diff options
Diffstat (limited to 'intern/cycles/kernel/closure/bssrdf.h')
| -rw-r--r-- | intern/cycles/kernel/closure/bssrdf.h | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/intern/cycles/kernel/closure/bssrdf.h b/intern/cycles/kernel/closure/bssrdf.h index 21a4d58598b..a3ca58461ad 100644 --- a/intern/cycles/kernel/closure/bssrdf.h +++ b/intern/cycles/kernel/closure/bssrdf.h @@ -181,8 +181,8 @@ ccl_device void bssrdf_cubic_sample(ShaderClosure *sc, float xi, float *r, float * the mean free length, but still not too big so sampling is still * effective. Might need some further tweaks. */ -#define BURLEY_TRUNCATE 30.0f -#define BURLEY_TRUNCATE_CDF 0.999966f // cdf(BURLEY_TRUNCATE) +#define BURLEY_TRUNCATE 16.0f +#define BURLEY_TRUNCATE_CDF 0.9963790093708328f // cdf(BURLEY_TRUNCATE) ccl_device_inline float bssrdf_burley_fitting(float A) { @@ -195,7 +195,7 @@ ccl_device_inline float bssrdf_burley_fitting(float A) */ ccl_device_inline float bssrdf_burley_compatible_mfp(float r) { - return 0.5f * M_1_PI_F * r; + return 0.25f * M_1_PI_F * r; } ccl_device void bssrdf_burley_setup(ShaderClosure *sc) @@ -215,20 +215,20 @@ ccl_device float bssrdf_burley_eval(ShaderClosure *sc, float r) const float d = sc->custom1; const float Rm = BURLEY_TRUNCATE * d; - if (r >= Rm) + if(r >= Rm) return 0.0f; - /* Clamp to avoid precision issues computing expf(-x)/x */ - r = fmaxf(r, 1e-2f * d); - /* Burley refletance profile, equation (3). * - * Note that surface albedo is already included into sc->weight, no need to - * multiply by this term here. + * NOTES: + * - Surface albedo is already included into sc->weight, no need to + * multiply by this term here. + * - This is normalized diffuse model, so the equation is mutliplied + * by 2*pi, which also matches cdf(). */ float exp_r_3_d = expf(-r / (3.0f * d)); float exp_r_d = exp_r_3_d * exp_r_3_d * exp_r_3_d; - return (exp_r_d + exp_r_3_d) / (8*M_PI_F*d*r); + return (exp_r_d + exp_r_3_d) / (4.0f*d); } ccl_device float bssrdf_burley_pdf(ShaderClosure *sc, float r) |