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Improved the clearcoat part by using GTR1 instead of GTR2

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This commit is contained in:
Pascal Schön
2016-11-07 08:13:41 +01:00
parent 3dfc240e61
commit f5897a9494
4 changed files with 37 additions and 12 deletions
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41
intern/cycles/kernel/closure/bsdf_microfacet.h
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@@ -38,6 +38,7 @@ CCL_NAMESPACE_BEGIN
typedef ccl_addr_space struct MicrofacetExtra {
float3 color, cspec0;
bool use_fresnel, is_disney_clearcoat;
float clearcoat;
} MicrofacetExtra;
typedef ccl_addr_space struct MicrofacetBsdf {
@@ -253,6 +254,14 @@ ccl_device_forceinline float3 reflection_color(const MicrofacetBsdf *bsdf, float
return F;
}
ccl_device_forceinline float D_GTR1(float NdotH, float alpha)
{
if (alpha >= 1.0f) return M_1_PI_F;
float alpha2 = alpha*alpha;
float t = 1.0f + (alpha2 - 1.0f) * NdotH*NdotH;
return (alpha2 - 1.0f) / (M_1_PI_F * logf(alpha2) * t);
}
/* GGX microfacet with Smith shadow-masking from:
*
* Microfacet Models for Refraction through Rough Surfaces
@@ -404,14 +413,18 @@ ccl_device float3 bsdf_microfacet_ggx_eval_reflect(const ShaderClosure *sc, cons
float cosThetaM2 = cosThetaM * cosThetaM;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float tanThetaM2 = (1 - cosThetaM2) / cosThetaM2;
D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
if(bsdf->extra) {
if(bsdf->extra->is_disney_clearcoat) {
/* the alpha value for clearcoat is a fixed 0.25 => alpha2 = 0.25 * 0.25 */
alpha2 = 0.0625f;
}
if(bsdf->extra && bsdf->extra->is_disney_clearcoat) {
/* use GTR1 for clearcoat */
D = D_GTR1(cosThetaM, bsdf->alpha_x);
/* the alpha value for clearcoat is a fixed 0.25 => alpha2 = 0.25 * 0.25 */
alpha2 = 0.0625f;
}
else {
/* use GTR2 otherwise */
D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
}
/* eq. 34: now calculate G1(i,m) and G1(o,m) */
G1o = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNO * cosNO) / (cosNO * cosNO)));
@@ -460,6 +473,9 @@ ccl_device float3 bsdf_microfacet_ggx_eval_reflect(const ShaderClosure *sc, cons
float common = D * 0.25f / cosNO;
float3 F = reflection_color(bsdf, omega_in, m);
if(bsdf->extra && bsdf->extra->is_disney_clearcoat) {
F *= 0.25f * bsdf->extra->clearcoat;
}
float3 out = F * G * common;
@@ -592,20 +608,26 @@ ccl_device int bsdf_microfacet_ggx_sample(KernelGlobals *kg, const ShaderClosure
float cosThetaM2 = cosThetaM * cosThetaM;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float tanThetaM2 = 1/(cosThetaM2) - 1;
D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
/* eval BRDF*cosNI */
float cosNI = dot(N, *omega_in);
/* eq. 34: now calculate G1(i,m) */
if(bsdf->extra && bsdf->extra->is_disney_clearcoat) {
/* use GTR1 for clearcoat */
D = D_GTR1(cosThetaM, bsdf->alpha_x);
/* the alpha value for clearcoat is a fixed 0.25 => alpha2 = 0.25 * 0.25 */
alpha2 = 0.0625f;
/* recalculate G1o */
G1o = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNO * cosNO) / (cosNO * cosNO)));
}
else {
/* use GTR2 otherwise */
D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
}
/* eq. 34: now calculate G1(i,m) */
G1i = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNI * cosNI) / (cosNI * cosNI)));
}
else {
@@ -639,6 +661,9 @@ ccl_device int bsdf_microfacet_ggx_sample(KernelGlobals *kg, const ShaderClosure
*pdf = common;
float3 F = reflection_color(bsdf, *omega_in, m);
if(bsdf->extra && bsdf->extra->is_disney_clearcoat) {
F *= 0.25f * bsdf->extra->clearcoat;
}
*eval = G1i * common * F;
}

1
intern/cycles/kernel/osl/osl_closures.cpp
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@@ -205,6 +205,7 @@ public:
bsdf->alpha_y = 0.1f * (1.0f - clearcoat_gloss) + 0.001f * clearcoat_gloss;
bsdf->extra->cspec0 = make_float3(0.04f, 0.04f, 0.04f);
bsdf->extra->clearcoat = clearcoat;
return bsdf;
}

2
intern/cycles/kernel/shaders/node_disney_bsdf.osl
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@@ -113,7 +113,7 @@ shader node_disney_bsdf(
}
if (Clearcoat > 1e-5) {
BSDF = BSDF + 0.25 * Clearcoat * disney_clearcoat(ClearcoatNormal, Clearcoat, ClearcoatGloss);
BSDF = BSDF + disney_clearcoat(ClearcoatNormal, Clearcoat, ClearcoatGloss);
}
}

5
intern/cycles/kernel/svm/svm_closure.h
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@@ -432,9 +432,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
if(kernel_data.integrator.caustics_reflective || (path_flag & PATH_RAY_DIFFUSE) == 0) {
#endif
if(clearcoat > CLOSURE_WEIGHT_CUTOFF) {
float3 clearcoat_weight = 0.25f * clearcoat * weight;
MicrofacetBsdf *bsdf = (MicrofacetBsdf*)bsdf_alloc(sd, sizeof(MicrofacetBsdf), clearcoat_weight);
MicrofacetBsdf *bsdf = (MicrofacetBsdf*)bsdf_alloc(sd, sizeof(MicrofacetBsdf), weight);
MicrofacetExtra *extra = (MicrofacetExtra*)closure_alloc_extra(sd, sizeof(MicrofacetExtra));
if(bsdf && extra) {
@@ -446,6 +444,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
bsdf->alpha_y = 0.1f * (1.0f - clearcoat_gloss) + 0.001f * clearcoat_gloss;
bsdf->extra->cspec0 = make_float3(0.04f, 0.04f, 0.04f);
bsdf->extra->clearcoat = clearcoat;
/* setup bsdf */
ccl_fetch(sd, flag) |= bsdf_microfacet_ggx_clearcoat_setup(bsdf);