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Fix: Huang hair sampling does not advance LCG

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The reason for this probably was the const nature of the shader data.
However, this is something counter-intuitive, as it potentially leads
to multiple BSDFs re-using the same LCG state.

Pull Request: https://projects.blender.org/blender/blender/pulls/132456
This commit is contained in:
Sergey Sharybin
2024-12-31 10:25:19 +01:00
committed by Sergey Sharybin
parent 39f7c506b5
commit ba4c79feee
2 changed files with 8 additions and 8 deletions
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14
intern/cycles/kernel/closure/bsdf_principled_hair_huang.h
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@@ -384,7 +384,7 @@ ccl_device Spectrum bsdf_hair_huang_eval_residual(KernelGlobals kg,
ccl_private const ShaderClosure *sc,
const float3 wi,
const float3 wo,
uint rng_quadrature)
ccl_private uint *rng_quadrature)
{
ccl_private HuangHairBSDF *bsdf = (ccl_private HuangHairBSDF *)sc;
@@ -420,8 +420,8 @@ ccl_device Spectrum bsdf_hair_huang_eval_residual(KernelGlobals kg,
const float3 wmi_ = sphg_dir(0.0f, gamma_mi, b);
/* Sample `wh1`. */
const float2 sample1 = make_float2(lcg_step_float(&rng_quadrature),
lcg_step_float(&rng_quadrature));
const float2 sample1 = make_float2(lcg_step_float(rng_quadrature),
lcg_step_float(rng_quadrature));
const float3 wh1 = sample_wh(kg, roughness, wi, wmi, sample1);
const float cos_hi1 = dot(wi, wh1);
@@ -486,8 +486,8 @@ ccl_device Spectrum bsdf_hair_huang_eval_residual(KernelGlobals kg,
/* TRT and beyond. */
if (bsdf->extra->TRT > 0.0f) {
/* Sample `wh2`. */
const float2 sample2 = make_float2(lcg_step_float(&rng_quadrature),
lcg_step_float(&rng_quadrature));
const float2 sample2 = make_float2(lcg_step_float(rng_quadrature),
lcg_step_float(rng_quadrature));
const float3 wh2 = sample_wh(kg, roughness, -wt, wmt, sample2);
const float cos_hi2 = dot(-wt, wh2);
if (!(cos_hi2 > 0.0f)) {
@@ -777,7 +777,7 @@ ccl_device int bsdf_hair_huang_sample(const KernelGlobals kg,
}
ccl_device Spectrum bsdf_hair_huang_eval(KernelGlobals kg,
ccl_private const ShaderData *sd,
ccl_private ShaderData *sd,
ccl_private const ShaderClosure *sc,
const float3 wo,
ccl_private float *pdf)
@@ -859,7 +859,7 @@ ccl_device Spectrum bsdf_hair_huang_eval(KernelGlobals kg,
const float projected_area = cos_theta(local_I) * dh;
return (bsdf_hair_huang_eval_r(kg, sc, local_I, local_O) +
bsdf_hair_huang_eval_residual(kg, sc, local_I, local_O, sd->lcg_state)) /
bsdf_hair_huang_eval_residual(kg, sc, local_I, local_O, &sd->lcg_state)) /
projected_area;
}

2
tests/data

Submodule tests/data updated: ded748c5cf...d821488a96