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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.
*/
CCL_NAMESPACE_BEGIN
/* Direction Emission */
__device float3 direct_emissive_eval(KernelGlobals *kg, float rando,
LightSample *ls, float u, float v, float3 I, float t, float time)
{
/* setup shading at emitter */
ShaderData sd;
float3 eval;
#ifdef __BACKGROUND_MIS__
if(ls->type == LIGHT_BACKGROUND) {
Ray ray;
ray.D = ls->D;
ray.P = ls->P;
ray.dP.dx = make_float3(0.0f, 0.0f, 0.0f);
ray.dP.dy = make_float3(0.0f, 0.0f, 0.0f);
shader_setup_from_background(kg, &sd, &ray);
eval = shader_eval_background(kg, &sd, 0);
}
else
#endif
{
shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v, t, time);
ls->Ng = sd.Ng;
/* no path flag, we're evaluating this for all closures. that's weak but
* we'd have to do multiple evaluations otherwise */
shader_eval_surface(kg, &sd, rando, 0);
/* evaluate emissive closure */
if(sd.flag & SD_EMISSION)
eval = shader_emissive_eval(kg, &sd);
else
eval = make_float3(0.0f, 0.0f, 0.0f);
}
shader_release(kg, &sd);
return eval;
}
__device bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
float randt, float rando, float randu, float randv, Ray *ray, BsdfEval *eval,
bool *is_lamp)
{
LightSample ls;
float pdf = -1.0f;
#ifdef __NON_PROGRESSIVE__
if(lindex != -1) {
/* sample position on a specified light */
light_select(kg, lindex, randu, randv, sd->P, &ls, &pdf);
}
else
#endif
{
/* sample a light and position on int */
light_sample(kg, randt, randu, randv, sd->time, sd->P, &ls, &pdf);
}
/* compute pdf */
if(pdf < 0.0f)
pdf = light_sample_pdf(kg, &ls, -ls.D, ls.t);
if(pdf == 0.0f)
return false;
/* evaluate closure */
float3 light_eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -ls.D, ls.t, sd->time);
if(is_zero(light_eval))
return false;
/* todo: use visbility flag to skip lights */
/* evaluate BSDF at shading point */
float bsdf_pdf;
shader_bsdf_eval(kg, sd, ls.D, eval, &bsdf_pdf);
if(ls.prim != ~0 || ls.type == LIGHT_BACKGROUND) {
/* multiple importance sampling */
float mis_weight = power_heuristic(pdf, bsdf_pdf);
light_eval *= mis_weight;
}
bsdf_eval_mul(eval, light_eval*(ls.eval_fac/pdf));
if(bsdf_eval_is_zero(eval))
return false;
if(ls.shader & SHADER_CAST_SHADOW) {
/* setup ray */
bool transmit = (dot(sd->Ng, ls.D) < 0.0f);
ray->P = ray_offset(sd->P, (transmit)? -sd->Ng: sd->Ng);
if(ls.t == FLT_MAX) {
/* distant light */
ray->D = ls.D;
ray->t = ls.t;
}
else {
/* other lights, avoid self-intersection */
ray->D = ray_offset(ls.P, ls.Ng) - ray->P;
ray->D = normalize_len(ray->D, &ray->t);
}
}
else {
/* signal to not cast shadow ray */
ray->t = 0.0f;
}
*is_lamp = (ls.prim == ~0);
return true;
}
/* Indirect Emission */
__device float3 indirect_emission(KernelGlobals *kg, ShaderData *sd, float t, int path_flag, float bsdf_pdf)
{
/* evaluate emissive closure */
float3 L = shader_emissive_eval(kg, sd);
if(!(path_flag & PATH_RAY_MIS_SKIP) && (sd->flag & SD_SAMPLE_AS_LIGHT)) {
/* multiple importance sampling, get triangle light pdf,
* and compute weight with respect to BSDF pdf */
float pdf = triangle_light_pdf(kg, sd->Ng, sd->I, t);
float mis_weight = power_heuristic(bsdf_pdf, pdf);
return L*mis_weight;
}
return L;
}
/* Indirect Background */
__device float3 indirect_background(KernelGlobals *kg, Ray *ray, int path_flag, float bsdf_pdf)
{
#ifdef __BACKGROUND__
/* evaluate background closure */
ShaderData sd;
shader_setup_from_background(kg, &sd, ray);
float3 L = shader_eval_background(kg, &sd, path_flag);
shader_release(kg, &sd);
#ifdef __BACKGROUND_MIS__
/* check if background light exists or if we should skip pdf */
int res = kernel_data.integrator.pdf_background_res;
if(!(path_flag & PATH_RAY_MIS_SKIP) && res) {
/* multiple importance sampling, get background light pdf for ray
* direction, and compute weight with respect to BSDF pdf */
float pdf = background_light_pdf(kg, ray->D);
float mis_weight = power_heuristic(bsdf_pdf, pdf);
return L*mis_weight;
}
#endif
return L;
#else
return make_float3(0.8f, 0.8f, 0.8f);
#endif
}
CCL_NAMESPACE_END
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