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de9dffc61e
blender/intern/cycles/render/film.cpp
Brecht Van Lommel de9dffc61e Cycles: initial subsurface multiple scattering support. It's not working as 
well as I would like, but it works, just add a subsurface scattering node and
you can use it like any other BSDF.

It is using fully raytraced sampling compatible with progressive rendering
and other more advanced rendering algorithms we might used in the future, and
it uses no extra memory so it's suitable for complex scenes.

Disadvantage is that it can be quite noisy and slow. Two limitations that will
be solved are that it does not work with bump mapping yet, and that the falloff
function used is a simple cubic function, it's not using the real BSSRDF
falloff function yet.

The node has a color input, along with a scattering radius for each RGB color
channel along with an overall scale factor for the radii.

There is also no GPU support yet, will test if I can get that working later.

Node Documentation:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Shaders#BSSRDF

Implementation notes:
http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/Subsurface_Scattering
2013-04-01 20:26:52 +00:00

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/*
* Copyright 2011, Blender Foundation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "camera.h"
#include "device.h"
#include "film.h"
#include "integrator.h"
#include "mesh.h"
#include "scene.h"
#include "tables.h"
#include "util_algorithm.h"
#include "util_debug.h"
#include "util_foreach.h"
#include "util_math.h"
CCL_NAMESPACE_BEGIN
/* Pass */
static bool compare_pass_order(const Pass& a, const Pass& b)
{
if(a.components == b.components)
return (a.type < b.type);
return (a.components > b.components);
}
void Pass::add(PassType type, vector<Pass>& passes)
{
foreach(Pass& existing_pass, passes)
if(existing_pass.type == type)
return;
Pass pass;
pass.type = type;
pass.filter = true;
pass.exposure = false;
pass.divide_type = PASS_NONE;
switch(type) {
case PASS_NONE:
pass.components = 0;
break;
case PASS_COMBINED:
pass.components = 4;
pass.exposure = true;
break;
case PASS_DEPTH:
pass.components = 1;
pass.filter = false;
break;
case PASS_NORMAL:
pass.components = 4;
break;
case PASS_UV:
pass.components = 4;
break;
case PASS_MOTION:
pass.components = 4;
pass.divide_type = PASS_MOTION_WEIGHT;
break;
case PASS_MOTION_WEIGHT:
pass.components = 1;
break;
case PASS_OBJECT_ID:
pass.components = 1;
pass.filter = false;
break;
case PASS_MATERIAL_ID:
pass.components = 1;
pass.filter = false;
break;
case PASS_DIFFUSE_COLOR:
pass.components = 4;
break;
case PASS_GLOSSY_COLOR:
pass.components = 4;
break;
case PASS_TRANSMISSION_COLOR:
pass.components = 4;
break;
case PASS_DIFFUSE_INDIRECT:
pass.components = 4;
pass.exposure = true;
pass.divide_type = PASS_DIFFUSE_COLOR;
break;
case PASS_GLOSSY_INDIRECT:
pass.components = 4;
pass.exposure = true;
pass.divide_type = PASS_GLOSSY_COLOR;
break;
case PASS_TRANSMISSION_INDIRECT:
pass.components = 4;
pass.exposure = true;
pass.divide_type = PASS_TRANSMISSION_COLOR;
break;
case PASS_DIFFUSE_DIRECT:
pass.components = 4;
pass.exposure = true;
pass.divide_type = PASS_DIFFUSE_COLOR;
break;
case PASS_GLOSSY_DIRECT:
pass.components = 4;
pass.exposure = true;
pass.divide_type = PASS_GLOSSY_COLOR;
break;
case PASS_TRANSMISSION_DIRECT:
pass.components = 4;
pass.exposure = true;
pass.divide_type = PASS_TRANSMISSION_COLOR;
break;
case PASS_EMISSION:
pass.components = 4;
pass.exposure = true;
break;
case PASS_BACKGROUND:
pass.components = 4;
pass.exposure = true;
break;
case PASS_AO:
pass.components = 4;
break;
case PASS_SHADOW:
pass.components = 4;
pass.exposure = false;
break;
}
passes.push_back(pass);
/* order from by components, to ensure alignment so passes with size 4
* come first and then passes with size 1 */
sort(passes.begin(), passes.end(), compare_pass_order);
if(pass.divide_type != PASS_NONE)
Pass::add(pass.divide_type, passes);
}
bool Pass::equals(const vector<Pass>& A, const vector<Pass>& B)
{
if(A.size() != B.size())
return false;
for(int i = 0; i < A.size(); i++)
if(A[i].type != B[i].type)
return false;
return true;
}
bool Pass::contains(const vector<Pass>& passes, PassType type)
{
foreach(const Pass& pass, passes)
if(pass.type == type)
return true;
return false;
}
/* Pixel Filter */
static float filter_func_box(float v, float width)
{
return (float)1;
}
static float filter_func_gaussian(float v, float width)
{
v *= (float)2/width;
return (float)expf((float)-2*v*v);
}
static vector<float> filter_table(FilterType type, float width)
{
const int filter_table_size = FILTER_TABLE_SIZE-1;
vector<float> filter_table_cdf(filter_table_size+1);
vector<float> filter_table(filter_table_size+1);
float (*filter_func)(float, float) = NULL;
int i, half_size = filter_table_size/2;
switch(type) {
case FILTER_BOX:
filter_func = filter_func_box;
break;
case FILTER_GAUSSIAN:
filter_func = filter_func_gaussian;
break;
default:
assert(0);
}
/* compute cumulative distribution function */
filter_table_cdf[0] = 0.0f;
for(i = 0; i < filter_table_size; i++) {
float x = i*width*0.5f/(filter_table_size-1);
float y = filter_func(x, width);
filter_table_cdf[i+1] += filter_table_cdf[i] + fabsf(y);
}
for(i = 0; i <= filter_table_size; i++)
filter_table_cdf[i] /= filter_table_cdf[filter_table_size];
/* create importance sampling table */
for(i = 0; i <= half_size; i++) {
float x = i/(float)half_size;
int index = upper_bound(filter_table_cdf.begin(), filter_table_cdf.end(), x) - filter_table_cdf.begin();
float t;
if(index < filter_table_size+1) {
t = (x - filter_table_cdf[index])/(filter_table_cdf[index+1] - filter_table_cdf[index]);
}
else {
t = 0.0f;
index = filter_table_size;
}
float y = ((index + t)/(filter_table_size))*width;
filter_table[half_size+i] = 0.5f*(1.0f + y);
filter_table[half_size-i] = 0.5f*(1.0f - y);
}
return filter_table;
}
/* Film */
Film::Film()
{
exposure = 0.8f;
Pass::add(PASS_COMBINED, passes);
filter_type = FILTER_BOX;
filter_width = 1.0f;
filter_table_offset = TABLE_OFFSET_INVALID;
need_update = true;
}
Film::~Film()
{
}
void Film::device_update(Device *device, DeviceScene *dscene, Scene *scene)
{
if(!need_update)
return;
device_free(device, dscene, scene);
KernelFilm *kfilm = &dscene->data.film;
/* update __data */
kfilm->exposure = exposure;
kfilm->pass_flag = 0;
kfilm->pass_stride = 0;
kfilm->use_light_pass = 0;
foreach(Pass& pass, passes) {
kfilm->pass_flag |= pass.type;
switch(pass.type) {
case PASS_COMBINED:
kfilm->pass_combined = kfilm->pass_stride;
break;
case PASS_DEPTH:
kfilm->pass_depth = kfilm->pass_stride;
break;
case PASS_NORMAL:
kfilm->pass_normal = kfilm->pass_stride;
break;
case PASS_UV:
kfilm->pass_uv = kfilm->pass_stride;
break;
case PASS_MOTION:
kfilm->pass_motion = kfilm->pass_stride;
break;
case PASS_MOTION_WEIGHT:
kfilm->pass_motion_weight = kfilm->pass_stride;
break;
case PASS_OBJECT_ID:
kfilm->pass_object_id = kfilm->pass_stride;
break;
case PASS_MATERIAL_ID:
kfilm->pass_material_id = kfilm->pass_stride;
break;
case PASS_DIFFUSE_COLOR:
kfilm->pass_diffuse_color = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_GLOSSY_COLOR:
kfilm->pass_glossy_color = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_TRANSMISSION_COLOR:
kfilm->pass_transmission_color = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_DIFFUSE_INDIRECT:
kfilm->pass_diffuse_indirect = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_GLOSSY_INDIRECT:
kfilm->pass_glossy_indirect = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_TRANSMISSION_INDIRECT:
kfilm->pass_transmission_indirect = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_DIFFUSE_DIRECT:
kfilm->pass_diffuse_direct = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_GLOSSY_DIRECT:
kfilm->pass_glossy_direct = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_TRANSMISSION_DIRECT:
kfilm->pass_transmission_direct = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_EMISSION:
kfilm->pass_emission = kfilm->pass_stride;
kfilm->use_light_pass = 1;
break;
case PASS_BACKGROUND:
kfilm->pass_background = kfilm->pass_stride;
kfilm->use_light_pass = 1;
case PASS_AO:
kfilm->pass_ao = kfilm->pass_stride;
kfilm->use_light_pass = 1;
case PASS_SHADOW:
kfilm->pass_shadow = kfilm->pass_stride;
kfilm->use_light_pass = 1;
case PASS_NONE:
break;
}
kfilm->pass_stride += pass.components;
}
kfilm->pass_stride = align_up(kfilm->pass_stride, 4);
/* update filter table */
vector<float> table = filter_table(filter_type, filter_width);
filter_table_offset = scene->lookup_tables->add_table(dscene, table);
kfilm->filter_table_offset = (int)filter_table_offset;
need_update = false;
}
void Film::device_free(Device *device, DeviceScene *dscene, Scene *scene)
{
if(filter_table_offset != TABLE_OFFSET_INVALID) {
scene->lookup_tables->remove_table(filter_table_offset);
filter_table_offset = TABLE_OFFSET_INVALID;
}
}
bool Film::modified(const Film& film)
{
return !(exposure == film.exposure
&& Pass::equals(passes, film.passes)
&& filter_type == film.filter_type
&& filter_width == film.filter_width);
}
void Film::tag_passes_update(Scene *scene, const vector<Pass>& passes_)
{
if(Pass::contains(passes, PASS_UV) != Pass::contains(passes_, PASS_UV))
scene->mesh_manager->tag_update(scene);
else if(Pass::contains(passes, PASS_MOTION) != Pass::contains(passes_, PASS_MOTION))
scene->mesh_manager->tag_update(scene);
passes = passes_;
}
void Film::tag_update(Scene *scene)
{
need_update = true;
}
CCL_NAMESPACE_END
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