diff options
author | Brecht Van Lommel <brechtvanlommel@gmail.com> | 2017-09-13 19:28:31 +0300 |
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committer | Brecht Van Lommel <brechtvanlommel@gmail.com> | 2017-09-20 20:38:08 +0300 |
commit | 90d4b823d72922922bb3d0af48ec2f592d210cdd (patch) | |
tree | 4b1a369c372d2223a8083a5abae41adc77dbe605 /intern/cycles/kernel/kernel_shader.h | |
parent | 095a01a73a35d3af57573fc724d381bcca019f54 (diff) |
Cycles: use defensive sampling for picking BSDFs and BSSRDFs.
For the first bounce we now give each BSDF or BSSRDF a minimum sample weight,
which helps reduce noise for a typical case where you have a glossy BSDF with
a small weight due to Fresnel, but not necessarily small contribution relative
to a diffuse or transmission BSDF below.
We can probably find a better heuristic that also enables this on further
bounces, for example when looking through a perfect mirror, but I wasn't able
to find a robust one so far.
Diffstat (limited to 'intern/cycles/kernel/kernel_shader.h')
-rw-r--r-- | intern/cycles/kernel/kernel_shader.h | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/intern/cycles/kernel/kernel_shader.h b/intern/cycles/kernel/kernel_shader.h index 5ef4475e259..bb3add5d7ca 100644 --- a/intern/cycles/kernel/kernel_shader.h +++ b/intern/cycles/kernel/kernel_shader.h @@ -494,6 +494,34 @@ ccl_device_inline void shader_merge_closures(ShaderData *sd) } #endif +/* Defensive sampling. */ + +ccl_device_inline void shader_prepare_closures(ShaderData *sd, + ccl_addr_space PathState *state) +{ + /* We can likely also do defensive sampling at deeper bounces, particularly + * for cases like a perfect mirror but possibly also others. This will need + * a good heuristic. */ + if(state->bounce + state->transparent_bounce == 0 && sd->num_closure > 1) { + float sum = 0.0f; + + for(int i = 0; i < sd->num_closure; i++) { + ShaderClosure *sc = &sd->closure[i]; + if(CLOSURE_IS_BSDF_OR_BSSRDF(sc->type)) { + sum += sc->sample_weight; + } + } + + for(int i = 0; i < sd->num_closure; i++) { + ShaderClosure *sc = &sd->closure[i]; + if(CLOSURE_IS_BSDF_OR_BSSRDF(sc->type)) { + sc->sample_weight = max(sc->sample_weight, 0.125f * sum); + } + } + } +} + + /* BSDF */ ccl_device_inline void _shader_bsdf_multi_eval(KernelGlobals *kg, ShaderData *sd, const float3 omega_in, float *pdf, |