diff options
author | Thomas Dinges <blender@dingto.org> | 2015-02-17 19:44:32 +0300 |
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committer | Thomas Dinges <blender@dingto.org> | 2015-02-17 19:48:18 +0300 |
commit | a0d7db503d82c1a5b56a5723da90364f11569b37 (patch) | |
tree | 3b66620b4692970cac29a86b9644dc3301ad2035 /intern/cycles/kernel/closure | |
parent | ea2fc5b9d6000a61dba5e8c37a36231a2f22e6d4 (diff) |
Cycles: Small tweaks for Henyey Greenstein closure code.
* Avoid duplicative fabs(g) check in sample code.
* Avoid dot product in eval code.
Helps like ~1% when Scatter Anisotropy is 0.
Diffstat (limited to 'intern/cycles/kernel/closure')
-rw-r--r-- | intern/cycles/kernel/closure/volume.h | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/intern/cycles/kernel/closure/volume.h b/intern/cycles/kernel/closure/volume.h index 9f519e2e2b1..1cf5e17b8f7 100644 --- a/intern/cycles/kernel/closure/volume.h +++ b/intern/cycles/kernel/closure/volume.h @@ -26,9 +26,6 @@ CCL_NAMESPACE_BEGIN * uniform sphere. g=0 uniform diffuse-like, g=1 close to sharp single ray. */ ccl_device float single_peaked_henyey_greenstein(float cos_theta, float g) { - if(fabsf(g) < 1e-3f) - return M_1_PI_F * 0.25f; - return ((1.0f - g * g) / safe_powf(1.0f + g * g - 2.0f * g * cos_theta, 1.5f)) * (M_1_PI_F * 0.25f); }; @@ -47,9 +44,13 @@ ccl_device float3 volume_henyey_greenstein_eval_phase(const ShaderClosure *sc, c float g = sc->data0; /* note that I points towards the viewer */ - float cos_theta = dot(-I, omega_in); - - *pdf = single_peaked_henyey_greenstein(cos_theta, g); + if(fabsf(g) < 1e-3f) { + *pdf = M_1_PI_F * 0.25f; + } + else { + float cos_theta = dot(-I, omega_in); + *pdf = single_peaked_henyey_greenstein(cos_theta, g); + } return make_float3(*pdf, *pdf, *pdf); } @@ -63,10 +64,12 @@ ccl_device int volume_henyey_greenstein_sample(const ShaderClosure *sc, float3 I /* match pdf for small g */ if(fabsf(g) < 1e-3f) { cos_theta = (1.0f - 2.0f * randu); + *pdf = M_1_PI_F * 0.25f; } else { float k = (1.0f - g * g) / (1.0f - g + 2.0f * g * randu); cos_theta = (1.0f + g * g - k * k) / (2.0f * g); + *pdf = single_peaked_henyey_greenstein(cos_theta, g); } float sin_theta = safe_sqrtf(1.0f - cos_theta * cos_theta); @@ -80,7 +83,6 @@ ccl_device int volume_henyey_greenstein_sample(const ShaderClosure *sc, float3 I make_orthonormals(-I, &T, &B); *omega_in = sin_theta * cos_phi * T + sin_theta * sin_phi * B + cos_theta * (-I); - *pdf = single_peaked_henyey_greenstein(cos_theta, g); *eval = make_float3(*pdf, *pdf, *pdf); /* perfect importance sampling */ #ifdef __RAY_DIFFERENTIALS__ |