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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)
{
/* setup shading at emitter */
ShaderData sd;
shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v);
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);
float3 eval;
/* 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, float randt, float rando,
float randu, float randv, Ray *ray, float3 *eval)
{
/* sample a position on a light */
LightSample ls;
light_sample(kg, randt, randu, randv, sd->P, &ls);
/* compute incoming direction and distance */
float t;
float3 omega_in = normalize_len(ls.P - sd->P, &t);
/* compute pdf */
float pdf = light_pdf(kg, &ls, -omega_in, t);
/* evaluate closure */
*eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -omega_in);
if(is_zero(*eval) || pdf == 0.0f)
return false;
/* evaluate BSDF at shading point */
float bsdf_pdf;
float3 bsdf_eval = shader_bsdf_eval(kg, sd, omega_in, &bsdf_pdf);
*eval *= bsdf_eval/pdf;
if(is_zero(*eval))
return false;
if(ls.prim != ~0) {
/* multiple importance sampling */
float mis_weight = power_heuristic(pdf, bsdf_pdf);
*eval *= mis_weight;
}
else {
/* ensure point light works in Watts, this should be handled
* elsewhere but for now together with the diffuse emission
* closure it works out to the right value */
*eval *= 0.25f;
}
/* setup ray */
ray->P = ray_offset(sd->P, sd->Ng);
ray->D = ray_offset(ls.P, ls.Ng) - ray->P;
ray->D = normalize_len(ray->D, &ray->t);
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_SINGULAR)) {
/* multiple importance sampling */
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;
}
CCL_NAMESPACE_END
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