forked from bartvdbraak/blender
5fc6f04fc8
* Render Passes are now available for Subsurface Scattering (Direct, Indirect and Color pass). This is part of my GSoC project, SVN merge of r58587, r58828 and r58835.
245 lines
6.7 KiB
C
245 lines
6.7 KiB
C
/*
|
|
* Copyright 2013, 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.
|
|
*/
|
|
|
|
CCL_NAMESPACE_BEGIN
|
|
|
|
#define BSSRDF_MULTI_EVAL
|
|
#define BSSRDF_SKIP_NO_HIT
|
|
|
|
__device float bssrdf_sample_distance(KernelGlobals *kg, float radius, float refl, float u)
|
|
{
|
|
int table_offset = kernel_data.bssrdf.table_offset;
|
|
float r = lookup_table_read_2D(kg, u, refl, table_offset, BSSRDF_RADIUS_TABLE_SIZE, BSSRDF_REFL_TABLE_SIZE);
|
|
|
|
return r*radius;
|
|
}
|
|
|
|
#ifdef BSSRDF_MULTI_EVAL
|
|
__device float bssrdf_pdf(KernelGlobals *kg, float radius, float refl, float r)
|
|
{
|
|
if(r >= radius)
|
|
return 0.0f;
|
|
|
|
/* todo: when we use the real BSSRDF this will need to be divided by the maximum
|
|
* radius instead of the average radius */
|
|
float t = r/radius;
|
|
|
|
int table_offset = kernel_data.bssrdf.table_offset + BSSRDF_PDF_TABLE_OFFSET;
|
|
float pdf = lookup_table_read_2D(kg, t, refl, table_offset, BSSRDF_RADIUS_TABLE_SIZE, BSSRDF_REFL_TABLE_SIZE);
|
|
|
|
pdf /= radius;
|
|
|
|
return pdf;
|
|
}
|
|
#endif
|
|
|
|
__device ShaderClosure *subsurface_scatter_pick_closure(KernelGlobals *kg, ShaderData *sd, float *probability)
|
|
{
|
|
/* sum sample weights of bssrdf and bsdf */
|
|
float bsdf_sum = 0.0f;
|
|
float bssrdf_sum = 0.0f;
|
|
|
|
for(int i = 0; i < sd->num_closure; i++) {
|
|
ShaderClosure *sc = &sd->closure[i];
|
|
|
|
if(CLOSURE_IS_BSDF(sc->type))
|
|
bsdf_sum += sc->sample_weight;
|
|
else if(CLOSURE_IS_BSSRDF(sc->type))
|
|
bssrdf_sum += sc->sample_weight;
|
|
}
|
|
|
|
/* use bsdf or bssrdf? */
|
|
float r = sd->randb_closure*(bsdf_sum + bssrdf_sum);
|
|
|
|
if(r < bsdf_sum) {
|
|
/* use bsdf, and adjust randb so we can reuse it for picking a bsdf */
|
|
sd->randb_closure = r/bsdf_sum;
|
|
*probability = (bsdf_sum > 0.0f)? (bsdf_sum + bssrdf_sum)/bsdf_sum: 1.0f;
|
|
return NULL;
|
|
}
|
|
|
|
/* use bssrdf */
|
|
r -= bsdf_sum;
|
|
sd->randb_closure = 0.0f; /* not needed anymore */
|
|
|
|
float sum = 0.0f;
|
|
|
|
for(int i = 0; i < sd->num_closure; i++) {
|
|
ShaderClosure *sc = &sd->closure[i];
|
|
|
|
if(CLOSURE_IS_BSSRDF(sc->type)) {
|
|
sum += sc->sample_weight;
|
|
|
|
if(r <= sum) {
|
|
#ifdef BSSRDF_MULTI_EVAL
|
|
*probability = (bssrdf_sum > 0.0f)? (bsdf_sum + bssrdf_sum)/bssrdf_sum: 1.0f;
|
|
#else
|
|
*probability = (bssrdf_sum > 0.0f)? (bsdf_sum + bssrdf_sum)/sc->sample_weight: 1.0f;
|
|
#endif
|
|
return sc;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* should never happen */
|
|
*probability = 1.0f;
|
|
return NULL;
|
|
}
|
|
|
|
#ifdef BSSRDF_MULTI_EVAL
|
|
__device float3 subsurface_scatter_multi_eval(KernelGlobals *kg, ShaderData *sd, bool hit, float refl, float *r, int num_r, bool all)
|
|
{
|
|
/* compute pdf */
|
|
float3 eval_sum = make_float3(0.0f, 0.0f, 0.0f);
|
|
float pdf_sum = 0.0f;
|
|
float sample_weight_sum = 0.0f;
|
|
int num_bssrdf = 0;
|
|
|
|
for(int i = 0; i < sd->num_closure; i++) {
|
|
ShaderClosure *sc = &sd->closure[i];
|
|
|
|
if(CLOSURE_IS_BSSRDF(sc->type)) {
|
|
float sample_weight = (all)? 1.0f: sc->sample_weight;
|
|
|
|
/* compute pdf */
|
|
float pdf = 1.0f;
|
|
for(int i = 0; i < num_r; i++)
|
|
pdf *= bssrdf_pdf(kg, sc->data0, refl, r[i]);
|
|
|
|
eval_sum += sc->weight*pdf;
|
|
pdf_sum += sample_weight*pdf;
|
|
|
|
sample_weight_sum += sample_weight;
|
|
num_bssrdf++;
|
|
}
|
|
}
|
|
|
|
float inv_pdf_sum;
|
|
|
|
if(pdf_sum > 0.0f) {
|
|
/* in case of non-progressive integrate we sample all bssrdf's once,
|
|
* for progressive we pick one, so adjust pdf for that */
|
|
if(all)
|
|
inv_pdf_sum = 1.0f/pdf_sum;
|
|
else
|
|
inv_pdf_sum = sample_weight_sum/pdf_sum;
|
|
}
|
|
else
|
|
inv_pdf_sum = 0.0f;
|
|
|
|
float3 weight = eval_sum * inv_pdf_sum;
|
|
|
|
return weight;
|
|
}
|
|
#endif
|
|
|
|
/* replace closures with a single diffuse bsdf closure after scatter step */
|
|
__device void subsurface_scatter_setup_diffuse_bsdf(ShaderData *sd, float3 weight)
|
|
{
|
|
ShaderClosure *sc = &sd->closure[0];
|
|
sd->num_closure = 1;
|
|
|
|
sc->weight = weight;
|
|
sc->sample_weight = 1.0f;
|
|
sc->data0 = 0.0f;
|
|
sc->data1 = 0.0f;
|
|
sc->N = sd->N;
|
|
sd->flag &= ~SD_CLOSURE_FLAGS;
|
|
sd->flag |= bsdf_diffuse_setup(sc);
|
|
sd->randb_closure = 0.0f;
|
|
|
|
/* replace CLOSURE_BSDF_DIFFUSE_ID with this special ID so render passes
|
|
* can recognize it as not being a regular diffuse closure */
|
|
sc->type = CLOSURE_BSDF_BSSRDF_ID;
|
|
|
|
/* todo: evaluate shading to get blurred textures and bump mapping */
|
|
/* shader_eval_surface(kg, sd, 0.0f, state_flag, SHADER_CONTEXT_SSS); */
|
|
}
|
|
|
|
/* subsurface scattering step, from a point on the surface to another nearby point on the same object */
|
|
__device void subsurface_scatter_step(KernelGlobals *kg, ShaderData *sd, int state_flag, ShaderClosure *sc, uint *lcg_state, bool all)
|
|
{
|
|
float radius = sc->data0;
|
|
float refl = max(average(sc->weight)*3.0f, 0.0f);
|
|
float r = 0.0f;
|
|
bool hit = false;
|
|
float3 weight = make_float3(1.0f, 1.0f, 1.0f);
|
|
#ifdef BSSRDF_MULTI_EVAL
|
|
float r_attempts[BSSRDF_MAX_ATTEMPTS];
|
|
#endif
|
|
int num_attempts;
|
|
|
|
/* attempt to find a hit a given number of times before giving up */
|
|
for(num_attempts = 0; num_attempts < kernel_data.bssrdf.num_attempts; num_attempts++) {
|
|
/* random numbers for sampling */
|
|
float u1 = lcg_step(lcg_state);
|
|
float u2 = lcg_step(lcg_state);
|
|
float u3 = lcg_step(lcg_state);
|
|
float u4 = lcg_step(lcg_state);
|
|
float u5 = lcg_step(lcg_state);
|
|
float u6 = lcg_step(lcg_state);
|
|
|
|
r = bssrdf_sample_distance(kg, radius, refl, u5);
|
|
#ifdef BSSRDF_MULTI_EVAL
|
|
r_attempts[num_attempts] = r;
|
|
#endif
|
|
|
|
float3 p1 = sd->P + sample_uniform_sphere(u1, u2)*r;
|
|
float3 p2 = sd->P + sample_uniform_sphere(u3, u4)*r;
|
|
|
|
/* create ray */
|
|
Ray ray;
|
|
ray.P = p1;
|
|
ray.D = normalize_len(p2 - p1, &ray.t);
|
|
ray.dP = sd->dP;
|
|
ray.dD = differential3_zero();
|
|
ray.time = sd->time;
|
|
|
|
/* intersect with the same object. if multiple intersections are
|
|
* found it will randomly pick one of them */
|
|
Intersection isect;
|
|
if(!scene_intersect_subsurface(kg, &ray, &isect, sd->object, u6))
|
|
continue;
|
|
|
|
/* setup new shading point */
|
|
shader_setup_from_subsurface(kg, sd, &isect, &ray);
|
|
|
|
hit = true;
|
|
num_attempts++;
|
|
break;
|
|
}
|
|
|
|
/* evaluate subsurface scattering closures */
|
|
#ifdef BSSRDF_MULTI_EVAL
|
|
weight *= subsurface_scatter_multi_eval(kg, sd, hit, refl, r_attempts, num_attempts, all);
|
|
#else
|
|
weight *= sc->weight;
|
|
#endif
|
|
|
|
#ifdef BSSRDF_SKIP_NO_HIT
|
|
if(!hit)
|
|
weight = make_float3(0.0f, 0.0f, 0.0f);
|
|
#endif
|
|
|
|
/* replace closures with a single diffuse BSDF */
|
|
subsurface_scatter_setup_diffuse_bsdf(sd, weight);
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|
|
|