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Cycles: Remove unused Beckmann slope sampling code

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It did not preserve stratification too well and lookup-table approach was
working much better. There are now also some more interesting forumlation
from Wenzel and OpenShadingLanguage which should work better than old code.
This commit is contained in:
Sergey Sharybin 2015-04-05 17:42:27 +05:00
parent 92755da471
commit 252b36ce77
1 changed files with 0 additions and 40 deletions
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40
intern/cycles/kernel/closure/bsdf_microfacet.h
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@ -137,44 +137,6 @@ ccl_device_inline void microfacet_beckmann_sample_slopes(
*G1i = G1;
#if 0
const float C = 1.0f - G1 * erf_a;
/* sample slope X */
if(randu < C) {
/* rescale randu */
randu = randu / C;
const float w_1 = 0.5f * SQRT_PI_INV * sin_theta_i * exp_a2;
const float w_2 = cos_theta_i * (0.5f - 0.5f*erf_a);
const float p = w_1 / (w_1 + w_2);
if(randu < p) {
randu = randu / p;
*slope_x = -sqrtf(-logf(randu*exp_a2));
}
else {
randu = (randu - p) / (1.0f - p);
*slope_x = approx_erfinvf(randu - 1.0f - randu*erf_a);
}
}
else {
/* rescale randu */
randu = (randu - C) / (1.0f - C);
*slope_x = approx_erfinvf((-1.0f + 2.0f*randu)*erf_a);
const float p = (-(*slope_x)*sin_theta_i + cos_theta_i) / (2.0f*cos_theta_i);
if(randv > p) {
*slope_x = -(*slope_x);
randv = (randv - p) / (1.0f - p);
}
else
randv = randv / p;
}
/* sample slope Y */
*slope_y = approx_erfinvf(2.0f*randv - 1.0f);
#else
/* use precomputed table, because it better preserves stratification
* of the random number pattern */
int beckmann_table_offset = kernel_data.tables.beckmann_offset;
@ -182,8 +144,6 @@ ccl_device_inline void microfacet_beckmann_sample_slopes(
*slope_x = lookup_table_read_2D(kg, randu, cos_theta_i,
beckmann_table_offset, BECKMANN_TABLE_SIZE, BECKMANN_TABLE_SIZE);
*slope_y = approx_erfinvf(2.0f*randv - 1.0f);
#endif
}
ccl_device_inline void microfacet_ggx_sample_slopes(