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blender/intern/cycles/kernel/kernel_accumulate.h
Brecht Van Lommel 01df756bd1 Cycles Volume Render: scattering support. 
This is done by adding a Volume Scatter node. In many cases you will want to
add together a Volume Absorption and Volume Scatter node with the same color
and density to get the expected results.

This should work with branched path tracing, mixing closures, overlapping
volumes, etc. However there's still various optimizations needed for sampling.
The main missing thing from the volume branch is the equiangular sampling for
homogeneous volumes.

The heterogeneous scattering code was arranged such that we can use a single
stratified random number for distance sampling, which gives less noise than
pseudo random numbers for each step. For volumes where the color is textured
there still seems to be something off, needs to be investigated.
2014-01-07 15:03:41 +01:00

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/*
* 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
*/
CCL_NAMESPACE_BEGIN
/* BSDF Eval
*
* BSDF evaluation result, split per BSDF type. This is used to accumulate
* render passes separately. */
ccl_device_inline void bsdf_eval_init(BsdfEval *eval, ClosureType type, float3 value, int use_light_pass)
{
#ifdef __PASSES__
eval->use_light_pass = use_light_pass;
if(eval->use_light_pass) {
eval->diffuse = make_float3(0.0f, 0.0f, 0.0f);
eval->glossy = make_float3(0.0f, 0.0f, 0.0f);
eval->transmission = make_float3(0.0f, 0.0f, 0.0f);
eval->transparent = make_float3(0.0f, 0.0f, 0.0f);
eval->subsurface = make_float3(0.0f, 0.0f, 0.0f);
if(type == CLOSURE_BSDF_TRANSPARENT_ID)
eval->transparent = value;
else if(CLOSURE_IS_BSDF_DIFFUSE(type) || CLOSURE_IS_PHASE(type))
eval->diffuse = value;
else if(CLOSURE_IS_BSDF_GLOSSY(type))
eval->glossy = value;
else if(CLOSURE_IS_BSDF_TRANSMISSION(type))
eval->transmission = value;
else if(CLOSURE_IS_BSDF_BSSRDF(type))
eval->subsurface = value;
}
else
eval->diffuse = value;
#else
*eval = value;
#endif
}
ccl_device_inline void bsdf_eval_accum(BsdfEval *eval, ClosureType type, float3 value)
{
#ifdef __PASSES__
if(eval->use_light_pass) {
if(CLOSURE_IS_BSDF_DIFFUSE(type) || CLOSURE_IS_PHASE(type))
eval->diffuse += value;
else if(CLOSURE_IS_BSDF_GLOSSY(type))
eval->glossy += value;
else if(CLOSURE_IS_BSDF_TRANSMISSION(type))
eval->transmission += value;
else if(CLOSURE_IS_BSDF_BSSRDF(type))
eval->subsurface += value;
/* skipping transparent, this function is used by for eval(), will be zero then */
}
else
eval->diffuse += value;
#else
*eval += value;
#endif
}
ccl_device_inline bool bsdf_eval_is_zero(BsdfEval *eval)
{
#ifdef __PASSES__
if(eval->use_light_pass) {
return is_zero(eval->diffuse)
&& is_zero(eval->glossy)
&& is_zero(eval->transmission)
&& is_zero(eval->transparent)
&& is_zero(eval->subsurface);
}
else
return is_zero(eval->diffuse);
#else
return is_zero(*eval);
#endif
}
ccl_device_inline void bsdf_eval_mul(BsdfEval *eval, float3 value)
{
#ifdef __PASSES__
if(eval->use_light_pass) {
eval->diffuse *= value;
eval->glossy *= value;
eval->transmission *= value;
eval->subsurface *= value;
/* skipping transparent, this function is used by for eval(), will be zero then */
}
else
eval->diffuse *= value;
#else
*eval *= value;
#endif
}
/* Path Radiance
*
* We accumulate different render passes separately. After summing at the end
* to get the combined result, it should be identical. We definte directly
* visible as the first non-transparent hit, while indirectly visible are the
* bounces after that. */
ccl_device_inline void path_radiance_init(PathRadiance *L, int use_light_pass)
{
/* clear all */
#ifdef __PASSES__
L->use_light_pass = use_light_pass;
if(use_light_pass) {
L->indirect = make_float3(0.0f, 0.0f, 0.0f);
L->direct_throughput = make_float3(0.0f, 0.0f, 0.0f);
L->direct_emission = make_float3(0.0f, 0.0f, 0.0f);
L->color_diffuse = make_float3(0.0f, 0.0f, 0.0f);
L->color_glossy = make_float3(0.0f, 0.0f, 0.0f);
L->color_transmission = make_float3(0.0f, 0.0f, 0.0f);
L->color_subsurface = make_float3(0.0f, 0.0f, 0.0f);
L->direct_diffuse = make_float3(0.0f, 0.0f, 0.0f);
L->direct_glossy = make_float3(0.0f, 0.0f, 0.0f);
L->direct_transmission = make_float3(0.0f, 0.0f, 0.0f);
L->direct_subsurface = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_diffuse = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_glossy = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_transmission = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_subsurface = make_float3(0.0f, 0.0f, 0.0f);
L->path_diffuse = make_float3(0.0f, 0.0f, 0.0f);
L->path_glossy = make_float3(0.0f, 0.0f, 0.0f);
L->path_transmission = make_float3(0.0f, 0.0f, 0.0f);
L->path_subsurface = make_float3(0.0f, 0.0f, 0.0f);
L->emission = make_float3(0.0f, 0.0f, 0.0f);
L->background = make_float3(0.0f, 0.0f, 0.0f);
L->ao = make_float3(0.0f, 0.0f, 0.0f);
L->shadow = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
L->mist = 0.0f;
}
else
L->emission = make_float3(0.0f, 0.0f, 0.0f);
#else
*L = make_float3(0.0f, 0.0f, 0.0f);
#endif
}
ccl_device_inline void path_radiance_bsdf_bounce(PathRadiance *L, float3 *throughput,
BsdfEval *bsdf_eval, float bsdf_pdf, int bounce, int bsdf_label)
{
float inverse_pdf = 1.0f/bsdf_pdf;
#ifdef __PASSES__
if(L->use_light_pass) {
if(bounce == 0 && !(bsdf_label & LABEL_TRANSPARENT)) {
/* first on directly visible surface */
float3 value = *throughput*inverse_pdf;
L->path_diffuse = bsdf_eval->diffuse*value;
L->path_glossy = bsdf_eval->glossy*value;
L->path_transmission = bsdf_eval->transmission*value;
L->path_subsurface = bsdf_eval->subsurface*value;
*throughput = L->path_diffuse + L->path_glossy + L->path_transmission + L->path_subsurface;
L->direct_throughput = *throughput;
}
else {
/* transparent bounce before first hit, or indirectly visible through BSDF */
float3 sum = (bsdf_eval->diffuse + bsdf_eval->glossy + bsdf_eval->transmission + bsdf_eval->transparent + bsdf_eval->subsurface)*inverse_pdf;
*throughput *= sum;
}
}
else
*throughput *= bsdf_eval->diffuse*inverse_pdf;
#else
*throughput *= *bsdf_eval*inverse_pdf;
#endif
}
ccl_device_inline void path_radiance_accum_emission(PathRadiance *L, float3 throughput, float3 value, int bounce)
{
#ifdef __PASSES__
if(L->use_light_pass) {
if(bounce == 0)
L->emission += throughput*value;
else if(bounce == 1)
L->direct_emission += throughput*value;
else
L->indirect += throughput*value;
}
else
L->emission += throughput*value;
#else
*L += throughput*value;
#endif
}
ccl_device_inline void path_radiance_accum_ao(PathRadiance *L, float3 throughput, float3 alpha, float3 bsdf, float3 ao, int bounce)
{
#ifdef __PASSES__
if(L->use_light_pass) {
if(bounce == 0) {
/* directly visible lighting */
L->direct_diffuse += throughput*bsdf*ao;
L->ao += alpha*throughput*ao;
}
else {
/* indirectly visible lighting after BSDF bounce */
L->indirect += throughput*bsdf*ao;
}
}
else
L->emission += throughput*bsdf*ao;
#else
*L += throughput*bsdf*ao;
#endif
}
ccl_device_inline void path_radiance_accum_light(PathRadiance *L, float3 throughput, BsdfEval *bsdf_eval, float3 shadow, float shadow_fac, int bounce, bool is_lamp)
{
#ifdef __PASSES__
if(L->use_light_pass) {
if(bounce == 0) {
/* directly visible lighting */
L->direct_diffuse += throughput*bsdf_eval->diffuse*shadow;
L->direct_glossy += throughput*bsdf_eval->glossy*shadow;
L->direct_transmission += throughput*bsdf_eval->transmission*shadow;
L->direct_subsurface += throughput*bsdf_eval->subsurface*shadow;
if(is_lamp) {
L->shadow.x += shadow.x*shadow_fac;
L->shadow.y += shadow.y*shadow_fac;
L->shadow.z += shadow.z*shadow_fac;
}
}
else {
/* indirectly visible lighting after BSDF bounce */
float3 sum = bsdf_eval->diffuse + bsdf_eval->glossy + bsdf_eval->transmission + bsdf_eval->subsurface;
L->indirect += throughput*sum*shadow;
}
}
else
L->emission += throughput*bsdf_eval->diffuse*shadow;
#else
*L += throughput*(*bsdf_eval)*shadow;
#endif
}
ccl_device_inline void path_radiance_accum_background(PathRadiance *L, float3 throughput, float3 value, int bounce)
{
#ifdef __PASSES__
if(L->use_light_pass) {
if(bounce == 0)
L->background += throughput*value;
else if(bounce == 1)
L->direct_emission += throughput*value;
else
L->indirect += throughput*value;
}
else
L->emission += throughput*value;
#else
*L += throughput*value;
#endif
}
ccl_device_inline void path_radiance_sum_indirect(PathRadiance *L)
{
#ifdef __PASSES__
/* this division is a bit ugly, but means we only have to keep track of
* only a single throughput further along the path, here we recover just
* the indirect path that is not influenced by any particular BSDF type */
if(L->use_light_pass) {
L->direct_emission = safe_divide_color(L->direct_emission, L->direct_throughput);
L->direct_diffuse += L->path_diffuse*L->direct_emission;
L->direct_glossy += L->path_glossy*L->direct_emission;
L->direct_transmission += L->path_transmission*L->direct_emission;
L->direct_subsurface += L->path_subsurface*L->direct_emission;
L->indirect = safe_divide_color(L->indirect, L->direct_throughput);
L->indirect_diffuse += L->path_diffuse*L->indirect;
L->indirect_glossy += L->path_glossy*L->indirect;
L->indirect_transmission += L->path_transmission*L->indirect;
L->indirect_subsurface += L->path_subsurface*L->indirect;
}
#endif
}
ccl_device_inline void path_radiance_reset_indirect(PathRadiance *L)
{
#ifdef __PASSES__
if(L->use_light_pass) {
L->path_diffuse = make_float3(0.0f, 0.0f, 0.0f);
L->path_glossy = make_float3(0.0f, 0.0f, 0.0f);
L->path_transmission = make_float3(0.0f, 0.0f, 0.0f);
L->path_subsurface = make_float3(0.0f, 0.0f, 0.0f);
L->direct_emission = make_float3(0.0f, 0.0f, 0.0f);
L->indirect = make_float3(0.0f, 0.0f, 0.0f);
}
#endif
}
ccl_device_inline float3 path_radiance_sum(KernelGlobals *kg, PathRadiance *L)
{
#ifdef __PASSES__
if(L->use_light_pass) {
path_radiance_sum_indirect(L);
float3 L_sum = L->emission
+ L->direct_diffuse + L->direct_glossy + L->direct_transmission + L->direct_subsurface
+ L->indirect_diffuse + L->indirect_glossy + L->indirect_transmission + L->indirect_subsurface;
if(!kernel_data.background.transparent)
L_sum += L->background;
return L_sum;
}
else
return L->emission;
#else
return *L;
#endif
}
ccl_device_inline void path_radiance_clamp(PathRadiance *L, float3 *L_sum, float clamp)
{
float sum = fabsf((*L_sum).x) + fabsf((*L_sum).y) + fabsf((*L_sum).z);
if(!isfinite(sum)) {
/* invalid value, reject */
*L_sum = make_float3(0.0f, 0.0f, 0.0f);
#ifdef __PASSES__
if(L->use_light_pass) {
L->direct_diffuse = make_float3(0.0f, 0.0f, 0.0f);
L->direct_glossy = make_float3(0.0f, 0.0f, 0.0f);
L->direct_transmission = make_float3(0.0f, 0.0f, 0.0f);
L->direct_subsurface = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_diffuse = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_glossy = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_transmission = make_float3(0.0f, 0.0f, 0.0f);
L->indirect_subsurface = make_float3(0.0f, 0.0f, 0.0f);
L->emission = make_float3(0.0f, 0.0f, 0.0f);
}
#endif
}
else if(sum > clamp) {
/* value to high, scale down */
float scale = clamp/sum;
*L_sum *= scale;
#ifdef __PASSES__
if(L->use_light_pass) {
L->direct_diffuse *= scale;
L->direct_glossy *= scale;
L->direct_transmission *= scale;
L->direct_subsurface *= scale;
L->indirect_diffuse *= scale;
L->indirect_glossy *= scale;
L->indirect_transmission *= scale;
L->indirect_subsurface *= scale;
L->emission *= scale;
}
#endif
}
}
CCL_NAMESPACE_END
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