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Fix T46760: Branched Path Tracing converges to different result than plain Path Tracing

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Multiple importance sampling for branched path tracing light samples needs to be
calculated separately per BSDF, not with Veach's one sample model.
This commit is contained in:
Stefan Werner
2015-11-20 17:44:19 +01:00
committed by Sergey Sharybin
parent 35cf545e3a
commit c8a041f489
2 changed files with 53 additions and 13 deletions
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20
intern/cycles/kernel/kernel_emission.h
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@@ -99,23 +99,23 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg, ShaderData *sd,
return false;
/* evaluate BSDF at shading point */
float bsdf_pdf;
#ifdef __VOLUME__
if(ccl_fetch(sd, prim) != PRIM_NONE)
shader_bsdf_eval(kg, sd, ls->D, eval, &bsdf_pdf);
else
shader_bsdf_eval(kg, sd, ls->D, eval, ls->pdf, ls->shader & SHADER_USE_MIS);
else {
float bsdf_pdf;
shader_volume_phase_eval(kg, sd, ls->D, eval, &bsdf_pdf);
if(ls->shader & SHADER_USE_MIS) {
/* Multiple importance sampling. */
float mis_weight = power_heuristic(ls->pdf, bsdf_pdf);
light_eval *= mis_weight;
}
}
#else
shader_bsdf_eval(kg, sd, ls->D, eval, &bsdf_pdf);
shader_bsdf_eval(kg, sd, ls->D, eval, ls->pdf, ls->shader & SHADER_USE_MIS);
#endif
if(ls->shader & SHADER_USE_MIS) {
/* multiple importance sampling */
float mis_weight = power_heuristic(ls->pdf, bsdf_pdf);
light_eval *= mis_weight;
}
bsdf_eval_mul(eval, light_eval/ls->pdf);
#ifdef __PASSES__