
}
uint total_bounces = max_bounce + transparent_max_bounce + 3 +
max(BSSRDF_MAX_HITS, BSSRDF_MAX_BOUNCES);
max_samples *= total_bounces;
int dimensions = PRNG_BASE_NUM + max_samples*PRNG_BOUNCE_NUM;
dimensions = min(dimensions, SOBOL_MAX_DIMENSIONS);
uint *directions = dscene->sobol_directions.alloc(SOBOL_BITS*dimensions);
sobol_generate_direction_vectors((uint(*)[SOBOL_BITS])directions, dimensions);
dscene->sobol_directions.copy_to_device();
/* Clamping. */
bool use_sample_clamp = (sample_clamp_direct != 0.0f ||
sample_clamp_indirect != 0.0f);
if(use_sample_clamp != scene->film->use_sample_clamp) {
scene->film->use_sample_clamp = use_sample_clamp;
scene->film->tag_update(scene);
}
need_update = false;
}
void Integrator::device_free(Device *, DeviceScene *dscene)
{
dscene->sobol_directions.free();
}
bool Integrator::modified(const Integrator& integrator)
{
return !Node::equals(integrator);
}
void Integrator::tag_update(Scene *scene)
{
foreach(Shader *shader, scene->shaders) {
if(shader->has_integrator_dependency) {
scene->shader_manager->need_update = true;
break;
}
}
need_update = true;
}
CCL_NAMESPACE_END